Synthesis, characterization and thermal properties of 4,4 '-bis (4-n-alkoxybenzoyloxy)benzylideneanilines and bis(4-benzylidene-4 '-n-alkoxyaniline) terephthalates

Series of novel thermotropic liquid crystalline compounds which serve as mo dels for mesogenic diols have been synthesized. The mesogen molecules are c onstructed from 1,4-disubstituted benzene rings linked through ester and az omethine units. Based on the number of phenyl rings, a tetrad or pentad cla ssification has been assigned to the core molecule. The structures of these compounds were established by FTIR and NMR spectroscopy, while the mesomor phic behaviour has been confirmed using polarizing optical microscopy and D SC. All the compounds of the homologues series are mesomorphic in nature. T he lower members of the series are nematogenic, while the higher members ex hibit both nematic and smectic character, with high melting behaviour and w ide mesophase ranges.