Hydrogen Bonded Thermotropic Liquid Crystalline Properties of some New Schiff Basses

A new homologous series of Schiff bases ester,2-hydroxybenzylidineanilines:N-[4-(4,-n-(alkoxybenzoyloxy)-2-hydroxybenzylidine]-4,,-carboxyanilines ( HAHC ) were (n=1-10) synthesized and characterized by spectroscopic techniques (IR and 1HNMR) and microelemental analysis. Mesomorphic behavior and phase transitions were studied using polarized hot stage optical microscopy (POM) and differential scanning calorimetry (DSC). It has been found that the compounds with(C?-C?) of the series exhibit enantiotropic nematic phase only while those compounds with (C?-C?) show smectic C in addition to nematic phase. While compounds with (C?-C??) show smectic C phase only. Key words: Schiff Basses Liquid crystals , Thermotropic liquid crystals, Nematic phase , Synthesis of Liquid Crystalline compounds , Smectic C phase , Hydrogen bonded liquid crystals phase