Mesomorphic Characteristics of Liquid Crystalline Esters p-Methoxyphenyl p-Alkoxycinnamates

Article abstract of DOI:10.1246/bcsj.65.559

The newly synthesized homologous series p-methoxyphenyl p-alkoxycinnamates (I) can be compared with the series N- p-anisidines (II).All the homologues of both series (I) and (II) from C₁ to C₁₈ are mesogens.In series (II) the first five members decompose due to high transitions at about 300 deg C.With decrease in length of the molecules of series (I) than that of series (II), the overall transitions also decrease by about 150 deg C.The first seven members in series (II) are nematogens; polymesomorphism begins from octyloxy homologue with the commencement of smectic mesophase and continues to be exhibited upto the last i.e. octadecyloxy homologue.In series (I) also the nematic phase is exhibited upto the heptyl derivative; the smectic phase commences from C₈-member in the form of monotropic phase thereby exhibiting polymesomorphism upto C₁₄ homologue.The last two members of series (II) are smectogens.The odd-even effect is missing in series (II) whereas in series (I), it is seen upto the fifth homologue.In both the series, the N-I curves show a falling tendency - a criterion of high melting series.From textures' point of view both the series have common features, the nematic phase is threaded when it is the only mesophase shown and homeotropic in polymesomorphic region, whereas the smectic mesophase is focal conic fan shaped of smectic-A variety.This series also yields interesting comparison with the series (III) p-nitrophenyl p-alkoxycinnamates and (IV) p-chlorophenyl p-alkoxycinnamates.