Hiroyoshi Kamogawa

New liquid crystal compounds (+)-4-[5-(2-Methylbutyl)-1,3-dioxan-2-yl]phenyl 4-alkoxybenzoate

Abstract New liquid crystal compounds, (+)-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl] phenyl 4-alkoxybenzoates (5), were synthesized. The mesomorphic behaviour of these compounds is compared with that of (+)-4-(5-alkyl-1,3-dioxan-2-yl)-phenyl 4-(2-methylbutoxy)benzoates (6). While compounds 6 exhibited a chiral smectic C phase, the corresponding compounds 5 did not. This might mean that for the appearance of a chiral smectic C phase in these types of compounds, it is necessary that the carbonyl and the chiral groups exist at nearby positions. Transition temperatures to those isotropic state for compounds 5 were lower than those for compounds 6. This result is common in both cases of (+)-4-alkoxycarbonylphenyl-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl]benzoates (7), and (+)-4-(2-methylbutoxy-carbonyl)phenyl 4-(5-alkyl-1,3-dioxan-2-yl)-benzoates (8).

Synthesis of mesomorphic aryl esters bearing a pyridine ring

Abstract Aryl carboxylic esters bearing disubstituted pyridine rings were synthesized starting with various pyridine mono- or dicarboxylic acids by means of reactions, principally, with phenolic compounds. Some of the pyridine monocarboxylates thus synthesized exhibited clear nematic phases at relatively low temperatures, whereas most of the 2,5-pyridine dicarboxylates bearing two benzene rings provided nematic phases, the ranges of which were some times wider and/or lower than those of the corresponding aryl esters bearing benzene rings alone.

Mesomorphic behaviour of di[(4-substituted phenyl)esters] of aromatic dicarboxylic acids

Abstract Some di(4-alkyloxyphenyl ester)s of aromatic dicarboxylic acids which presumably exert significant steric hindrance to molecular packing, such as di(2- and/or 3-methyl or -chloro-4-alkyloxyphenyl) 2,5-pyridinedicarboxylates, di(2- and/or 3-methyl-4-alkyloxyphenyl) 2,6-naphthalenedicarboxylates, and di(4-alkylxyphenyl) 3,5-pyrazoledicarboxylates, are shown to indicate nematic liquid-crystalline behaviour.

Polymers of 4-vinyl-2′-nitrodiphenylmethyl carboxylates capable of releasing functional acid by light

Abstract 4-Vinyl-2′-nitrodiphenylmethyl esters (VI) of functional carboxylic acids, such as benzoic, trans-cinnamic, hydrocinnamic, 2,4-dichlorophenoxyacetic, 2-methyl-4-chlorophenoxyacetic, and 2,2-dichloropropanoic acids, were synthesized by Friedel-Crafts acylation of (2-bromoethyl)benzene with 2-nitrobenzoyl chloride to afford 4-(β-bromoethyl)-2′-nitrobenzophenone, followed by reduction, dehydrobromination, and esterification with the acids. The polymers obtained by homo- or copolymerizations (principally with styrene) were subjected to near-UV irradiation (> 300 nm) either in THF solutions under N2 or in glass-sandwiched thin films to release functional acids, the extent of which depends upon various factors such as the chemical structure and the physical state of the polymer.