Synthesis and mesomorphic properties of Schiff base esters ortho-hydroxy-para-alkyloxybenzylidene-para-substituted anilines

A series of new compounds o-n-hydroxy-p-n-hexadecanoyloxybenzylideneaniline and its substituted derivatives was synthesized from the esterification of palmitic acid with intermediary Schiff bases, which posssess various terminal substituents X(X=H, F, Cl, Br, OCH3 , CH3 , and C2H5). All compounds possess mesomorphic properties wherein compounds with X=H, F, Cl, Br, and OCH3 exhibit smectic A(SmA)phases and those with terminal substituents CH3 and C2H5 are monotropic liquid crystals showing smectic C phases(SmC). Correlation studies of the clearing temperature (T-c) of the title compounds and polarizability related to mesophase stability and molecular anisotropy are reported.