Physical Properties of Schiff's Base Esters:n-Alkyl 4-[4′-(4″-n-octyloxybenzoyloxy)benzylidene] aminobenzoates

Abstract A homologous series, n-Alkyl 4-[4′-(4″-n-octyloxybenzoyloxy)benzylidene] aminobenzoates, exhibiting nematic (N), smectic A (SA) and smectic C (SC) trimorphism has been prepared. The liquid crystal behavior of the series is compared with that of a corresponding series, n-Alkyl 4-[4′-(4″-n-octyloxybenzoyloxy)-3-methoxy benzylidene] aminobenzoates. The effect of a lateral methoxy substitution on mesomorphic properties of the series is discussed. Physical properties, such as, transition temperatures, transition heats, optical textures, densities, refractive indices and the orientational order parameter are studied. The SA–SC phase transition is found to be second order. The SC phase appears to show a temperature dependent tilt angle. A binary phase diagram of one of the members of the series with terephthalylidene-bis-(4-n-butylaniline) (TBBA) is presented. It serves as an exception to the miscibility rule and also gives an induced smectic B phase.