具對-苯二胺取代基鋅紫質與咪唑作用的光譜與電化學研究

本論文研究具對-苯二胺取代基鋅紫質與咪唑作用的光譜與電化學性質。在吸收光譜研究中，鋅紫質與咪唑鍵結後，使鋅紫質吸收峰上升及紅移。鋅紫質循環伏安圖呈現兩個可逆的及一個不可逆的氧化還原波，利用改變弱配位陰離子的電解質，使不可逆的氧化還原波分成兩個可逆的，因此得知鋅紫質第一個氧化為對苯二胺取代基的氧化，第二個為紫質環的氧化，第三個氧化還原波為對苯二胺取代基的第二個氧化，第四個為紫質環的第二個氧化。咪唑會與紫質中心金屬形成配位鍵結，當鋅紫質的對苯二胺取代基氧化後，咪唑從中心金屬轉移至取代基，與取代基形成電化學誘導氫鍵。利用紫外光/可見光/近紅外光光譜電化學法得知，隨著咪唑加入的當量數增加，價間電子轉移吸收峰(IVCT band)的強度逐漸減少以及波長產生紅移的現象，表示鋅紫質結構中對苯二胺取代基與咪唑之間產生越多的電化學誘導氫鍵。

關鍵字

對苯二胺；鋅紫質；循環伏安法；電化學誘導氫鍵；光譜電化學

並列摘要

A ligand transfer system, zinc meso-tetrakis(p-phenylenediamine)porphyrin (ZnTPP-PD4), containing zinc porphyrin and p-phenylenediamine (PD) moieties was synthesized. In TBAP/CH2Cl2 medium, the cyclic voltammogram (CV) of ZnTPP-(PD)4 exhibited two reversible redox couples and one irreversible wave. The irreversible wave in the CV of ZnTPP-(PD)4 was deconvoluted into two reversible redox couples while the weakly coordinating anion electrolyte, NaBArF24, was used. The first to fourth redox couples represented the PD oxidation, the oxidation of porphyrin ring, the further oxidation of PD cation radical, and the formation of porphyrin dication, respectively. When imidazole was added to the ZnTPP-(PD)4 solution, the shift of the third redox couple to the first one gave the evidence of the electrochemically induced hydrogen bonding formation between imidazole and oxidized PD. The ligand transfer phenomenon from zinc porphyrin core to PD moiety was controlled by changing the applied potential, and was monitored by UV/Vis/NIR spectroelectrochemistry. In addition, the absorption spectrum changes from five coordinated to four coordinated zinc porphyrin also demonstrated the imidazole transfer behavior. The more imidazole was added, the intensity of intervalence charge transfer (IVCT) band decreased and red-shifted, which means the more completion of electrochemically induced hydrogen bonding was formed.