Synthesis and Mesomorphic Properties of Novel Ethylene Derivatives

Abstract

A novel homologous series, α-4-[-4′-n-alkoxy cinnamoyloxy] benzoyl-β-4″-methoxy phenyl ethylenes, has been synthesized, which consists of 12 homologues. The pentyl to tetradecyl homologues are enantiotropically mesomorphic, and the rest of the homologues are nonmesomorphic. The pentyl to octyl derivatives exhibit smectogenic character in addition to nematogenic character, but the decyl to tetradecyl homologues exhibit only nematogenic character without the exhibition of a smectic phase. A phase diagram of three transition curves shows a normal phase behavior. Analytical and spectral data confirm the molecular structure of the homologues. The optical microscopic textures are threaded or Schlieren for the nematic phase and the normal smectic A type, respectively. Liquid crystal properties and transition temperatures were determined using a hot stage polarizing microscope. The smectic and nematic thermal stabilities are 159.7°C and 174.1°C, respectively. Thus, the present novel series is predominantly nematogenic and partly smectogenic in nature and is compared with other structurally similar homologous series.

Keywords:

• Enantiotropy
• ethylene derivatives
• liquid crystal
• nematic
• smectic

Acknowledgments

The authors would like to thank K. K. Shah Jarodwala Maninagar Science College and S.P.T Arts & Science College, Godhra, for their valuable cooperation in this work. They would also like to thank Vaibhav Laboratory for their analytical services and Ankita Doshi, Department of Biochemistry, M.S. University of Baroda, Vadodara, for valuable support in the work.