Synthesis and Characterization of Some New Mesogenic Schief Base Esters N-[4-(4-n-Hexadecanoyloxybenzoyloxy)-Benzylidene]-4-Substituted Anilines

Series of elongated Schiff base esters containing three aromatic rings with palmitoyl moiety as one of the terminal carbon chain and various substituents R(R=H, F, Cl, Br, OCH3, CH3, and C2H5) at the other end of molecule have been isolated, and their structures were proposed via physical measurement. The mesomorphic properties of these compounds were investigated via differential scanning calometry and polarizing optical microscopy. The thermal data indicate that all of these compounds exhibit mesomorphic properties. Although compounds with R=H, OCH3, CH3, and C2H5 show nematic phases, the remaining compounds containing halogen F, Cl, and Br are smectogenic in nature. The structural changes that result in the variation of transition temperature and the electronic polarizability of the respective molecules are discussed.