摘要:

AbstractIn view of the nature of orderness in structure and the mesomorphism in property of liquid crystal, the function of which is further exploited by integrating it with the feature of crown ether. The monoarmed crown ether liquid crystals are successfully applied to the imitation of biomembrane transport. Binary component membrane composed of crown ether liquid crystal and PVC was first developed. Such a novel model of biomimetic membrane is capable of imitating ingeniously the thermocontrolling transport of biomembrane, thus the essential function of liquid crystal in membane transport is more fully exploited. It was suggested, consequently, that the molecules of the crown ether liquid crystal could assemble themselves to form ionic channels, as they exist in mesophase.Of still more significance is that the thermocontrolling transport of ions through the membrane is found to be operative selectively and the permeation of ion is under the direct influence of the thermal turmoil of the crown ether liquid crystal molecules as substantiated by the values of Arrhenius thermodynamic parameters, activation energy,Ea, and logarithmic Arrhenius constant, log A, in ion transport. Based on the aforementioned it is suggested that diffusion of ions is a rate determing step and change of rate of ion transport is varied in different phase. Influence of magnetic field on transport rate is investigated. On basis of above experimental findings, a dynamical equation of ion transportation is established which is applicable for the membrane system in general on one hands and expound the ion transport mechanism through the membrane on the other.

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130102

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe dehydrohalogenation mechanism of 2‐haloacetic acids (XCH2CO2H, X=F, Cl and Br) has been studied theoretically by HF/3–21G and AM1 methods. The results indicate that these reactions are most probably proceeded in terms of a polar five‐membered cyclic transition state in the gas phase. Their microscopic processes are beleived to be a stepwise reaction and the rate‐determining step is the first one. By comparing the energy barriers of different 2‐haloacetic acids, it can be realized that 2‐fluoroacetic acid is easier to react than 2‐chloroacetic and 2‐br

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130103

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe structural characteristics of silylenoids, H2SiMX, where M = Li or Na and X = F or Cl, have been studied byab initiocalculations. H2SiMX can be represented as adducts of silylene H2Si with alkali metal halogenides, MX. The associative energies at different calculational levels of various structures of H2SiMX are given. Effects of metallic and haloid atoms on the stability of various structures of H2SiMX are also discussed in this paper.

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130104

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe π electronic delocalization intrans‐C4H6andcis‐C4H6has been investigated in the frame ofab initiovalence bond theory with 6–31G basis set. The result shows that the Csp2‐Csp2single bond length (1.506 Å) is only about 0.024 Å shorter than the Csp3‐Csp3bond, thus the central bond length shortening would be mainly due to π conjugation. The theoretical resonance energies of thetrans‐C4H6andcis‐C4H6are 8.48 and 7.44 kcal/

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130105

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractPhotoinduced electron transfer and charge separation processes in zinc phthalocyanine‐viologen linked system have been studied and the distance effect of donor/acceptor on electron transfer reaction is discussed. It is indicated that the fluorescence from the zinc phthalocyanine moiety is appreciably quenched and the life‐time of singlet excited state is reduced by the pendant viologen. Time‐resolved transient absorption spectra measurements show that intramolecular quenching of the triplet state of zinc phthalocyanine by the attached viologen results in charge separation giving reduced viologen radical alive for a rather long period with hundred microsecond duration. The effect of the carbon chain length on the electron transfer rate constant and charge separation efficiency suggests that upon excitation, the zinc phthalocyanine and viologen groups tend to take closer conformation with the increase of the carbon chain examined. The rate constant for the intramolecular electron transferketwithn= 3 to 10 is in the order of 104s−1and in

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130106

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractReactions of (NH4)2MS4, AgBr and CuBr in γ‐methylpyridine produced one new compound, [MS4Cu4(γ‐MePy)8][M6O19] (1, M = W;2, M = Mo), of which 1 was characterized by single crystal X‐ray analysis. The crystal data: orthorhombic,Pbcn, a =15.434(4),b= 16.732(2), c = 28.657(7) Å,V= 7400.8(8) Å3,Z=4, R = 0.072 for 3121 independent data. The compound is the first example which contains both polyoxotungstate anion and heteropolynuclear cluster cation. In the structure of the cation four edges of the tetrahedral WS2−4core are coordinated by four copper atoms, giving a WS4Cu4aggregate of approximateD2hsymmetry. The differences between the reaction of Cu+with MS2−4and that of Ag+ with MS2−4in pyridine and its derivative

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130107

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe preparation and X‐ray crystal structures of the adducts of 10‐thiabenzo‐15‐crown‐5 and 10‐selenabenzo‐15‐crown‐5 with PdCl2are reported. [PdCl2(C14H20O4S)2] (1): orthorhombic, space groupPbcawith cell dimensions ofa=17.285(5),b=8.354(3),c=21.689(4) Å,V=3131.9 Å3, Z=4;R=0.0330 for 2301 reflections withI>3σ(I), [PdCl2(C14H20O4Se)2] (2): monoclinic, space groupP21/nwith cell dimensions ofa=18.928(4),b=8.912(3),c=9.813(2) Å, β=96.90(2)°, V=1643.4 Å3,Z=2;R=0.0289 for 2617 reflections withI>3σ(I), Both complexes are monomeric, square‐planar palladium(II) compounds with the Pd(II) ion situating on a crystallographic inversion centre, and the crown ligands all adopt the axial coordination with the Pd–‐S bond of 2.3233(7) Å and the Pd–‐Se bond of 2.4357(3) Å. Their complexing c

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130108

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractBased in the phase equilibrium study of the system Sm(C1O4)3‐4‐monochloroacetytantipyrine (C13H13ClN2O2)‐H2O at 30°C, we have synthesized the title complex [Sm(C13H13Cl‐N2O2)3(H2O)4](ClO4)3‐4H2O. The single crystal structure analysis on RASA‐IIS Rigaku diffractometer shows that the coordination number of the metal ion is nine and the geometry of the complex is tricapped trigonal prism. Two of the three molecules of organic ligand act as bidentate chelated through both carbonyl oxygens to the metal ion, but the other one as a monodentate coordinated only through the ring carbonyl oxygen, the side chain carbonyl is far away from the central ion. The crystal is monoclinic, space groupP21, α = 18.013(4),b= 14.709(3),c= 10.536(3) Å, β=94.69(2)°,

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130109

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe reactions of [Et3NH][μ‐CO)(μ‐RS)Fe2(CO)6] (1a‐d) (RnPr,nBu,tBu, Ph) withp‐MeC6H4C°CPh orm‐NO2C6H4C°CPh were studied and products of the vinyl type (μ‐σ,π‐p‐MeC5H4CCHPh)(μ‐RS)Fe2(CO)6(2) and (μ‐σ, π‐phCCHC6H4Me‐p) (μ‐RS)Fe2(CO)6(3) (RnPr,nBu,tBu, Ph) were obtained. While the structures of all the compounds 2a‐d and 3a‐d were characterized by elemental analysis, IR,1H NMR and MS spectroscopies, the single‐crystal structure of 2c(RtBu) was determined by X‐ray diffraction method. The X‐ray diffraction result of 2c showed that the substituted vinyl ligandp‐MeG6H4CCHPh bridges the two iron centers, being σ‐bonded to one metal through the olefinic carbon attached top‐MeC6H44 group, while π‐bonded to the other via olefinic linkage; the Fe2(CO)6and proton units are in acisfashio

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130110

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA novel homologous series of 4′‐methyoxyphenyl 4″‐[(4‐n‐alkoxy‐2,3,5,6‐tetrafluoro‐phenyl]benzyl ethers have been prepared via Pd‐catalysed Heck reactions. Polarizing microscopic textural observation shows that these compounds exhibit enantiotr

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130111

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY