Study of Molecular Flexibility Operated Mesomorphism

Abstract

Homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC14H29(P) of chalconyl novel derivatives have been synthesized and studied with a views to understand and establish the relation between molecular structure and the liquid crystal (LC) properties of thermotropic mesomorphs Series consists of thirteen homologues. Five homologues (C1 to C5) are nonliquid crystal (NLC) and the rest of the homologues (C6 to C18) are enantiotropically nematogenic without exhibition of smectic property. Transition temperatures and textures were determined by an optical polarizing microscope equipped with a heating stage (POM). Transition curves of a phase diagram (N-I and Cr-I/N) behaved in normal manner. N-I transition curve exhibited odd-even effect with negligible abnormality in its behaviour at the C14 homologue. Thermal stability for nematic is 99.75°C.The degree of mesomorphism vary minimum 19°C at the C6 homologue to maximum 28°C at the C8 homologue. Analytical and spectral data confirms the molecular structures of the novel homologues. Evaluated thermal data of present novel series are compared with other structurally similar homologous series. Textures of Nematic phase are threded or schlieren.