Synthesis and Evaluation of a Novel Homologous series of Carbonylethylene-Linked Liquid Crystals

Abstract

A novel homologous series of α-4-[4′-n-Alkoxy benzoyloxy] benzoyl β-phenyl ethylenes was synthesized with a view to understand the effect of molecular structure on liquid crystal (LC) properties. The novel series consists of 11 homolog derivatives. The LC properties commence from the hexyl derivative of the series. The methyl to pentyl derivatives of the series are not liquid crystalline; however, the hexyl to hexadecyl homolog derivatives are enantiotropically nematogenic with the absence of smectogenic phases. Thus the novel series is entirely nematogenic. The melting points, transition temperatures, and mesophase morphologies were determined by optical polarizing microscopy in conjunction with a heating stage. The microscopic textures show the nematic mesophase of the threaded or Schlieren type. Analytical and spectral data support the molecular structure. The nematic to isotropic liquid transition curve behaves in a normal manner without the exhibition of an odd–even effect. Typical melting points are around 140°C and the nematic-phase stability varies from around 150°C to 180°C. The LC properties of the novel series are compared with other structurally similar series.