双吡啶盐/酞菁体系的光诱导电子转移的ESR研究

ESR Studies for the Photoinduced Electron Transfer of the Phthalocyanine-Paraquat Systems

研究了五种金属酞菁化合物与一系列双吡啶高氨酸盐（PQ2+）之间在苯中的光诱导电子转移．对于酞菁／PQ2+／苯体系，在可见光辐照下，酞菁化合物的价带电子可被激发至导带，然后于界面发生电子转移使PQ2+盐变成离子基PQ，给出较弱的ESR信号；当有表面活性剂氯代十四烷基吡啶和电子给体三乙醇胺存在时，可使PQ基的ESR信号显著增强5～6信以上．当有氧存在时，PQ基信号迅速消失，给出较明显的超氧负离子基O2的信号．氧能严重抑制电子转移的过程．

Photoinduced electron transfer of metal-phthalocyanine MPc (M=Zn, Mg,Fe, Co, Cu) dispersions in the presence of electron acceptors such as paraquat (4,4’-[-1,4-phenylene-]-Bis-[-N-alkyl(oraryl)-2,6-(diphenyl-]-pyridinium perchlorates, i.e. PQ2+) has been studied by means of ESR spectroscopy. The results show that, when irradiated with visible light, electron in valence band (VB) of photoconductor can be excited to conduction band (CB) to form an electron-hole pair and the electron may transfer from CB to PQ2+ to produce a radical cation PQ, then a weak ESR signal was observed. As in the presence of catioinc surfactant Chloro-Tetradecyl-Pyridium, as well as of hole-quencher TEA or EDTA, the strength of ESR signal can be enhanced by 5-6 times as much or more. While in the presence of oxygen in the system, the signal of PQ radical disappeared and superokide radical anion O2 was detected. It is obvious that the existence of oxygen might seriously hinder the process of photoinduced electron transfer.