Molecular Crystals and Liquid Crystals, Vol.381, 169-178, 2002
Synthesis and mesomorphic properties of Schiff base esters p-n-octadecanoyloxybenzylidene-p-cyano-, p-hydroxy-, p-nitro, and p-carboxyanilines
Synthesis and mesomorphic behaviors of p -n-octadecanoyloxybenzylidene- p -substituted-anilines, C17H35 COOC6H4CH:NC6H4-R, where R= p -CN, p -OH, p -NO2 , and p -COOH were reported. The physical properties as well as the chemical formulations of these compounds were derived from microanalysis and spectroscopic methods (FTIR, H-1 NMR and C-13 NMR). Phase transition temperatures and the thermal parameters were obtained from differential scanning calorimetry (DSC). The texture observation was performed under polarizing optical microscopy (POM) attached with Mettler hot stage. All the compounds are thermotropic liquid crystals except p-n-octadecanoyloxybenzylidene-p-nitroaniline. While the compounds containing R= p-CN and p-OH exhibit smectic phases, the one consisting of p-COOH shows nematic and smectic characteristics. The investigation upon the existence as well as the dissociation of intermolecular hydrogen bonding at various temperatures in different phases has also been inferred from the FTIR analysis.