Study of the molecular structure on liquid crystal properties with reference to thermotropic azoester derivatives

ABSTRACTAn azoester homologues series: RO‒C6H4‒COO‒C10H6‒N˭N‒C6H4‒OC5H11 (para) as novel liquid crystalline (LC) materials has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on LC properties with reference to laterally substituted phenyl ring and terminally substituted ‒OR and ‒OC5H11 (n) groups; including ‒COO‒ and ‒N˭N‒ central bridges. Novel homologous series of thermotropic LC variety consists of thirteen homologues (C1 to C18). C1 to C3 derivatives are nonliquid crystal (NLC); C4 is only nematogenic and C5 to C18 are smectogenic plus nematogenic. All the mesogenic homologues (C4 to C18) are enantiotropically nematogenic or/and smectogenic as confirmed by a polarizing optical microscopy (POM) equipped with a heating stage. Transition curves Cr-I/M, Sm‒N, and N‒I behaved in normal manner in a phase diagram. Odd-even effect is exhibited by Sm‒N and N‒I transition curves. Analytical, spectral and thermal data confirms the molecular structure ...