Study of the Effect of Molecular Structure on Mesomorphic Properties Through a Novel Homologous Series α-3-[4′-n-Alkoxy cinnamoyloxy] Phenyl-β-4^″-nitro Benzoyl Ethylenes

Abstract

Eleven members of a novel homologous series α-3-[4′-n-Alkoxy Cinnamoyloxy] phenyl-β-4^″-nitro benzoyl ethylene are synthesized and evaluated for their mesomorphic properties. Seven members of the series are enantiotropically nematogenic without exhibition of smectogenic character, and the other four members are non-mesomorphic in character. Mesomorphic behavior from a phase diagram for solid to nematic and for nematic to isotropic transitions shows the normal behavior. The nematic to isotropic transition curve shows an odd–even effect. Analytical data support the structures of molecules. Nematogenic phase length ranges from 30°C to 62°C. Nematic-isotropic thermal stability is 175.7°C. The mesomorphic properties of the series are compared with the structurally similar isomeric series. Thus, the series is predominantly mesomorphic (nematogenic) and partly non-mesomorphic with middle-order melting points. Transition temperatures and other liquid crystal properties were determined by optical polarizing microscopy with a heating stage.

Keywords:

• Enantiotropy
• liquid crystal
• mesomorphism
• nematic
• smectic

Acknowledgments

The authors give thanks to the Principal Dr. R. R. Shah and the head of chemistry department Dr. R. B. Patel to permit and cooperate for research work with the permission of college management. Also, thanks are due to the Vaibhav Laboratory and head of chemistry department of S. P. T. Science college, Godhra for their valuable cooperation to facilitate analytical services and microscopic observations, respectively.