Synthesis and Study of Novel Mesogenic Homologous Series: 4-(4′-n-alkoxy benzoyloxy)-n-propyl Cinnamates

Abstract

A novel homologous series of liquid crystals viz. 4-(4′-n-alkoxy benzoyloxy) n-propyl cinnamates comprising of 11 homologues has been synthesized. It is a middle ordered melting type of series with exhibition of smectic and nematic mesophases. The first to fifth members of the series are non-mesomorphic. Mesomorphic behavior commences from the sixth homologue. The octyloxy (C8) and decyloxy (C10) homologues are polymesomorphic. The smectic–nematic and nematic–isotropic transition curves behave in a normal manner except for the hexadecyl derivative, which slightly deviates from normal behavior (N–I). An odd–even effect was not observed for the N–I or Sm–N transition curves. The texture of nematic phase is threaded or Schlieren and that of the smectic phase is focal conic fan shaped of the smectic-A type. Transition temperatures and textures of mesophases were observed through an optical polarizing microscope equipped with a heating stage. Thermal stability and mesomorphic characteristics are compared with a structurally related series. Analytical and spectral data support the structure of the molecules.