Liquid Crystalline Properties of Alkyl 4-[4-(4-Methoxybenzoyloxy)benzylideneamino]benzoates and 4-[4-(4-Methoxybenzylideneamino)benzoyloxy]benzoates

Abstract

Abstract The mesomorphic properties of homologous series of alkyl 4-[4-(4-methoxybenzoyloxy)benzylideneamino]benzoates and the isomeric compounds, 4-[4-(4-methoxybenzylideneamino)benzoyloxy]benzoates have been studied, employing thirty ester alkyl groups. The nematic phase appearing in the former series is thermally more stable than that in the latter: even the t-butyl and 1,1-dimethylpropyl esters are nematogenic. The mesophases in these esters are significantly promoted relative to those in the isopropyl and 1-methylpropyl esters, respectively. An alternation in the thermal stability of the nematic phase occurs when the branching methyl group is moved progressively to the penultimate carbon of the chain in both series. In the second series, the stabilization of the smectic A phase by 3- or 4-methylation is observed for both butyl and pentyl esters.