Shigekazu Kusabayashi

Mesomorphic phase transitions of tetraphenylporphyrins with four long aliphatic chains

Abstract Studies of 5,10,15,20-tetrakis(4-n-alkylphenyl)porphyrins revealed that the homologues with longer alkyl chains than hexyl were mesomorphic, in contrast to the non-mesomorphic alkoxy derivatives. Metal complexes (Co, Ni, Cu, Zn, and Pd) of the dodecyl derivative were also shown to exhibit mesophases. These mesophases were assigned as discotic lamellar (DL) phases by X-ray diffraction studies.

The Substituent Effect on the Thermal Stability of the Smectic A Phase in para- Phenylene Systems Incorporating Ester Linkages

Abstract Summary: The thermal properties of 4-Z-phenyl 4-(4-octyloxybenzoyloxy)benzoates (1), 4-octyloxy- phenyl 4-(4-Z-benzoyloxy) benzoates (2), 4-(4-octyloxybenzoyloxy) phenyl 4-Z-benzoates (3) and 4- octyloxyphenyl 4-(4-Z-phenoxycarbonyl)benzoates (4) have been examined, where the substituents (Z) are halogens, alkoxy, alkyl, formyl, acetyl, cyano, and nitro groups, etc. The smectic properties are strongly dependent on the orientation of the ester linkages. Compounds 1 and 4 having alkoxy and alkyl groups tend to show smectic A and C phases. Compounds 2 and 3 are intrinsically poor in smectic properties, and only a smectic C phase is formed by the long-alkoxy and alkyl derivatives. Throughout the compounds, the thermal stability of the smectic A phase is strongly dependent on the electrostatic nature of the substituents; that is, both electron-donating substituents such as the methoxy and methyl groups and electron-withdrawing ones such as the cyano and nitro groups, steeply lower the smectic A therma...

Thermal and X-ray diffraction studies of liquid crystals incorporating a perfluoroalkyl group

Thermal properties of perfluoroalkyl 4-(4-alkoxybenzoyloxy)benzoates (1), 4-(4-alkoxyphenoxycarbonyl)benzoates (2), and 4-trans-(4-alkoxyphenoxycarbonyl)cyclohexanecarboxylates (3) have been examined, and the layer spacings of the smectic A and C phases were obtained by X-ray diffraction experiments. The perfluoroalkyl group facilitates the formation of smectic A and C phases (SA and SC, respectively). For compound 1, the molecular arrangements in the SA and SC phases are concerned with the chain length of the alkoxy group, that is the layer spacing of the SA phase agrees with the calculated molecular length when the alkoxy group is the octyloxy group, and exceeds it when it is the butoxy one. The derivatives of compound 2 show only the SA phase, having a somewhat interdigited arrangement. Compound 3 preferentially forms the SA phase. The results are discussed in terms of the molecular structures and local interactions.

Singlet Excitation Energy Transfer in the Vinyl Polymers with Pendant Carbazolyl Groups

The triplet energy transfer in poly(N-vinylcarbazole)(PVCz) prepared by radical and cationic polymerization (PVCz(r) and PVCz(c) respectively), poly[2-(N-carbazolyl)ethyl vinyl ether](PCzEVE), and brominated PVCz (BPVCz) has been investigated by measuring the delayed emission spectra in solid films and rigid solutions at 77 K. The prompt and delayed fluorescence spectra both in the solid film and in the rigid solution at 77 K were different for PVCz(r) and PVCz(c). This seems to be due to the difference in tacticity between them. PCzEVE, in which the Cz groups are connected from afar to the skeletal chains by means of –O–CH2–CH2–bonds, showed the delayed fluorescence and the phosphorescence both in the rigid solutions and in the solid films at 77 K. The BPVCz film showed only the excimer phosphorescence. In the solid films of PVCz(r), PVCz(c), and PCzEVE, the Cz chromophore-delayed fluorescence increased with an increase in the concentration of triplet quenchers, such as naphthalene and fluorene. This phe...

Glass transition in charge carrier transport phenomena of amorphous photoconductive polymers

Abstract The critical temperature T o in Gills empirical equation for the charge carrier transport was found to have aclose connection with the glass transition temperature T g for poly-N-vinylcarbazole containing model compound systems. Interpretations of T 0 and μ 0 , i.e., the drift mobility at T 0 , were presented.

Thermal Properties of 4-Alkoxyphenyl 3,4-Di(4-alkoxybenzoyloxy)benzoates

Abstract A homologous series of 4-alkoxyphenyl 3,4-di(4-alkoxybenzoyloxy)benzoates has been prepared. All the members (from the ethoxy to nonyloxy homologs) show a nematic phase having a fine schlieren texture, and the nonyloxy homolog also shows a smectic A phase having a fine fan texture. The plot of the nematic-isotropic transition temperatures against the carbon number of the alkoxy chains shows a remarkable even-odd effect. The mesophases have an affinity with the nematic and smectic A phases of the usual rod-like liquid crystals. The nematic phase is highly viscous. The thermal properties are discussed in terms of the molecular structure. A geometrical boundary between rod-like and discotic liquid crystals has been discussed.

The Discotic Mesophases of 1,3,5-Trisubstituted Benzenes

Abstract Some homologous series of 1,3,5-trisubstituted benzenes have been prepared. A homologous series of 1,3,5-tri-(4-alkoxyphenoxycarbonyl)benzenes (the hexyloxy to decyloxy homologs) give rise to discotic mesophases having a nematic-like texture.

Reaction of ethyl iodide with bromide ion. Kinetics, transfer enthalpies of anions and extended Brönsted relationships in acetonitrile + methanol and NN-dimethylacetamide + methanol mixtures

Rate constants and activation parameters have been determined for the reaction of ethyl iodide plus bromide ion in acetonitrile + methanol and NN-dimethylacetamide + methanol mixtures. Single-ion transfer enthalpies have also been determined in these two solvent mixtures for the ions Br–, I–, ClO–4 and (n-Bu)4)B– on the basis of tetra-n-butylammonium/tetra-n-butylborate exchange. Experimental analysis and model calculations indicated that the halide-ion solvation enthalpy is a composite of the hydrogen-bonding energy and of the ‘more physical’ interaction energy. The physical meaning of the abnormal coefficient of the extended Bronsted relationships observed for the present reactions is discussed by dissecting anion transfer enthalpies into their constituent terms.

Thermal and X-Ray Diffraction Studies of Liquid Crystals Incorporating a Perfluoroalkyl Group

Abstract Thermal properties of some liquid crystals incorporating a perfluoroalkyl group have been examined. The perfluoroalkyl group tends to enhance the smectic properties. The layer spacing in the smectic A and C phases was examined by X-ray diffraction, showing that the ratio of the layer spacing to the calculated molecular length is dependent on the entirety of molecular structures rather than the length of the perfluoroalkyl chain, and is in the range between 1.0 and 1.4. Novel perfluoroalkyl 3- or 4-substituted benzenes exhibiting smectic A phase were also prepared.

Molecular Structure and Smectic Properties: Thermal Properties of Some Liquid Crystals Having a Nitro Group at the Terminal Position

Abstract The thermal properties of ortho (o)-, meta (m)-, and para(p)-nitrophenyl 4-(4-alkoxybenzoyloxy)benzoates (1), 4-(4-alkoxyphenoxycarbonyl)phenyl o-, m-, p-nitrobenzoates (2), 4-(4-alkoxybenzoyloxy)phenyl o-, m-, p-nitrobenzoates (3), o-, m-, p-nitrophenyl 4-(4-alkoxyphenoxycarbonyl)benzoates (4), and some related compounds have been reported. For the p-nitro derivatives of compounds 1–4 the smectic A phase having a partially bilayer arrangement (SAd ) commences from the hexyloxy, nonyloxy, pentyloxy, and nonyloxy homologs, respectively, where the smectic A-nematic transition temperatures are almost independent of the orientation of the ester linkages. The p-nitro derivatives of compounds 2 and 3 also show two kinds of smectic A phases having bilayer (SA2 ) and/or monolayer (SA 1) arrangements at low temperature. All the m-nitro derivatives show smectic A phases, where 2 and probably 4 have the SA 2 phase, and 1 and 3 show the SA 1 one. The o-nitro derivatives fof compounds 2 and 4 show the SA 2 ph...