Fluorescence Quenching Reactions due to the Intermolecular Electron Transfer Process in Solution

Mechanisms of the intermolecular electron transfer process in the electronically excited states of solute molecules have been studied in relation to the fluorescence quenching reactions in solution, employing pyrene as a fluorescer and some aromatic amine and cyano compounds as quenchers. The quenchers showed various strengths of the quenching actions which were classified and discussed on the basis of a new theoretical model of electron transfer process in excited state. Tetracyanoethylene showed a quite strong quenching action which was interpreted in terms of a long range electron transfer from excited pyrene to tetracyanoethylene. The relation between the exciplex formation, the electron transfer reaction due to the short range interaction and that due to the long range interaction have been discussed.