Molecular Flexibility of Longer n-Alkoxy Tail Group Operated Mesomorphism

Abstract

A novel homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC16H33 (n) para of chalconyl ester derivatives have been synthesized and studied with a view to understand and establish the effect of molecular structure on thermotropic liquid crystalline state of the substances and to provide novel liquid crystal (LC) materials to the researchers working in an unique multidisciplinary LC state of the substances. A novel chalconyl ester series consists of thirteen ( C1 to C18) homologues. C5 to C18 homologues are enantiotropically nematogenic without exhibition of smectogenic property, while the rest of the C1 to C4 homologues are nonliquid crystals (NLC). Transition temperatures and textures were determined by polarizing optical microscopy (POM) equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Cr-I/N and N-I transition curves of a phase diagram behaved in normal manner except negligible abnormality at C14 homologue. Odd-even effect is exhibited by N-I transition curve. Analytical and Spectral data supported molecular structures of the homologues. Thermal stability for nematic is 97.33°C and the degree of mesomorphism vary maximum 24.0°C at C5 homologue to minimum 11.0°C at C10 homologue respectively. Latent transition temperatures (LTT) are determined for nonmesomorphic homologues C4 (90°C) and C3 (114°C) homologues by extrapolation method of transition curve. LC properties of a novel series are (thermometric) compared with structurally similar series.