香豆素衍生物与碘鎓盐间的光诱导电子转移研究

研究了3种碘鎓盐对3种香豆素荧光的猝灭,发现猝灭曲线符合Stern-Volmer方程,并且猝灭过程受扩散控制.研究证实了猝灭的机理是由于发生了光诱导电子转移.通过香豆素衍生物-碘鎓盐体系能在光照下引发甲基丙烯酸甲酯单体的聚合进一步证实了这种机理.尽管香豆素有较强的分子内电荷转移倾向,但由于碘鎓盐阳离子很强的拉电子能力,它们间还是能发生快速的电子转移.

A STUDY ON THE ELECTRON-TRANSFER BETWEEN COUMARINS AND IODONIUM SALTS

The fluorescence quenching of three coumarin derivatives by three iodonium Salts was studied in this work. It is found that the quenching curves follow the Stern-Volmer equation and the quenching processes are controlled by diffusion. The results are thoroughly discussed. An electron transfer mechanism of the quenching was proposed and was proved by the ability of coumarin-iodonium salt systems to initiate the polymerization of MMA under irradiation. Due to the low redox potentials of iodonium salts' and excellent ability to accept electrons, the electron transfer rates between coumarins and iodonium salts are very fast when they are irradiated in spite of coumarins' tendency of intramolecular charge-transfer.