| dc.description.abstract | Abstract
In this thesis, we report the synthesis, characterization and mesomorphic properties of two novel series of new mesogenic derivatives based on [4-(6-alkoxybenzoxazol-2-yl)phenyl]-4-X-benzy lidenes (as shown below, X = CN, F, Cl, NO2, OCH3 and etc.) and metal complexes of 5-alkoxy-2-{[4-(6-alkoxybenzoxazol-2-yl)phenylimino] methyl}phenols. These compounds were all characterized by 1H-NMR and 13C-NMR spectroscopy, and their mesomorphic properties were studied by differential scanning calorimeter (DSC) and polarized optical microscopy (POM).
The results indicated that all compounds exhibited nematic (N) and/or smectic A phases (SmA) and/or smectic C phases (SmC), as expected by rod-like molecules. In addition, the mesomorphic properties observed by these compounds were found to be strongly dependent on the terminal group attached. The effect of mesomorphic properties, which was determined by the electronic and/or steric configuration of the terminal groups, will be also discussed. For example, smectic A phase was observed for the derivative with CN attached as terminal group, however, nematic phase was in fact observed for the derivative with OCH3 group. The effect of the carbon chain length of side chains on the mesomorphic properties will be also investigated. Copper(II), palladium(II), and nickel(II) complexes exhibited mesomorphic properties, however, cobalt(II) and zinc(II) complexes were not mesogenic. | en_US |