| dc.description.abstract | In this thesis, two series of new heterocyclic compounds, derived from benzothiazoles 2 and isoxazoles 3 were prepared and their mesomorphic properties investigated. In the first series, the synthesis, characterization and mesomorphic behavior of benzothiazole derivatives 2 and their palladium complexes 1 are described. All compounds were characterized by 1H, 13C NMR spectroscope and mass measurements. The mesomorphic properties were investigated using polarized optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffractions (XRD). The results indicated that ligands 2 based on benzothiazoles with a carbon length of n = 8 showed nematic (N) and smectic C (SmC) mesophases; while other derivatives with a carbon length of n = 10, 12, 14, 16 showed smectic C (SmC) mesophases. In contrast, their palladium(II) complexes of benzothiazoles 1 were not mesogenic. All palladium(II) complexes with a carbon length of n =10, 12, 14 showed glass (G) phase.
In the second series, the synthesis, characterization and mesomorphic behavior of isoxazole derivatives 3 are described. All compounds were characterized by 1H, 13C NMR spectroscope and mass measurements. The effect of substituent group on the formation of the mesophases was investigated, and their correlations with their dipole moments were also discussed. A SmA phase was observed for derivatives with a strong electron-donating substituent, whereas a crystal phase was observed for the derivatives with an electron-withdrawing substituent. | en_US |