| Summary: | 碩士 === 國立中央大學 === 化學研究所 === 100 === In the first series synthesis, characterization and mesomorphic behavior of a series of benzoxazole and benzothiazole derivatives 2 and their complexes 1 (M = Pd, Cu) are described. The mesomorphic properties were investigated using polarized optical microscopy (POM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD). The results indicated that ligands based on benzoxazole with carbon length of n = 8, 10 showed nematic (N) mesophase; with carbon length of n = 12, 14, 16 showed smetic C (SmC) mesophase. All palladium (II) and copper (II) complexes of benzoxazole derivatives were not mesogenic. Ligands based on benzothiazole with carbon length of n = 8 showed nematic (N) and smetic C (SmC) mesophase; with carbon length of n = 10, 12, 14, 16 showed smetic C (SmC) mesophase. Copper (II) complexes of benzothiazole derivatives were not mesogenic. However, palladium (II) comlexes of benzothiazole derivatives with carbon length of n = 8, 10, 12, 14, 16 showed smetic C (SmC) mesophase.
In the second series, the effect of substituent group on the formation of the mesophases were investigated by Hammett constant, and dipole moment. A SmA phase was observed for derivatives with a strong electrondrawing substituent, and a N phase was observed for the derivative with an electrondonating substituent.
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