Spectral And Electrochemical Studies Of Zinc Porphyrin Core Dendrimers With Triphenylamines As Dendron

• Main Authors: Huang, Chih-Yen, 黃智彥
• Other Authors: Su, Yuhlong Oliver
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/03618435926658001850

博士 === 國立暨南國際大學 === 應用化學系 === 99 === The spectral and electrochemical properties of a series of mono- to tetra-triphenylamine substituted zinc porphyrin (ZnP) and the second generation of zinc porphyrin core dendrimer with triphenylamine (TPA) as dendron have been studied. The varied shapes of absorption spectra of zinc porphyrin-triphenylamine conjugates (ZnP-(TPA-X)n) in comparison with zinc tetramesitylporphyrin (ZnTMP) indicate strong interactions between zinc porphyrin and TPA derivatives. The increasing electron-donating (ED) capability of substituent at TPA and the number of TPA derivatives bonding with zinc porphyrin would cause the Soret band broadening and intensifying in Q(0,0) band. Because of the antenna effect on these ZnP-(TPA-X)n, the intensity of emission was enhanced when more triphenylamine moieties were linked. Cyclic voltammetry and spectroelectrochemical method reveal the redox properties of ZnP-(TPA-X)n. Axial ligation of zinc porphyrin with N-methylimidazole (N-MeIm) is useful in differentiating the oxidation sites of ZnP-(TPA-X)n. The first one-electron oxidations of these conjugates are at porphyrin ring which becomes easier to oxidize as the ED capability of substituent at TPA and the number of TPA derivatives bonding with porphyrin increase. On the other hand, the dendrons of the second generation dendrimers with zinc porphyrin core are oxidized first, and an atmosphere of eight positive charges is thus generated. The porphyrin ring core is then oxidized with an anodic shift in potential due to the electron-withdrawing effect of the oxidized substituents. The charge-transfer bands present in near-infrared (NIR) region in the absorption spectra of [ZnP+‧-(TPA-X)n] are the evidence of electronic interaction between zinc porphyrin and TPA. The ED strength of the TPA group and the symmetry of the Por-TPA conjugate would affect the intensity of the charge-transfer band.