卟啉-噁二唑二元体系光诱导能量及电子传递研究

Photoinduced Energy and Electron Transfer in Porphyrin-Oxadiazole Dyads

以5-对氨基苯基-10,15,20-三苯基卟啉及2-苯基-5-(对氨基苯基)-1,3,4-噁二唑为原料合成了系列卟啉-噁二唑二元化合物,其结构通过1H NMR,ESI-MS,IR,UV-Vis确定.对合成化合物进行光谱性能测定,结果表明,在卟啉与噁二唑混合体系中,存在着卟啉激发态分子向噁二唑基态分子的分子间电子传递过程,导致卟啉激发态的荧光猝灭;在卟啉-噁二唑二元体系中,315nm激发下发生了由激发态噁二唑基团至卟啉基团的能量传递,导致噁二唑基团荧光猝灭,卟啉基团荧光增强.420nm激发下不存在分子内卟啉基团向噁二唑基团的电子回传竞争;电化学性能测定进一步表明从噁二唑基团向卟啉基团的电子传递是可能的.因此卟啉-噁二唑二元化合物可能作为一种模型,模拟光合作用中电子给体至叶绿素之间的电子传递过程。

A series of porphyrin-oxadiazole dyads were synthesized from 5-（p-aminophenyl）-10,15,20- triphenylporphyrin and 2-phenyl-5-（p-aminophenyl）-1,3,4-oxadiazole and characterized by 1H NMR, ESI-MS, IR and UV-Vis. The experiment results showed that fluorescence of porphyrin was quenched when porphyrin was mixed with oxadiazole, indicating the occurrence of photoinduced electron transfer from a porphyrin molecule to an oxadiazole molecule. However, intramolecular photoinduced energy transfer occurred in the porphyrin-oxadiazole dyads from excited oxadiazole moiety to porphyrin moiety, leading to the fluorescence quenching of oxadiazole moiety and the fluorescence enhancement of the porphyrin moiety. But no electron transfer was found from the excited porphyrin moiety to the oxadiazole moiety. Moreover, cyclic voltammetric studies of the dyads 5a, 3b and 4b further indicated that electron transfer from the oxadiazole moiety to the porphyrin moiety was possible. Hence the porphyrin-oxadiazole dyads might be used as PS II model compounds to simulating the electron transfer from an electron donor side to chlorophyll.