Mesomorphism Dependence on Terminal and Lateral Polar Groups in the Nonlinear Novel Azoester Series

Abstract

The synthesis of a novel azoester homologous series was carried out with a view to understanding and establishing the effect of molecular structure on liquid crystal (LC) behavior of a substance. The novel series consists of eleven homologs, and all are enantiotropically nematogenic without exhibition of any smectic property. Transition and melting temperatures, textures of LC were determined by an optical polarizing microscope equipped with a heating stage. The textures of the nematic phase are threaded or Schlieren. Transition curves of a phase diagram behave in normal manner. The nematic-isotropic transition curve exhibits an odd-even effect. Analytical and spectral data support and confirm the structures of the homologues. Average thermal stability for the nematic is 137.2°C. The mesomorphic phase length ranges from 15°C to 50°C. LC behavior of the novel series is compared with a structurally similar known homologous series. The novel azoester homologous series is entirely nematogenic without exhibition of smectogenic character and of a middle-ordered melting type.