Photo-induced Electron-relay Reaction Utilizing Electrostatic Field of Polymers

点击翻译按钮获取中文摘要

Molecular aggregates are formed between polystyrenesulfonate anions (PSS^-) and stilbazolium cations (Stz^+) by means of their electrostatic interactions. A co-adsorbed sensitizer, Ru(bpy)_3^<2+> 2+ transfers, on irradiation, its electron into stilbazolium cation resulting in the formation of stylbazole radical. An efficient electron relay takes place among the olefin aggregates, and highly efficient cis to trans isomerization of the olefins occurs, quantum yields being as high as 100. Firstly, we could show that the thousands of Stz^+ ions bound to PSS^- are divided into small aggregates of micelle-like clusters and that their aggregation numbers are constant in the range of 80-90, irrespective of the degree of polymerization of PSS^-. The electron-relay chain isomerization proceeds within one micellar cluster. Secondly, we could succeed in detecting directly stylbazole radical, as an unstable transient intermediate in the cis-trans isomerization. Photolysis of a mixture of p-dicyanobenzene (DCB) and naphthalene in the presence of stilbazolium cation yielded a transient species, (^<lambda>max 420 nm) at the expense of anion radical of DCB (^<lambda>max 340 nm). The transient spectrum is that of stylbazole radical, and decays satisfying a second-order kinetics. The decay rate constant has been found to be heavily increased by the addition of polystyrenesulfonate anions, which implies that an electron is rapidly relayed among the adsorbed stilbazolium ion aggregates.