Synthesis and Evaluation of a Novel Liquid Crystalline Homologous Series: α-4-[4′-n-Alkoxy Cinnamoyloxy] Benzoyl-β-3″,4″-Dimethoxy Phenyl Ethylenes

Abstract

The synthesis and evaluation of a novel series of 12 homologues is presented. Enantiotropic nematogenic mesomorphism is exhibited from the pentyl to hexadecyl homologues. The other homologues are not liquid crystalline. Smectic mesomorphism is absent in all homologues. Transition temperatures were determined using an optical polarizing microscope equipped with a heating stage. The transition curves of a phase diagram behave in a normal manner. An odd–even effect is observed for the N-I transition curve. The textures of the nematic phase are of the threaded or Schlieren type. Mesomorphic–isotropic transition temperatures range from 152°C to 178°C. The nematogenic phase length varies between 24°C and 51°C. The nematic thermal stability is 163.1°C. Thus, the novel homologous series is entirely nematogenic without the exhibition of smectogenic character, and is of a middle ordered melting type. Analytical and spectral data support the molecular structures. Liquid crystal (LC) properties of the novel series are compared with structurally similar homologous series.

Keywords:

• Liquid crystal
• mesomorphism
• nematic
• smectic
• thermotropic

Acknowledgments

Authors thank the president and all members of management of Bai Jivkor Lalubhai Trust as well as the principal Dr. R. R. Shah and the head chemistry department Dr. R. B. Patel of K. K. Shah Jarodwala Maninagar Science College, Ahmedabad, for their valuable cooperation into this work. Also, thanks are due to the Vaibhav Laboratory and head chemistry department of S. P. T. Science College, Godhra, for their valuable cooperation to facilitate microscopic observations and analytical services.