“Dependence of Mesomorphism in Combination with Fluoro and Chloro Groups”

Abstract

A novel azoester homologous series with chloro lateral group and a fluoro terminal end group was synthesized and characterized for mesomorphic properties. It consists of thirteen azo ester derivatives from trans-4-n-alkoxy cinnamic acid with 4-hydroxy-3-chloro phenyl azo-3-chloro-4-fluoro benzene. Mesomorphic property commences from C₄homologue as smectic.C₁ to C₃ member of the series are non-mesomorphic. C_{4 to} C₁₈ homologous are enantiotropic smectic A phase. The nematic mesophase is totally absent. Texture and transition temperatures of the homologues are determined by an optical polarizing microscopy equipped with heating stage. ¹H NMR, IR spectra, mass spectra, of some member is included. The spectroscopic analysis supports the molecular structure. A phase diagram is used to illustrate the mesomorphic behaviour across the series. Mesophaselength for smectic is varying from18.0^°C to 69.0⁰C. Mesomorphic properties of the novel azoester series are compared with structurally similar series.

KEY WORD:

• Liquid Crystal
• Mesomorphism
• Smectic A
• Nematic

Acknowledgements

Authors acknowledge thanks to the Department of Chemistry (DST-FIST Funded & UGC-SAP Sponsored), Saurashtra University, Rajkot, for research work. Authors are also thankful to Dr. A.V. Doshi, Ex. Principal M.V.M. Science and Home Science College Rajkot, for his valuable co-operation during present investigation as and when needed. Also thanks to the National Facility for Drug Discovery through New Chemical Entities (NCE’s) for analysis of samples.