摘要:

Journal of Materials Chemistry Scientific Advisory Editor Professor Martin R. Bryce Department of Chemistry University of Durham South Road Durham DH1 3LE, UK Associate Editor Professor Jean Etourneau ICMCB Avenue du Docteur Schweitzer 33600 Pessac France Editorial board Allan E. Underhill (Chairman) Bangor Peter G. Bruce St. Andrews Martin R. Bryce Durham Jean Etourneau Bordeaux Managing Editor Janet L. Dean Deputy Editor Zoe G. Lewin Assistant Editor Graham F. McCann Editorial Secretary Miss D. J. Halls Wendy R. Flavell UMIST John W. Goodby Hull Klaus Praefcke Berlin Brian J. Tighe Aston International advisory editorial board K. Bechgaard Rim, Denmark J. Y. Becker Beer-Sheva, Israel A. J. Bruce Murray Hill, USA E.Chiellini Pisa, Italy D. Coates Poole, UK P. Day-London, UK D. A. Dunmur Shefield, UK B. Dunn Los Angeles, USA W. J. Feast Durham, UK R. H. Friend Cambridge, UK A. Fukuda Tokyo, Japan D. Gatteschi Florence, Italy P. Hodge Munchester, UK Information for authors The Royal Society of Chemistry welcomes submission of manuscripts intended for publication in two forms, Articles and Materials Chemistry Communications. These should describe original work of high quality dealing with the synthesis, structures, properties and applications of materials, particularly those associated with advanced technology. Full papers contain original scientific work that has not been published previously. However, work that has appeared in print in a short form such as a Materials Chemistry Communication is normally acceptable.Four copies of Articles including a top copy with figures etc. should be sent to the Managing Editor at the Cambridge address. Journal of Materials Chemistry (ISSN 0959-9428) is published monthly by The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK. All orders accompanied with payment should be sent directly to The Royal Society of Chemistry, Turpin Distribution Services Ltd., Blackhorse Road, Letchworth, Herts SG6 lHN, UK. NB Turpin Distribution Services Ltd., distributors, is wholly owned by The Royal Society of Chemistry. 1996 Annual subscription rate EEA (incl. UK) &519.00, USA $934.00, Rest of World 6532.00.Customers A. B. Holmes Cambridge, UK H. Inokuchi Okazaki, Japan W. Jeitschko Miinster, Germany 0.Kahn Bordeaux, France J. Livage Paris, France R. McCullough Pittsburgh, USA J. S. Miller Salt Lake City, USA K. Mullen Mainz, Germany L. Niinisto Espoo, Finland M. Nygren Stockholm, Sweden Y. W. Park Seoul, Korea N. Plat6 Moscow, Russia Materials Chemistry Communications contain novel scientific work in short form and of such importance that rapid publication is warranted. The total length is normally restricted to two printed A4 pages. However, special consideration will be given to communications with a large amount of essential diagrammatic information. Submission of a Materials Chemistry Communication can be made either to the Managing Editor at the Cambridge address, or via a member of the International Advisory Editorial Board. In the latter case, the top copy of the manuscript including any figures etc., together with the name of the person to whom the Communication is being submitted, should be sent simultaneously to the Managing Editor at the Cambridge address.All authors submitting work for publication are should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank. Air freight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003. USA POSTMASTER: send address changes to Journal of Materials Chemistry, Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003.Second Class postage paid at Jamaica, NY 11431. All other dispatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Post outside Europe. PRINTED IN THE UK. Editorial Production Coordinator Stephanie Shah Technical Editors Carole J. Nerney Alan J. Holder Graphics Designer Ms C. Taylor-Reid Anthony R. West Aherdeen John D. Wright Canterhury Janet L. Dean (Secretary) M. Prato Trieste, Italy C. N. R. Rao Bangalore, India B. Raveau Caen, France T. Rojo Bilbao, Spain J. Rouxel Nantes, France A. Simon Stuttgart, Germany M. A. Subramanian Wilmington, USA S. Takahashi Osaka, Japan J. 0.Thomas Uppsala, Sweden M. Vallet-Regi Madrid, Spain D.E. W. Vaughan Annandale, USA Y. Yamashita Okazaki, Japan required to sign an exclusive copyright licence. All submissions should be accompanied by a completed form (a blank for photocopying is reproduced at the end of the Information for Authors in Issue l), without which publication cannot proceed. A completed graphical abstract template should also accompany each submission. Full details of the form of manuscripts for Articles and Materials Chemistry Communications, conditions for acceptance etc. are given in Issue 1 of Journal of Materials Chemistry published in January of each year, on the world wide web (htpp://chemistry.rsc.org/rschor may be obtained from the Managing Editor. There is no page charge for papers published in Journal of Muterials Chemistry. Fifty reprints are supplied free of charge. Janet L. Dean, Managing Editor Tel.: Cambridge (01223) 420066 E-Mail (INTERNET): DEANJ@RSC.ORG Fax: (01223) 420247 Advertisement sales: Tel. +44 (0)171-287 3091; Fax +44 (0)171-494 1134 0The Royal Society of Chemistry, 1996. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photographic, recording, or otherwise, without the prior permission of the publishers.

ISSN:0959-9428    

DOI:10.1039/JM99606FX017

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Guidelines for submission on disk These guidelines should be used in conjunction with the Instructions for Authors by authors wishing to submit a copy of their manuscript in electronic form. Successful utilisation of data on disk avoids duplication of effort and introduction of typographical error during typesettinghedrawing. The following points should be noted during preparation of the manuscript to allow us to make the best use of the data provided. Hardcopy -copies of the manuscript to be submitted in the usual way -submission on disk should accompany the revised version of the manuscript, such that the hardcopy to be edited and the data on the disk are identical. Disk -formatted for IBM (or compatible) PC or Macintosh -either 3.5 or 5.25” -clearly labelled (author name, word processor type, file format and file names) -accompanied on submission with a disk description form Data -text: MS-Word, Word for Windows, Wordperfect and WordStar files accepted -graphics: ChemDraw files accepted do not integrate text and graphic files (see below) Text -double spaced -unjustified -ranged left -not hyphenated Paragraphs -no indent on first line -separated by carriage return Spaces -single spaces only after all punctuation, including full point Characters -note distinction between ell (1)and one (1)and upper case oh (0)and zero (0) Tables -include at the end of the text file -use either the word processor’s table editor or tabs for formatting, but not a mixture of the two Graphics -ChemDraw files submitted on a separate disk -not to be integrated with text file Consistency -check the manuscript carefully for consistency, particularly in the representation of chemical formulae, compound names and words with alternative spellings Use of the data supplied, either in whole or in part, cannot be guaranteed.Mathematical equations and tables, in particular, may be re-keyed by the typesetter. Page proofs should be checked in the usual way. Submission of Structure Diagrams on Disk The Society is willing to receive ChemDraw-produced The preference settings to be used are as follows: fixed structure diagrams, reaction schemes, etc., on disk, length 0.7 cm; line width 0.025 cm; bold width 0.092 cm; provided that the data files are supplied in the appropriate hash spacing 0.099 cm; bond spacing 20% of width; font format.To facilitate this, the Society will provide, on Helvetica 12 pt; single width bold and dashed lines should request, a 3.5” Macintosh diskette containing the be used to show stereochemistry. Compounds should be preference files and column guides appropriate for numbered with bold arabic numerals and without producing suitable output with ChemDraw version 2.1.3. parentheses (1, 2 and 3, etc.). The page set-up for Authors wishing to take advantage of this arrangement preparation of drawings and printing should be 60%. will be advised to copy these files to their own storage Single column (8.3 x 22.8 cm) layout is preferred, for media (diskette or hard disk) for future use. No guarantee flexibility; however, double column (17.1 x 22.8 cm) is can be given that structures produced in this way will be acceptable. used in the journals as submitted, but it is expected that Files produced with the program ChemWindow can also this route will minimise duplication of the efforts of authors be supplied. Authors should choose the command Export and production staff. To obtain a copy of the diskette, from the ChemWindow File menu, and save the relevant contact Alan McNaught (General Manager, Production) at file to disk as <filename>.chm. the Society’s Cambridge office.

ISSN:0959-9428    

DOI:10.1039/JM99606BX019

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

ISSN 0959-0428 JMACEP(7) 1079-1248 (1996) Synthesis, structures, properties and applications of materials, particularly those associated with advanced technology CONTENTS Articles 1079 Liquid-crystalline rod-coil polymers based on poly(ethy1ene oxide)s and the influence of the complexation of LiCF,S03 on the liquid- crystalline assembly Myongsoo Lee and Nam-Keun Oh 1087 Molecular design of amphotropic materials: influence of oligooxyethylene groups on the mesogenic properties of calamitic liquid crystals Bernhard Neumann, Christiane Sauer, Siegmar Diele and Carsten Tschierske 1099 Poly [oxymethylene-oligo (oxyethylene)] network electrolytes Shao-Min Mai, Robert A. Colley, Jane H. Thatcher, Frank Heatley, Peter M. Budd and Colin Booth 1 107 Synthesis and characterization of organic conductors derived from (1H-pyrrol-3-y1)acetic acid esters Anh Ho-Hoang, Emmanuelle Schulz, Fabienne Fache, Giselle Boiteux and Marc Lemaire --~)~nOnOnO OHA-oH c15H3I 1 Amphiphilic oligoethylene glycol derivatives incorporating rigid structural units, such as 1, can form different thermotropic as well as lyotropic liquid-crystalline phases.1 1 13 N-(2,4,7-Trinitrofluorenylidene)anilines-new electron transport materials in positive charge electrophotography Masaki Mat sui, Kat suy 0shi Shibat a, Hiroshige Muramatsu and Hiroyuki Nakazumi 11 19 Strong optical second-harmonic generation in a chiral diaminodicyanoquinodethane system M. Ravi, D. Narayana Rao, Shmuel Cohen, Israel Agranat and T.P. Radhakrishnan 1123 The molecular dipole moment of the non-linear optical 3-methyl 4-nitropyridine N-oxide molecule: X-ray diffraction and semi-empirical studies Fodil Hamzaoui, Frangois Baert and Joseph Zyss 1131 Chemical vapour deposition of tantalum silicide thin films from difluorosilylene and tantalum halides C. Y. Lee, J. L. Huang and C. S. Liu 1135 Speciation and the nature of ZnO thin films from chemical bath deposition Paul O'Brien, Tahir Saeed and Jonathan Knowles 1141 A new metallic, ordered perovskite thin film La,,Sr,.,Cu80z2: pulsed laser deposition and microstructural characterization Jan L. Allen, Maryvonne Hervieu, Bernard Mercey, Jean-Frangois Hamet and Bernard Raveau NC n*I ji :The molecular dipole moment ( lPl= 1 Debye ) -\,Tax2 + SiF2 -X = F,CI Correlation of Supersaturation with Film Deposition I " .. Filii Dipsited I .OO 7 8 9 10 11 12 I3 PH 11 1149 Preparation by a 'chimiedouce' route and characterization of LiNi,Mn, -z02 (0.5 <z <1) cathode materials Daniel Caurant, Noel Baffier, Valkrie Bianchi, Gilles Grkgoire and Stephane Bach 1 157 Amorphous and crystalline copper sulfides, cus Heriberto Grijalva, Motomichi Inoue, Sajiv Boggavarapu and Paul Calvert 1 161 Electrochemical syntheses of two doped forms of poly(sul€ur nitride), ([SN],[AsF,]), and f[SN150IASF6II.r Arthur J.Banister, Zdenek V. Hauptman, Jeremy M. Rawson and Simon T. Wait 1165 A new method of nitrogenation of M2Fel, powder alloy via chemical reaction with sodium azide (NaN,) as a nitrogen source (M=Y or Ln) Peter Ezekwenna, Maya Febri, Philippe 1'Heritier and Jean-Claude Joubert 1169 Chemical synthesis of barium zirconate titanate powder by an autocombustion technique Nibedita Chakrabarti and Himadri S.Maiti 1175 Composition and microstructure of nanosized, amorphous and crystalline silicon nitride powders before, during and after densification Janos Szepvolgyi, Frank L. Riley, Ilona Mohai, Imre Bert6ti and Eric Gilbart 10 "C[C~(en)~]~'+(NH2),CS -amorphous CuS i100"C 30"C-crystalline CuS 593K 16hM2Fe17+ NaN3 -M2Fe17N3 + Na M2FeI7H4 + NaN3 573K 16h-M2FeI7N3 + NaH + $H2 111 1 187 1195 1199 1207 121 1 Structural chemistry of SrMn, -xFex03-6, x x0.3 Peter D. Battle, Courtenay M.Davison, Terence C. Gibb and Jaap F. Vente Powder neutron diffraction study of LiMnVO, M. Sato, S. Kano, S. Tamaki, M. Misawa, Y. Shirakawa and M. Ohashi Layered structures of hydrated vanadium oxides. Part 5.-Single-crystal structure of Rb0.,V2O5and phase changes of rubidium intercalate Takeshi Yao, Yoshio Oka and Naoichi Yamamoto Precursor dependence of the nature and structure of non-stoichiometric magnesium aluminium vanadates Fathi Kooli, Inmaculada Crespo, Cristobalina Barriga, Maria A. Ulibarri and Vicente Rives Synthesis and characterization of a novel microporous aluminophosphate AlP0,-JDF (2AlP04 HOCH2CH2NH,)from alcohol systems Qiuming Gao, Shougui Li, Ruren Xu and Yong Yue Intercalation reactions of UTeO, and USeO, Peter G.Dickens, Ewan P. Stradling, Christopher A. Bearchell and Ian D. Fawcett 00 00 00 00 " -MAW-700 07 I 1 200 400 600 800 TPC Li@MO5 BWLitI Li+,e-(solv)UMO, LI&JMO~ 1v 12 19 Synthesis and structure of Ba,InO,X (X =F, C1, Br) and Ba,ScO,F; oxide/halide ordering in K,NiF4-type structures Richard L. Needs, Mark T. Weller, Ulrich Scheler and Robin K. Harris F CI Br 1225 Volatile products formed by carboreduction and nitridation of clay mixtures with silica and elemental silicon Thommy C.Ekstrom, Kenneth J. D. MacKenzie, G. Vaughan White, Ian W. M. Brown and Glen C.Barris Materials Chemistry Communications 1231 Distinct ferroelectric smectic liquid crystals consisting of banana shaped achiral molecules T. Niori, T. Sekine, J. Watanabe, T. Furukawa and H. Takezoe 1235 New preparation method for surface-modified inorganic layered compounds Hideyuki Tagaya, Sumikazu Ogata, Hiroyuki Morioka, Jun-Ichi Kadokawa, Masa Karasu and Koji Chiba 1239 Precipitation of finely divided M,03powders by a molten salt method Yuansheng Du and Douglas Inman 1241 Modified carbothermal reduction for the synthesis of ultrafine particle tungsten compounds dispersed in a microporous carbon matrix Yusaku Sakata, Akinori Muto, Md. Azhar Uddin and Kazumasa Harino V 1245 Effect of aluminium for manganese substitution 0 30 0 25upon the GMR properties of the praseodymium manganites 0 20 m 3015 zChristine Martin, Antoine Maignan and 0 10Bernard Raveau 0 05 0 00 0 50 100 150 200 250 300 TIK i Cumulative Author Index ...111 Information for Authors V Copyright Licence vi Conference Diary viii Graphical Abstract Template Note: Where an asterisk appears against the name of one or more authors, it is included with the authors’ approval to indicate that correspondence may be addressed to this person. ~~~~~~~~~~ ~ COPIES OF CITED ARTICLES The Royal Society of Chemistry Library can usually supply copies of cited articles. For further details contact: The Library, Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK. Tel +44 (0)171-437 8656, Fax: +44 (0)171-287 9798, Telecom Gold 84: BUR2 10, Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library, the staff will be pleased to advise on its availability from other sources. Please note that copies are not available from the RSC at Thomas Graham House, Cambridge. vi

ISSN:0959-9428    

DOI:10.1039/JM99606FP048

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Cumulative Author Index 1996 Abe J., 711 Agranat I., 11 19 Albiston L., 871 Alcantara-Rodriguez M., 247 Ali F., 261 Ali-Adib Z., 15 Burggraaf A. J., 815 Busca G., 879 Bush T. S., 395 Bushnell-Wye G., 337,449 Byrn S. R., 123 Cabeza A,, 639 Cabrera S., 175 Elhsissen K. T., 573 Ellert 0. G., 207 Enoki T., 119 Enomoto M., 119 Etter the late M. C., Eustace P., 527 Evans P., 289, 295 123 Harrison W. T. A., 81 Hasegawa M., 711 Hasegawa N., 605 Hashimoto S., 753 Hauptman Z. V., 1161 Hayashi H., 459 Heald R. C., 311 Kitazawa T., 119 Klar G., 547 Klissurski D. G., 1035 Knowles J., 1135 Knowles J. A., 89 Kochubey D. I., 207 Koehler K., 579 Allen J. L., 165, 1141 Almond G. G., 843 Alonso P. J., 533 Al-Raihani H., 495 Amarilla M. J., 1005 Ando I., 719 Andreozzi G. B., 987 Andrews S.R., 539 Antonietta Massucci CaldCs M. T., 175 Calleja R. D., 547 Calvert P., 1157 Cameron N. R., 719 Campbell S. A., 295 Campillos E., 349, 533 Campostrini R., 585 Carleer R., 559 Carroll S., 559 Ewen R. J., 289 Ezekwenna P., 1165 Fache F., 1107 Fan Y., 1041 Farcy J., 37 Farr I. V., 103 Farrand L. D., 747 Fawcett I. D., 1211 Febri M., 1165 Heatley F., 1099 Hepel M., 993 Heppke G., 927 Hernan L., 37, 861 Herrera-Urbina R., 573 Hersans R., 149 Hervieu M., 165, 175, 1141 Hillman A. R., 993 Hiraoki T., 727 Kooli F., 1199 Koroglu A., 1031 Koto K., 459 Koyama S., 1055 Kremer R. K., 635 Kreuzer F-H., 935 Krist6f J., 567 Kr6wczynski A., 733 Kriierke D., 927 M., 645 Apperley D. C., Arai H., 455 1031 Carturan G., 585 Casal B., 1005 Catlow C. R. A., 653 FCrey G., 1073 Ferragina C., 645 Fitvet F., 1047 Hitch T.J. A. R., 285 Hiyama T., 753 Hobson R. J., 49 Kruidhof H., 815 Kudnig J., 547 Kuroda K., 69, 1055 Arai K., 11 Aranda M. A. G., 639 Caurant D., 1149 Ceccato R., 585 FiCvet-Vincent F., Flint S. D., 629 1047 Hodge P., 15, 375, 527 Hoffmann R-D., 429 Kurosu H., 719 Kusumoto T., 753 Ariza E., 1059 Arriortua M. I., 421 Ashwell G. J., Attfield J. P., 57 Bach S., 1149 23, 131, 137, 969 Cellucci F., 987 Cerrini R., 903 Chakrabarti N., 1169 Chakravorty A. K., 833 Chane-Ching K., 5 Charters R. B., 131 Foran G. J., 969 Forder S., 849 Fort A., 555 Foster D. F., 507 Fragala I. L., 1013 Franke U., 547 Ho-Hoang A., 1107 Holloway A., 629 Holloway J., 221 Holmes P. A., 539 Honeybourne C. L., 277, 285, 289, 323 Kionkowski A.M., 579 LabesM. M., 1 Lagow R. J., 917 Lai S-W., 469 Lambrecht W. R. L., 899 Lavela P., 41, 861 Baert F., 1123 Baffier N., 1149 Chassagneux F., Chasseau D., 5 495 Franklin K. R., 871 109, 843, Horita K., 795 Howlin B. J., 305, 31 1, 91 1 Lebuis A-M., Lecuire J-M., 1075 773 Bahloul-Hourlier D., 595 Chen C., 765, 815 Frauenheim T., 899 Hu Z., 1041 Lee C. K., 331 Bahra G. S., 23, 969 Banister A. J., 1161 Barberis G. E., 421 Chen J., 465 Chen K., 1041 Chen X., 1, 615 Fukuda A., 671, 753 Furukawa T., 1231 Gachard E., 867 Huang J. L., 1131 Huang K-S., 123 Hudson M. J., 49, 89 Lee C. Y., 1131 Lee E., 109, 871 Lee G. R., 187 Barcina J. O., 957 Barclay G. G., 905 Bardosova M., 375 Barrans Y., 5 Barrel1 K. J., 323 Barriga C., 1199 Barris G. C., 1225 Barton J.M., 305, 911 Barzoukas M., 555 Chiba K., 1235 Chippindale A. M., 611 Chisholm M. S., 527 Choi J. U., 365 Chung D. D. L., 469 Chung H., 365 Clarkson G. J., 315 Clearfield A., 639 Clemente D. A., 941 Gallardo Amores J. M., Ganguli M., 391 Gao Q., 1207 Gao Y., 369 Garcia J. R., 415 Garcia-Granda S., 415 Gay D. H., 653 Gazzoli D., 403 Geise H. J., 559 879 Hulinsky V., 975 Humberstone P., 315 Igarashi C., 953 Ihanus J., 161,983 Iimura N., 671 Ikemoto I., 501 lmae I., 117 Ingram-Jones V. J., 73 Inman D., 495, 1239 Lee M., 1079 Le Flem G., 381 Lemaire M., 1107 Lequan M., 5, 555 Lequan R. M., 5, 555 Lerner M. M., 103 Leskela M., 161, 983 Leskela T., 781 Lezama L. M., 421 Bassoul P., 5 Cohen S., 1119 Gentle 1. R., 137, 969 Inoue H., 455 l'Heritier P., 1165 Bast1 Z., 155, 975 Battisti A.De., 567 Battle P. D., 201, 395, 1187 Cole-Hamilton D. J., 507 Colley R. A., 1099 Condorelli G. G., 1013 George C. D., 131 Gerdanian P., 619 Gibb T. C., 1187 Inoue M., 1157 Inui S., 671 Irvine J. T. S., 895 Li S., 1207 Li Y-J., 691 Lin C. L., 1 Baur W. H., 271 Cook M. J., 149, 677 Gibson I. R., 895 Isozaki T., 753 Lin J., 265 Bay B. H., 331 Bearchell C. A., 1211 Behrens U., 547 Belloni J., 867 Berry F. J., 221 Bertoti I., 1175 Cooke S., 1 Cowley A. R., 611 Crayston J. A,, 187 Crespo I., 1199 Dafadar M. H., 833 DAndrea G., 585 Gilbart E., 1175 Glenis S., 1 Gogotsi Y. G., 595 Goldenberg L. M., 699 GomiY., 119 Goiii A., 421 Itaya A., 705 Iwane H., 671 Iyoda M., 501 Jackson P.D., 137 Jacobson A. J., 81 Jakob E., 935 Lindroos S., 161, 983 Liu C. S., 1131 Liu S., 305 Livage J., 505 Llavona R., 415 Loiseau T., 1073 Beteille F., 505 Daolio S., 567 Goodby J. W., 919 James M., 57 Lorriaux-Rubbens A., 385 Bianchi V., 1149 Daturi M., 879 Gorbenko 0. Y., 623 Janes R., 183 Loukatzikou L. A,, 887 Bieniok A., 271 Bikchantaev I., 733 Davies A., 49 Davies T. W., 73 Gore J. G., 201 Gozzi D., 987 Jansson K., 97, 213 Jarmo Koivusaari K., 449 Loveday D. C., 993 Lowendahl L., 213 Blin J. L., 385 Boggavarapu S., 1157 Boiteux G., 1107 Bomben A., 15 Booth C., 1099 Booth C. J., 919, 927 Davis F., 15 Davis S. J., 479 Davison C. M., 1187 Dawson D. H., 409 de Lacy Costello B. P. J., 289 Graboy I. E., 623 Graham P., 843 Green D.A., 449 Grkgoire G., 1149 Grijalva H., 1157 Grobelna B., 579 Jefferies G., 131, 137 Jiang H., 1075 Jimenez-Lopez E. R-C. A., 247 Jones J. R., 305,911 Joubert J-C., 1165 Lynch D. E., 23 Machida M., 69, 455 MacKenzie K. J. D., 821, Macklin W. J., 49 Madarhz J., 781 833, 1225 Bornholdt K., 271 Delmas C., 193 Grobet P., 239 Judeinstein P., 5 11 Madroiiero A., 1059 Boschi T., 953 Boulanger C., 773 Boutinaud P., 381 Bouwmeester H. J. M., Boyle D. S., 227 Branger C., 555 Bravic G., 5 Breen C., 253, 849 815 de Souza D. P. F., 233 de Souza M. F., 233 Diaz L., 975 Dickens P. G., 1211 Diele S., 1087 Dirken P. J., 337 Domingues-Rodrigues A., 207 Grozdanov I. S., 761 GunDer W., 547 Guzman G., 505 Haase W., 935 Haberle N., 935 Hahn J. H., 365 Hall S.B., 183 GUO L-H., 369 Jumas J-C., 41 Kaczorowski D., 429 Kadokawa J-I., 1235 Kagawa S., 97 Kakkar A. K., 1075 Kanamura K., 33 Kanniainen T., 161, 983 Kano S., 1191 Magri P., 773 Mai S-M., 1099 Maignan A., 1245 Maiti H. S., 1169 Maksimov Y. V., 207 Malandrino G., 1013 Mancini N. A., 1013 Mann B. E., 253 Brendel U., 271 Dommisse R., 559 Hamada D., 69 Karasu M., 1235 Manthiram A., 999 Brettle R., 747 Dotze M., 547 Hamer J. C. E., 849 Katerski A,, 377 Marcos M., 349, 533 Britton D., 123 Brooks J. S., 849 Brouca-Cabarrecq C., Brown C. R., 23, 969 789 Dragone R., 403 Du Y., 1239 Dunmur D. A., 747, 919 Durand B., 495 Hamerton I., 305, 311 Hamet J-F., 165, 1141 Hamilton D. G., 23 Hamzaoui F., 1123 Kaul A. R., 623 Kawaguchi K., 117 Kelder E.M., 765 Kennard C. H. L., 23, 137 Marrot B., 789 Marson C. M., 747 Martin C., 1245 Martinez E. S., 547 Brown I. W. M., 1225 Dussack L. L., 81 Hanack M., 957 Khomenko G. E., 595 Martinez J. I., 533 Bruque S., 639 Bryce M. R., 699, 903 Budd P. M., 1099 Duvauchelle N., Eadon D., 221 Eckert H., 801 573 Harding J. H., 653 Harino K., 1241 Harkema S., 357 Kikuchi K., 501 Kilian D., 935 Kim J. H., 365 Marucci A., 403 Marugan M. M., 667 Marzotto A., 941 Buist G. J., 911 Bukhtenko 0.V., 207 Eguchi K., 455 Ekstrom T. C., 1225 Harris R. K., 1219 843, 1031, Kim S. B., 365 Kinjo N., 727 MatijeviC E., 443 Matsui M., 1113 Matsuyama H., 501 Mattei G., 403 McKeown N. B., 315 McLendon G., 369 McMurdo J., 149 Meinhold R.H., 821, 833 Mercey B., 165, 1141 Merle-Mejean T., 595 Michel C., 175 Minami T., 459 Minceva-Sukarova B., 761 Misawa M., 1191 Mitov I. G., 1035 Miura O., 727 Miyachi K., 671 Miyasaka H., 705 Miyata F., 711 Miyazaki A., 119 Miyazaki K., 727 Moffat J. B., 459 Mohai I., 1175 Moine B., 381 Monk P. M. S., 183 Moon J. H., 365 Morales J., 37, 41, 861 Mori T., 501 MorigaT., 459 Morineau R., 505 Morioka H., 1235 Mosel B. D., 635, 801 Mosset A., 789 Mulley S., 661 Mullmann R., 635, 801 Muramatsu H., 11 13 Muto A., 1241 Nagase Y., 711 Naito H., 33 Najdoski M. Z., 761 Nakano H., 117 Nakaya T., 691 Nakazumi H., 1113 Narayana Rao D., 1119 Neat R. J., 49 Needs R.L., 1219 Nemoto N., 711 Neumann B., 1087 Newport R. J., 337, 449 Nickel K. G., 595 Nieminen M., 27 Nii H., 97 Niinisto L., 27, 781 Niori T., 1231 Noma N., 117 Nortier P., 653 Nygren M., 97 O’Brien P., 343, 1135 Oestreich S., 807 Ogata H. T. S., 1235 OgawaK., 143 Oh N-K., 1079 Ohashi M., 1191 Ohwaki K., 795 Ohyama T., 11 Oka Y., 1195 Olbrich F., 547 Olivera-Pastor P., 247 Olivier-Fourcade J., 41 Omenat A., 349 Oriakhi C. O., 103 Orpen G. A., 993 Otterstedt J-E., 213 Ouyang J-m., 963 Pac C., 143 Pagura C., 567 Parent C., 381 Park J. W., 365 Parker M. J., 911 Partridge R. D., 183 Pearson C., 699 Pedrini C., 381 Peeters K., 239 Pelloquin D., 175 Peng B-X., 559 Peng Z-H., 559 Pereira-Ramos J-P., 37 Perrin M-A., 653 Pertierra P., 415 Petrunenko I.A., 207 Petty M. C., 699 Picard C., 619 Piccirillo C., 567 Pickett N. L., 507 Pizarro J. L., 421 Pohmer J., 957 Pola J., 155, 975 Pomonis P. J., 887 Poojary D. M., 639 Pottgen R., 63, 429, 635, 801 Powell A. V., 807 Prellier W., 165 Pringle P. G., 993 Pyzuk W., 733 Qian M., 435 Qun L., 559 Radhakrishnan T. P., 1119 Ranjan R., 131 Rao K. J., 391 Rasheed R. K., 277 Rasika Abeysinghe J., 155 Ratcliffe N. M., 289, 295, 301 Rauhala E., 27 Rautanen J., 781 Raveau B., 165, 175, 1141, 1245 Ravi M., 1119 Rawson J. M., 1161 Rawson J. O., 253 Razafitrimo H., 369 Rigden J.S., 337, 449 Riley F. L., 1175 Rio C. d., 947 Rives V., 1199 Rodriguez J., 415 Rodriguez M. L., 415 Rodriguez-Castellon E., 247 Rohl A. L., 653 Rojo T., 421 Ruiz-Hitzky E., 1005 Russell D. A., 149 Saadoune I., 193 Sadaoka Y., 953 Saeed T., 1135 Saito K., 501 Saito Y., 1055 Sakata Y., 1241 Salvadb M. A., 415 Salvador S., 73 Samoylenkov S. V., 623 Sanchez C., 51 1 Sanchez Escribano V., 879 Sanchez L., 37, 861 Sanchis M. J., 547 Sanders G. M., 357 Sano T., 605 Santos M., 975 Sasaki S., 501 Sat0 M., 1067, 1191 Sauer C., 1087 Sayle D. C., 653 Scheler U., 1219 Schnelle W., 635 Schoonman J., 765 Schouten P. G., 357 Schulz E., 1107 Sdoukos A. T., 887 Segal N., 395 Sekine T., 1231 Sermon P.A., 1019, 1025 Serrano J. L., 349, 533 Sherrington D. C., 719 Shibata K., 691, 1113 Shinton S., 667 Shirai Y., 711 Shirakawa Y., 1191 Shirota Y., 117 Shitara Y., 11 Silvert P-Y., 573 Singh N., 629 Sironi A., 661 Skjerlie K. P., 595 Slade R. C. T., 73, 629 Smart L. E., 221 Smeulders J. B. A. F., 871 Smith I. K., 539 Smith J. R., 295 Smith M. E., 261, 337 Smrcok L., 629 Soraru G. D., 585 Southern J. C., 73 Stefanis A. De., 661 Steuernagel S., 261 Stoev M., 377 Stradling E. P., 1211 Su Q., 265 Suarez M., 415 Subramanian M. A., 867 Subrt J., 155 Sudholter E. J. R., 357 Sugahara Y., 69, 1055 Sugiyama S., 459 Sun Y., 1019, 1025 Sung K., 917 Suzuki H., 501 Suzuki T., 671 Suzuki Y-i., 753 SzCpvolgyi J., 1175 Szydlowska J., 733 Tagliatesta P., 953 Tai Z., 963 Takahashi H., 795 Takahashi M., 119 Takanishi Y., 671, 753 Takashima M., 795 Takeda H., 1055 Takeda M., 119 Takehara Z-I., 33 Takezoe H., 753, 1231 Tamaki S., 1191 Tamaura Y., 605 Tanaka K., 953 Tanaka M., 459 Tang W., 963 Tatam R.P., 131 Taylor R., 155 Teare G. C., 301 ten Elshof J. E., 815 Teraoka Y., 97 Teunis C. J., 357 Thatcher J. H., 1099 Thompson D. P., 1031 Tirado J. L., 37, 41, 861 Toda K., 1067 Tomkinson J., 449 Tomlinson A. A. G., 645, 66 1 Toriumi M., 705 Torncrona A,, 213 Toyne K. J., 919 Tran V. H., 429 Treacher K.E., 315 Tredgold R. H., 375 Tretyakov Y. D., 623 Trindade T., 343 Troc R., 429 Tschierske C., 1087 Tsodikov M. 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V., 947 Xu R., 465, 1207 Yamamoto N., 1195 Yamamoto T., 705 Yan Q., 1041 Yao J., 143 Yao T., 33, 1195 Yonehara H., 143 Yonezawa S., 795 Yoshino H., 501 Yue Y., 465, 1207 Zeng H. C., 435 Zhang B., 639 Zhang H., 265, 615 Zhang L., 999 Zhang P., 615 Zhong Q., 443 Zhou H., 1075 Zhou X-F., 559 Zimmer B., 547 Zyss J., 1123 11 Journal of Materials Chemistry Information for Authors 1996 Journal of Materials Chemistry is a monthly journal for the publication of original research papers (articles), feature articles and communications focusing on the chemistry of novel materials.There is no page charge for papers published in Journal of Materials Chemistry. Scope of the Journal Chemistry of materials, particularly those associated with areas of advanced technology: the modelling of materials, their synthesis and structural characterisation, physicochemical aspects of their fabrication, properties and applications. Materials Inorganics: ceramics; layered materials; microporous solids and zeolites; silicates and synthetic minerals; biogenic minerals. Organics: organometallic precursors for thin filmskeramics; novel molecular solids and synthetic polymers with materials applications; polymer composites; biopolymers; biocompatible and biodegradable polymers; liquid crystals (both lyotropic and thermotropic); Langmuir- Blodgett films.Properties and Applications Electrical properties: semi-, metallic and super-conductivity; ionic conductivity; mixed ionidelectronic conductivity; ferro-, pyro- and piezo-electricity; electroceramics; dielectrics. Optical properties: luminescence, phosphorescence, laser action; non- linear optical effects; photoconductivity; photo- and electro-chromism, resists, glasses, amorphous semiconductors; optical modulation and switching. Magnetic properties: ferro-, ferri- and antiferro-magnetism, spin glass behaviour, organic magnetism, magnetic bubbles and information storage.Chemical properties: ion exchange, molecular separation, catalytic action, sensor action, topochemical control of reactions. Structural properties: structural ceramics, refractories; hard materials; protective coatings; composites, adhesives, prosthetic applications. Thermodynamic properties and phase behauiour Articles Full papers contain original scientific work that has not been published previously. However, work that has appeared in print in a short form such as a Materials Chemistry Communication or Chemical Communication is normally acceptable. But note that the Society strongly discourages the fragmentation of a substantial body of work into a number of short publications.Papers should be typewritten in double spacing on one side only of the paper. 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The information required for deposition includes: (1) An electronic abstract form for each crystallographic determination.This is available from the Cambridge Crystallographic Data Centre (CCDC) either by e-mail (to filesel-v@chemcrys.cam.ac.ukwith the one-line message sendme depform) or via the World Wide Web (connect to the CCDC Home Page; the URL is http://www.ccdc.cam.ac.uW;the form can be saved as a simple text file). Graphical Abstracts A graphical abstract should accompany each submission (a template for photocopying appears in Issue 1). Authors are strongly encouraged to use diagrams or formulae only; the use of text will be allowed only when there is no alternative. Nomenclature Current IUPAC nomenclature and symbolism should be used. Attention is drawn to the following publications in which the rules themselves and guidance on their use are given: Nomenclature of Inorganic Chemistry, Blackwell Scientific Publications, Oxford, 1990.Nomenclature of Organic Chemistry, Pergamon, Oxford, 1979 edn. A Guide to IUPAC Nomenclature of Organic Compounds, Blackwell Scientific Publications, Oxford 1993. Biochemical Nomenclature and Related Documents, Portland Press, London, 1992. Compendium of Chemical Technology: IUPAC Recommendations, Blackwell Scientific Publications, Oxford, 1987. Units and Symbols The recommendations of IUPAC should be followed. Their basis is the Systbme Internationale d’Unit6s (SI). A detailed treatment is given in the so-called Green Book: Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, 1993 edn.(2) A table of final fractional atomic coordinates. (3)Any calculated coordinates (e.g. hydrogen). (4) A full list of bond lengths and angles with estimated standard deviations. (5) A full list of displacement parameters in the form Boor U, (in Az or pm2). Tables of structure factors (F,,, FJ should not be sent, but copies should be retained by the authors so that they may be made available to the referees via the Editorial Office if requested. Until the e-mail link is fully tested two hard copies of items 1-5 above should be included with the paper at the time of submission. The supplementary material will be deposited at the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 lEZ, once the paper has been accepted.Full details regarding presentation of crystallographic work can be obtained from the Editorial Office. 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We may from time to time sen$ you material relevant to your research interests, to provide in- formation about the RSC's products, or possibly to seek your advice on new products. If you do not wish to receive this or remain on our mail- ing list please contact the Production Administrative Officer. Conference Diary July 1-5 22nd International Conference in Organic Coatings -Waterborne, High Solids, Powder Coatings Athens, Greece Dr A.V.Patsis, Director, Institute for Materials Science, State TJniversity of New York, New Paltz, NY 12561.USA. Tel: +914 155 0757; Fax: +914 255 0978. July 6-12 Solid State Chemistry '96 Bratislava, Slovak Republic SSCH '96,Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-842 36 Bratislava, Slovak Republic July 7-12 XVIIth International Conference Organometallic Chemistry Brisbane, Australia XVIIth ICOMC Secretariat, Faculty of Science and Technology, Griffith University, Brisbane 4111,Australia. E-mail: ICOMC@sct.gu.edu.au; Tel: +61 (017 3875 7217; Fax: +61 (0)7 3875 7656.July 8-10 ESOPS 12 -"12th European Symposium on Polymer Spectroscopy" Lyon, France Dr G. Lachenal, Universite Lyon 1,Laboratoire des Materiaux Plastiques, Bld du 11Novembre 69622Villeurbanne, Cedex France. E-mail: lachenal@matplast.univ-1yonl.fr;Tel: +33 72 43 12 11; Fax: +33 72 43 12 49. July 15-17 2nd International Meeting of Pacific Rim Ceramic Societies Cairns, Australia PO Box 679Strawberry Hills, 2012 Sydney, Australia. E-mail: extra@mpx.com.au; Tel: 61 2 319 7329; Fax: 61 2 310 3710. July 28-International Conference on Science and Technology of Synthetic Metals August 2 Utah, USA Professor Z. Valy Vardeny, Secretary General, ICSM '96,Physics Department, 214JFB, University of Utah, Salt Lake City, Utah 84112,USA E-mail: icsm96@mail.physics.utah.edu; Tel: +801 581 8372; Fax: +801 581 4801 a July29-1st International Conference on Synchrotron Radiation in Materials Science August 2 Chicago, USA Professor T.I.Morrison, Armour College of Engineering and Science, Illinois Institute of Technology, 3301 South Dearborn Street, Chicago, Illinois 60616-3793,USA. Tel: 312 567 3579; Fax: 312 567 3576 July 29-Recent Advances in Polymer Synthesis August 2 York, UK Professor P. Hodge, Department of Chemistry, University of Manchester, Oxford Road, Manchester, UK M13 9PL. E-mail: Philip.Hodge@man.ac.uk; Tel: +44 (0)161 275 4706; Fax: +44 (0)161 275 4598. August 4-9 Third CanmetJACI International Conference on Performance of Concrete in Marine Environment St Andrews By-The-Sea, New Brunswick, Canada H.S. Wilson, Sec.Treas., St Andrews Conference, PO Box 3065,Station C, Ottawa, ON Canada K1Y 453 Tel: 613 992 6127; Fax: 613 992 9389. August 4-9 IUPAC MACRO SEOUL '96: 36th IUPAC International Symposium on Macromolecules Seoul, Korea Dr. Kwang Ung Kim, Secretariat of IUPAC MACRO SEOUL '96,Division of Polymers, Korea Institute of Science and Technology, P.O. Box 131,Cheongryang, Seoul 130-650,Korea. E-mail: iupac@kistmail.kist.re.kr;Tel: +82 2 957 6104; Fax: +82 2 957 6105. August 4-9 The Tenth American Conference on Crystal Growth Colorado, USA Anthony L. Gentile, American Association for Crystal Growth, PO Box 3233,Thousand Oaks, CA 91359-0233USA Fax: 805 492 4062 August 19-22 International Conference on Strongly Correlated Electron Systems Zurich, Switzerland Dr L.Degiorgi, Laboratorium fur Festkorperphysik ETH-Zurich, CH-8093Zurich, Switzerland E-mail: degiorgi@solid-phys.ethz.ch;Tel: +41 1 633 22 41; Fax: +41 1 633 10 72 August 28-31 10th Conference of the European Society of Biomechanics Leuven, Belgium Dr. J. Vander Sloten, Executive Secretary, 10th Conference of the European Society of Biomechanics, Katholieke Universiteit Leuven, Division of Biomechanics and Engineering Design, Celestijnenlaan 200A, B-30011Meverlee, Belgium. E-mail: jos.vandersloten@mech.kuleuven.ac.be;Tel: +32 16 32 7096;Fax: +32 16 29 27 16. September 1-6 XIth International Symposium on Organosilicon Chemistry Montpellier, France Professor R.J.P.Corriu, Laboratoire des Precurseurs Organonietalliques de Materiaux, UMR CNRS 44,Universit6 de Montpellier 11, Place E. Bataillon, CC 007, F34095 Montpellier Cedex 5,France Fax: +67 14 38 88. September 1-6 ECME 96, Third European Conference on Molecular Electronics Leuven, Belgium Professor F.C. De Schryver, Department of Chemistry, K.U. Leuven, Celestijnenlaan 200F, B-3001Heverlee, Belgium. 0 September 3-6 7th International Conference on Ferrites Bordeaux, France V. Cagan, Scientific organization, ICF 7 General Secretary Office, Laboratoires du CNRS, 92195Neudon, France E-mail: vladimir.cagan@physique.uvsq.fr;Tel: +33 39 25 46 62; Fax: +33 139 25 46 52 September 9-10 Molecular Modelling of Chemicals and Materials Amsterdam, The Netherlands Dr A.M.Brouwer, Laboratory of Organic Chemistry, Amsterdam Institute of Molecular Studies (AIMS), Nieuwe Achtergracht 129, 1018 WS Amsterdam, The Netherlands. E-mail: mgms@chem.uva.nl: Fax: 31 (0)20 5255670: WWW page: http://krop.chem.uva.nYmgms/ September 10-15 Reactivity in Organised Microstructures: Chemical Reactions and Physical Processes in Compartmentalized Systems Santiago de Compostela, Spain Dr Josip Hendekovic, European Science Foundation, 1 quai Lezay-MamCsia, 67080Strasbourg Cedex, France E-mail: euresco@esf.org; Tel: +33 88 76 71 35; Fax: +33 88 36 69 87 October 9-14 Physical Metallurgy: Interfacial Engineering in Materials Castelvecchio Pascoli, Italy Dr Josip Hendekovic, European Science Foundation, 1 quai Lezay-Marnesia, 67080Strasbourg Cedex, France.E-mail: eurescoC3esf.c-strasbourg.fr;Tel: +33 88 76 71 35; Fax: +33 88 36 69 87. October 13-18 ISLC '96 15th International Semiconductor Laser Conference Haifa, Can Carmel, Israel IEEELEOS, 445 Hoes Lane, P.O. Box 1331,Piscataway, NJ 08855-1331,USA. Tel: +1908 562 3898; Fax: +1 908 562 8434. October 27-12th International Congress on Advances in Non-Impact Printing Technologies November 1 San Antonio, TX, USA Conference Manager, IS&T, 7003 Kilworth Lane, Sprin&ield, VA 22151,USA. E-mail: imagesoc@us.net; Tel: +I 703 642 9090; Fax: +1 703 642 9094. November 16-23 IS&T/SID Fourth Color Imaging Conference: Color Science, Systems & Applications Scottsdale, AZ,USA Conference Manager, IS&T, 7003 Kilworth Lane, Springfield, VA 22151,USA.E-mail: imagesoc@us.net; Tel: +1 703 642 9090;Fax: +1 703 642 9094. 1997 April 8 International Symposium on Applications of Magnetic Resonance in Materials Science Guildford, UK Professor G.A. Webb or Dr J.N. Hay, The Department of Chemistry, University of Surrey, Guildford, GU2 5XH, UK Tel: +1483 300 800; Fax: +1483 259 514 0 April 22-25 12th International Conference on Solid Compounds of Transition Elements Saint-Malo. France H. Noel, E-mail: scte97@univ-rennesl.fr; Tel: +33 99 28 62 55; Fax: +33 99 63 57 04; http://www.univ-rennesl.fdscte97. 0 May 4-9 Gordon Research Conference on "Biodegradable Polymers" Barga, Italy Emo Chiellini, Department of Chemistry & Industrial Chemistry, University of Pisa via Risorgimento 35,56126Pisa, Italy, E-mail: chlmeoC3dcci.unipi.it; Tel: +39 50 918299; Fax: +39 50 28438; World Wide Web: http://www.grc.uri.edu.0 May25-28 Chemistry, Energy and the Environment 3 Estoril, Portugal Cesar Sequeira, Instituto Superior Tecnico, 1096 Lisboa Cedex, Portugal Phone/Fax: 351 17783594 May 26-28 EPDIC -5; 5th European Powder Diffraction Conference Parma, Italy Professor G. Artioli, Dipartimento di Scienze della Terra, Universita' di Milano, Via Botticelli 23,I-20133Milano, Italy E-mail: artioli@iummix.terra.unimi.it;Tel: +39 2 23698320; Fax: +39 2 70638681 July 21-25 The 3rd International Conference on Materials Chemistry University of Exeter, UK August 2 4-2 7 ZMPC '97 International Symposium on Zeolites and Microporous Crystals Tokyo, Japan Dr Takahashi Tatsumi, Secretary, ZMPC '97,Engineering Research Institute, Faculty of Engineering, The University of Tokyo, Yayoi, Tokyo 113,Japan. Denotes a new or amended entry this month. Entries in the Conference Diary are published free of charge. If you wish to include an announcement please send full details to: Journal of Materials Chemistry Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK, CB4 4WF. Tel: +44 1223 420066; Fax: +44 1223 426017. (vii) Graphical Abstracts for Iournal of Materials Chemistry Manuscript N uinber: ......................... /MAP Author: .................................... Template Using the template given above please provide a graphical abstract of the paper and return it to the Editorial Office as soon as possible. Authors are strongly encouraged to use diagrams or formulae only; the use of text will be allowed only where there is no alternative-Examples Novel Aromatic Poly(ether ketone)s. Part 2. -Synthesis and Thermal Properties of Poly(ether keto amide)s Anthony J Lawson. Peter L Pauson, David C Sherrington and Stella M Young Structure of LiN(CF,SOJ,, a Novel Salt for Electrochemistry Jan L Nowinski. Philip Lightfoot and Pcter G BNW YBCO and BSCCO Thin Films Prepared by Wet MOCVD 0Yu Gorbenko, V N Fuflyigin, Yu Yu Erokhin, I E Graboy, A R Kaul, Yu D Trctyakov, C Wahl and L Klippc (viii)

ISSN:0959-9428    

DOI:10.1039/JM99606BP054

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Liquid-crystalline rod-coil polymers based on poly(ethy1ene oxide) s and the influence of the complexation of LiCF,SO, on the liquid-crystalline assembly Myongsoo Lee* and Nam-Keun Oh Department of Chemistry, Yonsei University, Sinchon 134, Seoul 120-749, Korea The synthesis and characterization of rod-coil polymers of ethyl 4'-( 4'-oxy-4-biphenylcarbonyloxy)-4-biphenylcarboxylatewith poly(ethy1ene oxide) of three (3-4), seven (7-4), twelve (12-4) and sixteen (16-4) ethylene oxide units, of 4'-(4'-oxy-4- phenylcarbonyloxy)-4-biphenylcarboxylatewith poly(ethy1ene oxide) of sixteen ethylene oxide units (16-3), and of ethyl 4'-oxy-4- biphenylcarboxylate with poly(ethy1ene oxide) of sixteen ethylene oxide units (16-2) are described. All the rod-coil polymers except 16-2 display a layered smectic mesophase and, in particular, 16-4 shows a microphase-separated morphology.The complexes of 16-4 with up to 0.3 mol of LiCF,S03 per mol of ethylene oxide units are also prepared. The rod-coil polymer 16-4 exhibits an enantiotropic smectic B (S,) mesophase. The complexes with 0.05 and 0.1 mol of LiCF,S03, however, exhibit an enantiotropic smectic A (S,) mesophase in addition to an S, phase. In contrast with the complexes with 0.0-0.1 mol of LiCF,S03, the complexes with 0.2 and 0.3mol do not exhibit any smectic mesophases; however, they display a cylindrical micellar mesophase. Rod-coil diblock systems consisting of a flexible coil and a rigid rod, offer the opportunity to study new aspects of liquid-crystalline behavi~ur.l-~ The extent of immiscibility of these systems is expected to be large because of the large chemical differences between the stiff rod and the flexible coil segments, which allows block segregation to occur at relatively short chain-lengths, compared to that in typical flexible block copoly- mers.As a result of microphase segregation, the rod-coil diblock molecules self-assemble into well defined microstruc- tures such as lamellar and cylindrical structures in the melt state, depending on the block composition. Theoretical have shown that various supramolecu- lar structures such as nematic, layered smectic and cylindrical phases may be induced in these systems, depending on the relative volume fraction of blocks. For example, rod-coil molecules containing a short enough flexible coil exhibit a nematic phase. With increasing coil length, block micro- segregation occurs, resulting in a layered smectic assembly.As the coil length is increased further, molecular layers may collapse into discrete cylindrical micellar structures. Experimental works have also been performed on systems consisting of molecular rod blocks and poly(i~oprene)~*~ or poly(isoprene-block-styrene) coil blocks7 to form linear diblocks. The supramolecular structure in the rod-coil systems was observed to change from lamellar to micellar microphase- separated domains as the coil volume fraction was increased, although the molecular packing of the rod blocks was not described.6 To date, little work has been carried out on rod-coil diblock systems containing poly(ethy1ene oxide) coils. Liquid-crystal- line materials containing poly(ethy1ene oxide) have several advantages, in particular due to their complexation capability with alkali-metal cations, which can induce various liquid- crystalline supramolecular structures.A recent publication on poly(ethy1ene oxide) with flexible side groups has shown that complexation of polymer backbones with LiClO, induces a smectic lamellar mesophase from crystalline, uncomplexed polymer.8 Experimental works on taper-shaped molecules con- taining oligo(ethy1ene oxide) have also demonstrated that complexation of the molecules with alkali-metal trifluorome- thanesulfonates can induce a hexagonal columnar mesophase and can enhance the thermal stability of the rnesopha~e.~-'' It is in this context that we have synthesized rod-coil polymers, consisting of a molecular rigid rod and a poly(ethy1- ene oxide) coil, and we have investigated the influence of the rod and coil lengths, and of complexation with LiCF,SO,, on the molecular organization in the melt state.We describe herein the synthesis and thermal characterization of several rod-coil polymers X-Y, where X is the number of ethylene oxide units of the coil segment and Y is the number of phenyl rings of the rod segment, based on: ethyl 4'-(4-oxy-4-biphe- nylcarbonyloxy)-4-biphenylcarboxylate with poly(ethy1ene oxide) containing three (3-4), seven (7-4), twelve (12-4) and sixteen (16-4) ethylene oxide units; 4-(4-oxy-4-phenylcar- bonyloxy)-4-biphenylcarboxylatewith poly(ethy1ene oxide) containing sixteen ethylene oxide units (16-3); and ethyl 4'-oxy-4-biphenylcarboxylate with poly(ethy1ene oxide) contain- ing sixteen ethylene oxide units (16-2).We also describe the mesomorphic behaviour of the resulting rod-coil polymers and the mesophase change of 16-4 upon lithium complexation. Experimental Materials 4-Hydroxy-4'-biphenylcarboxylic acid (98YO),1,3-diisopro-pylcarbodiimide (DIPC, 99'%0), bromoethane (98%), toluene-p-sulfonyl chloride (98 %), 4-dimethylaminopyridine (99%), tetrabutylammonium hydrogen sulfate (TBAH, 97%), lithium trifluoromethanesulfonate (lithium triflate, 97%) (all from Aldrich) and the other conventional reagents were used as received.Poly(ethy1ene oxide) monomethyl ethers of average molecular masses ((M,}) 350,550 and 750 (Aldrich) were dried under vacuum at 50 "C for 40 h. Dichloromethane was washed initially with concentrated sulfuric acid, then with water, before being dried over magnesium sulfate, heated to reflux over calcium hydride and then freshly distilled under argon. Pyridine was heated to reflux over calcium hydride and was then distilled. Dimethyl sulfoxide (DMSO) was stirred with calcium hydride for 24 h at 100"C and then distilled under reduced pressure. Lithium triflate was dried at 120°C under vacuum for 24 h. 4-Dimethylaminopyridinium toluene-p-sulfonate (DPTS) was prepared as described previously.'2 Techniques 'HNMR spectra were recorded from CDCl, solutions on a Bruker AM 300 spectrometer operating at a proton frequency of 300 MHz or a Bruker AM 500 spectrometer, using Me4% as an internal standard.A Perkin Elmer DSC-7 differential scanning calorimeter equipped with a 1020 thermal analysis J. Muter. Chem., 1996, 6(7), 1079-1086 1079 controller was used to determine the thermal transitions which were reported as the maxima and minima of their endothermic or exothermic peaks, respectively. In all cases, the heating and cooling rates were 10°C min-' unless otherwise specified. A Nikon Optiphot 2-pol optical polarized microscope (magnifi- cation: 100 x) equipped with a Mettler FP 82 hot-stage and a Mettler FP 90 central processor was used to observe the thermal transitions and to analyse the anisotropic texture^.'^,'^ Molecular mass distributions were determined by size exclusion chromatography (SEC) with a Waters R401 instrument equipped with a US HR5E-500-H22 column and a Millenum data station. The measurements were made at 40°C using the UV detector with THF as solvent (1 ml min-l) and a cali- bration plot constructed with polystyrene standards was used to determine the molecular mass distributions.Microanalyses were performed with a Perkin Elmer 240 elemental analyser. All final rod-coil molecules were purified by repeated recrys- tallization from a mixture of CH2Cl, and hexane until their transition temperatures remain constant. The purity of the products was checked by thin layer chromatography (TLC; Merk, silica gel 60).Methylene chloride-methanol mixtures were used as eluents and the spots were detected by either UV irradiation or exposure in an iodine chamber. Synthesis The synthesis of rod-coil polymers with different coil lengths n is outlined in Scheme 1. The rod-coil polymers of poly(ethy1- ene oxide) monomethyl ether ({M,} =750) with two (16-2) and three phenyl rings (16-3) systems were synthesized as outlined in Schemes 2 and 3, respectively. Synthesis of compounds 5-8. Methyloxy di(ethy1eneoxy)ethyl tosylate 5 and methyloxy poly(ethy1eneoxy)ethyl tosylates 6-8 were all synthesized using the same procedure. A representative example is described for 8. Poly(ethy1ene oxide) monomethyl ether ({M,} =750, 15.7 g, 20.9 mmol) was dissolved in 5 ml dry pyridine under argon.A solution of toluene-p-sulfonyl chloride (4.4 g, 23 mmol) in 5 ml dry pyridine was then added dropwise to the mixture. The reaction mixture was stirred at room temperature under argon overnight. The resulting 1 n=3 5 n=3 2 n=7 6 n=7 3 n=12 7 n=12 8 n=16 KOH, EtOH H-COOH + CH3CH2Br 14 EtOH KOH t l3 I 15 0 n=3 10 n=7 11 n=12 DIPC, DPTS 12 n=16 CH2C12 n-4 Scheme 1 Synthesis of the rod-coil polymers 3-4,7-4, 12-4 and 16-4 1080 J. Muter. Chem., 1996, 6(7), 1079-1086 4 8 I 16-2 Scheme 2 Synthesis of the rod-coil polymer 16-2 I l6 15 I 16-3 Scheme 3 Synthesis of the rod-coil polymer 16-3 solution was poured into water and extracted with methylene chloride.The methylene chloride solution was washed with water, dried over anhydrous magnesium sulfate, and filtered. The solvent was removed in a rotary evaporator, and the crude product was purified by column chromatography (silica gel, methylene chloride eluent) to yield 14.0 g (74.1%) of a colourless oil. Compound 5. Yield, 95%. 'HNMR, 6 2.37 (s, 3H, CH,-phenyl), 3.38 (s, 3 H, CH,O), 3.55-4.10 (m, 12 H, OCH,), 7.33 (d, 2 Ar-H o to CH,, J =8.2 Hz), 7.74 (d, 4 Ar-H o to SO,, J = 8.3 Hz). Elemental analysis for C,,H,,O,S: Calc. C, 52.81; H, 6.96. Found C, 52.54; H, 6.83%. Compound 6. Yield, 80%. 'H NMR, 6 2.37 (s, 3 H, CH3- phenyl), 3.35 (s, 3 H, CH,O), 3.55-4.07 (m, 28 H, OCH,), 7.28 (d, 2 Ar-H, o to CH,, J= 8.2 Hz), 7.72 (d, 2 Ar-H, 0 to SO,, J= 8.3 Hz).Elemental analysis for C22H38010S: Calc. C, 53.43; H, 7.74. Found C, 53.28; H, 7.71%. Compound 7. Yield, 86%. 'H NMR, 6 2.37 (s, 3 H, CH,- phenyl), 3.34 (s, 3 H, CH,O), 3.55-4.10 (m, 48 H, OCH,), 7.30 (d, 2 Ar-H, o to CH,, J= 8.2 Hz), 7.74 (d, 2 Ar-H, o to SO,, J =8.3 Hz). Elemental analysis for C32H58015S: Calc. C, 53.77; H, 8.18. Found C, 53.45; H, 7.93%. Compound 8. Yield, 74%. 'H NMR, 6 2.37 (s, 3 H, CH,- phenyl), 3.31 (s, 3 H, CH,O), 3.55-4.10 (m, 64 H, OCH,), 7.28 (d, 2 Ar-H, o to CH,, J=8.2 Hz), 7.72 (d, 2 Ar-H, o to SO,, J =8.3 Hz). Elemental analysis for C,,H,,O,,S: Calc. C, 53.92; H, 8.37. Found C, 53.58; H, 8.44%. Synthesis of compounds 9-12.4-[ Methyloxy di(ethy1eneoxy)- ethyloxy]-4-biphenylcarboxylicacid 9 and 4'-[methyloxy poly- (ethyleneoxy)ethyloxy-4-biphenylcarboxylicacids 10-12 were all synthesized using the same procedure.A representative example is described for 12. 4'-Hydroxy-4-biphenylcarboxylic acid (1.5 g, 7.00 mmol) and KOH (0.9 g, 16.1 mmol) were dissolved in 100 ml methanol. The mixture was heated at reflux for 1 h, and compound 8 (6.33 g, 7.00mmol) was added dropwise. The resulting solution was heated at reflux for 24 h and then cooled to room temperature and acidified with 1 mol dm-, HC1. The resulting solution was poured into water and extracted with chloroform. The chloroform solution was washed with water, dried over anhydrous magnesium sulfate, and filtered.The solvent was removed in a rotary evaporator, and the crude product was then purified by column chromatog- raphy [silica gel, methylene chloride-methanol (15: 1) eluent] to yield 2.7 g (41%) of a waxy solid. Compound 9. Yield, 62%. Mp, 156°C; TSAPN162"C, TN-, 179°C. 'H NMR, 6 3.37 (s, 3 H, CH,O), 3.50-4.20 (m, 12 H, OCH,), 6.97 (d, 2 Ar-H, o to CH20, J=8.7 Hz), 7.55 (2 Ar-H, m to CH,O, J=8.6 Hz), 7.63 (d, 2 Ar-H, m to COOH, J = 8.3 Hz), 8.10 (d, 2 Ar-H, o to COOH, J= 8.3 Hz). Elemental analysis for C2,H2,06: Calc. c, 66.65; H, 6.71. Found C, 67.02; H, 6.83%. Compound 10. Yield, 54%. Mp, 113.7 "C. 'H NMR, 6 3.35 (s, 3 H, CH,O), 3.50-4.20 (m, 28 H, OCH2), 6.96 (d, 2 Ar-H, o to CH,O, J=8.7 Hz) 7.54 (2 Ar-H, m to CH,O, J=8.5 Hz), 7.62 (d, 2 Ar-H, m to COOH, J=8.1 Hz), 8.11 (d, 2 Ar-H, o to COOH, J =8.2 Hz).Elemental analysis for C,,H,,O,,: Calc. C, 62.71; H, 7.51. Found C, 63.11; H, 7.41%. Compound 11. Yield, 50%. Mp, 96.6"C. 'H NMR, 6 3.34 (s, 3 H, CH,O), 3.50-4.20 (m, 48 H, OCH,), 6.98 (d, 2 Ar-H, o to CH20, J=8.7 Hz) 7.55 (2 Ar-H, rn to CH20, J=8.6 Hz), 7.63 (d, 2 Ar-H, m to COOH, J=8.1 Hz), 8.11 (d, 2 Ar-H, o to COOH, J =8.2 Hz). Elemental analysis for C38H60015: Calc. C, 60.30; H, 7.99. Found C, 60.71; H, 7.84%. Compound 12. Yield, 42%. Mp, 44 "C. 'H NMR, 6 3.38 (s, 3 H, CH,O), 3.50-4.20 (m, 64 H, OCH,), 7.02 (d, 2 Ar-H, o to CH20, J=8.7 Hz) 7.56 (2 Ar-H, m to CH20, J=8.8 Hz), 7.64 (d, 2 Ar-H, m to COOH, J=8.4 Hz), 8.1 1 (d, 2 Ar-H, o to COOH, J =8.3 Hz). Elemental analysis for C46H76019: Calc. C, 59.21; H, 8.21.Found C, 59.69; H, 7.78%. Synthesis of ethyl 4-hydroxy-4-biphenyl carboxylate 15. 4'-Hydroxy-4-biphenylcarboxylic acid ( 5.0 g, 23.3 mmol) and KOH (1.3 g, 23.3 mmol) were added to 30 ml dry DMSO under nitrogen. The resulting solution was stirred at 120 "C for 1 h, then cooled to 70°C. To the resulting solution were added TBAH (1.3 g) and bromoethane (2.54 g, 23.3 mmol). After being stirred at 70 "C for 24 h, the light-yellow solution was poured into water. The resulting precipitate was recrys- tallized from toluene to yield white crystals (2.0 g, 35.4%). Mp, 142'C. 'H NMR, 6 1.40 (t, 3 H, CH,CH,, J=7.15 Hz), 4.37 (9, 2 H. CH2CH3, J=7.1 Hz), 6.96 (d, 2 Ar-H, o to OH, J= 8.65 Hz), 7.15 (d, 2 Ar-H, m to OH, J=8.61 Hz), 7.62 (d, 2 Ar- H, m to COO, J=8.36 Hz), 8.05 (2 Ar-H, o to COO, J = 8.42 Hz).Synthesis of polymers 3-4, 7-4, 12-4 and 16-4. Ethyl 4'-(4'- [methyloxy di(ethyleneoxy)ethyloxy]-4-biphenylcarbonyloxy} 4-biphenylcarboxylate 3-4 and ethyl 4'-(4'-[methyloxy poly(- eth yleneoxy) e th ylox y] -4- biphen ylcarbon ylox y } -4- bip henylcar- boxylates 7-4, 12-4 and 16-4 were all synthesized using the same procedure. A representative example is described for 16-4. Compound 12 (3.9 g, 4.12 mmol), compound 15 (1.0 g, 4.12 mmol) and DPTS (1.2 g, 4.12 mmol) were dissolved in 50 ml dry CH,C1, under argon. The resulting mixture was stirred for 1 h and neat DIPC (1.48 ml) was then added. The reaction mixture was stirred at room temperature overnight and was then poured into methanol, the resulting precipitate was filtered off and dried under vacuum.The product was purified by column chromatography using silica gel [methylene chloride-methanol (15: 1) eluent] to yield 1.95 g (39%) of a white solid, which was further purified by recrystallization from a mixture of methylene chloride and hexane. Polymer 3-4. Yield, 60.4%. 'H NMR, 6 1.40 (t, 3 H, CH,CH,, J=7.2 Hz), 3.37 (s, 3 H, CH,O), 3.50-3.80 (m, 8 H, OCH,), 3.88 (t, 2 H, CH,CH,O-phenyl, J=5.1 Hz), 4.18 (t, 2 H, CH,CH,O-phenyl, J =5.1 Hz), 4.40 (4, 2 H, OCH2CH3, J= 7.1 Hz), 7.02 (d, 2 Ar-H, o to CH20, J=8.7 Hz), 7.34 (d, 2 Ar- H, o to biphenylcarboxylate, J= 8.8 Hz), 7.60 (2 Ar-H, m to CH20, J=8.8 Hz), 7.63-7.80 (m, 6 Ar-H, m to C00-phenyl, m to biphenylcarboxylate and m to COOCH,), 8.10 (d, 2 Ar- H, o to COOCH,, J=8.5 Hz), 8.23 (d, 2 Ar-H, o to COO-phenyl, J =8.4 Hz).Elemental analysis for C,,H3,08: Calc. C, 71.90; H, 6.21. Found C, 71.82; H, 6.33%. Polymer 7-4. Yield, 30%. 'H NMR, 6 1.39 (t, 3 H, CH,CH,, J=7.0 Hz), 3.35 (s, 3 H, CH,O), 3.50-3.82 (m, 26 H, OCH,), 3.87 (t, 2H, CH,CH,O-pheny, J=4.9 Hz), 4.17 (t, 2 H, CH,CH,O-phenyl, J =4.8 Hz), 4.38 (4, 2 H, OCH,CH,, J = 7.1 Hz), 7.02 (d, 2 Ar-H, o to CH20, J=8.7 Hz), 7.33 (d, 2 Ar-H, o to biphenylcarboxylate, J =8.5 Hz) 7.59 (2 Ar-H, m to CH,O, J =8.6 Hz), 7.63-7.80 (m, 6 Ar-H, tn to C00-phenyl, rn to biphenylcarboxylate and in to COOCH,), 8.09 (d, 2 Ar-H, o to COOCH,, J =8.4 Hz), 8.22 (d, 2 Ar-H, o to COO- phenyl, J =8.4 Hz).Elemental analysis for C43H52012: Calc. C, 67.88; H, 6.89. Found C, 67.45; H, 6.83%. Polymer 12-4. Yield, 30%. 'H NMR, 6 1.42(t, 3 H, CH,CH3, J=7.1 Hz), 3.38 (s, 3 H, CH30), 3.50-4.20 (m, 44 H, OCH,), 3.87 (t, 2 H, CH,CH,O-phenyl, J=4.9 Hz), 4.17 (t, 2 H, CH,CH,O-phenyl, J =4.8 Hz), 4.40 (9, 2 H, OCH2CH,, J = 7.1 Hz), 7.04 (d, 2 Ar-H, o to CH20, J=8.7 Hz), 7.3 (d, 2Ar- H, o to biphenylcarboxylate, J= 8.6 Hz) 7.60 (2 Ar-H, m to CH20, J=8.7 Hz), 7.63-7.80 (m, 6 Ar-H, tn to C00-phenyl, m to biphenylcarboxylate and m to COOCH,), 8.12 (d, 2 Ar- H, o to COOCH,, J=8.4 Hz), 8.25 (d, 2 Ar-H, o to COO- phenyl, J =8.4 Hz). Elemental analysis for C53H72017: Calc. C, 64.88; H, 7.40. Found C, 64.44; H, 7.42%.Polymer 16-4. Yield, 39%. 'H NMR, 6 1.39 (t, 3 H, CH2CH,, J=7.2 Hz), 3.35 (s, 3 H, CH,O), 3.50-3.80 (m, 60 H, OCH,), 3.87 (t, 2 H, CH,CH,O-pheny, J= 5.0 Hz), 4.17 (t, 2 H, CH,CH,O-phenyl, J =5.1 Hz), 4.37 (9, 2 H, OCH,CH,, J = 7.2 Hz), 7.00 (d, 2 Ar-H, o to CH20, J=8.7 Hz), 7.3 (d, 2 Ar-H, o to biphenylcarboxylate, J=8.6 Hz) 7.60 (2 Ar-H, m to CH20, J= 8.7 Hz), 7.63-7.80 (m, 6 Ar-H, m to C00-phenyl, m to biphenylcarboxylate and rn to COOCH,), 8.13 (d, 2 Ar-H, o to COOCH,, J=8.4 Hz), 8.25 (d, 2 Ar-H, o to COO- phenyl, J =8.4 Hz). Elemental analysis for C,lH8,O21: Calc. C, 63.31; H, 7.66. Found C, 63.10; H, 7.75%. Synthesis of ethyl 4'-[methyloxy poly (ethy1eneoxy)ethyloxy 1-4-biphenylcarboxylate 16-2. Ethyl 4'-hydroxy-4-biphenylcarb-oxylate (1.87 g, 7.74 mmol) and KOH (0.46 g, 7.74 mmol) were dissolved in 100 ml methanol.The mixture was heated at reflux for 1 h, and compound 8 (6.54 g, 7.74 mmol) was added dropwise. The resulting solution was heated at reflux for 24 h, then cooled to room temperature, poured into water and extracted with chloroform. The chloroform solution was washed with water, dried over anhydrous magnesium sulfate, and filtered. The solvent was removed in a rotary evaporator, and the crude product was then purified by column chromatog- raphy (silica gel, methylene chloride eluent) to yield 2.9 g J. Muter. Chem., 1996, 6(7), 1079-1086 1081 (38 8%) of a waxy solid 'H NMR, 6 1 34 (t, 3 H, CH2CH3, J=7 2 Hz), 3 31 (s, 3 H, CH30), 3 50-3 80 (m, 60 H, OCH,), 3 82 (t, 2 H, CH2CH20-phenyl, J=5 1 Hz), 4 12 (t, 2 H, CH2CH20-phenyl, J=5 0 Hz), 4 32 (9, 2 H, CH2CH3, J= 7 1 Hz), 6 96 (d, 2 Ar-H, o to CH20,J =8 8 Hz), 7 48 (2 Ar-H, rn to CH20, J=8 8 Hz), 7 56 (d, 2 Ar-H, m to COOCH2, J= 8 3 Hz), 8 00 (d, 2 Ar-H, o to COOCH,, J =8 4 Hz) Synthesis of 4-[methyloxy poly (ethy1eneoxy)ethyloxy ]ben-zoic acid 16.Compound 16 was synthesized according to the procedure described for compound 12, but starting from 4-hydroxybenzoic acid (2 3 g, 16 6 mmol) and compound 8 (15 g, 16 6 mmol) Yield, 6 1 g (42 2%) 'H NMR, 6 3 37 (s, 3 H, CH30), 350-420 (m, 64H, OCH,), 697 (d, 2Ar-H, o to CH,O, J =8 7 Hz), 7 55 (2 Ar-H, rn to CH,O, J =8 6 Hz), 7 63 (d, 2 Ar-H, m to COOH, J=8 3 Hz), 8 10 (d, 2 Ar-H, o to COOH, J=8 3 Hz) Synthesis of ethyl 4-[4-[methyloxy poly(ethy1eneoxy)ethy- loxy]benzoyloxy]-4-biphenylcarboxylate 16-3.Compound 16-3 was synthesized according to the procedure described for compound 16-4, but starting from compound 16 (3 1 g, 3 56 mmol) and compound 15 (0 86 g, 3 56 mmol) Yield, 107 g (28%) 'H NMR, S 139 (t, 3 H, CH2CH3,J=7 2 Hz), 3 35 (s, 3H, CH,O), 350-375 (m, 60H, OCH,), 388 (t, 2H, CH2CH,0-phenyl, J =5 1 Hz), 4 20 (t, 2 H, CH,CH,O-phenyl, J =5 1 Hz), 4 39 (9, 2 H, OCH2CH3, J =7 1 Hz), 7 00 (d, 2 Ar-H, o to CH20, J =8 7 Hz), 7 30 (d, 2 Ar-H, o to benzoate, J = 8 8 Hz), 7 60-7 70 (m, 4 Ar-H, m to benzoate and rn to COOEt), 7 63-7 80 (m, 6 Ar-H, rn to C00-phenyl, rn to biphenylcarb- oxylate and m to COOCH,), 8 10 (d, 2 Ar-H, o to COOCH,, J=8 5 Hz), 8 15 (d, 2 Ar-H, o to C00-phenyl, J=8 4 Hz) Preparation of complexes of 16-4.Complexes of 16-4 with lithium triflate were prepared by mixing solutions of 16-4 (10 mg ml-') in dry methylene chloride with an appropriate volume of 0 724 mmol ml-' salt in dry acetonitrile solution, followed by slow evaporation of the solvent under reduced pressure at room temperature and subsequent drying in a vacuum oven at 60°C to maintain constant mass Addition of Table 1 Characterization of the rod-coil polymers (data on first line are from first heating and cooling scans, data on second line are from second heating scan) compound M,/M," 3-4 7-4 106 12-4 1 08 16-4 1 05 16-2 106 16-3 105 ~ ~~ ~~~~~ phase transitionsb (in "C) and corresponding enthalpy changes (in kJ mol ') heating g 1101 K 1606(102)SA 2852(18)N 3027(054)I g 982 K 1569 (96) SA 2801 (1 5) N 301 6 (048) I g 823 K 1557 (127) SA 231 8 (1 29) I g 73 5 K 1506 (11 7) SA 2322 (1 18) I g 68 5 K 135 2 ( 15 6) SA 148 1 (1 81) I g 603 K 1344 (149) SA 1479 (1 95) I g 32 0 K 55 7 (74 9) K 120 3 (19 4) SB 123 0' (-) I K347(444)K 1205(197)SB 1230'(-)I K432(673)1 K 349 (557) I K 325(703)SX352'(-)1 K 266 (51 6) S, 344 (1029) I cooling 12944(041)N 2713(165)SA 1473(100)K 852 g I2239 (1 01) SA 139 3 (7 5) K 643 g I 1440(192)SA 1289(154)K554g I ll94'(-)SB 1160(189)K 115(696)K I103 (602) K I258 (935) S, 5 l(53 1) K 'From SEC data bN, nematic, SA, smectic A, S,, smectic B, S,, unidentified smectic phases, K, crystalline, I isotropic 'Overlapped peak, data obtained from optical polarized microscopy d e 9 1 eg fdI la ll I I I 8.5 8-0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 6 Fig.1 300 MHz 'H NMR spectrum of 16-4 1082 J Muter Chern, 1996, 6(7), 1079-1086 3-4& (b 1 3-4 /'//" 16-21 7-4 12-4 10 90 170 250 330 10 90 170 250 330 TI" C Fig. 2 DSC traces (10"C min-') recorded during the second heating scan (a) and the first cooling scan (b)of 3-4, 7-4, 12-4 and 16-4 K 01 1 I I I90 5 10 15 20 c; JJU 300 250 200 150 100 A IrA5010 9 K 0 5 10 15 20 no. of EO units Fig. 3 Dependence of the phase-transition temperatures of rod-coil polymers 3-4, 7-4, 12-4 and 16-4 on the number of EO repeat units in the coil.(a) Data from second heating scan: A, q;0,T,; 0,TsA-TN;0, ?;. (b) Data from first cooling scan: A,q;U, TM;+, TsA-Tl; .,T. I 16-4 SB I K/ -10 30 70 110 150 7°C Fig. 4 DSC traces (10"C min-') recorded during the second heating scan (upper traces) and the first cooling scan (lower traces) of 16-2, 16-3 and 16-4 LMI I 1-10 30 70 110 150 -10 30 70 110 150 TI"C Fig. 5 DSC traces (10 "C min-') recorded during the second heating scan (a) and the first cooling scan (b)of the complexes of 16-4 with lithium triflate. [Li+]/[EO]=(i) 0, (ii) 0.05, (iii) 0.1, (iv) 0.2, (v) 0.3. a solution of the salt in acetonitrile to methylene chloride gave a precipitate free of 16-4.The absence of the free salt was verified by DSC (absence of the melting point of the free salt in the heating and cooling scans) and optical polarized microscopy. J. Mater. Chem., 1996, 6(7), 1079-1086 1083 Table 2 Thermal transitions of the complexes of rod-coil polymer 16-4 with lithium triflate (data on first line are from first heating and cooling scans, data on second line are from second heating scan) phase transitions‘ (in “C) and corresponding enthalpy changes (in kJ mol-’) heating cooling 0 00 0 05 0 10 0 20 0 30 g 32 0 K 55 7 (74 9) K 120 3 (19 4) SB 123 Ob (-) I K 34 7 (44 4) K 120 5 (19 7) SB 123 Ob (p)I K 22 4 (34 8) K 1104 (9 5) SB 117 3’ (-) SA 141 8 (1 04) I K 15 6 (22 5) K 113 3 (8 7) SB 116 7’ (-) SA 142 5 (097) I K 1007 (1 01) SB 108 2 (24) SA 147 5 (045) I K 994(123)SB 1076(195)S, 1467(038)1 K 825 (124)M 1342(024)I K 723 (O45)M 1334(018)1 K 128 4 (54 3) M 130 2’ (-) I Cr 63 4 (38 3) K 128 2 (38 4) M 130 0’ (-) I Ill94’(-)SB 1160(189)K 115(696)K I 138 9 (092) SA 116 3’ (-) S, 109 6 (645) K -6 I 141 0 (035) SA 1109’ (-) S, 107 3 (4 5)K I 130 7 (0 32) M 59 6 (7 14) K I 1074 (0 13) M 71 2 (154) K 5 (20 3) K “SA, smectic A, SB, smectic B, M, cylindrical mesophase, Cr, recrystallization, K, crystalline, I, isotropic bOverlapped peak, data obtained from optical polarized microscopy 180 13 0 80 3 0 9-20 R 00 0.1 0.2 0.3 1 13 n1 0 M 8 K 3 0 K K.-2 UI I I 00 0.1 0.2 03 [Li+]/[EO] Fig. 6 Dependence of the phase-transitlon temperatures of the com- plexes of 16-4 with lithium triflate on [LiCF,S03]/[EO] (a) Data from second heating scan 0,T,, A, TSB 0, T, (b)Data from first sA, cooling scan W, T,, A,TSBsA, 0,T, Results and discussion The synthesis of rod-coil polymers with different coil lengths is outlined in Scheme 1 Commercially available triethylene glycol monomethyl ether and poly(ethy1ene oxide) monomethyl ethers (normal average molecular masses {Mw},350, 550 and 750) were used as starting materials for 3-4, 7-4, 12-4 and 16-4, respectively To investigate the effect of the rod length, the rod-coil molecules of poly(ethy1ene oxide) monomethyl ether ((M,} = 750) with two (16-2) and three (16-3) phenyl 1084 J Muter Chem, 1996, 6(7),1079-1086 ring systems are synthesized as outlined in Schemes 2 and 3, respectively Remarkably, all rod-coil compounds could be isolated by column chromatography (silica gel) from the resulting mixture of each esterification reaction using a mixture of CH,Cl, and methanol (15 1 v/v) as eluent The rod-coil polymers were then recrystallized from methylene chloride and hexane to obtain highly monodisperse polymers It is well known that polydispersity influences the phase behaviour of polymers, especially of those with low molecular masses l5 Therefore, it is essential that the rod-coil polymer is highly monodisperse in order to investigate its accurate phase behavi our Table 1 shows the characterization of the rod-coil polymers All rod-coil molecules showed polydispersity values <1 1, as determined from SEC, indicative of high purity Fig 1 presents a typical ‘H NMR spectrum of 16-4 with its protonic assign- ments The resonances of the expected methoxy chain-end of the coil and the ethyl chain-end of the rod can be observed easily at 6 3 35 and 4 37, respectively No other signals indica- tive of impurities are observed The DSC traces obtained during the first and subsequent heating scans are identical for the rod-coil polymers The experimental data collected from both scans are summarized in Table 1 However, only the second heating and first cooling scans will be presented in more detail Fig 2 presents the DSC traces of 3-4, 7-4, 12-4 and 16-4 Rod-coil compound 3-4 exhibits enantiotropic nematic (N) and smectic A (S,) meso-phases On the optical polarizing microscope, the nematic mesophase of 3-4 exhibits a schlieren texture while the SA mesophase exhibits a focal conic texture Both 7-4 and 12-4 display a crystalline (K) melting and an enantiotropic SA mesophase Interestingly, 16-4, which contains the longest coil length in this study, exhibits two crystalline melting transitions in addition to an enantiotropic smectic B (S,) phase This is not unexpected because microphase separation between stiff rod and flexible coil segments occurs and consequently, each crystalline melting transition corresponding to the rod and coil segments is exhibited The dependence of the transition temperatures of the rod- coil molecules (n-4 series) determined by DSC as a function of the number of ethylene oxide units is plotted in Fig 3(a) (for the second heating scans) and Fig 3(b)(for the cooling scans) Both TMand 7;decrease with increasing number of ethylene oxide units However, the gradient of the 7;variation is much steeper than that of TM This is similar to the usual trend for liquid crystals containing flexible tails or spacer moieties l6 This plot demonstrates that the higher crystalline melting transition of 16-4 corresponds to the rod block because this agrees with the continuous character of the dependence of TM on the number of ethylene oxide units In the case of rod-coil molecules with short chain-lengths, Plate 1 Representative optical polarized micrographs (100x) of the texture exhibited by: (a) the SB mesophase of 16-4 at 120°C on the cooling scan; (b) the SA mesophase of the complex of 16-4 with 0.1 mol LiCF,SO, at 138°C on the cooling scan; (c) the cylindrical micellar mesophase of the complex of 16-4 with 0.2 mol of LiCF,SO, at 110 C on the cooling scan the coil may couple with the anisotropic rod owing to the relatively high miscibility between rods and coils with short length, which can induce a nematic phase as exhibited by rod-coil compound 3-4.However, as the length of hydrophilic poly(ethy1ene oxide) coil increases or the temperature decreases, the immiscibility between the hydrophobic rigid rods and the hydrophilic flexible coils increases. This allows for the increasing lateral intermolecular interactions of aro- matic rods.As a result, a layered S, phase can be induced, as exhibited by 3-4 (the lower-temperature mesophase), 7-4 and 12-4. As the length of the coil is increased further, the sharper interdomains between microphase-separated domains may exist to form a more ordered layered smectic phase,I7 as exhibited by rod-coil polymer 16-4 which displays an SB phase. This is well established by theoretical prediction^.'.^ This result indicates that the length of the poly(ethy1ene oxide) coil plays an important role in the transition temperature and the nature of the mesophase of the rod-coil polymer. To investigate the effect of the length of the molecular rod, the thermal behaviours of 16-2, 16-3 and 16-4 are compared in Fig.4 which presents the second heating and first cooling DSC scans. As can be seen, 16-2 exhibits only a crystalline melting, while 16-3 displays a crystalline phase followed by an enantiotropic smectic X (S,) phase and 16-4 exhibits two crystalline melting transitions in addition to an SB phase as described already. Upon increasing the length of the rod, 7; increases rapidly. However, within experimental error, TM is relatively constant and independent of the rod length. This indicates that the lower crystalline melting transition corre-sponds to the poly(ethy1ene oxide) coil segments. Rod-coil systems containing poly(ethy1ene oxide) can com- plex with alkali-metal cations. When alkali-metal cations are added to the host rod-coil polymer molecule, they will be dissolved selectively in the poly(ethy1ene oxide) coil segments of the rod-coil diblock system via ion-dipolar interactions.It has already been reported that alkali-metal salts are selectively soluble in the poly(ethy1ene oxide) segments of a block copoly- mer containing poly(ethy1ene oxide)." Therefore, complexation of the rod-coil polymer with an alkali-metal salt results in an increase of the relative volume fraction of coil compared to that of rod, which may give rise to a novel supramolecular architecture of the rod-coil system. In this context, we have investigated the mesomorphic behaviour of complexes of 16-4 with LiCF,SO,. The phase behaviour of the rod-coil polymer and its complexes with lithium triflate was characterized by a combination of DSC and thermal optical polarized microscopy.Fig. 5 shows DSC traces of the second heating and the first cooling scans of the rod-coil polymer and of its complexes with 0.05-0.3 mol lithium triflate per ethylene oxide unit. The first and subsequent heating scans and the first and subsequent cooling scans are identical except for the complex with 0.3 mol LiCF,S03, which undergoes recrystallization on the second heating scan. The phase transitions from Fig. 5 are summarized in Table 2 and are plotted in Fig. 6(a) (data from the second heating scan) and Fig. 6(b) (data from the cooling scan) as a function of the concentration of LiCF,SO, in the rod-coil polymer. As shown in Fig. 5, 16-4 exhibits an enantiotropic SBphase in addition to crystalline melting transitions.A representative texture of an SBphase exhibited by 16-4 is shown in Plate l(a). The complexes of 16-4 with 0.05 and 0.1 mol LiCF,SO, per ethylene oxide unit exhibit an enantiotropic S, mesophase in addition to the S, and K phases. Upon complexation of 16-4 with up to 0.1 mol LiCF,SO,, increases and both crystalliza- tions are suppressed. This trend agrees well with previous results" and is predicted by theory." Plate l(b) presents a representative texture displayed by the S, phase exhibited by the complex with 0.1 mol LiCF,SO,. However, in contrast to the thermal behaviour of the complexes with up to 0.1 mol LiCF,S03, the complexes with 0.2 and 0.3 mol do not exhibit smectic layered mesophases, but they display an enantiotropic cylindrical micellar mesophase (M) as their highest-tempera- ture mesophase.On cooling from the isotropic (I) phase, first a platelet-like growth of the texture can be observed with a final development of pseudo-focal conic domains which is characteristic of a conventional disordered columnar meso-phase, as shown in Plate ~(c).~O The complex with 0.3 mol LiCF3S03 undergoes salt-induced crystallization through endothermic and exothermic peaks on the second heating scan followed by the transition from M to I, indicating that com- plexation of 16-4 with LiCF,SO, induces an S, phase or a J. Mater. Chem., 1996,6(7), 1079-1086 1085 cylindrical micellar mesophase from its layered SB phase, depending on the salt concentration The existence of a cylindrical micellar mesophase is in contrast with the normal behaviour of rigid-rod calamitic mesogens which show lamellar smectic and/or nematic phases Lamellar and cylindrical micellar mesophases for a given compound are commonly found in lyotropic liquid crystals2' 22 and also contribute to the thermal behaviour of some amphi- philic molecules such as silver thi~lates,~~ and biforked mol- ecules2425 On the other hand, columnar mesophases are usually induced by disk-shaped mesogens and are consequently prone to this kind of stacking 26 Therefore, the system discussed here is an unusual case of a calamitic mesogenic system owing to the ability of the rod-coil polymer to change from lamellar to micellar upon complexation Apparently the lamellar smectic structure observed in the uncomplexed rod-coil polymer and the complexes with up to 0 1 mol LiCF,SO, is still the most efficient packing of melt coils because the volume fraction of the coil parts is not large enough For higher concentrations of LiCF,SO,, however, the volume fraction of coil segments increases by insertion of the salt into the coil domain through ionic interactions between Li' and electron-donor oxygen atoms, and the system becomes unstable owing to space crowding of the coil segments, conse- quently, the lamellar structure of the rod-coil polymer will break apart into cylindrical micelles, as predicted by theory The main advantage of these micelles relative to lamellae is that the coils grafted onto their top and bottom surfaces are able to fan out into a larger region of space, presumably to reduce the thermodynamic coil-stretching penalty This might explain qualitatively the phase behaviour of the complex system, although more distinctive morphological experiments, such as X-ray scattering methods, are required to support this speculative explanation, such studies are in progress In conclusion, a series of rod-coil molecules containing poly(ethy1ene oxide)s and the complexes of 16-4 with LiCF,SO, have been prepared The lengths of the coils and rods in the rod-coil molecule influence significantly the nature and the thermal stability of the mesophase The complexation of 16-4 with lithium cations induces either a thermo-dynamically stable smectic A phase or a cylindrical micellar mesophase, depending on the salt concentration In particular, transformation of a layered smectic phase into a cylindrical micellar assembly by simple complexation is promising These results provide access to a large variety of fundamental investi- gations and technological applications Financial support of this work by the Korea Science and Engineering Foundation ( 1995) is gratefully acknowledged References 1 A Halperin, Macromolecules, 1990,23, 2724 2 A N Semenov and S V Vasilenko, Sou Phys JETP (Engl Trans1 ), 1986,63,70 3 A N Semenov, Mol Cryst Liq Cryst, 1991,209,191 4 D R M Williams and G H Fredrikcson, Macromolecules, 1992, 25,3561 5 L H Radzilowski, J Wu and S I Stupp, Macromolecules, 1993, 26,879 6 L H Radzilowski and S I Stupp, Macromolecules, 1994,27,7747 7 S I Stupp, M Lee, S Son, L S Li and M Kesser, Polym Prepr, 1993,43,184 8 F B Dias, J P Voss, S V Batty, P V Wright and G Ungar, Makromol Chem , Rapid Commun , 1994,15,961 9 V Percec, J Heck, D Tomazos, F Falkenberg, H Blackwell and G Ungar, J Chem Soc Perkin Trans I, 1993,2799 10 V Percec, D Tomazos, J Heck, H Blackwell and G Ungar, J Chem SOC Perkin Trans 2,1994,31 11 V Percec, J Heck, G Johansson and D Tomazos, Makromol Chem Macromol Symp , 1994,77,237 and references therein 12 J S Moor and S I Stupp, Macromolecules, 1990,23,65 13 D Demus and L Richter, Textures of Liquid Crystals, Verlag Chemie, Weinheim, 1978 14 G W Gray and J W Goodby, Smectic Liquid Crystals Textures and Structures, Leonard Hill, Glasgow, 1984 15 V Percec and M Lee, Macromolecules, 1991,24, 1017 16 G W Gray, Molecular Structure and the Properties of Liquid Crystals, Academic Press, London, 1962, ch 9 17 J Adams and W Gronski, Makromol Chem Rapid Commun, 1989,10,553 18 M Watanabe, S Oohashi, K Sanui, N Ogata, T Kobayashi and Z Ohataki, Macromolecules, 1985, 18, 1945, M Watanabe, K Nagaoka, M Kanba and I Shinohara, Polym J , 1982,14,877 19 A Keller, G Ungar and V Percec, in Advances in Liquid Crystalline Polymers, ed C K Ober and R A Weiss, ACS Symp Ser 435, American Chemical Society, Washington DC, 1990, p 308 20 C Destrade, P Foucher, H Gasparoux and N H Tinh, Mol Cryst Liq Cryst, 1984,106,121 21 B Luemann and H Finkelmann, Colloid Polym Scz, 1987, 265, 506 22 H Hoffmann, Adu Mater , 1994,6,116 23 M J Baena, P Espinet, M C Lequerica and A M Levulet, J Am Chem SOC,192,114,4182 24 Y Fang, A M Levulet and C Destrade, Liq Cryst, 1990,7,265 25 C Destrade, N H Tinh, A Roubineau and A M Levulet, Mol Cryst Liq Cryst, 1988,159,163 26 K Praefcke, P Marquardt, B Kohne, Z Luz and R Poupko, Liq Cryst, 1991,9,711 Paper 5/05652G, Received 25th August, 1995 1086 J Mater Chem , 1996, 6(7),1079-1086

ISSN:0959-9428    

DOI:10.1039/JM9960601079

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

~~~~~~ ~ ~ ~ ~ ~ Molecular design of amphotropic materials: influence of oligooxyethylene groups on the mesogenic properties of calamitic liquid crystals Bernhard Neumann,‘ Christiane Sauer,b Siegmar Dieleb and Carsten Tschierske* aMart in -Luther-Universi ty Ha 11e-Wit te n berg, Depart men t of Chemistry, Institute of 0rga n ic Chemistry, We inb ergw eg 16, 0-06120 Halle, Germany bMartin-Luther-UniversityHalle- Wittenberg, Department of Chemistry, Institute of Physical Chemistry, Muhlpforte 1, 0-06099 Halle, Germany The syntheses and liquid-crystalline properties of novel oligoethylene glycol derivatives are described These are amphiphiles and podand-like trimesogens The hydrophobic sections of the amphiphiles consist of calamitic 4-( 5-pentadecyl- 1,3,4-thiadiazol-2-y1)- phenyl, 4’-dodecyloxybipheny1-4-y1or 4-decylphenyl units, which are connected by a hydrophilic 12,13-dihydroxy- 1,4,7,10- tetraoxatridecyloxy, 9,lO-dihydroxy- 1,4,7-trioxadecyloxy, 6,7-dihydroxy-1,4-dioxaheptyloxyor 2,3-dihydroxypropoxy groups All these amphiphiles contain a 1,2-diol unit In addition the 12-hydroxy-1,4,7,10-tetraoxadodecyl-,9-hydroxy-1,4,7-trioxanonyl, 6-hydroxy- 1,4-dioxahexyl and 2-hydroxyethoxy derivatives of 4’-dodecyloxybiphenyl are described These compounds have only a single hydroxy group at their hydrophilic termini The podand-like trimers consist of three 4’-dodecyloxybiphenyl units which are connected via oligooxyethylene chains with an a, a’,a”-mesitylenetriyl unit The thermotropic liquid-crystalline properties of these compounds were investigated by polarising microscopy, differential scanning calorimetry and, in some cases by X-ray scattering Most diol derivatives exhibited an SA-S, dimorphism However, one of the biphenyl derivatives [4-dodecyloxy-4’-( 6,7-dihydroxy- 1,4-dioxaheptyl)biphenyl] displays another phase instead of the S, phase, probably a phase with a ribbon structure The liquid- crystalline phases of these diol derivatives were influenced by the addition of protic solvents Only lamellar phases were found for the biphenyl derivatives Some thiadiazole derivatives additionally formed lyomesophases consisting of curved aggregates No thermotropic liquid crystalline properties could be detected for the oligoethylene glycol monoethers without the 1,2-diol group However, lyotropic liquid-crystalline phases could be induced by the addition of ethylene glycol or formamide Only those podands with a medium spacer length were thermotropic liquid crystals and no lyotropic mesophases were detected for the podands Some organic compounds can form fluid phases exhibiting anisotropic physical properties, resulting from the orientational order of the anisometric (calarnztzc=lath-like or discotic=disc-like) individual molecules These thermotropic liquid crystals play an important role in materials science and may be used for optoelectronics, information storage and self-reinforcing plastics Amphiphilic molecules consist of a polar head group which is connected to one or more flexible hydrophobic chains They form a wide variety of self-organising systems, such as micelles, monomolecular layers at interfaces and also liquid crystalline phases, which consist of anisometric polymolecular aggregates Many efforts have been made to combine these two types of mesomorphic materials to produce amphotropic liquid crystals In this context, tetraethoxycholesteryl semisuccinate has been reported, which combines the hydrophilic oligoethyl- ene glycol group with the hydrophobic rigid cholesteryl moiety However, several previous attempts were made to introduce rod-like molecular units into the hydrophobic part of oligoethylene glycol amphiphiles, and with one exception5 all the compounds described previously exhibited only lyotropic properties after the addition of water The amphotropic behaviour of simple alkane- 1,2-diols has recently been reported Their combination with rigid cores gives rise to extended thermotropic and lyotropic meso-morphic ranges In order to clarify further the relation between molecular structure and amphotropic behaviour, we herein report on new amphiphilic oligoethylene glycol derivatives incorporating ethers lo Furthermore, the terminal hydroxy groups were replaced by diol head groups or central linking units Results and Discussion Synthesis The synthesis of the diols is displayed in Scheme 1 Compounds 5, which possesses a podand-like structure with a central benzene ring coupling the mesogenic biphenyl units via oligooxy-ethylene spacers, were obtained in a multistep synthesis as outlined in Scheme 2 for the synthesis of the triethylene glycol derivative 5c Thereby 4’-dodecyloxy-4-hydroxybiphenylwas etherified by the Mitsunobu method using 10-phenyl-3,6,9-trioxadecano112 followed by hydrogenolytic debenzylation Alternatively 4 -dodecyloxy-4-hydroxybiphenyl could be etherified directly by reaction with 8-chloro-3,6-dioxaoctanolin the presence of potassium carbonate13 and tetrabutylammonium iodide l4 Both methods gave comparable yields of the oligoethylene glycol monoether 4c.After alkylation with 1,3,5-tris( bromome- thyl)benzene15 in the presence of potassium hydride in THF16 the podand 5c was obtained In order to evaluate the influence of the oligooxyethylene spacer on the mesomorphic properties of these compounds, the trimesogens 7, in which the oligooxyethylene chains are replaced by alkyl chains, were synthesised according to Scheme3 Owing to the readily occurring cyclisation of 4- bromobutanol under basic conditions, 4-tetrahydropyranyl- oxybutanol was used for the synthesis of compound 7b (n=4) different rigid cores and oligooxyethylene chains of different lengths Therefore, single phenyl rings, biphenyl ring systems Thermotropic behaviour or 2-phenyl-1,3,4-thiadiazoleunits were introduced into the The mesomorphic behaviour of the compounds synthesised hydrophobic sections of oligoethylene glycol monoalkyl- was investigated by polarised light micro~copy,~’ differential J Muter Chem, 1996, 6(7), 1087-1098 1087 L I L J" 8 9 MeOH, HlO 1cat.Py TosOH n =0,2,3 Scheme 1 Synthesis of the amphiphilic diols 1-3 1oc nnn0 0 OH HO 0 KZCOS, Bu~N'I' EtOOC-N=N-COOEt, PPh, AAA H2, Pd/C nnon C12H250w0 OH 4cIlc KH, cat Bu4N'I' THF Br Cl~H250-~OnOnOA0 5c C12H250-0 \ / \/ w0uw0 Scheme 2 Synthesis of the podand-like trimesogen 5c 1088 J. Muter. Chem., 1996, 6(7), 1087-1098 Table 1 Transition temperatures/"C and associated enthalpy values/kJ mol- (lower lines in brackets) of the pure and ethylene glycol-saturated samples of the biphenyl derivatives la-d" pure compound ethylene glycol-saturated sample comp n K, K2 SC I K SA I ~~ ~ ~ la 0 0 142 0 176 - (6 2) (273) lb 1 0 124 0 140 X (20.7) (172) lc 2 0 117 0 122 0 (15.5) (163) Id 3 0 - 0 112 0 (34.8) "K, crystalline solid, SA, smectic A phase; S,, smectic C phase, X, unknown mesophase; I, isotropic liquid.KH, cat. Bu,N'I' TH F Br 7a: n = 3 7b:n=8 7c: n= 11 Scheme 3 Synthesis of 1,3,5-tris[o-(4'-dodecyloxybipheny1-4-yloxy)-2-oxaalkyl] benzenes 7a, c and d scanning calorimetry and, in some cases, also by X-ray diffrac- tion measurements. For this purpose the samples were dried simply by heating on a cover glass for 1 min to a temperature ca. 60 "C above the clearing temperature.? Afterwards the samples were immediately sealed. The phase-transition tem-peratures and associated enthalpies are collected in Tables 1-7.Biphenyl derivatives incorporating an 1,2-diol structure. The biphenyl-derived diols 1 exhibit a smectic A (S,) phase as the high-temperature mesophase. The clearing temperatures and the melting temperatures decrease significantly with increasing length of the oligooxyethylene chain (Table 1). The biphenyl derivatives incorporating at least one oxyethyl- ene unit (lb-ld) display an additional phase transition within t The dependence of water desorption on the temperature was investigated by means of a special apparatus. Dry air was passed over a thermostatted sample of the diol The amount of desorbed water was determined by passing the gas through a Karl-Fischer apparatus l8 This method will be described in detail in a separate paper l9 Plate 1 Optical photomicrograph of the texture of the thermotropic S, phase of compound lc at 125°C as obtained by cooling the homeotropically aligned S, phase (crossed polarisers) the liquid crystalline state. Using polarising optical microscopy, in the cases of compounds lc and Id a schlieren texture was observed (Plate l), which is typical for the tilted smectic C (S,) phase.The X-ray patterns of the Sc and SA phases exhibited the characteristic features of these smectic phases with no order in the layers. Using CPK models and assuming an all-trans conformation for the alkyl chains and mainly gauche confor- mations for the oligooxyethylene chains, the molecular length of lc was estimated to be ca. 3.7 nm. Thus the thickness (d) of the smectic layers (d= 5.92 nm at 140"C) is significantly larger than the length of the individual molecules.This means that the molecules should be arranged in bilayersx with the diol groups placed between the layers.20 The dependence of the layer thickness on the temperature was investigated for com- pound lc (Fig. 1). In the Sc phase a typical temperature dependence was established: d decreases with decreasing temperature, which is due to the increasing tilt of the molecules. From this tempera- ture dependence a variation of the tilt angle from 0' (at the transition to the SA phase) to 11.3" (at 130°C) was estimated. In the SA phase, d is also clearly a function of temperature; however, d decreases with increasing temperature.This effect can be interpreted by a growing number of gauche confor- mations of the alkyl chains at higher temperatures. $ The layer thickness amounts less than twice the molecular length, because the alkyl chains are in a molten, liquid-like state and probably also because of the partial intercalation of the terminal groups J. Muter. Chew., 1996, 6(7), 1087-1098 1089 -62 -60 50 -?. 7J -56 0 52 110 120 130 140 150 160 170 Tl"C Fig. 1 Temperature dependence of the layer thickness of compounds lb and lc as determined by X-ray scattering In contrast to lc and Id, the low-temperature phase of compound lb displays a different texture (Plate 2) which is similar to the textures of lyotropic hexagonal and some thermo- tropic columnar phases.In the X-ray pattern of the S, phase of this compound (Fig. 2) the layer reflection and its second order, and an outer diffuse scattering (not displayed) were found. By cooling the sample to the X phase the outer amorphous halo was main- tained but an additional scattering of low intensity was detected in the small-angle region. The position of this reflection relative to the first one does not correspond to the ratio 1:,/3; Therefore a hexagonal columnar arrangement can be excluded. Plate 2 Optical photomicrograph of the texture of the thermotropic X phase (at 144 "C) obtained by cooling the homeotropically aligned SA phase of compound lb (crossed polarisers) 6000 I 1 a 130 OC I 0.8 1.o 1.2 1.4 1.6 I .8 eldegrees Fig. 2 X-Ray scattering (small-angle region of the Guinier-goniometer traces) of compound lb at different temperatures: (150 "C=S, phase; 140 "C=X phase; 130 "C=crystalline state) 1090 J.Muter. Clzem., 1996, 6(7), 1087-1098 SA X phase? Fig. 3 Schematic representations of the SA phase and two possible ribbon-like phases of compound lb This additional reflection disappears in the crystalline state. For the X phase, d is nearly independent of temperature (Fig. 1). Attemps to obtain oriented samples by applying a magnetic field were unsuccessful. The diffuse scattering in the wide-angle region suggests that the X phase is a phase with liquid-like behaviour concerning the lateral molecular distances. If it were smectic, it could be either an SA or an S, phase.The texture, however, is not characteristic of either of these phases. Taking into account all these observations, it seems possible that in the X phase the molecules are arranged in ribbons. Ribbon structures have been described for thermotropic phases of soaps2' and also for the low-temperature phase of a highly polar calamitic nitroben- zoate.22 These ribbons may result from the break up of the smectic layers due to the different space filling of the hydro- philic and the hydrophobic regions (Fig. 3). In order to evaluate this hypothesis, further experiments have been carried out. Protic solvents should increase the size of hydrophilic units and thus influence the mesophases.§ It was found that upon the addition of formamide the thermo- tropic X phase of compound lb was replaced by an Sc phase which changes by larger amounts of solvent to an SA phase.Also, in the contact zone of compound lb with the diethylene glycol derivative lc the X phase of lb was destabilised, whereas the S, phase of compound lc is slightly stabilised. Therefore it may be assumed, that the 6,7-dihydroxy-1,4-dioxaheptyl group of compound lb is a hydrophilic group which allows particularly efficient packing. Accordingly, the area of the hydrophobic sections should be greater than that of the hydrophilic regions, thus giving rise to the frustration of the layered arrangement. Interestingly, compound le, in which one ether oxygen of compound lb is replaced by a methylene group, does not display the X phase, but an Sc phase.\-I lb (X=O) K 140 X 146 SA 169 I le (X=CH2) K 134 S, 157 SA 169 I In order to further verify this hypothesis, further synthetic activities as well as physical measurements to characterise these phases are in progress. The thiadiazoles 2 (Table 2) exhibit exclusively an Sc-SA dimorphism and their transition temperatures decrease with increasing length of the oligooxyethylene spacer. The decrease of the Sc-SA transition with growing spacer 9 A more detailed discussion of the lyotropic behaviour is given later. Table 2 Transition temperaturesrc and associated enthalpy values/kJ mol (lower lines in brackets) of the water-free samples of the thiadiazole derivatives 2a9"and 2b-d phase transitions comp n K, SC I 2a 0 0 105 112 0 114 (52 O)b 2b 1 0 88 97 0 109 (21 3) (11 2) (1 9) 2c 2 72 0 91 101 (20 1) (12 4) (2 4) 2d 3 0 67 84 90 (13 7) (16 7) (4 2) "Abbreviations as in Table 1 bPhase transitions K, -+K,-+Sc-+SA are not resolved transition enthalpies refer to the total amount of these transitions length is less pronounced than for the other phase transitions This gives rise to an increase of the Sc range with increasing number of oxyethylene units The diols 3, incorporating only a single phenyl ring (Table 3) are also liquid crystals, but they form the SAphase exclusively Even diols without any anisometric unit, such as the hexade- cylether 9,23 exhibit thermo tropic liquid-crys talline phases 9 K <20 Lo 37 I This indicates that hydrogen bonding is a main driving force for the self-organisation of these amphiphilic compounds Hydrogen bonds between the diol groups and also between the hydroxy groups and the ether oxygens give rise to the formation of large hydrogen-bonding networks, which force the individual molecules to organise as mesophases 24 In these hydrogen bonds the two hydroxy groups of the diol units act Table3 Transition temperatures/"C and associated enthalpy values/kJ mol (lower lines in brackets) of the water-free samples of the phenyl derivatives 3a9eand 3b-d" r i/-OH phase transitions comp n K SA I 3a 0 0 68 0 91 0 3b 1 0 46 0 69 0 (38 3) (1 2) 3c 2 0 7 0 60 0 (25 0) (12) 3d 3 0 9 0 49 0 (43 6) (1 5) "Abbreviations as in Table 1 as proton donors as well as proton acceptors, whereas the ether oxygens act exclusively as acceptors Oligoethylene glycol monoethers.No thermotropic liquid- crystalline properties could be detected for the biphenyl deriva- tives 4 in which the terminal diol groups are replaced by a single hydroxy group (Table 4) Obviously a single proton- donating hydroxy group is not sufficient to produce stable aggregates which enable the formation of thermotropic liquid- crystalline phases Thermomesomorphic properties of podands and trimesogens. It seems that sufficiently strong terminal fixation of the individ- ual molecules via hydrogen bonding stabilises liquid-crystalline phases But can the covalent fixation of the individual calamitic mesogens via the termini of their oligooxyethylene chains replace the hydrogen bonding, and thus also give mesomorphic materials? This concept was realised by the podand-like trimesogens 5, in which the individual molecules are connected by a central mesitylene unit The transition temperatures of these podands are summarised in Table 5 Only compound 5b exhibits an S, phase over a small temperature range In order to evaluate the influence of the oligooxyethylene spacer on the mesomorphic properties of these trimesogens, compounds 7, in which the oligooxyethylene chains are replaced by alkyl chains, were also investigated (Table 6) Again, only the trimesogens 7a and 7b with medium spacer lengths display liquid-crystalline behaviour These com- pounds may be regarded as oligomeric liquid crystals In accordance with our recent results,25 only those oligomeric liquid crystals in which the calamitic units are decoupled by a spacer of medium length from the central linking unit display liquid-crystalline properties Mesomorphic properties in the presence of solvents Nonionic amphiphilic oligoethylene glycol alkyl ethers are known to exhibit lyotropic liquid crystalline phases in aqueous solution in defined concentration and temperature regimes lo 26 Thereby the mesophases are determined by the concentration, the temperature and the relation between the hydrophobic tails and hydrophilic head groups of the amphiphiles Owing to their amphiphilic structures the diols 1-3, the oligoethylene glycol monoethers 4 and the trimers 5 are assumed to self-organise in water or other protic solvents to give lyotropic mesophases We have studied the behaviour of compounds 1-5 in the presence of protic solvents using the solvent-penetration technique The pure amphiphiles were surrounded by the solvent between two cover slips These samples were then placed on a heating stage and the contact region was observed by means of optical microscopy between crossed polarisers The penetration of the solvent into the sample gives rise to a concentration gradient at the amphiphile/ solvent boundary, and the lyomesophases formed develop as bands and can be monitored as a function of the temperature Mesophases of diols in the presence of water.It was found that in the presence of water all the diol derivatives 1-3 form mesophases with clearing temperatures significantly above 100°C In the case of the biphenyl derived diols 1 the S,-S, transition temperature decreases significantly with increasing water concentration and the water-saturated samples exhibit exlusively the lamellar SAphase between the melting point and 100°C (Plate 3) Obviously the long alkyl chains, the limited length of the oligooxyethylene groups and the rigid biphenyl cores inhibit the formation of curved aggregates The thiadiazole derivatives 2, however, exhibit a more complicated phase behaviour Owing to the ability of the thiadiazole unit to participate in hydrogen bonds, the water J Muter Chern, 1996, 6(7),1087-1098 1091 Table 4 Transition temperatures/"C of the pure, ethylene glycol-saturated and formamide-saturated samples of the oligoethylene glycol monoethers 4a-d" ri comp n pure compound mP 4a 0 138 4b 1 128 4c 2 115 4d 3 104 "Abbreviations as in Table 1 ethylene glycol-saturated sample formamide-saturated sample K SA I K s'4 I a a110 124 a a a105 142 a a a98 133 a a a111 149 a a 098 124 a a 097 144 a a a93 122 a a a92 141 a Table 5 Transition temperatures/"C of the podand-like trimesogens 5a-d" (O \p / O \ /m 0c12H25 phase transitions comp n K SA I 5a 1 a 180 --a 5b 2 a 130 a 131 a 5c 3 a 120 --a -5d 4 a 106 -a "Abbreviations as in Table 1 Table 6 Transition temperaturesrc of the trimesogens 7a-d phase transitions comp n K sx SA I 7a 3 a 7 a 115 a 133 a 7b 4 a 7 a 131 a 141 a ----a7c 8 a 109 7d 11 a 119 --a "Sx,smectic low-temperature phase of unknown structure Other abbreviations as in Table 1 uptake is increased, and mesophases consisting of curved aggregates could also be obtained Compound 2d was used for preliminary phase-behaviour investigations With increasing water content the Sc-SA trans-ition temperature decreases rapidly and finally the Sc phase disappears Further increasing the water content gives rise to the formation of a hexagonal columnar (H,) phase at tempera- tures below the SA phase with a maximum of the H,-SA transition at 70 "C Increasing the water concentration still further slightly decreases the stability of the H, phase In the water-saturated state the SA-H, transition appears at 68 "C A section of the contact region between compound 2d and water at 69 "C is shown in Plate 4 On cooling the H, phase of the water-saturated sample, the transition to an isotropic (probably cubic) phase was observed 1092 J Muter Chem, 1996, 6(7), 1087-1098 at 64 "C Crystallisation occurs at 55 "C and reheating gives a melting point of approximately 67 'C Mesophases of diols in the presence of protic solvents.With the use of other protic solvents, such as ethylene glycol or formamide, broad mesomorphic ranges could also be observed These solvents can form hydrogen bonds with the polyether chains and thus allow the formation of lyotropic mesophases With increasing ethylene glycol concentration the clearing temperatures and the other phase transitions are depres-sed Obviously the incorporation of ethylene glycol into the hydrogen-bonding networks of the diol groups disturbs the mesophase formation In particular, the Sc-SA transition tem- perature decreases with increasing solvent concentration and therefore the S, phase was the only mesophase which was Plate 3 Optical photomicrograph of the oily streaks texture of the lyotropic s* phase Of the water-saturated compound Id at 96 "c (crossed polarisers) Plate 4 (u) Section of the contact zone of compound 2d with water at 69°C as seen between crossed polarisers (pure 2d on the left).(b)Texture of the H, phase appearing in the contact zone of compound 2d and water at 70 "C (crossed polarisers). observed for the solvent-saturated samples. The transition temperatures of the ethylene glycol-saturated samples of the compounds 1 are included in Table 1. Upon the addition of formamide, however, the stability of the SA phase is increased dramatically. The clearing temperatures are very high, and before they are reached extensive decomposition occurs (at 170-190 "C). The thiadiazole derivatives 2 are fairly soluble in formamide, especially at higher temperatures. The greatly increased solu- bility in polar must be caused by the This gives rise to the more COmPlicated Phase behaviour of the thiadiazole derivatives 2c and 2d in the presence of solvents.For example, a lyotropic nematic (N) phase appears in the mixture of compound 2c with ethylene glycol (Plate 5). Mesophases of the oligoethylene glycol monoethers in the presence of water and other protic solvents. In the case of the oligoethylene glycol monoethers 4 the rather high melting point obviously inhibits the formation of lyotropic phases with water below 100"C. However, by using other protic solvents with elevated boiling points, such as ethylene glycol or formam- ide, broad mesomorphic ranges could be induced (Table 4). In this way these oligoethylene glycol monoethers 4 are not amphotropic, but are lyotropic liquid-crystalline materials.The high-temperature mesophase is the SAphase. Only in two cases are additional mesophases found to occur: the induction of an Sc phase was observed at the phase boundary of the triethylene glycol derivative 4c and formamide in the temperature range 97-1 13 "c, and in the formamide-rich region of the &ethylene glycol derivative 4b, a H, phase, was observed within a limited concentration and temperature range below the S, phase (transition to S, occurs at 122°C. Neither the Sc phase nor the columnar phase could be observed for any of the other 4-solvent systems. Behaviour of the podands in the presence of water and other protic solvents. In the case of the podand-like trimers 5 no mesophases could be induced by water, ethylene glycol or formamide.It seems that the central hydrophobic connecting unit inhibits the uptake of solvent molecules. Conclusions Amphotropic materials can be generated by combination of amphiphilic oligoethylene glycol monoalkyl ethers" with appropriate hydrophilic terminal groups such as the diol group (Table 7). The formation of liquid-crystalline phases in these compounds is caused mainly by the hydrogen bonding net- works between their diol groups. The mesophases could be additionally stabilised or modified by the incorporation of rigid units (e.g. phenyl, biphenyl, 2-phenylthiadiazole), which arrange favourably parallel to each other. Alternatively, mesophase stabilisation could be achieved by the addition of solvents such as water and formamide, which reinforce the hydrogen-bonding networks between the hydrophilic units.In the absence of the diol unit no thermo- tropic properties were found, but lyotropic mesophases could still be induced by protic solvents. No mesophase induction by protic solvents was possible, however, if the termini of the oligooxyethylene chains were connected with hydrophobic substituents as in the case of the podand-like trimers 5. Plate 5 Optical photomicrograph of the lyotroplc nematic phase in the contact zone of compound 2c with ethylene glycol at 71 "C (crossed polarisers) J. Mater. Chem., 1996, 6(7), 1087-1098 1093 Table 7 Comparison of the clearing temperatures of the thermotropic and lyotropic mesophases" of the tetraethylene glycol hexadecyl ether 8" and the 1,2-diols9,23Id and 3d TImax/"C compound thermotropic 1yotropic 8 not liquid-crystalline 78 9 37 >100 c1 6H330 3d 49 >100 Id 135 >100 ~ ~~ "TImax =maximal values of the clearing temperature, observed in mixtures with water, determined by the solvent penetration method Experimental Section General Remarks 4'-Dodecyloxybipheny1-4-01,~~4-decylphenol, 4-( 5-pentadecyl- 1,3,4-thiadiaz01-2-yl)phenol,~~4-allyloxyethan01,~~ 1,3,5- tris( bromomethyl) benzene15 and the 1,2-O-isopropylidene-functionalised alcoholsgd were synthesised according to litera- ture procedures co-Bromoalkanols, co-chlorooligooxyethylene ethanols and diethyl azodicarboxylate (Aldrich) were used as received Confirmation of the structures of intermediates and products was obtained by 'H NMR spectroscopy (Varian Unity 500 or Bruker WP200 spectrometers), IR spectroscopy (Specord 71 IR) and mass spectrometry (AMD 402, electron impact, 70eV) The purity of all compounds was checked by thin layer chromatography (Merck, silica gel 60 F254) Light petroleum-ethyl acetate mixtures and chloroform-methanol mixtures (10 0 5) were used as eluents and the spots were detected by UV irradiation and/or by means of bromothymol blue solution Microanalyses were performed using a Leco CHNS-932 elemental analyser Most compounds incorporating at least one oxyethylene unit rapidly take up moisture from the air As determined by the Karl-Fischer method,I8 the water uptake is cu 0 5 mol,l9 while the phenyl derivatives 3 take up even larger amounts Therefore, the samples were dried by heating for 1 min to a temperature approximately 60 "C above the clearing tempera- ture Afterwards the samples were immediately sealed and investigated Transition temperatures were measured using a Mettler FP 82 HT hotstage and control unit in conjunction with a Nikon Optiphot 2 polarising microscope and these were confirmed using differential scanning calorimetry (Perkin Elmer DSC-7) X-Ray studies were performed by means of a Guinier goniometer (Fa Huber) The substances were melted into thin glass capillaries Lyotropic mesophases were studied by the penetration tech- nique A drop of pure amphiphile was surrounded by the solvent between two cover slips The concentration gradient at the amphiphile/solvent boundary allows the phases to develop as bands Their sequence was monitored as a function of temperature In addition, the solvent-saturated samples, obtained by mixing the amphiphile with excess solvent, were investigated by optical microscopy between crossed polarisers The phase structures were determined from the observed textures Etylene glycol and formamide, which were used as solvents, were distilled zn uucuo and stored over molecular sieves Synthesis of diols by Mitsunobu etherificationM with 1,242- isopropylidene functionalised alcohols 4-Dodecyloxy-4-( 3,2-dihydroxypropoxy) biphenyl, la 4'-Dodecyloxybiphenyl-4-01 (1 06 g, 3 0 mmol) and tri-phenylphosphine (1 2 g, 4 5 mmol) were dissolved in dry THF (15 ml) After addition of 1,2-O-isopropylidene glycerine (0 59 g, 4 5 mmol) the mixture was cooled to 0-5 "C At this temperature diethyl azodicarboxylate (0 78 g, 4 5 mmol) was added dropwise over 5min to the stirred mixture, and the solution was stirred for an additional 24 h at room temperature Afterwards the solvent was evaporated and the residue was crystallised twice from methanol-water (9 1) to remove the triphenylphosphine oxide The crude product (0 4 g, 0 8 mmol) was dissolved in wet ethanol (20 ml, containing 5% water) After addition of pyridinium toluene-p-sulfonate (50 mg, 0 2 mmol) the solution was heated at reflux for 3 h Removal of the solvent zn vucuo gave a residue which was dissolved in ethyl acetate (50 ml) and washed with water, saturated aqueous sodium hydrogen carbonate, water and brine successively After drying over sodium sulfate the solvent was evaporated and the residue was repeatedly crystallised from hexane to leave white crystals Yield 0 29 g (23%), transitions/"C K, 142 K, 176 SA 195 I, (MS found 4282908, C27H4004 requires 428 2926), SH (500 MHz, CDCl,, J/Hz) 0 86 (3 H, t, J 7, CH,), 120-1 40 (16 H, m, CH,), 145 (2 H, m, CH,), 1 50-1 70 (2 H, m, OH), 178 (2H, m, CH,), 377 (lH, dd, J 7, 11, CHH,-OH), 3 67 (1 H, dd, J 3, 11, CHbH-OH), 3 96 (2 H, t, J 6, Ar-0-CH,), 403-4 15 (3 H, m, 0-CH,-CCH-OH), 6 93 (4 H, m, Ar-H), 7 43 (4 H, m, Ar-H) 4-Dodecyloxy-4-( 9,1O-dihydroxy-l,4,7-trioxadecyl)biphenyl, lc.Prepared as described for la from 4'-dodecyloxybiphenyl- 4-01 (1 4 g, 4 mmol) and 1,2-O-1sopropylidene-4,7-dioxanon-ane-1,2,9-triol (1 3 g, 6 mmol) Yield 0 26 g (13%), transitions/"C K, 117 K, 122 Sc 136 SA 154 I, (found C, 71 13, H, 928 C31H4806 05H,O requires C, 7082, H, 939%), dH (500 MHz, CDCl,, JIHZ) 0 86 (3 H, t, J 7, CH,), 1 20-1 38 (16H, m, CH,), 145 (2H, m, CH,), 178 (2H, m, CH,), 1 85-2 35 (2 H, br s, OH), 3 54-3 75 (8 H, m, CH,-0), 3 87 (3 H, m, 0-CH,-CCH-OH), 3 98 (2 H, t, J 6, Ar-0-CH,), 1094 J Muter Chem, 1996, 6(7), 1087-1098 4.17 (2 H, m, CH2-O), 6.90-6.98 (4 H, m, Ar-H), 7.44 (4 H, m, Ar-H).4-Dodecyloxy-4-(12,13-dihydroxy-l,4,7,1O-tetraoxatridecyl)-biphenyl, Id. Prepared as described for la from 4'-dodecyloxybiphenyl-4-01 ( 1.06 g, 3 mmol) and 1,2-O-isopro-pylidene-4,7,10-trioxadodecane-1,2,12-triol( 1.18 g, 4.5 mmol).Yield 0.58 g (35%); transitions/"C K 112 S, 121 SA 135 I; (found C, 69.57; H, 9.49. C3,H5,07.0.5 H,O requires: C, 69.56; H, 9.38%); 6H (500 MHz; CDC13; JIHz); 0.86 (3 H, t, J 7, CH3), 1.20-1.38 (16 H, m, CH,), 1.46 (2 H, m, CH,), 1.78 (2 H, m, CH,), 1.95-2.10 (2 H, br s, OH), 3.52-3.76 (12H, m, CH, -0),3.80-3.88 (3 H, m, 0-CH, -CH- OH), 3.97 (2 H, t, J 6, Ar-0-CH,), 4.16 (2H, t, J 5, CH,-0), 6.93 (4H, m, Ar-H), 7.43 (4 H, m, Ar-H). 4-Dodecyloxy-4'-( 5,6-dihydroxyhexyloxy) biphenyl le. Pre-pared as described for la from 4'-dodecyloxybipheny1-4-01 ( 1.06 g, 3 mmol) and 1,2-O-isopropylidenehexane-1,2,6-triol (0.78 g, 4.5 mmol).Yield 0.88g (62 YO);transitions/"C K 134 Sc 157 SA 169 I; 6, (500 MHz; CDC13; J/Hz): 0.87 (3 H, t, J 7, CH,), 1.25-1.83 (26 H, m, CH,), 3.46 (1 H, dd, CHH,-OH), 3.67 (1 H, dd, CHbH-oH), 3.74 (1H, m, CH-OH), 3.95-4.01 (4H, 2t, Ar-0-CH,), 6.92 (4H, 2d, Ar-H), 7.43 (4H, 2d, Ar-H). 2-Pentadecyl-5-[ 4-( 2,3-dihydroxypropoxy) phenyll- 1,3,4- thiadiazole, 2a. Prepared as described for la from 2-( 4-hydroxy- phenyl)-5-pentadecyl-1,3,4-thiadiazole(1.16 g, 3 mmol) and 1,2-O-isopropylidene glycerine (0.59 g, 4.5 mmol). Yield 0.35 g (25%); transitions/"C K, 105 K2 112 S, 114 S, 148 I; (MS: found 462.2891. C26H,203N,S requires 462.29 16); dH (500 MHz; CDC1,; JIHz): 0.86 (3 H, t, J 7, CH3), 1.18-1.38 (22H, m, CH,), 1.42 (2H, m, CH,), 1.70 (2H, m, CH,), 1.85-2.08 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH,-thiadiazole), 3.77 (1 H, dd, J 3, 11, CHH,-OH), 3.87 (1 H, dd, J 3, 11, CH,H-OH), 4.06-4.18 (3 H, m, CH,-CH-OH), 6.98 (2 H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).2-Pentadec yl-5-[4-( 9,l 0-dihydroxy- 1,4,7- trioxadecy1)- phenyl]-l,3,4-thiadiazole, 2c. Prepared as described for la from 2-(4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole ( 1.1 6 g, 3 mmol) and 1,2-O-isopropylidene-4,7-dioxanonane-1,2,9-triol (1 g, 4.5 mmol). Yield 0.3 g (18%); transitions/"C K, 72 K, 91 Sc 101 SA 119 I; (found: C, 64.77; H, 9.27; N, 5.11; S, 5.93. C30H5005N2S.0.5H20requires C, 64.37; H, 9.18; N, 5.00; S, 5.73%); 6, (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (22H, m, CH,), 1.42 (2H, m, CH,), 1.82 (2H, m, CH,), 2.15-2.36 (2H, br s, OH), 3.12 (2H, t, J 7, CH, -thiadiazole), 3.52-3.78 (8 H, m, CH, -O), 3.80-3.93 (3 H, m, 0-CH,-CH-OH), 4.19 (2 H, t, J 6, Ar-0-CH,), 6.99 (2 H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).2-Pentadecyl-5-[ 4-( 12,13-dihydroxy-l,4,7,1O-tetraoxatri-decyl)phenyl]-1,3,4-thiadiazole 2d. Prepared as described for la from 2-(4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole (1.16 g, 3 mmol) and 1,2-O-isopropylidene-4,7,lO-trioxadode-cane-1,2,12-triol (1.18 g, 4.5 mmol). Yield 0.2 g (11%); transitions/"C K, 67 K2 84 S, 90 SA 104 I; (found: C, 63.94; H, 9.14; N, 4.77; S, 5.50. C3,H5,06N,S-0.5H,0 requires: C, 63.95; H, 9.18; N, 4.64; S, 5.31%); SH (500 MHz; CDCl3; J/Hz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (22 H, m, CH,), 1.42 (2 H, m, CH,), 1.81 (2 H, m, CH,), 1.95-2.30 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH, -thiadiazole), 3.50-3.73 (12 H, m, CH2-O), 3.81-3.90 (3 H, m, 0-CH,-CH-OH), 4.19 (2H, t, J 6, Ar-0-CH,), 6.98 (2H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).4-Decyl-(9,10-dihydroxy-l,4,7-trioxadecyl)benzene 3c. Pre-pared as described for la from 4-decylphenol (1.17 g, 5 mmol) and 1,2-O-isopropylidene-4,7-dioxanonane-1,2,9-triol( 1.65 g, 7.5 mmol). Yield 0.31 g (16%); transitions/"C K 7 SA 60 I; (found: C, 67.52; H, 9.88. C,,H4,0,-0.5H20 requires: C, 68.1 1; H, 10.19%); 8H (500 MHz; CDC13; J/'Hz): 0.85 (3 H, t, J 7, CH,), 1.23 (14 H, m, CH,), 1.53 (2 H, m, CH,), 2.50 (2 H, t, J 7, Ar-CH,), 3.53-3.63 (SH, m, CH,-0), 3.65 (3H, m, CH2-CH-OH), 4.09 (2 H, t, J 5, Ar-0-CH,), 6.81 (2 H, d, J 8, Ar-H), 7.03 (2 H, d, J 8, Ar-H).4-Decyl-(12,13-dihydroxy-l,4,7,10-tetraoxatridecyl)benzene 3d. Prepared as described for la from 4-decylphenol (1.17 g, 5 mmol) and 172-O-isopropylidene-4,7,1 O-trioxadodecane- 1,2,12-triol (2 g, 7.5 mmol). Yield 0.57 g (26%); transitions/"C K 9 SA49 I; (MS: found 440.3125, C25H4406 requires 440.3137); SH (500 MHz; CDC13; JIHz): 0.86 (3 H, t, J 7, CH,), 1.24-1.28 (14 H, m, CHJ, 1.53 (2 H, m, CH,), 2.51 (2 H, t, J 7, Ar-CH,), 3.55-3.72 (12H, m, CH,-0), 3.80-3.86 (3H, m, CH2-CH-OH), 4.09 (2H, t, J 5, Ar-0-CH,), 6.81 (2H, d, J 8, Ar-H), 7.05 (2H, d, J 8, Ar-H). Synthesis of diols via ally1 ethers 2-Pen tadecyl-5-[ 4-( 6,7-dihydroxy-1,Qdioxaheptyl)phenyl 1-1,3,4-thiadiazole 2b.2-Pentadecyl-5-[ 4-( 1,4-dioxahept-6-enyl)- phenyl]-1,3,4-thiadiazole was prepared as described for la by Mitsunobu etherification of 2-( 4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole (1.16 g, 3 mmol) and 2-allyloxyethanol(l.53 g, 15 mmol). Yield 0.87 g (61%); mp 72 "C; dH (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.22-1.44 (24 H, m, CH,), 1.80 (2 H, m, CH,), 3.09 (2 H, t, J 7, CH,-thiadiazole), 3.81 (2 H, t, J 5.2, CH,-0), 4.09-4.19 (2H, m, H,C=CH-CH,-0), 4.18 (2H, t, J 5, CH,-0), 5.20 (lH, dd, J 1.5, 10, H,HbC=CH), 5.30 (1 H, dd, J 1.5, 17, H,HbC=CH), 5.89-5.97 (1 H, m, H,HbC=CH), 6.98 (2 H, d, J 7, Ar-H), 7.84 (2 H, d, J 7, Ar-H). This compound (0.47 g, 1.0 mmol) was added to a solution of N-methylmorpholine N-oxide (0.15 g, 1.5 mmol) in THF (20 ml). To this solution water (0.1 ml) and osmium tetroxide solution (0.05 ml of 1% solution in tert-butyl alcohol) were added.31 The resulting mixture was stirred for 24 h at room temperature.After this time starting materials could no longer be detected and the mixture was worked up as follows. Sodium bisulfite (saturated solution, 5 ml) was added and the resulting slurry was stirred vigorously for 30 min at room temperature. Afterwards the solids were filtered off through a pad of silica gel, the residue was washed twice with ethyl acetate (2 x 50 ml) and the solvents were distilled off using a rotary evaporator. The residue was dissolved in ethyl acetate (50 ml) and the solution was washed three times with water (25 ml) and brine and was finally dried over Na,S04.After evaporation of the solvent the residue was crystallised from hexane-ethyl acetate (10: 1). Yield: 0.41 g (81%); transitions/"C K1 88 K, 97 S, 109 SA 135 I; (found: C, 66.21; H, 9.02; N, 5.40; S, 6.39. C28H4604N2Srequires: C, 66.37; H, 9.15; N, 5.53; S, 6.33%); 6, (500 MHz; CDCl,; J/Hz): 0.86 (3 H, t, J 7, CH3), 1.18-1.38 (22H, m, CH,), 1.44 (2H, m, CH,), 1.83 (2H, m, CH,), 1.86-2.10 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH, -thiadiazole), 3.60-3.75 (4H, m, CH,-0), 3.83-3.91 (3H, m, 0-CH2-CH-OH), 4.19 (2H, t, J 6, Ar-0-CH,), 6.97 (2 H, d, J 7, Ar-H), 7.85 (2 H, d, J 7, Ar-H). 4-Dodecyloxy-4'-(6,7-dihydroxy-1,4-dioxaheptyl)biphenyl, 1b.Prepared as described for 2b from 4'-dodecyloxybiphenyl- 4-01 ( 1.06 g, 3 mmol). Total yield0.3 g (21 YO);transitions/"C K, 124 K2 140 Sx 146 SA 169 I; (found: C, 72.58; H, 9.36. C,,H,,05~0.5H,0 requires: C, 72.31; H, 9.42%); 6, (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (16 H, m, CH,), 1.48 (2 H, m, CH,), 1.40-1.70 (2 H, br s, OH), 1.78 (2 H, m, CH,), 3.62-3.78 (4 H, m, CH2-0), 3.85-3.93 (3 H, J. Muter. Chern., 1996, 6(7), 1087-1098 1095 m, O-CCH2-CCH-OH), 3 97 (2 H, t, J 6, Ar-0-CH,), 4 09 (2H, m, CH2-0), 6 96 (4 H, m, Ar-H), 7 43 (4 H, m, Ar-H) 4Decyl-(6,7-dihydroxy-l,4-dioxaheptyl)benzene, 3b Prepared as described for 2b from 4-decylphenol (1 17 g, 5 mmol) Total yield 0 2 g (1 YO), transitions/"C K 46 S, 69 I, (MS found 352 2607, C21H3604 requires 352 2613), dH (500 MHz, CDCI,, JIHz) 0 86 (3 H, t, J 7, CH3), 1 23 (14 H, m, CH,), 1 53 (2 H, m, CH,), 2 09 (1H, t, J 5, OH), 2 51 (2 H, t, J 7, Ar-CH,), 2 70 (1H, d, J 5, OH), 3 59-3 73 (4 H, m, CH,-0), 385 (3H, m, CH,-CH-OH), 409 (2H, t, J 5, Ar-0-CH,), 681 (2H, d, J 8, Ar-H), 705 (2H, d, J 8, Ar-H) Synthesis of the oligoethylene glycol monoethers 4-Dodecyloxy-4-( 2-hydrox yethox y)biphenyl, 4a 4'-Dodecyl-oxybiphenyl-4-01 (3 54 g, 100 mmol) was dissolved in dry dimethyl formamide (50ml) Potassium carbonate (12 4 g, 90 mmol) and tetrabutylammonium iodide (0 5 g, 3 0 mmol) were added to the solution, followed by addition of 2-bromo- ethanol (1 38 g, 11 mmol) The mixture was then stirred at 70°C for 16 h After cooling to room temperature dichloro- methane (50 ml) was added and the suspension was filtered The solid residue was washed once with dichloromethane (50ml), the solutions were combined and the solvent was distilled off using a rotary evaporator The residue was dis- solved in dichloromethane (100ml) and was washed with two 20 ml portions of dilute hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate and brine, successively, and then dried over sodium sulfate Evaporation of the solvent gave a solid residue, which was recrystallised several times from light petroleum (60-85 "C) and ethyl acetate to give pure 4a Yield 2 3 g (58%), mp 138 "C, (found C, 78 86, H, 9 84 C26H3803 requires C, 78 34, H, 9 62%) 4-Dodecyloxy-4-( 6-hydroxy-1,4-dioxahexyl)biphenyl, 4b 4-Dodecyloxy-4'-( 6-benzyloxy- 1,4-dioxahexyl) biphenyl was pre- pared as described for la from 4'-dodecyloxybipheny1-4-01 (7 08 g, 20 mmol) and 7-phenyl-3,6-dioxaheptanol (3 9 g, 22 mmol) Yield 3 83 g (36%), mp 84 "C, (found C, 78 93, H, 9 10 C35H4804 requires C, 78 89, H, 9 09%), 6, (200 MHz, CDCl,, J/Hz) 0 87 (3 H, t, J 7, CH3), 144 (20 H, m, CH,), 356-410 (10H, m, CH,-0), 450 (2H, s, Ar-CH,-0), 688 (4H, d, J 9, Ar-H), 725 (5 H, m, Ar-H), 734 (4H, d, J 9, Ar-H) This compound was hydrogenated in the presence of 10% palladium on charcoal in 60ml ethyl acetate The catalyst was filtered off and the solvent was evaporated and the residue was repeatedly recrystallised from light petroleum (60-85 "C) to give pure 4b Yield 2 8 g (890/), mp 128 "C, (found C, 76 02, H, 9 62 C28H4204 requires C, 75 97, H, 9 57%) 4-Dodecyloxy-4'-(9-hydroxy-l,4,7-trioxanonyl)biphenyl, 4c 4-Dodecyloxy-4'-( 9- benzyloxy -1,4,7- trioxanonyl )biphenyl was prepared as described for la from 4'-dodecyloxybipheny1-4-01 ( 10 62 g, 30 mmol) and 10-phenyl-3,6,9-trioxadecanol(8 8 g, 33 mmol), Yield 8 3 g (48%), mp 88 "C, (found C, 77 05, H, 9 22 C37H520, requires C, 77 03, H, 9 09 YO),6, (200 MHz, CDCI,, J/Hz) 0 90 (3 H, t, J 7, CH,), 172 (20 H, m, CH2), 3 72 (4 H, m, CH,-0-Ar), 3 88-4 16 (10 H, m, CH2-0), 460 (2 H, s, Ar-CH,-0), 700 (4 H, d, J 9, Ar-H), 7 36 (5 H, m, Ar-H), 7 55 (4 H, d, J 9, Ar-H) The hydrogenation was carried out as as described for the synthesis of 4b Yield 5 9 g 4c (85%), mp 115 "C, (found C, 74 28, H, 9 58 C30H4605 requires C, 74 02, H, 9 53 YO),hH (200 MHz, CDC13, J/Hz) 0 80 (3 H, t, J 7, CH,), 1 22-1 72 (20H, m, CH,), 354-410 (14H, m, CH2-O), 684 (4H, m, Ar-H), 7 36 (4 H, d, J 9, Ar-H), m/z 486 (M+,49%) 1096 J Muter Chern, 1996, 6(7), 1087-1098 4-Dodecyloxy-4'-(12-hydroxy-1,4,7,10-tetraoxadodecyl)-biphenyl 4d 4-Dodecyloxy-4'-(12-benzyloxy-l,4,7,10-tetraox-adodecy1)biphenyl was prepared as described for la from 4'- dodecyloxybiphenyl-4-01 (5 3 g, 15 mmol) and 13-phenyl-3,6,9,12-tetraoxatridecanol(4,8g, 17 mmol) Yield 2 3 g (25%), mp 75 "C, (found C, 75 52, H, 9 13 C39H5606 requires C, 75 43, H, 9 10"/0), 6, (200 MHz, CDCl3, JIHz) 0 84 (3 H, t, J 7, CH,), 118-1 77 (20H, m, CH,), 355-4 13 (18 H, m, CH,-0),454(2H,s,Ar-CH,-0),691(4H,d,J9,Ar-H), 7 31 (5 H, m, Ar-H), 742 (4 H, d, J 9, Ar-H) The catalytic hydrogenation was carried out as described for 4b Yield 1 65 g 4d (83Y0), mp 104 "C, (found C, 72 53, H, 9 63 C32H5006 requires C, 72 41, H, 9 50%), JH (200 MHz, CDCl,, J/Hz) 0 86 (3 H, t, J 7, CH,), 1 20-1 75 (20 H, m, CH,), 33-427(18H,m,CH2-O),693(4H,m,Ar-H),743 (4 H, d, J 9, Ar-H) Preparation of the podands 5 1,3,5-Tris-[ 24 4-dodecyloxybiphenyl-4-yloxy)ethoxymethyll-benzene 5a To a stirred suspension of potassium hydride (008 g, 20mmol), which was washed three times with dry hexane under an argon atmosphere, in dry THF (5 ml) was added 4- dodecyloxy-4-(2-hydroxyethoxy)biphenyl 4a (078 g, 19 mmol) dissolved in dry THF (20 ml) After stirring at room temperature for 2 h a solution of 1,3,5-tris(bromomethyl)benzene(0 21 g, 0 6 mmol) and tetrabutylammonium iodide (007 g, 0 2 mmol) in dry THF (25 ml) was added The mixture was then stirred under reflux for 16 h After cooling to room temperature, the mixture was hydrolysed carefully with 15 ml water and extracted with dichloromethane The organic extract was washed with two 10 ml portions of dilute hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate and brine, successively, and then dried over sodium sulfate Evaporation of the solvent gave a solid residue, which was recrystallised several times from a CHC1,-MeOH (9 1) mixture to give pure 5a Yield 39 mg (5%), mp 180 "C, (found C, 80 27, H, 9 17 C87H,,OO9 requires C, 79 76, H, 9 24%), m/z 1310 (M', 2%) 1,3,5-Tris-[ 1-( 4'-dodecyloxybiphenyl-4-yloxy)-3,6-dioxa-heptyllbenzene, 5b Prepared as described for 5a from 4- dodecyloxy-4'-( 6-hydroxy- 1,4-dioxahexyl) biphenyl 4b (0 88 g, 1 9 mmol) and 1,3,5-tris( bromomethy1)benzene (021 g, 0 6 mmol) Yield 97 mg (12%), transitions/"C K 130 S, 131 I, (found C, 76 85, H, 9 18 C93H132012 requires C, 77 45, H, 9 23%), 6, (200 MHz, CDCI,, J/Hz) 0 76 (9 H, t, J 7, CH,), 1 15-1 66 (60 H, m, CH,), 3 50-4 02 (30 H, m, CH, -0),4 44 (6 H, s, Ar-CH,-0), 680 (12 H, m, Ar-H), 7 12 (3 H, s, Ar-H), 7 32 (12 H, d, J 9, Ar-H), m/z 1440 (M+, 13%) 1,3,5-Tris-[ 1-(4'-dodecyloxybipheny1-4-yloxy)-3,6,9-trioxa-decyllbenzene, 5c Prepared as described for 5a from 4-dodecyloxy-4 -( 9-hydroxy- 1,4,7-trioxanonyl) biphenyl 4c (024 g, 0 5 mmol) and 1,3,5-tris(bromomethyl)benzene (0053g, 0 15 mmol) Yield 23 mg (llY~), mp 12OoC, (found C, 75 04, H, 9 10 C99H144015 requires C, 75 52, H, 9 23%), SH (200 MHz, CDCl,, J/Hz) 0 85 (9 H, t, J 7, CH3), 1 24-1 75 (60H, m, CH,), 362-410 (42H, m, CH,-0), 451 (6H, s, Ar-CH,-0), 690 (12 H, m, Ar-H), 721 (3 H, s, Ar-H), 7 41 (12 H, d, J 9, Ar-H), m/z 1572 (M', 8%) 1,3,5-Tris-[ 1-( 4-dodecyloxybipheny1-4-yloxy)-3,6,9,12-tetraoxatridecyl] benzene 5d Prepared as described for 5a from 4-dodecyloxy-4-( 12-hydroxy- 1,4,7,10-tetraoxadodecyl) biphenyl 4d (0 15 g, 0 28 mmol) and 1,3,5-tris( bromomethy1)- benzene (0 03 g, 0085 mmol) Yield 11 mg (8%), mp 106°C (found C, 73 43, H, 9 10 C,o5H15@18 requires C, 73 89, H, 9 22%), 6, (200 MHz, CDC13, J/Hz) 0 81 (9 H, t, J 7, CH3), 1 17-1 64 (60 H, m, CH,), 3 33-4 29 (54 H, m, CH, -0),4 45 (6H, s, Ar-CH2-0), 684 (12 H, m, Ar-H), 7 16 (3H, s, Ar-H), 7 35 (12 H, d, J 9, Ar-H) Preparation of the 4-dodecyloxy-4'-(o-hydroxyalkoxy)-biphenyls 6 4-Dodecyloxy-4-(3-hydroxypropoxy) biphenyl, 6a Prepared as described for 4a from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and 3-bromopropanol(l 53 g, 11 mmol) Yield 1 5 g (36%), mp 146 "C, (found C, 78 54, H, 9 82 C27H4003 requires C, 78 58, H, 9 78%), 6, (200 MHz, CDCl,, J/Hz) 0 87 (3 H, t, J 7, CH,), 130 (20H, m, CH,), 208 (2H, t, J 7, CH,-CH,--CH,-O), 370-425 (6 H, m, CH,-0), 695 (4 H, d, J 9, Ar-H), 749 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4-(4-tetrahydropyranyloxybutoxy) biphenyl. Prepared as described for la from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and 4-tetrahydropyranyl-2-yloxybutanol (19 g, 10 mmol) Yield 13 g (BY0), mp llO"C, 6, (200 MHz, CDCI,, J/Hz) 0 85 (3 H, t, J 7, CH,), 1 50 (30 H, m, CH,), 3 35-3 80 (8 H, m, CH,-0), 4 52 (1 H, t, J 3, O-CH-0), 6 90 (4 H, d, J 9, Ar-H), 7 42 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 4-hydroxybutoxy) biphenyl 6b 4-Dodecyl-oxy-4 -( 4-tetrahydropyranyloxybutoxy)biphenyl ( 1 3 g, 2 8 mmol) was dissolved in wet ethanol (50ml, containing 5% water) After addition of pyridinium toluene-p-sulfonate (50 mg, 0 2 mmol) the solution was heated at reflux for 3 h Removal of the solvent zn vucuo gave a residue which was dissolved in ethyl acetate (50 ml) and washed with water, saturated aqueous sodium hydrogen carbonate, water, and brine successively After drying over sodium sulfate the solvent was evaporated and the residue was repeatedly crystallised from hexane to leave white crystals Yield 1 06 g (89%) 6b, mp 140"C, 8, (200 MHz, CDCl,, J/Hz) 0 85 (3 H, t, J 7, CH,), 150 (24 H, m, CH, ), 3 38-3 85 (6 H, m, CH,-0), 6 92 (4 H, d, J 9, Ar-H), 7 42 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 8-hydroxyoctyloxy) biphenyl 6c Prepared as described for 4a from 4'-dodecyToxybipheny1-4-01(3 54 g, 10 mmol) and 8-bromooctanol (2 3 g, 11 mmol) Yield 1 35 g (BY0), mp 127"C, (found C, 7942, H, 1028 C3,HS0O3 requires C, 79 61, H, 10 45%), 6, (200 MHz, CDCl,, J/Hz) 0 85 (3 H, t, J 7, CH,), 13-1 8 (32 H, m, CH,), 3 63 (2 H, t, J 3, CH2-0), 396 (4H, t, J 3, CH,-0), 692 (4H, d, J 9, Ar-H), 7 43 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 1 l-hydroxyundecyloxy) biphenyl 6d Pre-pared as described for 4a from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and ll-bromoundecanol (2 76 g, 11 mmol) Yield 28g (55%), mp 131"C, (found C, 7968, H, 1053 C3sHs603 requires C, 80 09, H, 10 76%), 6, (200 MHz, CDCl,, J/Hz) 088 (3H, t, J 7, CH,), 13-1 8 (38H, m, CH,), 369 (2H, t, J 3, CH2-O), 402 (4H, t, J 3, CH,-0), 698 (4H, d, J 9, Ar-H), 7 49 (4 H, d, J 9, Ar-H) Preparation of the trimesogens 7.l,3,5-Tris[3-(4'-dodecyloxybiphenyl-4-yloxy)propoxy-methyllbenzene, 7a Prepared as described for 5a from 4- dodecyloxy-4 -(3-hydroxypropoxy) biphenyl 6a (0 82 g, 1 9 mmol) and 1,3,5-tris(bromomethyl)benzene (021 g, 0 6 mmol) Yield 97 mg (12%), transitions/"C K 9 Sx 115 SA 133 I, (found C, 79 31, H, 9 18 Cy0H,260y requires C, 79 94, H, 9 4O%), 6, (200 MHz, CDCI,, J/Hz) 0 78 (9 H, t, CH,), 120-1 72 (60H, m, CH,), 201 (6H, t, J 7, CH2-CCH,-CH,-O), 3 55 (6 H, t, CH2-O), 3 88 (6 H, m, Ar-0-CH,), 401 (6H, m, CH,-0), 438 (6H, s, Ar-CH,-0), 684 (12H, d, J 9, Ar-H), 710 (3H, s, J 9, Ar-H), 7 36 (12 H, d, J 9, Ar-H), m/z 1352 (M', 20%) 1,3,5-Tris[4-( 4'-dodecyloxybiphenyl-4-yloxy)butoxymethyll-benzene, 7b Prepared as described for 5a from 4-dodecyloxy- 4'-(4-hydroxybutoxy)biphenyl6b(0 15 g, 0 35 mmol) and 1,3,5- tris(bromomethy1)benzene (0035 g, 0 1 mmol) Yield 15 mg (11?40), transitions/"C K 7 Sx 131 S, 141 I, (found C, 79 86, H, 9 43 C9,HI3,O9 requires C, 80 12, H, 9 55%), 8, (200 MHz, CDCl,, J/Hz) 0 86 (9 H, t, J 7, CH,), 1 24-1 79 (96 H, m, CH,), 3 45 (6 H, m, CH,-O), 3 95 (12 H, t, J 6, Ar-0-CH,), 447 (6H, s, Ar-CH,-0), 690 (12H, d, J 9, Ar-H), 720 (3 H, s, Ar-H), 742 (12 H, d, J 9, Ar-H), m/z 1560 (M', 70%) 1,3,5-Tris[8-( 4'-dodecyloxybiphenyI-4-yloxy)octyloxy-methyllbenzene, 7c Prepared as described for 5a from 4- dodecyloxy-4'-( 8-hydroxyoctyloxy) biphenyl 6c (0 58 g, 12 mmol) and 1,3,5-tris(bromomethyl)benzene (0 13 g, 0 36 mmol) Yield 56 mg (lo%), mp 109 "C, (found C, 80 26, H, 10 15 C,O~H~&, requires C, 80 71, H, 1007%), BH (200 MHz, CDCI,, J/Hz) 0 85 (9 H, t, J 7, CH,), 1 50 (72 H, m, CH,), 338-385 (18H, m, CH,-0), 440 (6H, s, Ar-CH,-0), 6 92 (12 H, d, J 9, Ar-H), 7 18 (3 H, s, Ar-H), 7 42 (12 H, d, J 9, Ar-H) l,3,5-Tris[1 1-( 4'-dodecyloxybiphenyl-4-yloxy)undecyloxy-methyllbenzene 7d Prepared as described for 5a from 4- dodecyloxy-4'-( 1 l-hydroxyundecyloxy) biphenyl 6d ( 1 04 g, 198 mmol) and 1,3,5-tris(bromomethyl)benzene (0 21 g, 0 6 mmol) Yield 81 mg (SOLO), mp 119 "C, (found C, 80 63, H, 1048% C114H1740y requires C, 81 08, H, 1039%), 6, (200 MHz, CDCl,, J/Hz) 0 86 (9 H, t, J 7, CH,), 1 24-1 79 (114H, m, CH2), 343 (6H, m, O-CH,), 395 (12H, t, J 6, Ar-0-CH,), 447 (6H, s, Ar-CH,-0), 691 (12 H, d, J 9, Ar-H), 7 20 (3 H, s, Ar-H), 7 43 (12 H, d, J 9, Ar-H), m/z 1688 (M', 6%) This work was supported by the Deutsche Forschungs-gemeinschaft and the Fonds der Chemischen Industrie References H Ringsdorf, B Schlarb and J Venzmer, Angew Chem ,1988,100, 1 and references therein Examples for the combination of discotic rigid units and oligooxy- ethylene chains N Boden, R J Bushby and C Hardy, J Phys Lett, 1985, 46, L-325, H Zimmermann, R Poupko, Z Luz and J Billard, Liq Cryst, 1989,6, 151, V Percec, J Heck, D Tomazos, F Falkenberg, H Blackwell and G Ungar, J Chem Soc Perkin Trans I, 1993, 2799, C Piechocki and J Simon, Nouv J Chem, 1984,9,159, N B McKeown and J Painter, J Mater Chem 1994 4,1153 Examples for oligooxyethylene chains as spacers in liquid-crystal- line polymers R Duran and P Gramain, Makromol Chem , 1987, 188, 2001, R Duran, D Guillon, P Gramain and A Skoulios, J Phys (Pans), 1988, 49, 1455, H R Allcock dnd C Kim, Macromolecules, 1989, 22, 2596, V Percec and C-S Hsu, Polym Bull, 1990, 23,463, V Percec, D Tomazos, J Heck H Blackwell and G Ungar, J Chem Soc Perkin Trans 2,1994,31 G Decher and H Ringsdorf, Lzq Cryst, 1993,13,57 J Billard, Z Chem , 1986,26,25 B Luhmann and H Finkelmann, Colloid Polvm Sci, 1987, 265, 506, B Luhmann, H Finkelmann and G Rehage, Makromol Chem, 1985, 186, 1059, B Luhmann and H Finkelmann, Coll Polym Sci 1987,265, 506, M A Schafheutle and H Finkelmann, Liq Cryst, 1988,3,1369 C Tschierske, G Brezesinski, F Kuschel and H Zaschke, Mol Cryst Liq Cryst Lett 1989,6, 139 Thermotropic liquid-crystalline properties of 3-alkoxy propane- 1,2-diols H A van Doren, R van der Geest, R M Kellog and H Wynberg, Recl Traz; Chim Pays-Bas, 1990, 109, 197, C Tschierske, G Brezesinski, S Wolgast, F Kuschel and H Zaschke, Mol Cryst Lzq Cryst Lett, 1990,7, 131 (a) C Tschierske, A Lunow, D Joachimi, F Hentrich, D Girdziunaite, H Zaschke, A Madicke, G Brezesinski and F Kuschel Lzq Cryst, 1991,9,821, (b)N Pietschmann A Lunow, J Muter Chem, 1996,6(7), 1087-1098 1097 G Brezesinski, C Tschierske, F Kuschel and H Zaschke, Colloid Polym Sci, 1991, 269, 636, (c) C Tschierske, D Joachimi, H Muller, J H Wendorff, L Schneider and R Kleppinger, Angew Chem , 1993, 32, 1165, (d)F Hentrich, C Tschierske, S Diele and C Sauer, J Muter Chem, 1994, 4, 1547, (e) C Tschierske, F Hentrich, D Joachimi and H Zaschke, Lzq Cryst , 1991,9,571 10 D J Mitchell, G J T Tiddy, L Waring, T Bostock and M P McDonald, J Chem SOC,Faraday Trans 1,1983,79,975 11 F Vogtle and E Weber, Angew Chem , 1974,86,896 12 C J Pederson, J Am Chem SOC,1967,89,7017 13 C F H Allen and J W Gates, Org Synth, Coll Vol III,1955, 140 14 K Kanai, I Sakamoto, S Ogawa and T Suami, Bull Chem SOC Jpn , 1987,60,1529 15 L Horner and E H Winckelmann, Angew Chem ,1959,71,49 16 A B Padias, H K Hall, D A Tomalia and J R McConnell, J Org Chem , 1987,52,5305 17 D Demus and L Richter, Textures of Liquid Crystals, Verlag fur Grundstoffindustrie, Leipzig, 1978,G W Gray and J W Goodby, Smectic Liquid Crystals-Textures and Structures, Leonhard Hill, Glasgow, 1984 18 K Fischer, Angew Chem ,1935,48,394, 19 R Dunkel, M Hahn, B Neumann, H H Ruttinger and C Tschierske, unpublished results 20 S Diele, A Madicke, E Geissler, K Meinel, D Demus and H Sackmann, Mu1 Cryst Lzq Cryst, 1989,166,131 21 B Gallot and A Skoulios, Acta Crystallogr , 1962, 15,826 22 F Hardouin, N T Tinh, M F Achard and A M Levelut, J Phys Lett, 1982,43, L-327, J Charvolin, J Chim Phys, 1983,80, 15 23 C Tschierske, unpublished work 24 A Kobe, H-M Vorbrodt and C Tschierske, 2 Chem, 1986, 26, 33 25 K Zab, D Joachimi, 0 Agert, B Neumann and C Tschierske, Liq Cryst, 1995, 18, 489, K Zab, D Joachimi, E Novotna, S Diele and C Tschierske, Liq Cryst, 1995, 18, 631, H Budig, S Diele, P Goring, R Paschke, C Sauer and C Tschierske, J Chem SOC Perkzn Trans 2, 1995,767 26 G J T Tiddy, Phys Rep, 1980,57,1 27 C E Ruhrup, Ph D Thesis, Halle, 1971 28 C Tschierske and D Girdziunaite, J Prakt Chem , 1991,333, 135 29 C D Hurd and M A Pollack, J Am Chem Soc, 1938,60, 1908, R Riemenschneider and H J Kotzsch, Mh Chem ,1559,90,787 30 0 Mitsunobu, Synthesis, 1981, 1 31 V van Rheenen, R C Kelley and D F Cha, Tetrahedron Lett, 1976, 1973 Paper 5/07606D, Received 22nd November, 1995 1098 J Mater Chem, 1996, 6(7), 1087-1098

ISSN:0959-9428    

DOI:10.1039/JM9960601087

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Poly [oxymethylene-oligo (oxyethylene)] network electrolytes Shao-Min Mai Robert A. Colley Jane H. Thatcher Frank Heatley Peter M. Budd* and Colin Booth Manchester Polymer Centre and Department of Chemistry University of Manchester Manchester UK M13 9PL Poly [oxymethylene-oligo(oxyethy1ene)l s have been prepared with a proportion of the chain units having pendant unsaturated groups Radical chemistry was used to crosslink either the polymers alone or mixtures of the polymers with LiClO Swelling and tensile measurements were used to determine the extent of crosslinking and differential scanning calorimetry and dynamic mechanical thermal analysis to determine glass transition and melting temperatures Conductivities of network-salt mixtures were measured by ac impedance spectroscopy The conductivities and thermal properties of crosslinked and uncrosslinked materials were essentially identicalIonically conducting polymer electrolytes based on lithium .salts and high-molar-mass poly(oxyethy1ene) (POE) have been studied extensively over the last two decades Unplasticised POE electrolytes have low conductivities at ambient tempera- ture (e g o< S cm ' at 25 "C) and a number of modified polymer-salt systems with relatively high ambient-temperature conductivities (o<10-5-10-4 S cm-' at 25 "C) have been developed the work has been well reviewed' One such polymer is poly[oxymethylene-oligo(oxyethy1ene)l (POMOE) The repeat unit is -OCH2(0CH20CH2),- where n an average value over a narrow distribution of oxyethylene sequence lengths is typically in the range 4-20 Starting from polyethylene glycol 400 (PEG400 n z9 l),poly-mers of number-average molar mass greater than 100000 g mol -'have been prepared corresponding to chains containing on average about 200 repeat units The oxymethylene groups (acetal groups) which link the oxyethylene sequences disrupt the crystallinity With a suitably chosen value of n these polymers can be non-crystalline at room temperature and all have low glass transition temperatures i e Tg 2 -65 "C In common with other elastomers with flexible chains e g poly(dimethylsi1oxane)s and poly( phosphazene)s non-crystal- line POMOE is a soft rubber and is subject to creep The present work was directed towards removing this disadvan- tage by including sites for crosslinking along the polymer chain thereby allowing formation of a true network after mixing the polymer with the salt in the usual way It was expected that the local environment in the polymer would be unchanged by limited crosslinking and so since the conduc- tivity of a polymer electrolyte depends on local viscosity (segmental mobility) it was expected that the conductivity would not differ significantly between crosslinked and conven- tional forms of the polymer electrolytes Indeed this was our experience when working with polymer electrolytes formed from highly branched POMOE,* and also the experience of Sloop et d9who subjected conventional POMOE to UV irradiation in the presence of benzophenone and found no significant change in conductivity in polymer electrolytes on crosslinking The normal reaction used in preparing POMOE is between PEG (eg PEG400) and dichloromethane (DCM) in the pres- ence of an excess of powdered KOH It proceeds through formation of a chloroether -OCH2CH20H+CH2C12-+ -OCH,CH20CH2Cl +HCl followed by very rapid reaction of the chloroether with a second hydroxy group to form an oxymethylene link __ --OCH2CH20CH2C1+HOCH2CH2-+ -OCH2CH20CH20CH2CH2-Because of the extreme difference in reactivities of the chloromethylene and chloroether groups the polymerisation proceeds effectively as an RA2 self-condensation," yielding high-molar-mass products without need for balancing the concentrations of reagents as would be necessary to achieve high molar masses in a conventional RA2 +RB2 polycondens- ation lo Indeed the difference in reactivities is so large that the DCM can be used as the solvent for the reaction ie at a molar ratio [Cl]/[OH] x 10 (see later).Reactions starting from PEG400 or PEG200 were adapted to our present purposes by the inclusion of a diol bearing an unsaturated group In the work described below the diol used was normally 2-methylenepropane-l,3-diol(MPD) which was included in the polymerisation recipe at levels of 1-10 mol% relative to PEG One polymer was made using a second diol hexa-1,5-diene-3,4-diol (HDD) The diol residues were incor- porated statistically in the chain but had an insignificant effect on the melting point since that was determined by the dis- ordered-block structure of the linked poly(oxyethy1ene) chain.In related work Alloin and co-workers'' l3 explored poly- condensations based on the reaction of PEG with 3-chloro-2- chloromethylprop-1-ene [CCMP ClCH2C(=CH2)CH2Cl] under similar conditions to those described above This method of introducing unsaturated units has the advantage of avoiding the acetal link which is sensitive to hydrolysis in the presence of Lewis acids Enhanced reactivity of the substituted CCMP was noted,13 but the molar mass obtained with PEG400 (ca 30000 g mol ') was significantly lower than that normally obtained for PEG400 reacted with DCM Moreover the double-bond content in the polymers prepared in the present work was not fixed by the choice of PEG precursor (ie by the average oxyethylene-sequence length) as it is in the CCMP- linked systems Finally the hydrocarbon content (as distinct from oxyethylene and oxymethylene content) in DCM-linked PEG400 is low (< 1 mass%) compared with ca 13 mass% for CCMP-linked PEG400 These advantages of DCM linked polymers may well outweigh the disadvantage of the lability of their acetal links which is a significant problem only for impure systems14 or for electrolytes based on trivalent cations Notation.The notation used for the present polymers indicates the molar mass of the PEG precursor the diol (M or H) and the mol% J Muter Chem 1996 6(7) 1099-1 106 1099 of diol (relative to PEG) used in the polymerisation z e P400-M5 denotes a crosslinkable polymer prepared from PEG400 with 5 mol% MPD Conventional polymer (no MPD) is denoted by eg P400 Networks are denoted by adding the letter N e g P400-M5-N Polymer electrolytes formed from the polymers by adding LiC10 are distinguished by adding a number denoting the mole ratio (O/Li) of salt in the material e g P400-M5-N30 is a network polymer electrolyte containing LiClO at O/Li =30 Experimenta1 Preparation of polymers Polyethylene glycols PEG400 and PEG200 (Fluka AG) were dried under vacuum (10-3mmHg RT 24 h) before use Dichloromethane (DCM Fison) was purified by fractional distillation KOH (85 mass% BDH) was powdered immedi- ately before use 2-methylenepropane- 1,3-diol (MPD Aldrich) and hexa-l,5-diene-3,4-diol (HDD Aldrich) were used as received The polymerisation reaction followed the general procedures described previously For example a sample of conven-tional poly [oxymethylene-oligo (oxyethylene)] P400 was pre- pared by reacting PEG400 with an excess of dichloromethane in the presence of an excess of finely powdered KOH Finely ground potassium hydroxide (50 g) was mixed with dichloro- methane (40cm3) under nitrogen at room temperature in a resin kettle equipped with a condenser To this was added PEG400 (50 g) and the whole was stirred until the viscosity became too high (ca 30 min) More DCM (10 cm3) was added to allow stirring for a further period (ca 15 min) The polymeric mass was allowed to stand under nitrogen for a further 16 h after which it was divided and dissolved in additional dichloro- methane (1 5 dm3) and filtered through compacted diato-maceous earth Residual potassium (determined by microanalysis) after this treatment was below 0 1 mass% The rubbery polymer was isolated by rotary evaporation before finally drying on a vacuum line (12 h mmHg) and storing at low temperature in a refrigerator.Crosslinkable polymers were prepared in a similar way but with inclusion of MPD or HDD in the recipe Hydroquinone (002 mol% based on diol) was added to certain reactions as a precaution against premature crosslinking All polymers were examined by gel permeation chromato- graphy (GPC) Tke system comprised 4 p-Styragel columns (porosity 500-106A) with N N-dimethylacetamide (DMA) at 70°C as eluent at a flow rate of 1 cm3 min-l Samples were injected through a 100mm3 loop at a concentration of 2g dm-3 The emerging polymer was detected by differential refractometry The system was calibrated with eight poly(oxy- ethylene) standards covering the molar mass range 1500-106 g mol-I The elution volume of water (present as an impurity in the undried solvent) was used as flow-rate marker.One broad polymer peak was found in the GPC curves of each of the samples with little or no signal attributable to low-molar- mass cyclics The broad peaks were characteristic of conden- sation polymers z e of most probable distributions lo It was convenient to characterise a polymer by the molar mass at the peak (Mpk)and examples of the values obtained are listed in Table 1 together with corresponding values of degree of polym- erisation (DP) As can be seen high-molar-mass polymers were consistently produced from PEG400 by our procedure with lower molar masses recorded for polymers prepared from PEG200 The approximate DP values listed in Table 1 show that the low molar masses of the 200 series are not solely a result of the lower molar mass of the starting glycol but reflect a lower efficiency of the reaction with respect to chain extension The general chain structure i e alternating oxymethylene 1100 J Muter Chem 1996 6(7),1099-1106 Table 1 Conventional and crosslinkable POMOE P400 18 450 P400-MO 5 18 450 P400-M 1 06 17 430 P400-M2 18 17 430 P400 M5 35 17 430 P200 -0 54 270 P200-M5 42 0 40 200 P200-M 10 74 0 55 280 P200-H5 32 0 34 170 Too low a level to measure and oligo(oxyethy1ene) chain units was confirmed by ‘H and 13C NMR spectroscopy much as described previously l5 In the case of the crosslinkable polymers NMR was also used to verify the incorporation of unsaturated groups into the chain The following labelling scheme was used for polymers prepared with MPD -OCH20CH2CH2[OCH2CH2]n-20CH2CH20CH20 abccc cb a CH2C(=CH2)CH20-defd The assignments (with chemical shifts taken from the spectrum of sample P400-M5 0) were a b C d e f 8 467 368 362 406 - 5 16 8 954 668 704-705 682 1419 1142 Comparison of integrals gave the mole percentages of MPD residues incorporated into the chain which are listed in Table 1 A similar analysis of I3C NMR spectra was carried out for the polymer prepared with HDD the chemical shifts of the carbons in the unsaturated side groups being 6 133 8 (-CH=) and 6 118 4 (=CH2) As can be seen 100% incorporation of diol into the polymer was not achieved but the proportion was generally high.Preparation of polymer networks When necessary the inhibitor used for protection during polymerisation was removed by precipitating the polymer from solution in toluene by adding heptane The precipitated poly- mer was separated by vacuum filtration redissolved in dichloromethane and finally dried under vacuum ( lop3mmHg RT >24 h) Crosslinking reactions were carried out using benzoyl per- oxide (BPO BDH Ltd ) or a,@’-azobisisobutyronitrile(AIBN BDH) as thermal initiators or photochemically using UV radiation and benzophenone (BzPh Fison) as sensitizer BPO or AIBN were added to the polymers at approximately 50 mol% based on double bonds This reflected the expected chemistry of the reaction z e two radicals formed per initiator molecule and crosslinking by combination BzPh was added at 0 5 mass% based on polymer regardless of the double-bond content ze at about one-tenth of the concentration used by Sloop et a/’ This was intended to reduce crosslinking by hydrogen abstraction from saturated chain units relative to crosslinking uza the unsaturated groups For the examples reported here all involving polymers based on PEG200 this concentration of BzPh corresponded to 5-15 mol% based on double bonds reflecting its role as a sensitizer rather than a primary source of radicals.Preliminary experiments served to define satisfactory con- ditions for crosslinking with the observation of limited swelling with retention of shape of a sample immersed in water being used as a simple indicator of formation of a satisfactory network. Crosslinking with AIBN was more satisfactory than that with BPO and that initiator was used for thermally initiated crosslinking in subsequent work In the experiments a solution of polymer (15 g) and the required quantity of AIBN or BzPh in dry acetonitrile (10 cm3) was poured into a PTFE dish under dry nitrogen and the solvent slowly evapor- ated to form a thin film (ca 1mm) before finally drying extensively in vacuum For thermal crosslinking films were heated to 70 "C under dry nitrogen for 24 h while for photoch- emical crosslinkingfilms were exposed under dry nitrogen to UV radiation from a Spectroline R-51/F (short wave UV 140 W) lamp at a distance of between 15 and 20 cm from the films for the same time period Films were turned once during exposure to promote an even cure.Polymers with no unsaturation (P400 P200) and that prepared from HDD (P200-H5) were not thermally crosslinked under the conditions employed All polymers (with or without unsaturation) could be crosslinked by UV radiation in the presence of BzPh but crosslinking was much improved if unsaturation was present For example polymer P200 was not crosslinked after exposure to the UV radiation for 72 h (I e soluble in water) and was poorly crosslinked after 96 h (I e highly swollen in water with loss of shape) On the other hand polymer P200-M5 was adequately crosslinked after exposure for 24 h (I e limited swelling in water with retention of shape) Network polymers in the form of swollen gels were exam- ined by NMR spectroscopy Swelling with CDCl resulted in slow degradation of the network presumably a result of acid- catalysed hydrolysis of the acetal links Swelling with D,O gave long-term stable systems Attention was focused on the resonances assigned to =CH eg at 6 117 for MPD-crosslinked systems (note 6 114 in CDC1,) The integral of this resonance was much decreased after crosslinking but typically a small fraction of double bonds (<20%) remained Preparation of polymer electrolyte networks Polymer electrolytes were prepared from samples (purified if necessary see above) which were dried extensively The salt was anhydrous LiC10 (Aldrich) dried by heating under high vacuum (10 mmHg 50 "C 48 h) immediately before use Acetonitrile yas heated to reflux and distilled from molecular sieve type 4A 4-8 mesh All operations were carried out in a dry nitrogen atmosphere in a dry box The procedures for film formation from the polymer-LiC10,-initiator solution In acetonitrile and its subsequent crosslinking followed those described above Polymer electro- lytes with mole ratios O/Li=30 and 50 were prepared for the samples based on PEG400 while a wider range of salt concen- trations (O/Li =10-100) was investigated for the samples based on PEG200 The O/Li ratio was calculated for all oxygens in the chain O/Li mole ratios in the range 25-50 (depending on temperature) are known to give maximum conductivities in the P400-LiClO system l6 Tensile properties .A strip of known area of cross-section was clamped at its upper end and suspended vertically in a constant temperature (+ 1 "C) enclosure Stress-strain measurements were made at 25 or 30 "C z e above the melting range The undeformed length between marks was determined before weights were clamped to the lower end of the strip and the strain (1 ratio of deformed to undeformed length) was measured over a range of applied stress for increasing load A steady reading was achieved after cu 20 min Selected samples were measured with both increasing and decreasing load in order to verify that equilibrium was achieved under the conditions employed Swelling Weighed strips of the network polymers were immersed in water at 25 "C for 3 days before removing surface drying and reweighing.Approximate volume fractions of water in the swollen gel were calculated from the densities of water and liquid poly(oxy- ethylene) at 25 "C (p=1 1g cm-,) Differential scanning calorimetry A Perkin-Elmer DSC-4 instrument was used A sample of polymer or polymer electrolyte (ca 10mg) were dried under vacuum sealed into aluminium pans under dry nitrogen and cooled rapidly (quenched) in the calorimeter to -100°C Starting at this temperature the sample was heated at +10°C min-' to 100 "C The samples were then quenched from +100 to -100°C and re-heated at +1O"C min-l Melting and glass-transition temperatures were obtained from the DSC curves as the temperature at the melting peak and the mid- point of the inflection respectively The correction for thermal lag at the heating rate used was -2"C as determined by experiments on standards at various heating rates Calibration of the power and temperature scales was with pure indium The temperature scale was checked in the temperature range of interest either by melting organic standards or against a sample of POMOE (P400) with established properties Dynamic-mechanical-thermal analysis Dynamic-mechanical-thermal analysis (DMTA) was carried out by means of a Polymer Laboratories MKII DMTA instrument used in the shear-sandwich mode Samples (ca 4mm diameter 1 mm thick) were cooled to -lOO"C and measurements of complex shear modulus (G") were made at frequencies in the range 0 3-50 Hz whilst heating from -50 to +100"C in steps of 5 "C allowing 10 min for equilibration at each temperature Samples were clamped at low tempera- tures to counteract shrinkage but were not further adjusted during heating which meant that values of log,,(G*/Pa) at the higher temperatures were known only to +O 3 Pa as judged by replicate measurements At low temperatures the modulus approached the limit of measurement for the instrument in the geometry used (z e G* z lo8 Pa) which meant that Tg could not be determined by our DMTA technique Conductivity Conductivities of solutions of LiC10 in selected polymers were determined over a range of temperatures (20-80 "C) by ac impedance spectroscopy A Schlumberger Model 1260 impedance/gain phase analyser was used over a frequency range of 5 Hz to 15 MHz The resistance was obtained as the point where the extrapolations of the semicircle and the inclined spike cut the real impedance axis A dried film was sandwiched between two gold-plated brass electrodes and held in place by springs within a cylindrical glass cell This operation took place under a dry nitrogen atmosphere The assembled cell maintained under a slight positive pressure of dry nitrogen was placed in a temperature-controlled oven (Buchi Model TO-51 & 1 "C) The temperature (measured by a thermocouple to lfI0 1 "C) was raised to 80 "C and resistances were deter- mined at several temperatures on cooling from 80 to 20°C About 20 min was allowed for thermal equilibration at each temperature of measurement Film thickness was monitored at all times either by means of a travelling microscope (+O 001 cm) or by mounting a Schlumberger SM3 linearly variable differential transducer (& 0 0001 cm) in parallel with the electrodes The conductivities were obtained from the resistance measurements using cell constants determined from the electrolyte thicknesses and electrode areas in each case J Mater Chern 1996 6(7),1099-1106 1101.Results and Discussion The results described below are for polymers based on PEG400 which were thermally crosslinked and for polymers based on PEG200 which were photochemically crosslinked This separa- tion of technique and polymer type had no particular signifi- cance In part it arose because photochemically crosslinked P400 (our notation) and related polymer-salt mixtures had been studied by Sloop et UE' Our own experiments designed to crosscheck our results (eg on photochemically crosslinked P400-M5) gave consistent results. Characterisationof networks by mechanical properties The tensile properties of several polymer networks were investi- gated in this way Polymer electrolyte networks were too hygroscopic to study by our technique which did not allow for a dry atmosphere As described in Section 2 4 stress-strain curves obtained for selected polymers with increasing and decreasing load showed little or no hysterisis The observation that the networks supported significant stress without creep was very satisfactory in view of the intended end-use of the materials. Plots of nominal stress (o=ratio of tensile force to unde- formed cross-sectional area) us strain function (A-A-~) for increasing load were used to obtain values of the shear modulus (G) from O=G(&3.-2) (1) Example of the plots are shown in Fig 1 and values of G are listed in Table 2 The values of G are much as expected for unreinforced crosslinked elastomers The kinetic theory of elasticity of an ideal affine network18 provided an approximate guide to the network characteristics I I I I 01 (d56 0 05 0 0 02 04 06 08 A-A-2 Fig.1 Nominal stress us strain function for POMOE networks (0) P400-MO 5-N (0)P400-Ml-N (m) P400-M2-N (G) P400-M5-N through the equations G/Pa= vkT and ~/cm-~=N,p/M (2) where v is the density of network chains (I e chains terminating in crosslinks) M is the molar mass of the network chains p is the density of the network and NAis the Avogadro constant For approximate values the density of a network was taken to be that of non-crystalline poly(oxyethy1ene) Values of the network parameters are listed in Table 2 the values of v being converted to concentration of network chains c (mol dm-3) in order to facilitate comparison with published results In fact the values of c obtained were similar to those reported previously' The present results show that low extents of crosslinking adequately support reversible elastic behaviour in these systems.The concentration of network chains (c,) is plotted against the concentration of double bonds (c=) in the precursor poly- mers (determined by NMR spectroscopy) in Fig 2 The approximation pz 1 1 g cm-3 was used for the density (see above) Because of the approximations inherent in deriving c via eqn (1) and (2) and because of the presence of unreacted unsaturated groups in the networks (see Section 22 NMR) the results in Fig 2 cannot be interpreted rigorously However within a realistic estimate of the uncertainty (the error bars in Fig 2 are _+25%) the number of network chains formed corresponds to the number of unsaturated groups introduced This is as it should be in the crosslinked systems since two unsaturated groups produce one crosslink and there are two network chains per tetrafunctional crosslink in the networks As can be seen in Table 2 the photochemically crosslinked networks based on P200 were also characterised by tensile I I 0 200 400 c,/mmol dm-3 Fig.2 Concentration of network chains (c,) us concentration of double bonds (c-) in the prepolymers determined from (0 a)mechanical properties or ( CI)from swelling The prepolymers were derived from (0)P400 and ( m 0)P200 The full line IS c =c-The error bars are f25% Table 2 Network characteristics tensile swelling network G/MPa c,/mol dm M,/g mol ha c,/mol dm AIBN P400-MO 5-N 0 052 0 021 53000 X P400-M 1-N 0 096 0 038 29000 P400-M2-N 0 17 0 067 16000 P400-M 5-N 0 28 0 11 10000 v' UV/BzPh P400-N P200-M5-N 0 14 0 42 0 056 0 17 20000 6500 v' 0 14 0 21 P200-M 10-N 0 59 0 24 4600 0 17 0 35 a J denotes swelling and retention of shape x denotes swelling and loss of shape 1102 J Muter Chem 1996 6(7),1099-1106 properties The moduli of the two sets of networks are in satisfactory correspondence as illustrated by the values of c for the two systems which are compared in Fig 2 As mentioned above sample P200-H5 proved impossible to crosslink thermally but could be crosslinked photochemically However the networks so prepared had irreproducible charac- teristics whether determined by mechanical properties or swelling Accordingly results for this system are not included in Table 2 and are not considered further Characterisationof networks by swelling .The polymer networks swelled in water the more tightly crosslinked samples swelling the least In general swelling was useful for qualitative characterisation of the polymer networks Samples which swelled and retained their shape were judged satisfactory Of the polymer networks studied in detail only the least crosslinked sample (P400-MO 5-N) failed this test (see Table 2) and even that sample (when dry) formed a satisfactory free-standing film with no detectable creep The results reported below for polymer electrolyte networks all refer to samples which had satisfactory swelling properties The highly swollen soft gels were difficult to handle and consequently the extent of swelling could not be determined with precision The values of 42 given in Table 2 are averages of a spread of results Given the extent of swelling the approximate equation for swelling of a network [eqn (3)],19 (3) was used to find the density of network chains In eqn (3) and q52 are volume fractions of solvent and network respect- ively V is the molar volume of the solvent (ca 18 cm3 mol-') and v is in cmP3 Malcolm and Rowlinson2' have shown that the parameter x for poly(oxyethy1ene)-water mixtures depends strongly on d2 eg increasing from 0 4 at q52=025 to 124 at 42=0 9 Here a constant value representative of the semi-dilute range (y=O45) was used in order to maintain comparison with other authors' Values of c determined in this way for photochemically crosslinked networks based on polymers pre- pared from PEG200 and MPD are listed in Table2 The values from swelling compare favourably with those obtained from mechanical properties a systematic difference being explicable in view of the approximations used in the treatments of the two sets of data The extents of crosslinking were similar to those reported by Sloop et al ,9 which emphasises the action of BzPh as a UV sensitizer for crosslinking via the double bonds since in the present work BzPh was added at one- tenth of the concentration used previously The results obtained for the photochemically crosslinked networks based on P200 are compared with those obtained for thermally crosslinked networks based on P400 in Fig 2 The data points for the P200 systems map well onto those for the P400 systems and are in correspondence with the line c,= c= ,consistent with crosslinking under our conditions originat- ing predominantly from the unsaturated groups Differential scanning calorimetry Thermal properties of linear POMOE and its mixtures with salts have been reported previously from both our laboratory and elsewhere The following picture has emerged for POMOE prepared from PEG4005 1621 23 The DSC curves of quenched samples of high-molar-mass polymer show a glass transition in the approximate range -60 to -65°C and complex melting behaviour in the approximate range -20 to +20 "C the latter effect being caused by premelting of unstable crystals followed by recrystallisation to a more stable form Annealing at a few degrees below T leads to a DSC curve with a single melting endotherm peaking at ca 15T7 Enthalpies of fusion measured over the full melting range are typically 50 J g-' or less indicative of an extent of crystallinity of 25-30% Addition of salt raises Tp and suppresses the rate of crystallisation leading to DSC curves of quenched samples showing cold-crystallisation exotherms above the glass trans- ition followed (at low salt concentrations only) by complex melting The extent of crystallinity is supressed on adding salt so much so that essentially complete supression is the rule at O/Li mole ratios <20-25 .The present samples based on PEG400 fit into this general picture Examples of DSC curves obtained for polymers networks and polymer electrolyte networks based on PEG400 are shown in Fig 3 Examples of the values of Tg T and Af,,,H obtained are given in Table 3 Crosslinking made no significant difference to the thermal properties A similar conclusion regarding networks of POMOE prepared from PEG400 was reached by Sloop et al However Alloin et a/ l1 l2 observed a small change in Tg (ca + 6 "C) and elimination of crystallinity for their networks which was probably related to a high crosslink density in their system although their networks were not characterised The thermal properties of POMOE based on PEG200 have been investigated less extensively l4 22 Glass transitions of the high-M polymers have been located consistently in the range -60 to -65 "C Evidence of crystallinity is less consistent with limited crystallinity (eg 15% at low T) and melting at -9 "C reported5 22 on the one hand and zero crystallinity reported14 on the other The DSC curves obtained in the present work for P200 and its crosslinkable and crosslinked derivatives indicated glass transitions at or about -65 C and negligible crystallinity see Fig 4 and Table 3 for examples We speculate that this dichotomy in the crystallinity of the P200 system originates in different chain-length distributions in the various PEG200 precursors In this respect it is that crystallinities of POMOEs prepared from uniform oligoethy- lene glycols are indeed sensitive to E-sequence length in the range E3 to E In Fig 5 values of reciprocal Tp are plotted us salt concen- tration for the P400 and P200 systems.The plot also includes I I I I I PWM5 N 2 loo I 50 I 0 I 50 I 100 0a I I P4WM5 N30 J I I 100 50 0 50 100 TI'C Fig.3 DSC curves for networks and network electrolytes based on PEG400 (a) POMOE networks P400-M1 N and P400-M5-N (h) POMOE network electrolytes (with LiClO,) P400-M5-N50 and P400-M5-N30 All samples were quenched from the melt to -100 C The power scales zeros and slopes are arbitrary The temperature scale is uncorrected for thermal lag Fig.4 DSC curves for networks and network electrolytes based on PEG200 (a) POMOE networks P200-M5-N and P200-M10-N (b) POMOE network electrolytes (with LiClO,) P200-M5-N75 P200- M5-N50 P200-MSN25 and P200-M5-N10 All samples were quenched from the melt to -100°C The power scales zeros and slopes are arbitrary The temperature scale is uncorrected for thermal lag results for a high-molar-mass POMOE (Mpkz 110000) pre- pared from tetraethylene glycol (M = 194 g mol-l) here denoted P194 The results for P400 are in good agreement with others reported for P400-LiC104 systems l6 21 As can be seen within the estimated error the effect of salt on Tg is the same for all systems Dynamic-mechanical-thermal analysis Because of the low modulus of the rubbery materials the DMTA was used in its shear-sandwich mode Consequently the equipment reached its limit at dynamic moduli in the range lO7-lO8 Pa,25 which meant that Tg could not be detected Because of this limitation DSC was the preferred method of thermal analysis and DMTA was used only for selected samples Plots of storage modulus for samples P400 and P400-M1-N are shown in Fig 6 The two plots are essentially identical since the difference at high modulus (low tempera- ture) could well result from a minor difference in sample mounting at the limit of the range of the instrument The large fall in the temperature range 0-20°C is caused by the melting transition The storage modulus at 30°C was ca lo6 Pa as expected for an flexible elastomer and in keeping with the shear modulus determined at that temperature Conductivity As shown in Fig 7(a) conductivities of mixtures of sample P400 with LiC104 at constant temperature (27 "C 300 K) reached a maximum at salt concentration 0 5 g (kg polymer)-' (I e OILiw45) before falling away at high concentrations Plots of this kind have been reported previously for POMOE electrolytes based on PEG400 and a range of salts l6 21 24 The effect has been explained by competition between an increase in concentration of charge carriers and an increase in Fig.5 Reciprocal glass transition temperature us LiClO concen-tration for POMOE chains and networks (0)Linear P400 (+) linear P194 from ref 24 (A) network P400-M2-N,(V) network P400-M5-N (0)network P200-M5-N (0)network P200-M10-N polymer and network systems is seen to extend over the full temperature range examined.I I 5' -;o 0 50 100 TIT Fig. 6 DMTA curves of log,,(storage modulus) us. temperature for POMOE chains and networks (0)linear P400; (A) network P400- M2-N. The estimated uncertainty in log,,G' is k0.2. I I I I As discussed in Section 2.1 it proved difficult to prepare linear POMOE of high molar mass from PEG200 and the prepolymers used to form networks had M,,(GPC) M 50000 g mol-l. As a result polymer electrolytes based on uncrosslinked P200 were less resilient than those based on high-M POMOE (e.g.those of the P400 system) and determination of their conductivities was not attempted. No such problem was enco- untered in measuring the conductivities of the network polymer electrolytes. Examples of Arrhenius plots of the conductivities of polymer electrolytes P200-M5-N25 and P200-M 10-N25 are shown in Fig. 8(u). These are similar one to another and are similar in shape to the corresponding curves shown for P400 systems in Fig. 7(b). Comparison can also be made with results reported24 for polymer electrolytes prepared from P194 i.e. the sample of POMOE prepared from tetraethylene glycol which had a high molar mass (MPkz110000 g mol-l). This comparison shown in Fig.8(b)for conductivities measured at a given temperature (27 "C,300 K) indicates that crosslinking had little if any effect on the conductivity. Conductivities at 27 "C of network polymer electrolytes based on linear P400 and network P200-MS are compared in Fig. 9. The lower conductivities found for the P200 system (compared to the P400 system) are not a consequence of crosslinking but are consistent with previous results concern- ing the effect of E-sequence length on ionic conductivity in POMOE electrolytes. Finally conductivities at 27 "C interpolated from Arrhenius plots published by other worker^^.'^ for network electrolytes based on PEG400 are listed in Table4. Close comparison is not possible since the electrolytes were formed from different salts at different concentrations.However we note that the local viscosity the latter effect being associated with the increase in the glass-transition The network polymer electrolytes based on PEG400 were not examined in the same detail. Instead two compositions within the region of the maximum in conductivity were exam- ined i.e. O/Li=30 and 50. These results are included in Fig. 7(u) and within experimental error fall on the curve established for the uncrosslinked system. A more detailed comparison over the complete temperature range investigated is shown in Fig. 7(b) i.e. via Arrhenius plots of log loc(CT= conductivity) us. reciprocal temperature. The general form of ratio O/Li=25 (0)network P200-M5-N25; (0)network P200-MlO- these curves is similar to that found in previous ~ork.~*~~v~~ N25.(b) Log,,(conductivity) us. LiC104 concentration for POMOE Fig. 7 (a) Log,,(conductivity) us. LiClO concentration for POMOE electrolytes based on (0)linear P400; (A) network P400-M2-N; (V ) network P400-M5-N. (b) Arrhenius plots for POMOE/LiC104 electro- lytes with mole ratio O/Li=30 (0)linear P400-30; (A) network P400-M2-N30; (V ) network P400-M5-N30. The good agreement between the conductivities of the linear electrolytes based on (0)linear P194; (0)network P200-M5-N. J. Muter. Chem. 1996,6(7) 1099-1106 1105 I I4t i I I I I 0 1 2 3 chol kg-l Fig. 9 Log,,(conductivity) us LiCIO concentration for POMOE electrolytes based on (0)linear P400 (0)network P200-M5-N Table 4 Comparison of conductivities reported for network polymer electrolytes based on PEG400 ref Salt O/Li or O/Na 0/10 ’S cm 9 NaClO 15 <o 1 50 1 to 2 12 LiTFSI 15 06 30 1 present work LiClO 50 30 4 4 levels of conductivity measured in the present work compare favourably with those measured for related systems Conclusions Network POMOE electrolytes can be prepared by inclusion of unsaturated groups in the polymer chain and after mixing with salt crosslinking by radical chemistry The thermal and dynamic-mechanical-thermal properties of the polymers and the thermal properties and conductivities of the polymer electrolytes are unchanged by crosslinking but creep of the polymer electrolyte is eliminated Unsaturated groups are essential for thermally crosslinking the polymer but not for photochemical crosslinking However the presence of unsatu- rated groups improves the rate of photochemical crosslinking We thank Mr S K Nixon and Mr M Hart for help with the experimental work Financial support came from the British Council and from Trigon Packaging Systems (UK) Ltd J H T and R A C held EPSRC Research Studentships References 1 Polymer Electrolyte Reviews-1 and 2 ed J R MacCallum and C A Vincent Elsevier Applied Science London vol 1 1987 and vol 2,1989 2 J R Owen in Comprehensive Polymer Science ed C Booth and C Price Pergamon Oxford 1989 vol 2 ch 21 3 P G Bruce and C A Vincent J Chem Soc Faraday Trans 1993 89,3187 4 F M Gray Solid Polymer Electrolytes VCH New York 1991 5 J R Craven R H Mobbs C Booth and J R M Giles Mukromol Chem Rapid Commun ,1986,7,81 6 C Booth C V Nicholas and D J Wilson in ref 1 vol 2 ch 7 7 C V Nicholas D J Wilson C Booth and J R M Giles Br Polym J 1988,20,289 8 Y Pang S-M Mai K-Y Huang Y-Z Luo J H Thatcher R A Colley C V Nicholas and C Booth J Muter Chem ,1995,5 831 9 S E Sloop M M Lerner,T S Stephens,A L Tipton,D G Paul1 and J D Stenger-Smith J Appl Polym Sci 1994,53,1563 10 P J Flory Principles of Polymer Chemistry Cornell UP Ithaca 1953,ch 3 11 F Alloin J-Y Sanchez and M Armand Solid State Ionics 1993 60 3 12 F Alloin J-Y Sanchez and M Armand J Electrochem Soc 1994 141,1915 13 F Alloin C R Herrero J-Y Sanchez D Delabouglise and M Armand Electrochim Acta 1995,40 1907 14 S Besner A Vallee G Bouchard and J Prud’homme Macromolecules 1992,25,6480.15 J R Craven C V Nicholas R Webster D J Wilson R H Mobbs G A Morris F Heatley C Booth and J R M Giles Br Polym J 1987,19,509 16 S Nagae M Nekoomanesh C Booth and J R Owen Solid State Ionics 1992,53-56 11 18 17 F T Simon and J M Rutherford J Appl Phys ,1964,35,82 18 J P Quesnel and J E Mark in Comprehensive Polymer Science ed C Booth and C Pnce Pergamon Oxford 1989 p 297 19 ref 18 p 300 20 G N Malcolm and J S Rowlinson Trans Faraday Soc 1957 53,921 21 J H Thatcher K Thanapprapasr S Nagae S-M Mai C Booth and J R Owen J Muter Chem 1994,4,591 22 B-X Liao Y-M Chen C Booth and Y-Z Luo Polym Commun 1991,32,348 23 P G Bruce F M Gray J Shi and C A Vincent Philos Mag 1991,64,1091 24 M Nekoomanesh H S Nagae C Booth and J R Owen J Electrochem Soc 1992,139,3046 25 Polymer Laboratories MKIIDMTA Specification Polymer Laboratories Ltd Thermal Sciences Division Loughborough UK. 26 J F LeNest A Gandini and H Cheradame Br Polym J 1988 20,253 27 G C Cameron M D Ingham and G A Sorrie J Chem Soc Faraday Trans I 1987,83,3345 28 G C Cameronand M D Ingham,mref 1,vol 2,ch 5 Paper 5/07610B Received 22nd November 1995 1106 J Muter Chem 1996,6(7) 1099-1106

ISSN:0959-9428    

DOI:10.1039/JM9960601099

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Synthesis and characterization of organic conductors derived from (1H-pyrrol-3-y1)acetic acid esters Anh Ho-Hoang," Emmanuelle Schulz," Fabienne Fache," Giselle Boiteuxb and Marc Lemaire"" "Laboratoire de Catalyse et Synth2se Organique, Institut de Recherches sur la Catalyse, UCB-Lyon 1, CPE, 43 Bd du 11 Novembre 191 8, 69622 Villeurbanne Cedex, France bLEMPB, UCB-Lyon 1, URA CNRS 507, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France The synthesis and characterization of various poly( pyrro1e)s derived from (1H-pyrrol-3-y1)acetic acid are described. The stability and the conductivity of polymers from ester derivatives of (1H-pyrrol-3-y1)acetic acid with linear or branched alkyl chains, ether or thioether functions and polyfluorinated chains are evaluated.The electroactivity of these new conducting materials has been determined in both aqueous and organic media by cyclic voltammetry. Some of these polymers show ionoselective or enantioselective properties. Heterocyclic compounds such as pyrroles and thiophenes have given rise to great interest in the field of organic conductors,' due largely to the multiple possibilities of modification of the properties of the conductive backbone by adding chemical substituents at the p position of the heteroaromatic ring compatible with the formation of the polymer by chemical or electrochemical reaction^.^,^ The introduction of various functional groups on the het- eroaromatic ring has already permitted the polymer solu- bilit~,,~and lipophilicity to be increased,6 the formation of enantio~elective~or ionoselective* materials and polymers able to absorb microwaves9 or to exhibit catalytic properties." In this article we describe the synthesis and characterization of various poly( pyrro1e)s derived from ( 1H-pyrrol-3-y1)acetic acid.This starting material can be easily obtained in good yields'' and appears as a 'synthetic platform' of large potential interest if the corresponding derivatives are compatible with the formation of stable conducting materials. In this work we have therefore evaluated ester derivatives of ( lH-pyrrol-3-y1)acetic acid with linear or branched alkyl chains, ether or thioether functions and polyfluorinated chains. Experimental The syntheses of the different monomers studied are presented in Scheme 1.The key intermediate, ( 1H-pyrrol-3-y1)acetic acid, was syn- thesized via the thallium transposition of the corresponding acetyl derivative (Willgerodt-Kindler reaction)', starting from the pyrrole moiety which first underwent Friedel-Crafts acyl- ation at the 3 position, oriented by substitution on the nitrogen the different monomers has been optimized for each com-pound:I3 monomers 1-4 have been synthesized via a method using trimethylchlorosilane14 in 60, 60, 75 and 65% yields, respectively. The water-soluble carbodiimide deri~ative'~ [1-(3-dime thylaminopropy1)- 3 -e thylcarbodiimide hydrochloride] was used to prepare esters 5-7 in 30, 35 and 41% isolated yields, respectively. General procedure with trimethylsilylchloride reagent To a solution of 1 g (8 mmol) of (1H-pyrrol-3-y1)acetic acid in 20 ml tetrahydrofuran (THF) were added sequentially 24 mmol of the appropriate alcohol and 0.5 ml (4 mmol) of trimethyl- silylchloride. After 5 h stirring at room temperature, the solvent was evaporated. The residue was extracted with CH2C12 and this organic phase was washed with water and then dried over MgSO,.Purification was performed over SiO, (Et,O). (1H-Pyrrol-3-y1)acetic acid hexyl ester, 1. Yield 60%; 'H NMR (200 MHz, CDCl,) 6: 8.55 (NH), 6.7 (m, 2 H, H,, H5), 6.1 (m, 1 H, H4), 4.1 (t, 2H, J=6.7Hz, OCH,R), 3.5 (s, 2H, CH,CO), 1.3-1.6 (m, 8 H, CH,), 0.9 (t, 3 H, J=6.5 Hz, CH,); I3C NMR (50 MHz, CDC1,) 6: 173.1 (CO), 118.1 (C2), 116.6 (C'), 115.2 (C')), 108.8 (C4), 64.8 (OCH,), 32.8, 31.4, 28.5, 25.4, 22.5 (CH,), 14 (CH,); IR v/cm-': 3397, 2956,2871, 1730, 1071; HRMS: Calc.209.1415; Found 209.1410. (1H-Pyrrol-3-y1)acetic acid 2-methylbutyl ester, 2. Yield 60%; 'H NMR (200 MHz, CDC1,) 6: 8.6 (NH), 6.7 (m, 2 H, H,, H5), 6.3 (m, 1 H, H4), 3.9 (m, 2 H, OCH,), 3.5 (s, 2 H, atom with a tosyl group. Subsequent esterification to afford CH,CO), 1.1-1.7 (m, 3 H), 0.9 (d, 3 H, J=6.8 Hz, CH,), 0.85 (t, 3 H, J =6.8 Hz, CH,); I3C NMR (50 MHz, CDCl,) 6: 173 (CO), 118.2 (C2), 116.7 (C5), 115.1 (C')), 108.8 (C4), 69.3 esterification (OCH,), 34.1 (CH), 33.1 and 26 (CH,), 16.3 and 11.2 (CH,); Q4steps, floH~ moRIR v/cm-': 3397, 2964, 2878, 1729, 1072; HRMS: Calc.I I I 195.1259; Found 195.1260: [a]k5+2.78 (c 0.94, CHCl,). H H H (1H-Pyrrol-3-y1)acetic acid 2-methoxyethyl ester, 3. Yield 75%; 'H NMR (200 MHz, CDC1,) 6: 8.4 (NH), 6.7 (m, 2 H, H,, H5), 6.3 (m, 1 H, H,), 4.3 (m, 2 H, COOCH,), 3.6 (m, 4 H, CH2CO+CH20), 3.4 (s, 3 H, CH,); I3C NMR (50 MHz, CDCl,) 6: 172.8 (CO), 118.1 (C'), 116.7 (C5),115.1 (C3), 109 (C'), 70.4 (COOCH,), 63.6 (OCH,), 58.9 (OCH,), 32.8 (CH,CO). IR v/cm-': 3392, 2932, 1734, 1163, 1099. HRMS: Scheme 1Synthesis of monomers 1-7 tested for electropolymerization Calc. 183.0895; Found 183.0890. J. Muter. Chem., 1996, 6(7), 1107-1112 1107 (123-Pyrrol-3-y1)acetic acid 2-( 2methoxyethoxy)ethyl ester, 4. Yield 65%; 'H NMR (200 MHz, CDC1,) 6: 9 (NH), 6.7 (m, 2 H, H,, Hs), 6.3 (m, 1 H, H4), 4.3 (m, 2 H, COOCH,), 3.6 (m, 8 H, CH2C0 + CH,O), 3.4 (s, 3 H, CH,); 13C NMR (50 MHz, CDCl,) 6: 173.1 (CO), 118.1 (C'), 116.8 (C'), 115 (C'), 108.7 (C'), 72.5,71.8,70.1,61.4 (OCH,), 58.8 (OCH,), 32.9 (CH,CO); IR v/cm-l: 3370, 2883, 1735, 1137, 1071.HRMS: Calc. 227.1 157; Found 227.1 160. General procedure with water-soluble diimide as reagent Alcohol (24 mmol) and 1-( 3-dimethylaminopropyl)-3-ethylcar-bodiimide hydrochloride (1.9 g, 10 mmol) were added to 1 g (8 mmol) of (1H-pyrrol-3-y1)acetic acid and 1 ml of triethyl- amine in 20ml CH3CN and stirred at room temperature for 1 day. After evaporation of the organic solvent and extraction with CH2C12, the product was purified by chromatography over SiO, (CH,Cl,). (1H-Pyrrol-3-y1)acetic acid 2-(3-methylsulfanylpropylsulfan-yl )ethyl ester, 5.Synthesis of 2-( 3-methylsulfanylpropylsu~anyl) ethanol. NaOH (5.16g, 129mmol) was dissolved in 60ml EtOH, and 13 ml(l29 mmol) of dithiol were then added. After 1 h stirring at room temperature, 4.8 ml (129 mmol) of CH31 in 10 ml EtOH were added dropwise. After 6 h stirring, 7.74 g (193 mmol) of NaOH in 50 ml EtOH were added, and after a further 15 min, 13 ml (193 mmol) of 1-chloroethanol were added. The reaction mixture was stirred at room temperature for 2 days, then heated at reflux for 1 day. The solution was extracted with Et,O, the organic phase thus obtained was washed with water, and then with NaHCO, (10Y0 in water). Purification SiO, (heptane-AcOEt, 1 : 1). Yield 50%; 'H NMR (200 MHz, CDC1,) 6: 4.2 (t, 2 H, OCH,), 2.6 (m, 6 H, CH,S), 2.1 (s, 3 H, SCH,), 1.8 (m, 2 H, CH,).Esterification. Product 5: Yield 30%; 'H NMR (200 MHz, CDCl,) 6: 8.5 (NH), 6.7 (m, 2 H, H,, Hs), 6.3 (m, 1 H, H4), 4.3 (t, 2 H, OCH2), 3.5 (s, 2 H, CH,CO), 2.6 (m, 6 H, CH,S), 2.1 (s, 3 H, CH,S), 1.8 (m, 2 H, CH,). ( 1H-Pyrrol-3-y1)acetic acid 2,2,2-trifluoroethyl ester, 6. Yield 35%; 'H NMR (200 MHz, CDC1,) 6: 6.6 (m, 2 H, H,, Hs), 6.1 (m, 1 H, H,), 4.4 (9, 2 H, JHFz8.5 Hz, CH,CF,), 3.6 (s, 2 H, CH2CO); 13C NMR (50 MHz, CDC1,) 6: 171.3 (CO), 123.1 (9, CF3, JcF=277 Hz), 118.4 (C'), 116.9 (C'), 114.3 (C'), 109 (C'), 60.5 (9, OCH,, JCF=37 Hz), 32.3 (CH,CO); 19F NMR (188 MHZ, CDC13) 6: -74.2 (t, 3 F, JFH=8 HZ); IR v/cm-': 3406, 2974, 1757, 1285, 1169; HRMS: Calc.207.0507; Found 207.0506. ( 1H-Pyrrol-3-yl) acetic acid 2,2,3,3,4,4,4-heptafluorobutyI ester, 7. Yield 41%; 'H NMR (200 MHz, CDCI,) 6: 6.7 (m, 2 H, H,, H5), 6.1 (m, 1H, H4), 4.6 (tt, 2 H, JHF= 13.6, 1.3 Hz, CH,CF,), 3.6 (s, 2 H, CH,CO); 13C NMR (50 MHz, CDC1,) 6: 171.3 (CO), 120.8 (qt, JcF=286, 32 Hz, CF,), 118.4 (C2), 116.9 (C'), 115.1 (tt, J0=285, 31 Hz, CF,), 114.3 (C'), 109.2 (m, CF2), 109 (C'), 60 (t, OCH,, JcF=28 Hz), 32.4 (CH,CO); "F NMR (188 MHz, CDC13) 6: -81.4 (t, 3 F, JFH=9 Hz), -120.9 (m, 2F), -128.1 (m, 2F); IR v/cm-': 3407, 2970, 1757, 1349, 1296, 1128; HRMS: Calc. 307.0443; Found 307.0440. In order to achieve a clear comparison of the effects of the different substituents on the properties of the material, we systematically used the same conditions for the synthesis of all the polymers.The products were then compared with poly(pyr- role) itself, obtained under similar conditions. Analyses of the electrochemical properties were performed in standardized conditions, as were the evaluations of the hydrophobic/hydro- philic character. The electroactivities and stabilities of the 1108 J. Muter. Chem., 1996, 6(7), 1107-1112 polymers during cyclic voltammetry and conductivities of thick free-standing films were also determined. Electrochemical experiments were performed using a Tacussel PJT 24-1 potentiostat galvanostat, a Tacussel PIL 101T generator and a Tacussel IG 6N coulometer equipped with a BBC SE 790 recorder, an undivided three-electrode cell containing a Pt working electrode (0.7cm2), a Pt counter electrode and a saturated calomel electrode (SCE) as reference. All the solvents (Acros) were used without further purification, but the solutions were degassed by argon bubbling prior to electropolymerization or electrochemical analysis.The oxidation potentials of the monomers (EoX,,,,) were determined by cyclic voltammetry in acetonitrile containing 0.5mol dmP3 of LiC10, and a low monomer concentration (0.01 mol dm-3); a fast scan rate (500 mV s-l) was used, in order to prevent polymerization, between -0.2 and 1.4 V (us. SCE).16 The cyclic voltammetry figures obtained each show an irreversible peak corresponding to the oxidation potential of the monomers. The electropolymerization of the monomers was performed under galvanostatic conditions in propylene carbonate at room temperature with 0.1 mol dmP3 of electrolyte (LiClO,) and 0.1 mol dm-, of monomer.After polymerization, the anode was rinsed out with acetone and transferred to another three-electrode cell containing the solution of the electrolyte to be tested. Analyses of the different electroactivities (potentials and current intensities for the oxi- dation and for the reduction: E,, E,, I,, I,) and calculations of the apparent doping level were determined by cyclic vol tamme try. The apparent doping level (Y) was calculated from the amount of charge measured during the oxidation of the polymer (Qox) and the amount of charge used for the film deposition (Qd) using the relation: = C2 Qox/(Qd-Qoxll x 100 The current density for the synthesis was optimized by the obtention of several polymer films under galvanostatic con- ditions at different I values.Then the apparent doping level was determined by cyclic voltammetry. Optimized galvano- static conditions are defined as the I value for the highest Y% value. The conductivity measurements were carried out as follows. Several thick films (4-8 pm, depending on the polymer) of each polymer were synthesized using the same conditions as those chosen for the cyclic voltammetry studies. A 2 cm2 IT0 glass electrode was used as the working electrode with a deposition charge of 2 Ccrn-,. The polymer films thus obtained were washed with acetone and dried under vacuum at room temperature.Conductivities were measured with the standard four-probe te~hnique.'~ The conductivities of various electrolytic solutions were measured with a Radiometer Copenhagen CDM 83 conductivity meter. Results and Discussion Monomers bearing linear and branched (chiral ) alkyl chains (1 and 2) The oxidation potentials of monomers 1 and 2 are similar to that of pyrrole itself, determined under similar conditions (0.9 V us. SCE, compared to 0.8 V us. SCE for the naked pyrrole ring). The electroattractive effect of the carbonyl group has probably only a very small influence on the oxidation potential, owing to the methylene group which separates this function from the ring.The electrochemical characteristics of the poly- mers are given in Table 1. Introducing an alkyl ester group at the 3 position of the aromatic ring has a weak effect on the electrochemical proper- ties of the resulting polymer compared to the poly(pyrro1e) Table 1 Electrical properties of poly( pyrro1e)s substituted with alkyl ester groups optimal current Y po1ym e r density/mA cm-' E,(poly)/V(vs. SCE) Ea-EcIV Ia /I, (Yo) 1.2 0.14 1.2 0.14 itself. This is also proved by the cyclic voltammograms shown in Fig. 1. Note that poly(2) possesses an additional redox step at ca. 0.2V (us. SCE). This behaviour may be attributed to the movement of cations, in this case Li+.18 This phenomenon is known to be more pronounced for the polymers bearing chelating substituents and is described in the next paragraph.Derivatives of poly( pyrrole) with deconjugated carbonyl substituents in the third position [a-(3-pyrroly1)estersl have already been studied by cyclic voltammetry and investigated by conductivity meas~rements.'~ Their electrochemical behav- iours and their conductivities are very similar to those rep- orted for poly( 3-alkylpyrrole) compared to poly( 3-acylpyrrole) derivatives. These last materials showed poor electrical proper- ties, attributed to the conjugation between the carbonyl group and the pyrrole ring.20 The hydrophobic character of poly( pyrrole) derivatives has already been evaluated by comparison of the electroactivity determined by cyclic voltammetry in different electrolytic solu- tions in the case of p0ly(3-alkylpyrrole).~ We have therefore used the same methodology and found that the main modifi- cation induced by the alkyl ester group lies in the decrease of the hydrophilic character of the organic conductor compared to poly(pyrro1e) (Table 2; the apparent doping levels are calcu- lated by cyclic voltammetry).The electroactivity of poly( 1) and poly(2), in contrast to observations on poly (pyrrole), increases when organic solvents and organic electrolytes are used instead of water and inorganic salts. These two polymers have no electroactivity in KCI/H20 but exhibit a large apparent doping level in acetonitrile. The influence of water on the electrochemical behaviour of \ -\ Fig.1 Cyclic voltammograms of poly(1) (---) and poly(2) (-). Synthesis: propylene carbonate, 0.1 mol dm-3 LiClO,, 0.1 mol dm-3 monomer. Analysis: acetonitrile, 0.1 mol dm-3 LiClO,, 50 mV s-'. Table 2 Apparent doping level of poly( pyrrole) and its deriviatives in different electrolyte solutions electrolyte (0.1 mol dmP3) POlY (pyrrole) Y (Yo) POlY(1) Y (Yo) POlY (2) Y (Yo) H,O/KCl CH3CH/B u,NB F4 CH,CN/Bu,NCF,SO, 23 11.5 4.6 0 29.1 20.8 0 27.5 27.8 0.09 1.16 30 0.06 1.22 31 several poly (3-acylpyrroles) has been studied by cyclic voltam- metry.21 Changes in the macroscopic properties of the films, such as their electrical conductivities, have been observed. The introduction of a branched alkyl chain (and thus a chiral substituent) has little effect on the overall properties of the material compared to the polymer with a linear alkyl chain.However, considerable recent interest has been focused on the preparation of modified electrodes able to perform enantioselective recognition during an electrochemical process, in particular, the determination of enantiomeric excess or for the preparation of materials devoted to asymmetric electro- catalysis [see ref. 7(&)]. We have therefore evaluated the enantioselective properties of poly(2) by cyclic voltammetry: under such conditions, diastereoselectivity can be observed via sterical and/or elec- tronic recognition of a chiral electrolytic solution and the chiral polymeric film. We first tested poly(2) under the same conditions as described in the literature [see ref.7(c)]: our material is, however, not electroactive with enantiomerically pure camphorsulfonic acid (CSA) as the electrolyte in organic solvents. Camphorsulfonic acid is probably not sufficiently dissociated in such solvents. The conductivities of various electrolytic solutions are summarized in Table 3. The use of a 95:5 mixture of CH3CN-H20, where the polymeric film is still electroactive permits us to evaluate poly(2) with CSA (R) and (S) by cyclic voltammetry (see Fig. 2). Under these conditions, the polymer exhibits apparent Table 3 Conductivities of various electrolytic solutions measured at 20 "C electrolyte (0.1 mol dm-3) alms cm-' NaCl/H,O (100%) 12.15 LiC104/CH3CN ( 100%) 12.08 CSA (R)/CH,CN (100%) 40 x 10-3 CSA (S)/CH,CN (100%) 39.4 x 10-3 CSA (S or R)/H,O (100%) 32.8 CSA (S or R)/H20 (5%)-CH,CN (95%) 8 Fig.2 Cyclic voltammograms of poly(2) in the presence of CSA [-, (R); ---, (S)].Synthesis: as in Fig. 1. Analysis: CH3CN-H,O (95 :5), 0.1 mol dm-3 CSA, 50 mV s-'. J. Muter. Chem., 1996,6(7), 1107-1112 1109 Table 4 Electrochemical properties of poly(pyrro1e)s bearing oxyalkyl chains polymer optimal current density/mA cm E, (POlY)/V (0s SCE) POlY(3) POlY(4) 10 14 0 11 0 11 doping levels that depend on the configuration of the doping agent 21 6% for CSA (S)or 18 6% for CSA (R)as electrolytes We assume that the different doping levels obtained with the chiral electrolytes show an enantioselective behaviour of poly(2) during cyclic voltammetry The partition coefficient a (factor of enantioselective recognition, Y,/Y,) has a value of 1 16 (comparable to the values obtained for similar thiophene derivatives) 22 Such values are often reported, and are, for example, representative for the description of matenals used for enantioselective recognition in the field of chromatogra- phy 23 Poly(2) can be considered as a model for the synthesis of chiral polymers towards the preparation of modified electrodes Monomers with ether and thioether functional groups in the third position (3,4 and 5) Although tested under various conditions (e g different sol- vents, electrolytes, electrode types), the monomer 5 was unable to form polymeric films by electrochemical oxidation We assume that the thioether functional group is oxidized at a lower potential than the pyrrole ring and/or passivates the electrode to prevent the electropolymerization Conversely, oxyalkyl chains have no inhibiting effect, poly(3) and poly(4) were obtained with our standardized method The electro- chemical properties of these two polymers are described in Table4 The values of the apparent doping levels for these polymers have been determined by two methods, cyclic voltam- metry and elemental analysis, these values are in good agree- ment for poly(3), but this is not the case for poly(4), which is probably a better chelating agent for Li+ The values of oxidation potentials and apparent doping levels for these two polymers are similar to those obtained by Delabouglise and Garnier' who also studied poly( pyrro1e)s bearing oxyalkyl chains with no ester spacer groups The voltammograms obtained in our case appear to be similar to those described in their work (Fig 3) Indeed, the use of ( 1H-pyrrol-3-y1)acetic acid derivatives induces little effect on the electrochemical properties of the corresponding polymers compared to poly(pyrro1e) itself The addition of the ether functions, however, makes interesting the evaluation of the electrochemical activities of these materials Fig 3 Cyclic voltammograms of poly( pyrro1e)s bearing alkyloxy ester chains [-poly(3) poly( 411 Synthesis and analysis as in Fig 1 1110 J Muter Chem, 1996, 6(7), 1107-1112 Ea -Ec/V lalIc Y (Yo) (CV) Y (Oh) (anal calc) 0 05 117 37 36 0 05 110 32 49 in different electrolytic solutions (Table 5) The two polymers exhibit a higher electroactivity if they are used in a non-aqueous solution of organic salts Nevertheless, poly( 3) having a smaller oxyalkyl ester functional group was electroactive in both aqueous and non-aqueous media Because of the known complexing properties of oxyethylene chains, the effect of the variation of both the cation and the anion of the electrolyte on their oxidation and reduction potentials, was also studied in the case of poly(3) (Table 6) Vanation of the anion of the doping agent has little effect on the oxidation (E,) and reduction (E,) potentials of poly(3) In contrast, modification of the cation (lithium to tetrabutylammonium) induces a shielding of more than 100 mV on both E, and E,, confirming that poly(3) bearing a chelating substituent is very sensitive to the nature of the cation This effect is compatible with the complexing properties of these types of polymers for these cations and has already been observed in the cases of poly-(thiophene)s containing oxyalkyl substituents 24 Monomers containing polyfluorinated ester groups (6 and 7) Fluorinated polymers exhibit numerous original and interes- ting properties such as thermal and chemical stabilities, low toxicity, piezo- and pyro-electrical properties The synthesis of several polyfluorinated poly( thiophene)s has been described previo~sly,~~as well as the synthesis and characterization of poly( 3-trifluoroethylpyrrole) 26 The synthesis of the corre-sponding monomers was not easy and led to rather poor overall yields The use of (1H-pyrrol-3-y1)acetic acid as the starting material allows us to achieve readily the synthesis of poly(6) and poly(7) on a gram scale As observed for the alkyl or oxyalkyl ester derivatives of ( 1H-pyrrol-3-y1)acetic acid, the fluorinated chain has little effect on the polymerization of the monomers 6 and 7 The oxidation potentials of these two products [0 9 V (us SCE)]are closed to that of pyrrole itself In contrast, 3-trifluoroethyl- pyrrole has a much higher oxidation potential [1 2 V us SCE) This result illustrates the higher efficiency of the acetoxy group as spacer, as compared to the methylene group to minimize Table5 Effect of different electrolytes on the apparent doping levels of poly(3) and poly(4) electrolyte POlY(3) POlY(4)(0 1 mol dm ') Y (Yo) Y (Yo) H,O/KCl 16 3 CH,CN/Bu,NBF, 33 26 5 CH,CN/Bu,NCF,SO, 31 28 Table6 Effect of vanation of both the anion and the cation of the electrolyte on the oxidation potential (E,) and reduction potential (E,) of POlY(3) electrolyte (0 1 mol dm CH,CN) Eaa/mV E,"/mV LiClO, 130 10 LiCF,SO, 150 -30 Bu,NC10, 220 140 Bu,NCF,SO, 210 120 'vs SCE Table 7 Electrochemical properties of polymers substituted with fluorinated chains polymer poly (trifluoroethylpyrrole) POlY (6) POlY(7) optimal current density/mA cm-' Ea(poly)/V (us.SCE) Ea -Ec/V Ia lIc Y (Yo) 1.2 1.2 0.7 the effect of electron-withdrawing substituents on the oxidation potential.Table 7 shows the electrochemical properties of poly(6) and poly(7) compared to those of poly( 3-trifluoroethylpyrrole). Poly(6) and poly( 7) exhibit electrochemical behaviours which are much more similar to that of poly(pyrrole), in contrast to poly (trifluoroethylpyrrole) previously described. The oxidation potentials of poly(6) and poly(7) are lower and the apparent doping levels are higher. This is also illustrated by the compari- son of the cyclic voltammograms described in Fig. 4. Taking into account the high hydrophobic character of fluorinated chains, it is not surprising that these polymers present no electroactivity in an aqueous medium (KC1/H20).Evaluation of the conductivity and stability of the synthesized polymers The electrical conductivities (0)of thick films of the polymers and the evaluation of their electrochemical stabilities are given in Table 8. The evaluation of electrochemical stability of organic conductors is rather difficult owing to the lack of a simple and generally accepted method. We chose to evaluate this important parameter by cyclic voltammetry using thin films (200 mC cm-'). The same synthesis and cyclic voltamme- try conditions as described previously were used. Comparison of the doping level [Y(%)] before and after 400 A L/ .@ Fig. 4 Cyclic voltammograms of poly(6) (-), poly(7) (---) and poly( trifluoroethylpyrrole) (+ + +).Synthesis and analysis: as in Fig. 1. Table 8 Conductivity and stability of 3-substituted poly(pyrro1e)s decrease of Y after 400 polymer o/S cm-l voltammetric cycles (%) 50 6 6 6 9 10 12 0.60 0.15 1.10 17 0.27 0.10 1.14 25 0.26 0.05 1.12 24 Fig. 5 Cyclic voltammograms of poly(3) in LiC1-H20. Synthesis: as in Fig. 1. Analysis: H,O, 0.1 mol dm-3 LiCl, 50 mV s-'. cycles at 250 mV s-l shows that 3-substituted pyrroles exhibit a rather good stability compared to poly(pyrro1e) itself. In addition, the conductivities of polymers of 1-4 are closed to that obtained under similar conditions for poly( pyrrole). Only the polymers with fluorinated chains exhibited conductivities significantly lower than that of poly(pyrro1e).This may be ascribed to weaker interchain conductivities due to the dielec- tric properties of fluorinated chains. The stability of poly(3), which is interestingly electroactive in both organic and aqueous solution, was also evaluated in LiCl/H,O solution. In this electrolytic medium, two maxima are observed during cyclic voltammetry between -0.7 and +0.5 V (us. SCE) (see Fig. 5). The material is unstable under these conditions and a decrease of apparent doping level of 20% is observed after 20 cycles, corresponding to the damaging of the polymer above 0.1 V (us. SCE). In contrast, when only the first system ([E,= -0.13 V (us. SCE)] is used during cyclic voltammetry [-0.7 to +0.1 V (us. SCE)], a stable system is obtained and no decrease of the Y value, which reaches lo%, is observed after more than 100 cycles at 50 mV s-' (see Fig.6). Conclusion Self-supported films are obtained by electropolymerization of ( 1H-pyrrol-3-y1)acetic ester derivatives bearing linear and branched alkyl chains, ether substituents or polyfluorinated alkylchains. The new materials thus obtained have similar stabilities, demonstrated by cyclic voltammetry, to that of poly( pyrrole) itself. Most of the obtained polymers are hydro- phobic materials, except for poly(3) which is electroactive in both water and organic media because of the presence of the ether groups. Moreover, some of these polymers possess a conductivity similar to that of poly(pyrrole), synthesized under the same conditions.Chiral poly (pyrrole) derivatives with enantioselective properties towards chiral doping agents in aqueous media can be obtained using derivatives of (1H-pyrrol-3-y1)acetic acid. Poly( pyrrole) showing ionoselectivity and electroactivity in J. Muter. Chem., 1996, 6(7), 1107-1112 1111 R J Waltman, J Bargon and A F Diaz, J Phys Chem, 1983, 87,1459 P Audebert, P Aldebert, N Girault and T Kaneko, Synth Met, 1993,53,251 M R Bryce, A Chissel, P Kathirgamanathan, D Parker and N R M Smith, J Chem SOC Chem Commun, 1987,466 D Delabouglise, J Roncali, M Lemaire and F Garnier, J Chem SOC Chem Commun ,1989,475 (a) A Tallec, Bull SOC Chzm Fr, 1985, 5, 743, (b) J-C Moutet, E Saint-Aman, F Tran-Van, P Angbeaud and J-P Utille, Adv Mater , 1992, 4, 51 1, (c)M Lemaire, D Delabouglise, R Garreau, A Guy and J Roncali, J Chem SOC Chem Commun, 1988,658, (d) M Salmon, M Saloma, G Bidan and E M Genies, Electrochim Acta, 1989, 34, 117, (e) D Delabouglise and F Garnier, Synth Met, 1990,39, 117 8 9 D Delabouglise and F Garnier, Adv Mater ,1990,2,91 L Olmedo, P Hourquebie and F Jousse, Adv Mater ,1993,5,373, L Olmedo, P Hourquebie and F Jousse, Synth Met, 1995, 69, 205 10 A Deronzier, J Chim Phys ,1989,86,31 11 A Ho-Hoang, F Fache, G Boiteux and M Lemaire, Synth Met, 1994, 62, 277, M Kakkushima, P Hamel, R Frenette and J Rokach, J Org Chem, 1983,48,3214 12 A McKillop, B P Swann and E C Taylor, J Am Chem SOC, 1973,95,3340 13 A Ho-Hoang, F Fache and M Lemaire, Synth Commun, 1996, Fig.6 Cyclic voltammograms of poly(3) in an aqueous electrolyte of LiCl, between -0 7 and 0 1 V (vs SCE, 100 cycles) Synthesis as in Fig 1 Analysis as in Fig 5 14 15 26,1289 R Nakao, K Oka and T Fukumoto, Bull Chem SOC Jpn, 1981, 54,1267 J C Sheehan, J Preston and P A Cruickshank, J Am Chem SOC,1965,87,2492 both organic and aqueous media is also descnbed with (1H- pyrrol-3-y1)acetic acid denvatives Finally, the introduction of polfluorinated chains was easier from this building block, and the acetoxy group seemed to be a much more efficient spacer than the methylene group, allowing the preparation of fluon-nated materials with higher conductivities and activities We have thus shown that (1H-pyrrol-3-y1)acetic acid is a useful synthetic platform for the easy and efficient functionalis- ation of the pyrrole nng in the third position to afford new conductive materials A facile access to enantioselective, ionose- lective, hydrophilic and/or hydrophobic matenals is provided with this synthon as a building block 16 17 18 19 20 21 22 23 24 J Roncali, R Garreau, A Yassar, P Marque, F Garnier and M Lemaire, J Phys Chem ,1987,91,6706 F M Smiths, Bell Syst Tech J, 1958,37,711 G Bidan and B Ehui, J Chem SOC Chem Commun, 1989,1568 M Voigt, U Geissler, V Haase, B Voigt, M L Hallensleben and L Toppare, Synth Met, 1993,55-57,1441 G Wegner, W Wernet, D T Glatzhofer, J Ulanski, C Krohnke and M Mohammadi, Synth Met, 1987,18,1 M Voigt, N Rohde, M L Hallensleben and L Toppare, Synth Met, 1993,5557,1489 E Schulz, V Bethmont, K Fahmi, F Fache and M Lemaire, J Chim Phys, 1995,92,783 L I Anderson and K Mosbach, J Chromatogr , 1990,516,313 L H Shi, F Garnier and J Roncali, Synth Met, 1991,41-43,547, L H Shi, F Garnier and J Roncali, Solid State Commun, 1991, References 77, 811, J Roncali, L H Shi and F Garnier, J Phys Chem, 1991, 95,8983 1 2 A F Diaz and K Keiji Kanazawa, J Chem SOC, Chem Commun , 1979,635, J Roncali, Chem Rev, 1992,92,711 R Casas, A Dicko, J M Ribo, M A Valles, N F Anglada, R Bonnett, N Hanly and D Bloor, Synth Met, 1990, 39, 275, A Merz, R Schwarz and R Schropp, Adv Mater, 1992, 4, 409, T Kaneko, N Matsui, M Kamiyama and T Yaghara, Synth Met, 1993,5557,1091,J M Ribo, M Carme Anglada, J M Tura and N Ferrer-Anglada, Synth Met, 1995,72, 173 25 26 W Buchner, R Garreau, M Lemaire, J Roncali and F Garnier, J Electroanal Chem, 1990, 277, 355, A Kassmi, W Buchner, F Fache and M Lemaire, J Electroanal Chem, 1992, 326, 357, A Kassmi, F Fache and M Lemaire, J Electroanal Chem, 1994, 373,241 A Ho-Hoang, F Fache and M Lemaire, New J Chem, 1992, 16,1017 Paper 5/06893B, Received 18th October, 1995 1112 J Muter Chem, 1996, 6(7), 1107-1112

ISSN:0959-9428    

DOI:10.1039/JM9960601107

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

~~~ ~~~~~ ~ ~ N-(2,4,7=Trinitrofluorenylidene)anilines-new electron transport materials in positive charge electrophotography Masaki Matsui,"' Katsuyoshi Shibata," Hiroshige MuramatsuO and Hiroyuki Nakazumib 'Department of Chemistry, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1 1, Japan bDepartment of Applied Materials Science, College of Engineering, University of Osaka Prefecture, Sakai, Osaka 593, Japan New electron transport materials, N-( 2,4,7-trinitrofluorenylidene)-2,6-dialkylanilines,show excellent properties in positive charge electrophotography. Single-crystal X-ray diffraction analyses of two of these compounds are reported. The high solubility of N-(2,4,7-trinitrofluorenylidene)-2,6-diethylanilinescould be mainly attributed to the loss of overlap between intermolecular fluorene rings due to the bulkiness of the ethyl groups.The generation of harmful ozone during the photocopying process has been reported.' Although positive charge electro- photography, in which ozone generation is much less, can solve this problem, little is known about electron transport materials used in dual type organic photoconductors (OPCs). The properties required for electron transport materials are a stable reversible redox process, good solubility in organic solvents, high compatibility with a polymer matrix and high electron affinity. 2,4,7-Trinitrofl~orenone,~diphenoq~inones,~ butyl 9-dicyanomethylenefluorene-4-carboxylate,44H-thiopy-ran l,l-dioxides,' dicyanomethylenefluorenes,6 4-butoxycar-bonylfluoren-9-ylidenemalononitrile,7 anthraquinone and anthrone derivatives,* and azulenesg can be used as electron transport materials. In our previous report, we reported the synthesis of N-(nitrofluorenylidene) 2-substituted anilines and evaluated them as electron transport materials in positive charge electropho- tography.It was found that (i) bulky 2-substituents on the anilino moiety remarkably increased the solubility in organic solvents and compatibility with polycarbonate (PC), (ii) tri- nitro derivatives were the most soluble among di-, tri-, and tetra-nitrofluorenylidene derivatives, (iii) drift mobility of N-(2,4,7-trinitrofluorenylidene)-2-methylanilinewas found to be 5 x cm2 V-' s-', (iv) N-(2,4,7-trinitrofluorenylidene)-2-isopropylaniline showed the best features as an electron trans- port material, and (v) N-( 2,4,7-trinitrofluorenylidene)-2-alkyl-anilines were negative in the Ames test." In our continuing study on electron transport materials in positive charge electro- photography, new N-(2,4,7-trinitrofluorenylidene)di- and tri- substituted anilines have been prepared and evaluated as electron transport materials in OPC.Results and discussion Scheme 1 shows the synthesis of N-( 2,4,7-trinitrofluorenylid-ene)anilines 1-20. They were prepared by the condensation of R3 2,4,7-trinitrofluoren-9-one with substituted anilines in the pres- ence of zinc chloride in moderate to good yields. The solubility and compatibility with polycarbonate of 1-20 are indicated in Table 1.2,6-Disubstituted anilines were more soluble than the 2-monosubstituted ones (13 and 16). For the 2,6-substituents the solubility was in the order of CH3<CzH5<CH(CH3)2(7,11,16, respectively). This suggests that the more the bulky the substituent, the higher the solu- bility. Introduction of chloro, bromo and nitro groups into the para-position of the anilino moiety lowered the solubility (6, 8, 11-14). 2,4,6-Triisopropyl derivative 18 was the most soluble. Highly soluble derivatives showed high compatibility with PC. A solubility of more than 1O.Og per 100ml in chloroform was required to prepare the photoconductor at 25 "C. To investigate the reason for the high solubility and compati- bility of 2,6-dialkyl derivatives, X-ray crystallographic analyses were performed.ORTEP drawings and packing diagrams of 1 and 11 are shown in Figs. 1 and 2, respectively. Two crystallo- graphically independent molecular units were present in com- pound 11. Dihedral angles between the nitro groups or the benzene ring and the fluorene ring in compounds 1 and 11 are shown in Table 2. In both the derivatives, only the E-forms were obtained. The fluorene rings were planar. The two nitro groups at the 2- and 7-positions [C(11) and C(4) in Figs. 1 and 2, and C(34) and C(27) in Fig. 2, respectively] lie almost on the same plane, while the nitro group at the 4-position [C(9) in Figs. 1 and 2, and C(32) in Fig. 2) was not conjugated with the fluorene ring.No significant difference in dihedral angles between the anilino group and fluorene ring in 1(85.8") and 11 (78.6') was observed. However, a significant difference in interplanar spacing between adjacent fluorene rings in .1 and 11 was noticed. The interplanar spacing dn 11 was 6.46 A, which was much greater than that of 1 (3.40 A). The two ethyl groups at the 2,6-positions on the anilino moiety of 11 can act 1-20 Scheme 1 J. Muter. Chem., 1996, 6(7), 1113-1118 1113 Table 1 Solubility and compatibility with PC of N-(2,4,7-trinitrofluorenylidene)anilines comp R' R2 R3 R4 R5 solubility"/ g loom1 compatibility with PC 1 H H H H 2 89 low 2 3 c1 H H c1 H H H H 3 36 2 84 low low 4 H H c1 H 2 14 low 5 H Br H H 166 low 6 7 8 H H H H Br NO2 H H H H CH3 CH3 112 19 59 5 14 low high low 9 H Br H H 8 95 medium 10 H Br H Br 8 11 medium 11 12 13 14 15 16 17 18 19 20 H H H H H H NO2 H H H H Br H Br Br H H H H (CH3)2CH H H H H H H H H H c(CH313 C2H5 C2H5 H H Br (CH3)2CH (CH3 )2CH (CH3)2CHH H 37 15 22 37 18 90 14 42 8 49 61 86 13405 18808 43 28 31 23 high high high high high high high high high high ' " Measured in CHC1, at 25 "C TNF =2 85 g 100ml as a spacer to inhibit intermolecular interactions between adjacent fluorene rings This may also reflect the lower melting point of 11 (159-160 "C) than 1 (227-229 "C) It is concluded that the high solubility of 11 can be mainly attributed to the loss of intermolecular overlap between the fluorene planes due to the bulkiness of the 2,6-diethyl groups in the anilino moiety Fig 3 shows the construction of a dual type OPC consisting of a charge generation layer (CGL) and a charge transport layer (CTL) The photoinduced discharge curve of an OPC for a test cycle during the photocopying process is depicted in Fig 4 The electrical potential of the photoconductor surface reaches a fixed potential by corona discharge (6 kV), followed by dark decay (2 s) Upon irradiation (780 nm, 1 pW cm 2), the poten- tial decreases The properties of the OPCs are evaluated using the following parameters (1) charge acceptance (V,/V),(11) dark decay ratio (DDR) [(V,-V,)/V,] x loo%, (iii) sensitivity (Elj2) [tl/2 s x light intensity (pJ ~m-~)]and (iv) residual potential (V,/V) For an OPC of practical use, V, should be in the range a 600-800 V DDR >90%, <0 50 p.J cm and V, <50 V Highly compatible N-(2,4,7-trinitrofluorenylidene)anilines with PC were evaluated as electron transport materials in electrophotography The results are listed in Table 3 For the 2-isopropyl derivatives 13 and 14, the introduction of a bromine atom into the anilino moiety was disadvantageous to the properties A similar result was observed for 2,6-diethyl deriva- tives 11 and 12 Interestingly, 2- and 2,6-isopropyl derivatives 13 and 16 showed better properties than the most soluble 2,4,6-triisopropyl derivative 18 It is concluded that only 2,6- dialkyl derivatives 7, 11 and 16 show as good features as 2- isopropyl derivative 13 Experimenta1 Instruments Melting points were measured with a Yanagimoto MP-S2 micro melting point apparatus NMR spectra (CDC1, solution) were recorded on JEOL 270-GX and a-400 spectrometers using a tetramethylsilane as an internal standard J Values are in Hz Mass spectra (70 eV, EI) were measured with Shimadzu QP-1000 and 9020-DF spectrometers UV spectra were taken on a Shimadzu UV-160A spectrometer Fig.1 (a) Packing diagram of tnnitrofluorenylidene aniline 1 Column Synthesis of N-(2,4,7-Trinitrofluorenylidene)anilines1-20 view along the b axis Interplanar spacing of adjacent fluorene nngs between two symmetry operations (x,y,z) and (x,l +y,z) (b) ORTEP To the appropriate aniline (10mmol) were added 2,4,7-trinitro- view of tnnitrofluorenylidene aniline 1 fluorenone (5 mmol) and zinc chloride (0 1 g) and the mixture 1114 J Muter Chern, 1996, 6(7), 1113-1118 Fig.2 (u) Packing diagram of N-(2,4,7-trinitrofluorenylidine)-2,6-diethylaniline11. Column view along the c axis. Interplanar spacing of adjacent fluorene rings between two symmetry operations (x,y,z)and (~$1 +z). (b) ORTEP view of 11 showing the two independent molecules in the unit cell. Table 2 Dihedral angles (") between the nitro groups or the benzene ring and the fluorene ring" in compounds 1and 11 1 11 O(l)-N(2)-0(2) 13.5 O(l)-N(2)-0(2) 0(3)-N(3)-0(4) 48.5 0(3)-N(3)-0(4) 0(5)-N(4)-0(6) 10.3 0(5)-N(4)-0(6) benzene ringb 85.8 benzene ringb 15.1 0(7)-N(6)-N(8) 14.7 27.9 0(9)-N(7)-0( 10) 21.1 9.4 O(l1)-N(8)-O(l2) 4.0 78.6 benzene ringb 78.4 a C1 -C2- C3-C4- C5 -C6- C7- C8 -C9- C10- C11 -C12- C13 and C24- C25-C26 -C27- C28 -C29- C30- C3 1 -C32- C33 - C34- C35-C36.C 14- C 15 -C 16- C17 -C18-C19 and C37- C38 -C39- C40- C41- C42. J. Muter. Chem., 1996, 6(7), 1113-1118 1115 CTL II substrate (Al) Fig. 3 Construction of an OPC 8 I charge ; darkdecay ; exposure I I vR II 0 2.0 3.5 t/s Fig. 4 Photoinduced discharge curve of an OPC during a test cycle Table 3 Evaluation of N-(2,4,7-trinitrofluorenylidene)anilinesas elec- tron transport materials 7 643 93 0.30 49 11 603 93 0.30 42 12 774 98 0.44 125 13 608 93 0.30 41 14 701 96 0.40 71 15 662 95 0.38 53 16 621 97 0.38 41 17 690 94 0.50 118 18 722 97 0.56 176 19 868 99 0.42 120 20 678 96 0.78 220 was heated at 150-170°C.After the reaction was complete, the product was extracted with chloroform, purified by column chromatography, and crystallised from chloroform-hexane. Physical and spectral data are shown below. N-( 2,4,7-Trinitrofluorenylidene)aniline 1. Yield 73YO;mp 227-229 "C (lit.," 224-225 "C). N-( 2,4,7-Trinitrofluorenylidene)-3-chloro-2-methylaniline2. Yield 92%; mp 206-208 "C (Found: C, 54.4; H, 2.3; N, 12.7. C20HllCIN406requires C, 54.75; H, 2.53; N, 12.77%); 6, 2.24 (3 H, s), 6.75 (1 H, d, J7.8), 7.22-7.30 (1 H, m), 7.42 (1 H, d, J7.8), 7.73 (1 H, d, J2.0), 8.32 (1 H, d, J8.8), 8.40(1 H, dd, J 8.8 and 2.0), 8.98 (1 H, d, J 2.0), 9.14 (1 H, d, J 2.0); m/z 438 (M', 100%); &,,(CHCI,)/nm 281 (&/dmW3 mol-'cm-' 3 1 000), 330 ( 15000). N-(2,4,7-Trinitrofluorenylidene)-~chloro-2methy~an~ine3.Yield 58%; mp 217-218°C (Found: C, 54.6; H, 2.4; N, 12.7. C20HllC1N406requires C, 54.75; H, 2.53; N, 12.77%); 6, 2.18 1116 J. Mater. Chem., 1996,6(7), 1113-1118 (3 H, s), 6.77 (1 H, d, J 7.7), 7.32 (1 H, d, J 7.7), 7.42 (1 H, s), 7.81 (1 H, d, J2.2), 8.33 (1 H, d, J8.6), 8.41 (1 H, dd, J8.6 and1.8),8.97(1H,d,J2.2),9.12(1H,d,J1.8);m/z438(M', 100%); &,(CHCl,)/nm 280 (~/dm-, mol-' cm-' 30000), 328 (15 000). N-( 2,4,7-Trinitrofluorenylidene)-5-chloro-2-methylaniline 4. Yield 34%; mp 222-223 "C (Found: C, 54.4; H, 2.5; N, 12.9.C20HllClN406requires C, 54.75; H, 2.53; N, 12.77%); 6, 2.17 (3 H, s), 6.88 (1 H, d, J 1.8), 7.30 (1 H, d, J 1.8), 7.33 (1 H, s), 7.69 (1 H, d, J2.0), 8.33 (1 H, d, J8.8), 8.42 (1 H, dd, J8.8 and 2.0), 8.98 (1 H, d, J 2.0), 9.12 (1 H, d, J 2.0); m/z 438 (M', 100%); A,,(CHCl,)/nm 281 (&/dm-, mol-' cm-' 32000), 330 (15 000). N-( 2,4,7-Trinitrofluorenylidene)-4-bromo-2-methylaniline5. Yield 30%; mp 231-233 "C (Found: C, 50.1; H, 2.4; N, 11.6. C20HllBrN406 requires C, 49.71; H, 2.29; N, 11.59%); 6, 2.21 (3 H, s), 6.72 (1 H, d, J 8.3), 7.47 (1 H, dd, J 8.3 and 1.8), 7.58 (1H,d,J1.8),7.80(1H,d,J2.1),8.33(1H,d,J8.6),8.41(1 H, dd, J8.6 and 2.1), 8.98 (1 H, d, J2.1), 9.12 (1 H, d, J2.1); m/z 484 (M'+2, 88%), 482 (M+, 100); &aX(CHC13)/nm281 (&/dm-, mol-' cm-' 31 OOO), 333 (15 000).N-(2,4,7-Trinitrofluorenylidene)-2-methyl-~nitroani~ine6. Yield 43%; mp 253-255°C (Found: C, 53.3; H, 2.3; N, 15.5. C20H11N508requires C, 53.46; H, 2.47; N, 15.59%); 6, 2.24 (3 H, s), 6.99 (1 H, d, J8.4), 7.65 (1 H, s), 8.26 (1 H, d, J8.4), 8.34 (1 H, s), 8.36-8.45 (2 H, m), 9.01 (1 H, s), 9.12 (1 H, s); m/z 449 (M', 100%); A,,,(CHCl,)/nm 289 (&/dmP3 mol-I cm-I 39 OOO), 328 (26 000). N-(2,4,7-Trinitrofluorenylidene)-2,6-dimethylaniline 7. Yield 40%; mp 192-194°C (Found: C, 60.5; H, 3.2; N, 13.2. C2,H14N406requires c, 60.29; H, 3.37; N, 13.39%);6, 2.03 (6 H, s), 7.21-7.26 (3 H, m), 7.46 (1 H, d, J 1.8), 8.31 (1 H, d, J 8.6), 8.39 (1 H, dd, J 8.6 and 1.8), 8.98 (1 H, d, J 1.8), 9.21 (1 H, d, J 1.8); m/z 418 (M', 100%); &,(CHCl,)/nm 278 (~/dm-~mol-' cm-' 30000), 327 (16000). N-( 2,4,7-Trinitrofluorenylidene)-4-bromo-2,6-dimethy~aniline 8.Yield 61%; mp 234-236°C (Found: C, 50.6; H, 2.8; N, 11.5. C21H13BrN406requires C, 50.72; H, 2.63; N, 11.27%); 6, 2.01 (6 H, s), 7.39 (2 H, s), 7.58 (1 H, d, J2.2), 8.33 (1 H, d, J8.8), 8.42(1H,dd,J8.8and2.2),8.99(1H,d,J2.2),9.18(1H,d, J 2.2);m/z 498 (M' +2,91%), 496 (M', 100); A,,(CHCl,)/nm 279 (&/dm-, mol-' cm-' 32000), 331 (17000). N-(2,4,7-Trinitrofluorenylidene)-4-bromo-2-(trifluoromethy1)-aniline 9. Yield 45%; mp 207-210°C (Found: C, 45.1; H, 1.5; N, 10.6. CzoH8BrF,N406 requires C, 44.72; H, 1.50;N, 10.43%); 6.89 (1 H, d, J 8.3), 7.59 (1 H, s), 7.82 (1 H, d, J 8.3), 8.02 (1 H, s), 8.36 (1 H, d, J 8.6), 8.44 (1 H, d, J 8.6), 9.00 (1 H, s), 9.07 (1 H, s); m/z 538 (M'+2,90"/0), 537 (27), 536 (M', 100); A,,,(CHCl,)/nm 282 (&/dm-, mol-' cm-' 36000), 326 (18 000).N-(2,4,7-Trinitrofluorenylidene)-2,4-dibromo-6-(trifluoro-methy1)aniline 10.Yield 14%; mp 224-228 "C (Found: C, 39.2; H, 1.3; N, 9.0. C20H,Br2F,N406 requires C, 38.99; H, 1.15; N, 9.09%); 6H 7.54 (1 H, s), 7.98 (1 H, s), 8.12 (1 H, s), 8.35-8.59 (2 H, m), 9.03 (1 H, s), 9.13 (1 H, s); m/z 618 (M'+4, 58%), 616 (M' +2, loo), 614 (M', 56); &,,(CHCl,)/nrn 293 (~/dm-, mol-'cm-' 19000), 326 (16000). N-( 2,4,7-Trinitrofluorenylidene)-2,6-diethylaniline 1 1. Yield 42%; mp 159-160°C (Found C, 61.6; H, 4.1; N, 12.4. Cz3H18N406requires C, 61.88; H, 4.06; N, 12.55%); 6, 1.07 (6 H, t, J 7.3), 2.35 (4 H, q, J 7.3), 7.26-7.29 (3 H, m), 7.42 (1 H, d, J 2.1), 8.31 (1 H, d, J 8.6), 8.37 (1 H, dd, J 8.6 and 2.1), 8.98 (1 H, d, J 2.1), 9.20 (1 H, d, J 2.1); m/z 446 (M+, 100%); R,,(CHCl,)/nm 279 (&/dmp3 mol-' cm-' 30000), 327 (16000).N-( 2,4,7-Trinitrofluorenylidene)-4-bromo-2,6diethylaniline 12. Yield 61%; mp 196-198 "C (Found: C, 52.8; H, 3.0; N, 10.5. C23Hl,BrN406 requires C, 52.59; H, 3.26; N, 10.67%); 6H 1.08 (6 H, t, J 7.3), 2.22-2.43 (4 H, m), 7.26 (2 H, s), 7.54 (1 H, d, J 1.8), 8.33 (1 H, d, J 8.9), 8.41 (1 H, dd, J 8.9 and 1.8), 8.99 (1 H, d, J 1.8), 9.17 (1 H, d, J 1.8); m/z 526 (M++2, loo%), 525 (29), 524 (M', 98); R,,(CHCl,)/nm 280 (&/dm-, mol-' cm-' 33OW), 330 (17000).N-( 2,4,7-Trinitrofluorenylidene)-2-isopropylaniline 13. Yield 87%; mp 184-186 "C." N-( 2,4,7-Trinitrofluorenylidene)-4-bromo-2-isopropylan~ine 14.Yield 92%; mp 185-187 "C (Found: C, 51.9; H, 2.7; N, 10.8. C2,Hl5BrN4O6 requires C, 51.68; H, 2.96; N, 10.96%); & 1.18 (6 H, d, J 6.7), 3.02-3.09 (1 H, m), 6.69 (1 H, d, J 7.9), 7.43 (1 H, dd, J7.9 and 1.8), 7.63 (1 H, d, J 1.8), 7.82 (1 H, d, J 1.8), 8.33 (1 H, d, J8.5), 8.41 (1 H, dd, J8.5 and 1.8), 8.98 (1 H, d, J 1.8), 9.11 (1 H, d, J 1.8); m/z 512 (M++2, 94%), 511 (27), 510 (M+, lW), 495 (32); &,,(CHCl,)/nm 281 (~/dm-, mol-' cm-' 31 OW), 330 (17000). N-( 2,4,7-Trinitrofluorenylidene)-2,4aibromo~-isopropyl-aniline 15. Yield 70%; mp 115-117°C (Found: C, 44.5; H, 2.1; N, 9.6.C22H14Br2N406requires C, 44.77; H, 2.39; N, 9.49%); 8H 1.25 (6 H, d, J 6.6), 2.83-2.91 (1 H, m), 7.57 (1 H, d, J 1.8)7 7.63 (1 H, d, J 1.8), 7.75 (1 H, d, J 1.8), 8.35 (1 H, d, J8.4), 8.44 (1 H, dd, J 8.4 and 1.8), 9.00 (1 H, d, J 1.8), 9.16 (1 H, d, J 1.8); m/z 592 (M'+4, 52%), 590 (M++2, loo), 588 (M', 48), 575 (21); A,,(CHCl,)/nm 283 (~/dm-~mol-' cm-' 26000), 328 (12000). N-(2,4,7-Trinitrofluorenylidene)-2,6-diisopropy~aniline16. Yield 85%; mp 149-152°C (Found: C, 63.3; H, 4.8; N, 11.9. C,,H2,N4O6 requires C, 63.29; H, 4.67; N, 11.81Y0);dH 0.94 (6 H, d, J 6.6), 1.19 (6 H, d, J 6.6), 2.65-2.74 (2 H, m), 7.30-7.36 (3 H, m), 7.41 (1 H, d, J 1.9), 8.31 (1 H, d, J 8.6), 8.37 (1 H, dd, J 8.6 and 1.9), 9.01 (1 H, d, J 1.9), 9.21 (1 H, d, J 1.9); m/z 474 (M+, loo%), 459 (82); &,,(CHC13)/nm 279 (&/dmF3 mol-' cm-' 30000), 333 (16000).N-(2,4,7-Trinitrofluorenylidene)-2,6-diisopropyl-3-nitro-aniline 17.Yield 92%; mp 238-240 "C (Found: C, 57.6; H, 3.9; N, 13.2. C25H,,N50s requires C, 57.80; H, 4.07; N, 13.48%); 6, 1.01 (3 H, d, J6.9), 1.04 (3 H, d, J6.9), 1.15 (3 H, d, J6.9), 1.22 (3 H, d, J 6.9), 2.65 (2 H, heptet, J 6.9), 3.17 (1 H, heptet, J 6.9), 7.45 (2 H, s), 7.57 (1 H, s), 8.37 (1 H, d, J 8.7), 8.86 (1 H, d, J 8.7), 9.03 (1 H, s), 9.16 (1 H, s); W/Z 519 (M+, 34%), 502 (24), 219 (100); ;1,,,(CHCl,)/nm 281 (&/dm-, mol-' cm-' 36000), 331 (17 100). N-( 2,4,7-Trinitrofluorenylidene)-2,4,6-triisopropylaniline 18. Yield 75%; mp 166-167°C (Found: C, 65.1; H, 5.2; N, 11.1.C2&&406 requires C, 65.11; H, 5.46; N, 10.85%); 6, 0.92 (6 H, d, J 6.8), 1.19 (6 H, d, J6.8), 1.37 (6 H, d, J6.8), 2.68 (2 H, heptet, J 6.8), 3.01 (1 H, heptet, J 6.8), 7.17 (2 H, s), 7.30 (1H,s),8.29(lH,d,J8.8),8.35(1H,d,J8.8),9.02(1H,s), 9.21 (1 H, s); m/z 516 (M', 87%), 501 (loo), 216 (47); R,,,(CHCl,)/nm 278 (&/dm-, mol-' cm-' 34000), 335 (17000). N-( 2,4,7-Trinitrofluorenylidene)-2,5-di-tertbutylaniline19. Yield 70%; mp 165-167°C (Found: C, 64.3; H, 4.9; N, 11.4. C,,H2,N4O6 requires C, 64.53; H, 5.22; N, 11.15Y0);BH 1.22 (9 H, s), 1.24 (9 H, s), 6.72 (1 H, d, J1.8), 7.37 (1 H, dd, J8.6 and 1.8), 7.54(1 H, d, J8.6), 7.73 (1 H,d, J 1.8), 8.31 (1 H,d, J8.6), 8.37 (1 H, dd, J8.6 and 2.4), 8.97 (1 H, d, J 1.8), 9.11 (1 H, d, J 2.4); m/z 502 (M', 61%), 487 (100); L,,(CHCl,)/nm 281 (&/dm-, mol-' cm-' 29000), 334 (18000).N-(2,4,7-Trinitrofluorenylidene)-2-[2,4-bis (trifluoromet hy1)-2,3,3,4,5,5,5-heptafluoropentyl]aniline 20. Yield 30%; mp 155157°C (Found: C, 43.2; H, 1.5; N, 7.6. C26HllF13N406 requires C, 43.23; H, 1.53; N, 7.76%); aH3.80 (2 H, s), 7.00-7.02 (lH,m),7.42-7.43(3H,m),8.13(1H,d,J2.0),8.34(1H,d, J 8.7), 8.42 (1 H, dd, J 8.7 and 2.1), 8.98 (1 H, d, J 2.0), 9.06 (1 H, d, J 2.1); m/z 722 (M+,9%), 553 (24), 403 (42), 357 (45), 312 (24), 311 (loo), 265 (44), 264 (33); L,,(CHCl,)/nm 324 (&/dm-, mol-' cm-' 14 loo), 452 (3340). X-Ray crystallographic analysis Crystals were obtained by recrystallisation from a saturated ethanol solution at room temperature.All data were collected at 23°C on a Rigaku AFC-5R diffractometer Yith graphite- monochromated Mo-Ka radiation (A=0.71069 A) in the range 6" <28 <55" of 01-28 scan mode. The three standard reflections were remeasured periodically and showed no significant dis- crepancy. Reflections having F >3a(F,) were used in the structure refinement. The structures were solved by direct method using MITHRIL', in TEXAN (TEXRAY Structure Analysis Package, 1985) crystallographic software, and refined by the full-matrix least-squares. The 16 and 12 non-hydrogen atoms in 1 and 11 respectively were assigned anisotropic thermal parameters, and others were assigned isotropic thermal parameters. There were so few reflections that it was not meaningful to refine more than a limited number of anisotropic thermal parameters.The high R-factor for compound 11 is responsible for the limited number of anisotropic thermal parameters. All the hydrogen atoms for 1 and 11 were placed in calculated positions. Crystallographic data for 1 and 11 are summarized in Table 4. Selected bond length and bond angles are shown in Table 5. Tables of atomic coordinates, anisotropic and isotropic thermal parameters, full list of bond lengths and angles have been deposited at the Cambridge Crystallographic Data Centre (CCDC). For details of the deposition scheme, see 'Instructions for Authors', J. Muter. Chem., 1996, Issue 1. Table 4 Crystallographic data for 1 and 11 1 11 formula ClJ 1ON406 C23HMN4O6 mol.wt. 390.32 446.42 crysal system monoclinic triclinic crystal sizelmm 0.9 x 0.28 x 0.03 0._4x 0.23 x 0.15 spac: group P21la P1 a/+ 12.986( 6) 12.881(6) bl+ 6.627( 7) 16.470( 7) CIA 20.747( 7) 10.455( 4) aldegrees 90.0 98.45 (4) Bldegrees 101.86(4) 90.93( 4) yldegrees 90.0 105.62( 3) VIA3 1747( 2) 2109(2)z 4 4" DJg cmP3 1.484 1.406 p/cm -1.06 0.97 no. of total reflections 3871 8278 no. of unique reflections 3684 7702 no. of observed reflections 1129 1448 [Z >3.0a(Z)] absorption correction type none none no. of refined parameters 197 325 k in w =l/(a2F, +kFO2) 0.01 0.01 final R 0.078 0.107 final R, 0.061 0.098 density range in final Amaple A-3 -0.38, 0.45 -0.39, 0.46 final shiftlerror ratio 0.01 0.09 " Two crystallographically independent molecular units were present.J. Muter. Chem., 1996,6(7), 1113-1118 1117 Table 5 Selected bond lengths (A)and bond angles (") for 1 and 11 Bond lengths (A) 1 11 C( 11-W) C( 1)-C( 13) C(l)-N(l)N( 1)-C( 14) C(4)-N(2) C(9)--N(3)C( 11)-N(4) 1 47( 1) 149( 1) 1286(9)1 44( 1) 1 49( 1) 1 53( 1) 1 48( 1) C( 1)-C(2) C( 1)-C( 13) C(l)-N(l)N( 1)-C( 14) C(4)-N(2) C(9)-N(3)C( 1 1 )-N( 4) 150(3) 157(3) 131(3)149(3) 144(3) 145(3) 146(3) C(24)-C(25) C(24)-C(36) C(24)-N(5) N(5)-C(37) C(27)-N(6) C(32)-N(7) C(34)-N(8) 1 49( 3) 152( 3) 1 30(3) 148(3) 145(3) 145(3) 143(3) Bond angles (") 1 11 C(2)-C( 1)-C( 13) 106 6(7) C(2)-C( 1)-C( 13) 108(2) C( 25)- C( 24)- C(36) 108 (2) C( 1)-N( 1)-C( 14) 117 5( 8) C( 1)-N( 1)-C( 14) 120(2) C( 24)-N( 5)- C( 37) 122( 2) Any request to the CCDC for this material should quote the 1984 (Chem Abstr, 1986, 104, 99467h), (c) K F Doessel, full literature citation and the reference number 1 145/1 H J Schlosser and W Wiedemann, Ger Offen, DE 3 135 460, March 17,1983 (Chem Abstr ,1983,99,30719~),(d) H Hasegawa, H Taniguchi and T Igawa, US Patent, US 4 296 190, October 20, Preparation of an OPC 1981 (Chem Abstr , 1982, 96, 26849r), (e)Y Kato, UK Pat Appl, The aluminized polyester film was coated with a thin charge GB 2 070 268, September 3,1981 (Chem Abstr ,l982,96,113481h),(f)T Nakazawa, K Nagahashi and T Aizawa, Ger Offen, 2 832 generation layer (CGL) of metal-free phthalocyanine using 859, February 15, 1979 (Chem Abstr, 1979, 91, 30543a),the drawbar technique N-(2,4,7-Tnnitrofluorenylidene)aniline (8)K Nagahashi and T Aizawa, Ger Offen, 2 801 914, July 27, (50g) was mixed with a chloroform-chlorobenzene (7 3) 1978(Chem Abstr , l979,90,14651h), (h)A M Horgan, US Patent solution (45 ml) of PC (5 0g) and stirred for 1 h A thin film US 4 047 949, September 13,1977 (Chem Abstr ,l978,88,81833r), (I) S Takeuchi and M Maezawa, Jpn Kokaz Tokkyo Koho, JP 74 of the resultant mixture was coated on the CGL and the resultant film was dried lo 20 548, May 25, 1974 (Chem Abstr, 1975, 82, 105207u), (1)T Furuyama, K Mori, H Komoto and K Oomura, Jpn Kokaz Tokkyo Koho, JP 73 40 850, June 15,1973 (Chem Abstr ,1974,80,Evaluation of N-( 2,4,7-Trinitrofluorenylidene)anilines as 9102u), (k) H Helmut, US Patent, US 3 287 114-3 287 123, electron transport materials in positive charge electro- November 22,1966 (Chem Abstr , 1967,66,66746~-66755~) photography 3 M Yamaguchi, H Tanaka and M Yokoyama, Denshi Shaszn Gakkar Shr, 1991,30,266 The products were evaluated as descnbed in our previous 4 R 0 Loutfy, B S Ong and J Tadros, J Imaging Scr ,1985,29,69 report lo 5 M R Detty, J A Sinicropi, J R Cowdery and R H Young, US Patent, US 5 300 385, Apnl 5, 1994 (Chem Abstr, 1994, 121, The authors are grateful to Messrs Jyuich Hirose, Tatsushi 46586r) Kobayashi and Takeshi Matsumoto of Tomoegawa Seishi Co , 6 D E Bugner, T M Kung and L J Row, US Patent, US 4 997 737, March 5,1991 (Chem Abstr ,1991,115,123848h)Ltd for evaluation of N-(2,4,7-trinitrofluorenylidene)anilines 7 D K Murti, P M Kazmaier, G DiPaola-Baranyi, C K Hsiao as electron transport matenals in positive charge electro- and B S Ong, J Phys D Appl Phys, 1987,20,1606 photography 8 B S Ong, D K Murti and B Keoshkenan, US Patent, US 4 609 602, September 2,1986 (Chem Abstr ,1986,105,235823~) 9 Sumitomochemical Co ,Ltd ,Jpn Kokai Tokkyo Koho, JP 6 055 345, March 30,1985 (Chem Abstr ,1985,103,45785~)References 10 M Matsui, K Fukuyasu, K Shibata and H Muramatsu, J Chem 1 Ozone News, 1992,20,15 Soc ,Perkzn Trans 2,1993,1107 2 (a)H Nomori and K Matsuura, Jpn Kokai Tokkyo Koho, JP 02 11 M E Taylor and T L Fletcher, J Org Chem ,1956,21,523 207 261, February 7, 1989 (Chem Abstr, 1991, 114, 218024e), 12 C J Gilmore and J Mithnl, J Appl Crystallogr ,1984,17,42 (b) S Kajiura, M Maeda, K Mizushima, M Sugiuchi and Y Nakajima, Jpn Kokaz Tokkyo Koho, JP 60 165 654, February 9, Paper 5/07229H, Received 2nd November 1995 1118 J Muter Chern, 1996,6(7), 1113-1118

ISSN:0959-9428    

DOI:10.1039/JM9960601113

出版商:RSC    

年代:1996

数据来源: RSC

摘要:

Strong optical second-harmonic generation in a chiral diaminodicyanoquinodimethane system M. Ravi," D. Narayana Rao,b Shmuel Cohen,c Israel Agranatd and T. P. Radhakrishnan"" "School of Chemistry, University of Hyderabad, Hyderabad-500 046, India bSchool of Physics, University of Hyderabad, Hyderabad-500 046, India 'Department of Inorganic Chemistry, The Hebrew University of Jerusalem, Jerusalem-91 904, Israel dDepartmentof Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem-91 904, Israel A series of amine donor-substituted dicyanoquinodimethane molecules with large calculated hyperpolarizabilities has been investigated. Molecular and crystal structure details of a prototypical system are presented. Moderate to strong phase-matched powder second-harmonic generation is observed in chiral amine-substituted compounds. The synthesis of molecules with large hyperpolarizability values, jl,and the fabrication of non-centrosymmetric crystals for quadratic non-linear optical (NLO) applications like second-harmonic generation (SHG),electro-optic modulation and optical parametric oscillation are fascinating problems in molecular materials chemistry.' Although a number of mol- ecules have been developed in recent years, very few with large p values form suitable non-centrosymmetric crystal lattices having large quadratic electric susceptibilities. Transparency in the visible range, thermal and chemical stability and phase- matchability of the SHG, which are desirable for device applications, are also not obtained in many cases.Although push-pull quinonoid systems are potential candi- dates for NLO materials, we are not aware of any demon- stration of strong SHG in crystalline materials based on such molecules. Amine-substituted dicyanoquinodimethane mol-ecules, first synthesised by a du Pont group,, are an attractive class of substrates towards this goal.3 The prototypical mol- ecule, 2-(4-dicyanomethylenecyclohexa-2,5-dienylidine)imida-zolidine [R,, R,=NH(CH,),NH in Fig. 13 was reported4 to have a very large p value of (-240+60) x esu at an excitation energy of 1.17 eV. Some related systems (unpub- Ncm;:NC nR' -N WNH H* R' = -N , R2= -N-CH-Naph3 I methylpyrrolidine was added and the solution was stirred at CH3 50 "C for 10 min.After standing for 5 h at 30 "C, the solution was cooled to 10°C and filtered to obtain 90% yield of the 6 light green compound 6,which was recrystallized from aceto- nitrile as pale yellow crystals. The relevant IR vibrational frequencies, elemental analytical data and crystal structure or mass spectral data for compounds Fig. 1 Molecules considered in this study 1-6 are provided below. J. Muter. Chem., 1996,6(7),1119-1122 1119 lished) have been mentioned in Appendix I of ref. 1. Tricyanoquinodimethane zwitterionic structures deposited as Z-type Langmuir-Blodgett films have been shown to produce strong SHG.' The crystal structures of the zwitterionic chromo- phores and new synthetic procedures for their preparation have also been reported.6 Semi-empirical quantum chemical calculations indicated that amine-substituted dicyanoquinodimethanes have large molecular hyperpolarizabilities. The calculations also indicated zwitterionic ground states with appreciable dipole moments.We have synthesised substituted dicyanoquinodimethanes (Fig. 1) with a variety of amine donors; R1=R, =pyrrolidinyl (1), and piperazinyl (2); R, =pyrrolidinyl with R,=S-a-methylbenzylamino (3), R-a-methylbenzylamino (4), S-naph-thylethylamino (5) and S-2-methoxymethylpyrrolidinyl(6).We have also prepared derivatives with R, =R, =piperidinyl, mor- pholinyl, p-toludinyl, etc., but these will not be discussed in this paper. We have investigated the powder SHG efficiency of these materials and report here the observation of moderate activity in 3 and 4 and strong activity in 6.Crystal structure determinations indicated centrosymmetric lattices in 1 and 2 and non-centrosymmetric lattices in 3 and 6.Molecular and crystal-structure characterisation of 3 and preliminary struc- tural data on 6 are presented. We believe this to be the first case of crystalline quinonoid systems which satisfy several of the requirements for useful device materials noted above.Experimental Syntheses Compounds 1 and 2were prepared using the general procedure reported in ref. 2 and 3-6 were prepared using an extension of this procedure. The following details of the synthesis of 6 provide an illustrative example. 7-P yrrolidino-7,8,8-tricyanoquinodime t hane was prepared as described in ref.2. To a warm solution of 0.10 g of this compound in 20 ml tetrahydrofuran, 0.04 ml S-( +)-2-methoxy- 7,7-Dipyrrolidino-8,&dicyanoquinodimethane, 1. Ref 2 reported the preparation of this compound FTIR (KBr pellet) v/cm-l 2175, 2130 (conjugated nitnle), 1595, no N-H vibration Elemental analysis Found (Cak for C18H2oN4) C, 74 35 (73 94), H, 6 82 (6 89), N, 18 72 (19 17) Molecular and crystal structure detFrmined space group P21/c, a= 16 473, b=8481, c=25383A, a=900, p=l052, y=899", R=O046, Rw=0081 7,7-Dipiperazino-8,8-dicyanoquinodimethane,2. FTIR (KBr pellet) v/cm-' 3150 (N-H stretch), 2180, 2140 (conjugated nitnle stretch), 1595 Elemental analysis Found (Calc for C18H22N6) C, 66 31 (67 08), H, 6 82 (6 83), N, 25 39 (26 08) Molecular and crystal structureodetermined space group Pi, u=13372, b=15614, c=8756A7 a=993, p=1056, y=971", R=O034, Rw=0061 7-Pyrrolidino-7-[(S)-a-methylbenzylamino]-8,8-dicyano-quinodimethane (MBPDQ), 3.MS(E1) m/z 342(4), 327(4), 105(76), 91(76), 77(30), 70(100) FTIR (KBr pellet) v/cmP1 3387 (N-H stretch), 2174, 2128 (conjugated nitnle stretch), 1601cm-' Optical rotation, [a]k5-395 (c 004, MeOH) Compound 3 was recrystallized from dichloromethane for elemental analysis Found (Calc for C22H22N4 H20) C, 73 13 (73 33), H, 6 22 (6 66), N, 15 26 (15 55) Crystal structure details are provided in the next section 7-Pyrrolidino-7-[ (R)-a-met hylbenzylamino]-8,8-dicyano-quinodimethane, 4.MS(E1) m/z 342( 14), 327( 17), 105(52), 91(61), 77(23), 70(100) FTIR (KBr pellet) v/cm-' 3390 (N-H stretch), 2173, 2128 (conjugated nitrile stretch), 1601 Optical rotation, [a]h5 +240 (c 0 05, MeOH) Elemental analy- sis Found (Calc for C22H2,N4) C, 77 60 (77 19), H, 6 85 (6 43), N, 15 54 (16 37) 7-P yrr olidino-7-[(S)-naph th yle thylamino] -8,&dicyano- quinodimethane, 5. MS(E1) m/z 392( 16), 377( 16), 222(8), 155(64), 141(81), 97(14), 70(100) FTIR (KBr pellet) v/cm-' 3350 (N-H stretch), 2172, 2131 (conjugated nitnle stretch), 1597 Optical rotation, Calk5+69 (c 0 05, MeOH) Elemental analysis Found (Calc for C26H24N4) C, 79 60 (79 59), H, 6 42 (6 12), N, 13 85 (1429) 7-grITolidb7- [(S)-2-methoxymet hylpyrrolidino]-8,&yano-quinodimethane (PMPDQ), 6.MS(E1) m/z 336( loo), 222(8), 181(8), 167(13), 71(24) FTIR (KBr pellet) v/cm-l 1448 (CH, -0-CH, stretch), 2170, 2129 (conjugated nitnle stretch), 1599 Optical rotation, [a];' +1687 (c 0 08, CHC1,) Elemental analysis Found (Calc for C20H24N40) C, 71 34 (71 43), H, 741 (7 14), N, 16 65 (16 67) Crystal structure details are provided in the next section Techniques The IR and UV-VIS spectra were recorded on a Jasco-5300 FTIR spectrometer and a Jasco-7800 spectrophotometer, respectively Powder SHG measurements were carried out using the Kurtz-Perry powder techniqueg with the fundamental wave- length (1064 nm) of a Q-switched Nd YAG laser The powders were graded using standard sieves and packed between glass plates The sample thickness was maintained constant by means of uniform 02mm thick Teflon sheets inserted as spacers between the glass plates Study of the SHG intensity as a function of particle size indicated that 3-6 were all phase- matchable matenals The materials showed no sign of decomposition even on prolonged irradiation with a laser power of 1 GW cmP2 (6 ns, 10 Hz) Crystal structure data were collected on an Enraf-Nonius CAD4 computer-controlled diffractometer Cu-Ka (A= 1120 J Muter Chem, 1996,6(7), 1119-1122 1 54178 A) radiation with a graphite crystal monochromator in the incident beam was used The standard CAD4 centnng, indexing and data collection programs were used The unit- cell dimensions were obtained by a least-squares fit of 24 centred reflections in the range 23 d8d 31 Atomic coordinates, thermal parameters, and bond lengths and angles have been deposited at the Cambndge Crystallographic Data Centre (CCDC) See Information for Authors, J Muter Chem, 1996, Issue 1 Any request to the CCDC for this material should quote the full literature citation and the reference number 1145/2 Results and Discussion To assess the potential of the diaminodicyanoquinodimethane systems for quadratic NLO applications, we obtained theoreti- cal estimates of their molecular hyperpolanzabilities Molecular geometries were optimised using the AM1 semi-empirical quantum chemical procedure The calculated geo- metnes were in reasonable agreement with the molecular structures obtained in the single-crystal studies descnbed below In particular, the calculations indicated strong out-of- plane twisting of the N-C-N donor groups The p values were evaluated using a sum-over-states method"? with all single and pair excitations within a manifold of twelve molecu- lar orbitals included in the configuration interaction scheme Table 1 gives the calculated ground-state dipole moments (pg),the changes in dipole moment for the lowest excitation states (Ap) and the ~,,,(O) values of the molecules 1-6 The pg values are high and indicate a strongly zwitterionic ground state Several excited states involve reverse charge-transfer leading to large, negative Ap values as seen in the case of the first excited state Stokes' shift studies based on our recently reported procedure" revealed negative solvatochromism of these molecules in support of this mechanism pveC(O)are the projections of the hyperpolarizability tensor on the major dipole axis, calculated for Jzm=O eV These static p values reported in Table 1 for 1-6 are quite large in view of the short conjugation lengths [for cornpanson, j3,,(0) of p-nitroani1inel0 is ca -9 x loP3' esu] This may arise from the large Ap contnbutions A detailed theoretical analysis12 carried out on the parent system 7,7-diamino-8,8-dicyanoquinodimethane indicates that the contribution of the first excited state to p is approximately 50% and the rest is made up of contributions from a large number of excited states, the usual p2 level approxi-mation is not quite applicable to these quinonoid molecules The Amx values of the electronic absorption bands of compounds 1-6 are all close to 400nm (Table 1) and the crystals appear light yellow or nearly colourless Therefore these materials are potentially useful for applications in the visible range where resonant absorption effects will be minimal t p values calculated using this program agree well with expenmental results, eg the calculated value of the molecule in ref 4 is -243 x 10 30 esu (ho=117 eV) Table 1 Calculated ground-state dipole moments, changes in dipole moment for the lowest excitation state and hyperpolanzabilities, expenmental absorption maxima in acetonitnle solution, melting points and powder SHG efficiencies (phase-matchable) relative to urea (ca 150 pm particles) of molecules 1-6 molecule pg/D Ap/D p,,(Op Lax/nm mp/"C SHG/U 1 141 -94 61 375 305 00 2 122 -151 60 415 300 00 3 125 -112 31 368 245 30 4 125 -112 31 368 245 32 5 132 -121 39 370 270 05 6 143 -183 66 398 290 275 "In units of esu, Calculated at fio=0 Melting points are all >245 'C (Table l), about twice those of the well known organic NLO materials.'7l3 This probably arises from the strongly zwitterionic nature of these molecules and the resultant electrostatic crystal forces.The thermal stability is relevant for poling processes and in enhancing the damage thresholds. Table 1 also provides the SHG activities of 1-6 relative to urea powder with particle sizes of ca.150 pm, which are discussed below. The dipyrrolidinyl (1)7 and dipiperazinyl (2)* derivatives gave centrosymmetric crystals (space groups P2Jc and Pi, respectively) and showed no SHG, as did the other achiral derivatives we prepared. The large pg values appear to encour- age centrosymmetric crystal-lattice formation. The chiral derivatives 3-6 were prepared with the intention of fabricating non-centrosymmetric crystal lattices. Single-crystal X-ray structure analysis of the transparent plate-like crystals of MBPDQ (3) obtained from acetonitrile solution indicated an acentric space group, P2', with two MBPDQ molecules and two solvent molecules in the unit cell. The crystallographic data are provided in Table 2.The molecu- lar structure and the unit cell view along the b axis are shown in Fig. 2. The N9-C7-N14 plane on the donor side is twisted out of the quinonoid ring plane by ca. 49.8'. This general feature is observed in all bis(dialky1amine)-substituted dicyano-quinodimethanes we have characterised structurally, and it arises from the steric repulsion between the ortho-H atoms on the quinonoid ring and the H atoms on the C atom attached to the N in the donor moiety. The bond lengths (Table 3) in the conjugation unit indicate a strongly benzenoid character resulting from the intramolecular charge transfer which is accentuated by the out-of-plane twisting of the donor group. The molecular alignments in the crystal are nearly head-to- tail, the non-centricity arising from the presence of the chiral carbon atoms alone.Powders of MBPDQ with particles of size 3150 pm showed a moderate SHG, ca. 3 times that of urea (Table 1). The particle-size dependence of the SHG inten- sity (Fig. 3) indicates that MBPDQ is a phase-matchable material. In support of this, the 3U SHG intensity is obtained in the crystals as well. The stereoisomer of 3 (i.e. 4) showed very similar linear and non-linear optical properties (Table 1); the specific choice of the configuration (R or S) therefore does not appear to be crucial. The naphthyl derivative, 5, was found to have a low SHG (Table 1). Owing to the presence of the chiral centres these systems are also expected to show non-centrosymmetric crystal lattices.However, we did not investigate their crystal structures, since their NLO properties did not show any improvement over those of 3. Since the chiral centres in 3, 4 and 5 are on a side chain, non-centrosymmetry may be attained by small bond rotations, rather than by reorientation of the molecular dipoles. Thus, deviation from a centric lattice would be small. To overcome this problem, we prepared the (S)-2- methoxymethylpyrrolidine derivative 6 (PMPDQ) where the Table 2 Crystallographic data for 3 molecular formula C22H22N4* CH3CN sp$ce group p2144 12.715( 3)bl+ 8.068 (2) CIA 10.422( 2) P/dFgrees 91.03(2) VIA3 1068.9(5) Z 2 Pcalclg cm -1.19 p (Cu-Ka)/cm-' 5.36 no. of unique reflections 2182 no.of reflections with 1220(Z) 2063 R 0.050 Rw 0.076 Fig. 2 (a)Molecular structure of 3 from single-crystal X-ray analysis; H atom of only the stereogenic centre is shown. (b)Stereoview of the unit cell of 3 along the b axis. Table3 Significant bond lengths in 3 from single-crystal X-ray analysis; the atom labellings are as shown in Fig. 2(a) bond bond length/A 1.393 1.383 1.400 1.406 1.378 1.398 1.467 1.447 1.308 1.343 1.402 1.403 1.146 1.153 chiral centre is part of one of the five-membered rings that form the donor moiety. Crystals of PMPDQ were grown from acetonitrile solution as prisms. Preliminary reflection data were indexed to the non- centric orthorhombic space group, P212121. However, structure refinement only converged to an R value of 0.1 1 (R, =0.15), though data from several crystals were tried.Our SHG studies corroborate the non-centric space group. Large intensities of ca. 25-30 U (Table 1)were obtained for powders with particle sizes 3300 pm and for crystals; the saturation of the SHG intensity at large particle sizes again indicated phase-match- ability (Fig. 3). The large SHG indicates improved alignment of the molecular dipoles; the unit-cell structure at the present state of refinement indicates near-neighbour molecules roughly J. Muter. Chem., 1996, 6(7), 1119-1122 1121 A 0 100 200 300 400 average particle size/pm Fig. 3 Powder SHG intensity (relative to urea particles of ca 150 pm size) at different particle sizes of 3 (0)and 6 (A) orthogonal to each other Note that the molecular twisting in PMPDQ (58 2") is higher than in MBPDQ The large R factor appears to result from disorders or single-bond rotations in the methoxymethyl side chain Conclusion The chiral amine donor-substituted quinonoid molecules reported in this paper open up a new class of easily synthesized compounds with moderate to strong solid-state SHG activity We note that although powder SHGs of up to 100OU have been reported in strongly coloured materials, and thin films capable of efficient SHG have been fabricated, among colour- less or lightly coloured crystalline organic compounds there are only a few which surpass the large SHG we find in this class of push-pull quinonoid systems The phase-matchability observed in these materials is particularly relevant and their thermal stability is superior to the well known crystalline materials showing strong SHG These quinonoid systems, which are mostly colourless or light yellow, are suitable candidates for the development of materials for visible-range applications Finally, the potential derivatives are innumerable and incorporation as pendant groups in polymer chains is possible We are pursuing these possibilities, as well as inclus- ion of these molecules in a variety of matrices for poling experiments We thank Dr J Chandrasekhar for providing the subroutine for hyperpolarizability calculations Financial support from the CSIR and the DST, New Delhi are gratefully acknowledged by M R and T P R respectively References Nonlinear Optical Properties of Organrc Molecules and Crystals, ed D S Chemla and J Zyss, Academic Press, New York, 1987 L R Hertler, H D Hartzler, D S Acker and R E Benson, J Am Chem SOC,1962,84,3387 M Ravi, D N Rao, S Cohen, I Agranat and T P Radhaknshnan, Curr Scz (India), 1995,68,1119 S J Lalama, K D Singer, A F Ganto and K N Desai, Appl Phys Lett, 1981,39,940 G J Ashwell, E J C Dawnay, A P Kuczynski, M Szablewski, I M Sandy, M R Bryce, A M Grainger and M Hasan, J Chem SOC Furaday Trans, 1990, 86, 11 17, G J Ashwell, G Jefferies, E J C Dawnay, A P Kuczynski, D E Lynch, Y Gongda and D G Bucknall, J Muter Chem ,1995,5,975 6 R M Metzger, N E Heimer and G J Ashwell, Mol Cryst Lzq Cryst, 1984,107, 133, J C Cole, J A K Howard, G H Cross and M Szablewski, Acta Crystallogr Sect C, 1995, 51, 715, M Szablewski, J Org Chem ,1994,59,954 7 M Raw, D N Rao, S Cohen, I Agranat and T P Radhakrishnan, unpublished results 8 M Ram, S Cohen, I Agranat and T P Radhakrishnan, Struct Chem , 1966,7,225 9 S K Kurtz and T T Perry, J Appl Phys, 1968,39,3798 10 T Clark and J Chandrasekhar, Isr J Chem B, 1993,33,435 11 M Ravi, A Samanta and T P Radhakrishnan, J Phys Chem, 1994,98,9133 12 M Ravi and T P Radhakrishnan, J Phys Chem ,1995,99,17 624 13 H L Bhat, Bull Muter Sci ,1994, 17, 1233 Paper 5/061671, Received 19th September, 1995 1122 J Muter Chern, 1996,6(7), 1119-1122

ISSN:0959-9428    

DOI:10.1039/JM9960601119

出版商:RSC    

年代:1996

数据来源: RSC