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.

Keywords:

• Enantiotropy
• liquid crystals
• mesomorphism
• nematic
• smectic

Acknowledgment

Authors acknowledge thanks to the Green Circle Inc. Lab for research facilities services as and when needed. Authors also thank Dr. N. N. Vyas, Dr. Vipul Patel, and Dr. M. L. Chauhan for their valuable helping hand and microscopic facility. Thanks are due to the Sophisticated Analytical Instrumentation Facility, Punjab University, Chandigarh for analytical services.