Study of the Effects of Lateral Substitution (Bromo) on Mesomorphic Behaviours of Chalconyl Ester Derivatives

Novel homologous series: RO-C sub( 6)H sub( 4)-COO-C sub( 6)H sub( 3)-Br-CO-CH=CH-C sub( 6)H sub( 4)-OC sigma ib 18 Phi sub( 3) (n) (ortho bromo to -COO-) is synthesized and studied with a view to understand and establish the relation between mesomorphic properties and the molecular structure with reference to lateral substitution of bromine -Br at middle phenyl ring. Chalconyl homologous series consists of thirteen homologues between (C sub( 1) to C sub( 18)). Nematogenic mesomorphism commences from C sub( 5) homologue and continues up to C sub( 18) homologue in enantiotropic manner. Transition and melting points were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Textures of nematic phase are threaded or schlieren. Transition curve Cr-N/I behaved in normal manner. N-I transition curve exhibited odd-even effect up to C sub( 8) homologue. It (N-I) rises and fall with negligible deviations from its normal descending tendency which appears in case of homologues C sub( 10) to C sub( 18). Liquid Crystal properties of present series are evaluated and compared with structurally analogous series and relative group efficiency order derived.