Mesomorphism and Molecular Structure: Novel Homologous Series 4-(4′-n-alkoxy cinnamoyloxy)-4′′-methoxy Benzyl Benzoates

Abstract

A novel homologous series consists of 11 homologues, studied with a view to understand and establish the relations between mesomorphism and molecular structure of novel substances. All the novel members of a series except methoxy and pentyloxy homologue derivatives are liquid crystalline [LC] in nature. Mesomorphism commences from a second member of a series ethoxy, propyloxy, butyloxy, and hexyloxy to hexadecyloxy homologue derivatives are nematogenic while decyloxy, dodecyloxy, and tetradecyloxy homologue derivatives are smectogenic, in addition to nematogenic. All mesogenic homologues of a series are enantiotropic mesomorphic. Phase transition curve for Smectic-Nematic behave in normal manner without exhibition of odd-even effect, whereas nematic-isotropic transition curve adopts serpentile shape as rising and falling nature with exhibition of very minor odd-even effect. Textures of nematic phase are threaded or schlieren and that of a smectic mesophase is a focal conic fan shaped of the type smectic A or C. Analytical and spectral data supported molecular structures of homologues. The mesomorphic behaviors of present series are compared with a structurally similar other known series. Smectic and nematic thermal stabilities are 182.6 and 246.0°C, respectively. Present series is partly smectogenic and predominantly nematogenic with considerable degree of mesomorphism (maximum 100 °C) and high melting type.