摘要:

J. MATER. CHEM., 1991, 1(4),705-706 Chemical Intercalation of Magnesium into Solid Hosts Peter G. Bruce,*" Franciszek Krok,t" Jan Nowinski," Vernon C. Gibson,*b and Kayumars Tavakkolib a Department of Chemistrx University of St. Andrews, St. Andrews, Fife KY16 9ST, UK Department of Chemistrx University of Durham, South Road, Durham DHI 3LE, UK The use of two organometallic reagents, di-rrbutylmagnesium and magnesium bis(2,6-di-tert-butylphenoxide) for the intercalation of magnesium into a range of solid hosts is investigated. New magnesium intercalation compounds based on cubic and layered TiS, are described. Keywords: Intercalation; Magnesium; Titanium disulphide The intercalation of monovalent cations into solid-state hosts has been studied widely for a number of years.This is particularly true in the case of lithium, owing in part to the availability and ease-of-use of n-butyllithium as a chemical intercalating agent.' The intercalation of divalent cations has received only limited attention; also studies to date have concentrated on materials prepared by electrochemical inter- ~alation.~,~In order to carry out structural studies on divalent intercalates by, for example, neutron diffraction, relatively large quantities of material are desirable and these are most conveniently prepared by a chemical route. It is therefore important to develop chemical routes to intercalation com- pounds with new guest ions. The intercalation of magnesium is of particular interest both because the ion is of similar size to lithium and because of the possibility of fabricating batteries based on magnesium.In this paper we report on the use of the organometallic reagents di-n-butylmagnesium [(C,H,),Mg] and magnesium bis(2,6-di-tert-butylphenoxide) (1) for the intercalation of magnesium into a variety of hosts. The intercalation compounds were prepared and handled in an argon-filled, Miller-Howe, glove box in which the H20 and O2 levels were not permitted to exceed 5 ppm. The two polymorphs of titanium di~ulphide,~,~ V60136 and A-MIIO,~ were prepared as described in the references cited. The remain- ing hosts are commercially available. V205 (Koch Light, >99Y0), W03 (Johnson-Matthey, A1 grade), y-MnO, (Aldrich, >99"/0), P-MnO, (Strem, 99.9%), MOO, (Aldrich, 99.5%).Compound 1 was prepared by the reaction of (C4H9),Mg with two equivalents of 2,6-di-tert-butylphenol in toluene.8 The crystalline phenoxide was exposed to dynamic vacuum (ca. Torrl) for 2 days in order to remove toluene of crystallization. The same experimental procedure for mag- nesium intercalation using di-n-butylmagnesium (Lithco) was used for each host. Finely powdered solid (ca. 1 g) was added to a flask containing a solution of (C4HJ2Mg in dry heptane (BDH, AnalaR). (C4H9),Mg (2 mol) was added for each mole of the host compound and the solution concentration was ca. 0.2 mol dmP3. The mixture was stirred continuously for 1 week at 30°C then filtered and the residue washed with dry heptane.In the case of the preparations carried out using the phenoxide, the solid host was added to a flask containing the phenoxide in toluene and again stirred for 1 week before removal of the solid product. As in the case of the synthesis using (C4H9)*Mg, a 2 molar excess of the phenoxide was added. Chemical analysis of the intercalates was carried out by atomic absorption measurements using a Pye Unicam SP9. The solids were dissolved in an aqueous mixture of HC1 and ~ ~~ ~~~~ On leave from The Warsaw University of Technology. $ 1 Torrzl33.322 Pa. HN03 and standard magnesium solutions were prepared in the same medium. Powder X-ray diffraction was carried out on a Stoe diffractometer using Cu-Ka, radiation. The diffractometer incorporates a focusing geometry, thus provid- ing high-resolution data.Unit-cell parameters were refined using the program POWREF. In Table 1 we present the maximum magnesium contents obtained by the action of di-n-butylmagnesium on a variety of intercalation hosts. Although V6OI3 appears to accommo- date the highest magnesium content of any of the systems studied, when expressed with respect to the number of vanadium ions the Mg2+ content is in fact rather low. Therefore with the exception of y-Mn02, which possesses a complex intergrowth structure consisting of pyrolusite elements within a ramsdellite matrix, the magnesium contents of the oxides are all low. Such small values may possibly be accounted for by reactions on the surface of the oxide particles rather than intercalation into the bulk.Further studies of these oxides will be required to distinguish unequivocally between these two possibilies. In contrast the Mg content in both polymorphs of TiS2 is significantly higher than is the case for the oxides suggesting intercalation does occur. These results are consistent with the classification, frequently used in solution co-ordination chemistry, of cations and their co- ordinating groups as hard or soft acids and bases.' Mg2+ is a hard cation and when co-ordinated by a hard anion, such as an oxide, a strong and highly stable association should be formed, whereas in a sulphide environment the interactions should be weaker. As a consequence, mobility, and hence the degree of intercalation, would be greater in sulphide, as is observed experimentally.During the course of this work Gregory et al." reported wide-ranging studies of the non- aqueous electrochemistry of magnesium. These studies included intercalation into several oxides and sulphides. Of the oxide hosts reported in ref. 10 three are common to our study, namely V205, W03 and MOO,; the maximum mag- nesium contents obtained by Gregory et a]. are Mg0.66V205, Table 1 Maximum magnesium contents obtained by chemical intercal- ation using (C,H,),Mg at 30 "C host Mg content (mol fraction of host) TiS, layered 0.22 TiS, cubic 0.25 V,On 0.48 v205 0.10 WO, 0.08 MOO, 0.05 y-MnO, 0.32 A-MnO, 0.09 P-MnO, 0.02 J. MATER. CHEM., 1991, VOL. 1 1000i .-L 4000-L 10.0 20.0 30.0 40.0 50.0 60.0 2elo Fig.1 High-resolution powder X-ray diffraction patterns for (i) pure and (ii) magnesium-intercalated (a) cubic TiS, and (b) layered TiS2. In the case of magnesium-intercalated layered TiS, the magnesium content refers to the overall composition Mg0.,,WO3 and Mgo~,oMo03. The maximum Mg content in layered TiS, is found to be Mg,.,,TiS,. Therefore, in contrast to our results these authors find that intercalation into oxide hosts is generally more facile than into layered TiS,. In particular they obtain a lower magnesium content in layered TiS, than in any of the other hosts that they studied. They do not report intercalation of magnesium into the cubic polymorph of Ti&. In Fig.1 we present high-resolution powder X-ray diffrac- tion patterns for the products obtained by intercalating mag- nesium into cubic and layered Ti$,. In the case of cubic TiS,, diffraction data indicate that the compound retains its cubic symmetry but with an expansion of the a axis from 9.742(1) to 9.857(1)A at the maximum magnesium content of Mg0.,,TiS2 cubic. X-Ray data at intermediate compositions confirm the existence of a continuous range of solid solutions for O<x<O.25. Analysis for carbon and hydrogen confirms that the organic moiety does not intercalate along with magnesium. In contrast, magnesium intercalation into layered TiS, does not yield a homogeneous product. The original phase coexists with a magnesium rich phase which retains the same layered structure but with a considerable expansion of the lattice.This expansion is particularly pronounced along the c axis, which is located in a direction perpendicular to the van der Waals bonded sulphur layers. The c axis expands from 5.699(2) to 6.127(9) A whereas the a axis expands from 3.407(1) to 3.488(4)A. Since the magnesium intercalates into only a proportion of the original solid, the composition of the magnesium rich compound is significantly greater than the average value of 0.22 magnesium atoms per TiS, formula unit. Furthermore, the maximum magnesium content is greater in the layered polymorph of TiS, than in its cubic counterpart. This is consistent with the 13% increase in the unit-cell volume associated with the formation of the layered intercalates compared with only 3.6% for the cubic phase.Again, C, H analysis indicates that only magnesium enters the layered structure. Turning to the reaction between the phenoxide and the titanium disulphide hosts, no evidence for magnesium intercal- ation into cubic TiS2 can be found in the X-ray diffraction patterns. The peaks of the host cubic TiS, lattice remain unaltered. In contrast, diffraction patterns of layered TiS2 immediately after treatment of the solid with phenoxide indicate the existence of a single-phase material which retains the layered structure but with an expanded unit cell. Atomic absorption suggests a maximum magnesium content of Mg0.,,TiS2; how- ever analysis for carbon and hydrogen reveals the presence of hydrocarbon in the host. It therefore appears that at least some of the phenoxide groups enter the solid along with magnesium, possibly in the form of compound 1 itself or possibly as the partially reduced moiety magnesium 2,6-di- tert-butylphenoxide. Diffraction patterns taken after 1 month show that with the passage of time magnesium and the organic moieties are expelled, reforming pure, layered TiS,.The original intercalate is therefore not stable. In summary, di-n-butylmagnesium is a convenient intercal- ating agent for magnesium, its use permits the preparation of large quantities of the intercalated materials. In the case of Mg intercalation into cubic TiS2 a continuous range of solid solutions are formed.In contrast the phenoxide does not intercalate into cubic TiS,, although intercalation does occur into layered TiS,; the process is complex including the inser- tion of both Mg and organic moieties. P.G. B. and V. C. G. are indebted to SERC for financial support. P. G. B. is also grateful to the Royal Society for the award of a Pickering Research Fellowship. References 1 A. R. West, J. Muter. Chem., 1991, 1, 157. 2 E. Gocke, W. Schramm, P. Dolscheid and R. Schollhorn, J. Solid State Chem., 1987, 70, 71. 3 M. Z. A. Munshi, A. Gilmore, B. B. Owens and W. H. Smyrl, Proc. Electrochem. SOC., 1989, 89-4, 281. 4 P. G. Bruce and M. Y. Saidi, Electrochimica Acta, 1991, 36, 569. 5 P. G. Bruce and M. Y. Saidi, J. Solid State Chem., 1990, 88, 41 1. 6 P. G. Bruce and F. Krok, Electrochimica Acta, 1988, 33, 1669. 7 J. C. Hunter, J. Solid State Chem., 1981, 39, 142. 8 J. Calabrese, M. A. Cushing Jr., S. D. Ittel, Inorg. Chem., 1988, 27, 867. 9 R. G. Pearson, J. Am. Chem. SOC., 1963, 85, 3533. 10 T. D. Gregory, R. J. Hoffman and R. C. Winterton, J. Electro-chem. SOC., 1990, 137, 775. Communication 1/02404C; Received 22nd May, I99 1

ISSN:0959-9428    

DOI:10.1039/JM9910100705

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

J. MATER. CHEM., 1991, 1(4), 707-708 . 707 Correlation between Absolute Configuration of Benzylic Chiral Centre and Sign of Spontaneous Polarization of Chiral Dopants for Fe r r oe Iect r ic Liquid CrystaIs Tetsuo Kusumoto," Akiko Nakayama," Ken-ichi Sato," Tamejiro Hiyama,*" Sadao Takehara,b Masashi Osawab and Kayoko Nakamurab a Sagami Chemical Research Center, 44-1 Nishiohnuma, Sagamihara, Kanaga wa 229, Japan Central Research Laboratories, Dainippon Ink and Chemicals lnc., 631 Sakado, Sakura, Chiba 285, Japan The absolute configuration of a polar-group-substituted benzylic chiral carbon of a chiral dopant for ferroelectric liquid crystals is found to be predictable by the sign of spontaneous polarization of the ferroelectric liquid- crystalline mixtures containing the chiral dopant.Keywords: Liquid crystal; Chirality; Ferroelectricity In view of developing displays for the future, ferroelectric liquid crystals (FLCs) have attracted much attention recently.' Of the various physical properties required of the FLC material, spontaneous polarization (P,) is the most important for fast switching. We have disclosed previously that chiral dopants of type 1,2 z3 and 3,4 all having a chiral centre connected directly to a mesogenic core aromatic ring and also to a polar cyano group, exhibit large values of P,. On reviewing the sign of P, of 1-3, we recognized that the absolute configuration of the benzylic chiral centre correlates well with the sign of P,, as summarized in Fig. 1; the chiral centre within R affects less the sign of P, and more the helicity of the resulting FLC mixtures.' This empirical rule is now found to apply not only to new dopants 4a, 4b and 4c n-c8Hl70-1 4a Cr87Si 1 04SA1371 4b (non-polar) Cr104SA1221 4c (polar) Cr106SA1111 but to various types of chiral compound (Fig.l), and accord- ingly the absolute configuration of the benzylic chiral centre of a new compound is predictable by determining the sign of P, in the FLC. The carbanion of 4-methoxyphenylacetonitrile, 5 was allowed to react with (R)-1,2-epoxyoctane (92% ee) to give a ca. 1:l mixture of 6a and 6b (70% yield). Each was easily separated by silica gel column chromatography. Tosylation followed by reduction with NaBH, gave 7 and cyclopropanes of type 3, (ca.1:l). Demethylation of 7 with Me2S-AlC1,6 gave a phenol derivative 8 (18% yield from 6a) which was esterified with 4-(4-octyloxyphenyl)benzoylchloride to give rise to 4a whose P, was -85 nC cm-2 at 94 "C (Scheme 1). Alkylation of the carbanion of 5 with (S)-2-tosyloxyoctane (>98'/0 ee) gave a diasteromeric mixture of 9 of 98 and 97% ee, respectively, which was separated and converted into 4b and 4c as above. As these did not exhibit chiral smectic C phase (S,*), each was added to a host liquid-crystalline mixture A.? The mixtures containing 5 wt.% of 4a, 4b and 4c showed, at 25 "C, values of P, of -2.6, -5.7 and +5.9 nC cmP2, response times of 218, 116 and 90 ps and tilt angles of 22,24 and 25", respectively.$ [Note that the response times are not particularly short, because the viscosity of the host A is not low and the additional quantities of dopants are small.These are not the best conditions for achievement of high-speed response.] By analogy with the correlation of absolute configuration with sign of P, as discussed for 1-3, the benzylic chiral centres of 4b and 4c are predicted to be S and R, respectively. This prediction was confirmed by the alternative synthesis of each (+,-)-diastereoisomer as shown in Scheme 2. Hydrogenation of the (2)-alkene with Rh-carbon provided (+, -)-syn-9 whose 'H NMR data were identical to those of the diastereoisomer that led to 4b.g Similarly, (+,-)-anti-9 corresponded to 4c. Although Goodby and co-workers related absolute con- figuration to the sign of P, and twist sense in FLCS,~ their conclusions are limited to chiral materials having a methyl or chloro substituent on a single chiral carbon, separated by several methylenes from polar groups such as C02 or OCO and the mesogenic core aromatic ring.Accordingly, many exceptions have appeared later.8 Compounds having a polar cyano group at the benzylic carbon, in Fig. 1, exhibit a consistent correlation between absolute configuration and sign of P,, irrespective of the kind of side-chain R[a-con- figuration, (P:); P-configuration, (P,-)] and independent of the components of the achiral host mixture. This empirical rule extends further to sulphoxides fluoro epoxides 11," t The host liquid-crystalline mixture A consists of 2-(4-decyloxy- phenyl)-5-octylpyrimidine (28 wt.%), 2-(4-nonyloxyphenyl)-5-octyl-pyrimidine (28 wt.%), 2-(4-octyloxyphenyl)-5-octylpyrimidine (24 wt.%), and 2-(2-fluoro-4-octyloxyphenyl)-5-(4-heptylphenyl) pyrimidine (20 wt.%). The phase-transition temperatures (in "C) of the host A were Cr 13 Sc 68 SA 74 N 84 I.$ The liquid-crystalline mixture was sealed in a polyimide rubbing cell of ca. 2 pm thickness, and a square wave of 10 V pm-' (peak to peak) was applied to the cell. The change of transmittance (from 10 to goo/,) of light was observed. P, was measured by the triangular- wave method. 9 Spectroscopic data, 'H NMR in CDCI,. syn-9: 6 0.88 (t, J= 6.6 Hz, 3 H), 0.97 (d, J=6.7 Hz, 3 H), 1.27-1.52 (m, 10 H), 1.86 (m, 1 H), 3.78 (d, J=5.4 Hz, 1 H), 3.81 (s, 3 H), 6.89 (d, J=8.7 Hz, 2 H), 7.21 (d, J=8.7 Hz, 2 H).anti-9: 6 0.87 (t, Jz6.7 Hz, 3 H), 0.98 (d, J= 6.7 Hz, 3 H), 1.16-1.38 (m, 9 H), 1.47-1.54 (m, 1 H), 1.90-1.96 (m, 1 H), 3.63 (d, J=6.5 Hz, 1 H), 3.81 (s, 3 H), 6.89 (d, J=8.7 Hz, 2 H), 7.20 (d, J=8.7 Hz, 2 H). J. MATER. CHEM., 1991, VOL. 1 1 2 3 4 10 11 12 Fig. 1 Correlation between benzylic chiral centre and sign of P,. II,ill-pc6H13-n Me0 p OH 7 /o"'" C6H13-n Me0 8 Me0 6b HO& -4a 5 CN 4 ~ 24band 4c Me0 9 Scheme 1 (i) BuLi, (R)-1,2-epoxyoctane; (ii) TsCl, pyridine, DMAP; (iii) NaBH,, DMSO; (iv) AlCI,, Me,S; (v) n-C,H,,0C,H4C6H4COC1, pyridine; (vi) BuLi, (S)-TsOCHMeC,H,, (Ts=tosyl). CN CN H2 Me0Me0 Scheme 2 (a)(+, -)-syn-9; (b)(+, -)-anti-9.2 3 4 5 6 T. Kusumoto, T. Hanamoto, T. Hiyama, S. Takehara, T. Shoji, M. Osawa, T. Kuriyama, K. Nakamura and T. Fujisawa, Chem. Lett., 1990, 1615. T. Kusumoto, T. Hanamoto, K. Sato, T. Hiyama, S. Takehara, T. Shoji, M. Osawa, T. Kuriyama, K. Nakamura and T. Fujisawa, Tetrahedron Lett., 1990, 31, 5343. T. Kusumoto, A. Nakayama, K. Sato, T. Hiyama, S. Takehara, T. Shoji, M. Osawa, T. Kuriyama, K. Nakamura and T. Fujisawa, Tetrahedron Lett., 1991, 32,939. T.Kusumoto, T. Hiyama, S. Takehara and T. Shoji, Yuki Gosei Kagaku Kyokai Shi, 1991, 49, 475. K. Fuji and M. Node, Yuki Gosei Kagaku Kyokai Shi, 1984,42, 193. and lactones 12." The basis of the rule should rely heavily on the stable conformation of FLCs as discussed by Goodby.Note that the conformational fluctuation is a minimum at the benzylic chiral carbon and thus the empirical rule of Fig. 1 becomes valid. This rule may be applied to the determination of the absolute configuration of the benzylic chiral centre, as exemplified by 4b and 4c. 7 8 9 10 J. W. Goodby, E. Chin, T. M. Leslie, J. M. Geary and J. S. Patel, J. Am. Chem. SOC., 1986, 108, 4729, J. W. Goodby and E. Chin, J. Am. Chem. SOC., 1986, 108, 4736. A. Fukuda and H. Takezoe, Structure and Properties of Ferroelec-tric Liquid Crystals (in Japanese), Corona Publishing, Tokyo, 1990, p. 296. K. Nishide, A. Nakayama, T. Kusumoto, T. Hiyama, S. Takehara, T. Shoji, M. Osawa, T. Kuriyama, K. Nakamura and T. Fujisawa, Chem. Lett., 1990, 623. D. M. Walba, H. A. Razavi, N. A. Clark and D. S. Parmar, J. Am. Chem. SOC., 1988, 110, 8686. References 1 N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett., 1980, 36, 899. 11 T. Kusumoto, A. Nakayama, K. Sato, K. Nishide, T. Hiyama, S. Takehara, T. Shoji, M. Osawa, T. Kuriyama, K. Nakamura and T. Fujisawa, J. Chem. SOC.,Chem. Commun., 1991, 3 11. Communication 1/02484A; Received 1st May, 1991

ISSN:0959-9428    

DOI:10.1039/JM9910100707

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

J. MATER. CHEM., 1991, 1(4), 709-711 BOOK REVIEWS Quasicrystals, Networks, and Molecules of Fivefold Sym- metry. Ed. I. Hargittae. VCH, Weinheim, 1990. Pp. xiii +314. Price f55.00. This book, consisting of a collection of 19 chapters and involving no fewer than 37 authors, aims to present a cross- section of work in quasicrystal research at the end of the 1980s. It is an interesting, fascinating and mystifying book. Interest is aroused by the bringing together of a wide range of concepts all associated with the phenomenon of fivefold symmetry. Fascination comes about because some of these concepts are so unfamiliar to the typical chemist, and yet relevant to the main theme. Mystification develops since, despite its title, it makes no mention of familiar small molecules of fivefold symmetry, such as ferrocene.Indeed, by far the greater portion of the book (12 chapters) is devoted to somewhat abstract considerations of fivefold symmetry, dealing with the problem of devising model lattices with some degree of appropriate symmetry present, which might be able to give rise to diffraction patterns similar to those obtained from various quasicrystalline alloys. Ideas such as special tiling patterns to obtain localised fivefold symmetry, which are relatively simple in themselves, are introduced. But there are also excursions into the unfamiliar (to many chem- ists) territory of topology-and even into Islamic architectural art. The thirteenth chapter considers the application of fivefold symmetry in relation to potential surfaces and reaction path- ways, and establishes by a graph-theoretical argument that mutual interconversion of five different entities by all of the possible direct pathways is impossible.The only significant chemical considerations are of various aspects of buckminsterfullerene and a chapter on centro-polyindans. In the former case, the experimental evidence for the occurrence of a C60 material is reviewed, and the possible candidacy of buckminsterfullerene as a source of interstellar absorption bands is discussed. Theoretical calculations of Hiickel energy levels, of the number of possible KCkulC structures, and of molecular vibration frequencies for the molecule are discussed in separate chapters.The main con- clusions are that until adequate experimental evidence of the spectroscopic properties of the molecule can be obtained, these exercises are little more than demonstrations of the application of various mathematical techniques. The calcu- lations of energies certainly produce widely differing results according to the method employed. Perhaps one set will eventually be found to correspond with observation. The final chapter on centropolyindans reviews the various methods in which five-membered rings can be joined together, and outlines synthetic routes to various different structures. Very few of these have fivefold symmetry, so that the inclusion of much of this chapter is somewhat surprising. The book is well produced.Considering the variety of different original languages of the several authors, the text is generally easily read. Sometimes, however, the mathematical concepts and symbolism are introduced with little or no explanation, which may prove difficult for the uninitiated. Most of the diagrams are clear and easily understood, although some of the stereo projections of four-dimensional items are difficult to appreciate. The use of colour from time to time is helpful in increasing clarity. There are commendably few typographical errors, but one figure referred to in the text appears to be missing. For a solid-state scientist who wishes to obtain a feeling for the current state of knowledge of the phenomenon of quasi-crystallinity, the book is an excellent source of infor- mation.For the curious, who would experience a widening of outlook in relation to all sorts of aspects of symmetry, crystallography etc., the book will prove an interesting, if somewhat expensive, investment. But for the chemist who wants to increase his or her knowledge of molecules of fivefold symmetry and little else, it is sadly deficient. J. A. Hunter Received 7th May, 1991 Surface Analytical Techniques. (Monographs on the Physics and Chemistry of Materials.) By J. C. Riviere. Oxford University Press, London, 1990. Pp. xiv +702. Price f75.00. Words like ‘magnum opus’, or ‘Herculean task’, spring to mind when coming to describe this book. The initial concept had been to write a book describing six or so of the major surface analytical techniques.However, during the writing Riviere decided that he could not justify omitting the minor techniques, so that what was produced ultimately was a volume of 23 chapters, 20 of which describe the techniques, 12 of them describing two or more techniques. The book deals with the range of application and with the advantages and disadvantages of each of the current tech- niques of surface compositional analysis. (The term ‘compo- sitional’ is used deliberately by the author in preference to elemental, since while some of the techniques do not give elemental information, they yield chemical information which is complementary to the elemental.) The book is well structured. The techniques are introduced according to the method of excitation of the effect.They are in the order: (i) electron excitation (chapters 4-9), with the techniques Auger electron spectroscopy (AES), scanning Auger electron microscopy (SAM), electron energy-loss spectroscopy (ELS), core-electron energy-loss spectroscopy (CEELS), high- resolution electron energy-loss spectroscopy (HREELS), soft X-ray appearance potential spectroscopy (SXAPS), Auger electron appearance potential spectroscopy (AEAPS), disap- pearance potential spectroscopy (DAPS), inverse photoemis- sion spectroscopy (IPES), cathodoluminescence spectroscopy (CLS), electron-stimulated desorption (ESD) and electron- stimulated desorption ion angular distribution (ESDIAD); (ii) photon excitation (chapters 10-12), X-ray photoelectron spec- trocopy (XPS), X-ray excited Auger electron spectroscopy (XAES), ultraviolet photoelectron spectroscopy (UPS), synchrotron radiation photoelectron spectroscopy (SRPS), reflection-absorption infrared spectroscopy (RAIRS) and sur- face-enhanced Raman spectroscopy (SERS); (iii) ion excitation (chapters 13- 18), ion-excited Auger electron spectroscopy (IAES), proton-excited Auger electron spectroscopy (PAES), ion-neutralization spectroscopy (INS), metastable quenching spectroscopy (MQS), ion-beam spectrochemical analysis (IBSCA), glow discharge optical spectroscopy (GDOS), ion- scattering spectroscopy (ISS), static secondary-ion mass spec- troscopy (SSIMS), secondary-neutral mass spectrometry (SNMS) and glow discharge mass spectrometry (GDMS); (iv) neutral excitation (chapter 19), fast atom bombardment mass spectrometry (FABMS); (v) high-field excitation (chapters 20-22), inelastic electron tunnelling spectroscopy (IETS), atom probe field ion microscopy (APFIM), scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS); and (vi) thermal excitation (chapter 23) thermal desorp- tion spectroscopy (TDS).While it may have appeared tedious to have cited this long list of techniques it was done to show the comprehensive and compendious nature of this tome. Amazingly, considering the size of this book, techniques of studying the structure of surfaces have been specifically excluded, but are referred to from time to time throughout the text.Chapter2 is a resume of the physical principles of the methods of excitation described in (i)-(vi) above, while chapter 3 deals with the instrumentation, e.g. vacuum conditions, sources, analysers. Chapters 4-23, with minor additions in some, are structured in the same clear way: (i) operation, which is an enlarged experimental method (ii) theory, (iii) quantification and (iv) applications. The book is well presented and well written. It is written in a laconic, urbane style with just a hint of humour, e.g. in suggesting that scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) should be considered as different aspects of the same technique, the sentence finishes with, ‘(STMS?)’. Minor quibbles relate to the sheer enormity of the book so that the author, like the reviewer, could not possibly be familiar with all the techniques. Some chapters, therefore, seem slightly learned with a somewhat thin and esoteric bibliography.The book is aimed at those in surface science who wish to know more about other techniques and also at those outside the field wishing to gain some knowledge of surface analysis. In both areas it succeeds admirably. It is also an indispensable addition to any academic or industrial library as a reference volume. K. C.Waugh Received 7th May, 1991 Polymers for Microelectronics-Science and Technology. Ed. Y. Tabata, I. Mita, S. Nonogaki, K. Horie and S. Tagawa. VCH, Weinheim, 1990.Pp. xxv+870. Price f112,DM 280.This book comprises 67 papers of varying quality and interest, which were presented to the International Symposium on ‘Polymers for Microelectronics-Science and Technology’ held in Tokyo in 1989. They are presented in three sections which deal with aspects of the photophysics, radiation physics and chemistry of resists (36 papers), photosensitive polymers mainly in relation to optical-memory applications (1 1 papers), and polyimides and related polymers of interest to the micro- electronics industry as dielectric films for electric isolation (20 papers). These topics are of considerable current importance to the microelectronics industry but I have reservations about the general usefulness of this particular volume. At a price of &112, I cannot recommend this book for individual purchase since most papers are too specific to glean easily a general understanding of the subject, and the book is not sufficiently well produced to provide an effective source book for the expert.What is lacking, primarily, are general review papers to provide a framework to each topic, although some of the papers, notably those by Reichmanis et al. on deep UV lithography, by Moerner on persistent spectral-hole burning and by Senturia on the mechanical and adhesion properties of polyimide films, do cover some of the background to these fields. It would also have been illuminating to have included some of the discussion which presumably followed the presen- tation of the papers to the Symposium. Such background would have helped to highlight the topics and possibly answer questions the reader might have.With such a large number of authors it is always a difficult task to produce a coherent book, particularly when, as in this case, it is produced as camera-ready copy. There are many variations in typographical style with such poor printing of some of the papers as to make them difficult to read. There J. MATER. CHEM., 1991, VOL. 1 are places where chemical formulae have not been adequately finished, with bonds missing, unlabelled axes in some figures and poor reproduction of some of the photographic evidence, faults which all should have been dealt with by either the referees or the editors. There is a subject index but it is not comprehensive and lacks much cross referencing.Another fault here is that the pages cited refer to the start of the paper and not specifically to the page where the citation occurs. There are some strange listings. For example, benzene is quoted; this turns out to be a reference to its use as a resist- developing solvent. A few papers deal with Langmuir-Blodg- ett films and these are cited under that heading, but a paper dealing with continuous uptake of LB film is not quoted under Langmuir-Blodgett films but appears variously under aligning layer, molecular orientation, ultrathin film and water surface spreading method. For the two papers dealing with aspects of spiropyrans one is quoted under that heading and the other under ‘normal spiropyran’. I also found it surprising that there were no papers dealing with side-chain liquid-crystalline polymers for optical infor- mation storage using thermal writing, although there is a contribution dealing with combined LC/photochromic poly- mers as potential storage media.The opening address refers to the conductive and non-linear optical properties of poly- mers in microelectronics, but these aspects were mentioned only very briefly. H. Block Received 13th May, 1991 Pore Size Engineering in Zeolites. By E. F. Vansant. Wiley- Salle and Sauerlander, New York, 1990.Pp xii +367. Price f24.95. Zeolitic channel systems, which may be one-, two- or three- dimensional, are normally filled with water. When water is removed, other species such as gaseous elements, C02, ammonia, alkali-metal vapours, hydrocarbons, alkanols and many other organic and inorganic species may be accommo- dated in the intracrystalline space.Depending on pore diam- eter and on molecular dimensions, this process may be highly selective. Thus dehydrated chabazite, with pore openings <5 8, wide, can sorb water, methanol, ethanol and formic acid, but not acetone, ether or benzene. By contrast, the remarkable porous aluminophosphate molecular sieve VPI-5 containing 18-membered rings of tetrahedral atoms has a very large channel diameter of ca. 12 A, which gives it considerable potential for the separation of large molecules and for catalytic cracking of heavy fractions of petroleum.Sorption on molecu- lar sieves is a powerful method for the resolution of mixtures. Commercial applications are wide and include drying of organics, separation of hydrocarbons and of N, and O2 in air and the removal of NH3 and CS2 from industrial gases. The mechanism of synthesis of molecular sieves is not well understood, and the various materials have been prepared largely by trial and error. Variables during the synthesis include the type of base and of the organic template (if any), concentration of the components and the temperature. One cannot, at least at present, talke of ‘designing’ molecular sieves in the ordinary sense of the word. Exchangeable cations also influence the dimensions of the channels and cavities. The sodium form of zeolite A sorbs both N2 and O2 while the calcium form sorbs nitrogen preferentially to oxygen.The size of channel apertures can be modified (or, more correctly, reduced) further by lining the intracrystalline space with pre-adsorbed polar molecules and J. MATER. CHEM., 1991, VOL. 1 by chemical derivatization (for example by silanation) of the framework itself. It is these processors that are the subject of this slim volume. Given their limited scope, the title of the book is a considerable exaggeration, and the contents a disappointment. Vansant deals mostly with the modification of the channel openings in mordenite, one of about 10 zeolites which have found actual industrial applications, and refers largely to his own work.This is unexceptional in a thesis or a review article, but seems unsatisfactory in the hard-back book under such a beguiling title. This having been said, there is nothing wrong with the science discussed here, as opposed to the presentation which is inadequate. Still, the text contains things that would not pass the referees’ muster in a respectable journal. For example, Fig. 59 plots the percentage of encapsulated xenon released from mordenite as a function of temperature. The horizontal axis spans temperatures 323-773 K, but the results given are for 603 and 673 K only. Modern computer software makes it possible to draw bar diagrams easily, but this does not justify a figure with a total of two experimental points. Clearly the manuscript has been submitted in camera-ready form. I consider this particular practice, often used in confer- ence proceedings, to be a scourge of modern science.It is not only that almost the entire publication effort is passed on to the authors (although this is rarely reflected in the royalties or in the price of the final product) but more seriously, the 71 1 problem is the abdication of editorial intervention which, when dealing with quality publishing houses, is often invalu- able. The book under review has suffered badly from not having been edited properly. Thus the numbering of figures is continuous throughout the text, but the numbering of tables re-starts at the beginning of each chapter. By contrast, sec- tions are elaborately numbered (boranation is discussed in Section 2.3.2.3), which is of little use since there are no running heads. The title of Chapter 2 is the same as that of the book itself. The Index contains curious entries, such as ‘Acids of phosphor and salts’. The plates serve no useful purpose. The overall impression is one of a homemade text which has been hastily put together. I see no reason for publishing books like this one. To a new research student wishing to survey the state-of-the-art in this particular field, it offers little more than a list of 38 references. The wider applications and possibilities of chemical modification of zeolitic architecture are given little attention; vision, synthesis and foresight are lacking. Aluminophosphate molecular sieves, materials with most interesting sorptive properties, are not even mentioned. The kindest comment I can make about this book is that it fits nicely on a standard size book-shelf. J. Klinowski Received 20th May, 1991

ISSN:0959-9428    

DOI:10.1039/JM9910100709

出版商:RSC    

年代:1991

数据来源: RSC

摘要:

J. MATER. CHEM., 1991, 1(4), 713 CORRIGENDUM Corrigendum to Paramagnetic Rod-like Liquid Crystals, Bis[5-(4-alkoxybenzoyloxy)salicylaldehyde]copper( 11) Eduardo Campillos, Mercedes Marcos, Jose Luis Serrano, Quirnica Urganica, lnstituto de Ciencia de Materiales de Aragon, Facultad de Ciencias, Universidad de Zaragoza-C.S. 1. C., 50009-Zaragoza, Spain, Pablo J. Alonso, Espectroscopia de Solidos, lnstituto de Ciencia de Materiales de Aragon, Facultad de Ciencias, Universidad de Zaragoza-C.S. I.C., 50009-Zaragoza, Spain J. Mater. Chem, 1991, 1, 197 Eight rows of data were omitted from Table 2 of the paper n transition T/ "C AHlkJ mol-' 12 cI -c2 155.6 2.49 12 C2-C3 182.3 7.47 12 c3-s, 236.0 27.40 12 14 &-I( dec.) Cl-c2 248.0 133.4 13.22 14 C2-C3 178.3 4.52 14 C3-Sc 226.7 16.34 14 S,-I(dec.) 243.3

ISSN:0959-9428    

DOI:10.1039/JM9910100713

出版商:RSC    

年代:1991

数据来源: RSC