Laser flash photolysis study of photosensitized oxidation of phenols in the organized aqueous media

摘要

The quenching of triplet 4,4'-dimetylbenzophenone (B) by phenol (PhOH) and its halogen substituted analogs in aqueous micellar solution of sodium dodecyl sulfate as well as formation and decay kinetics of the corresponding radical pairs (RP) have been examined using the laser flash technique. The quenching kinetics was described in terms of PhOH distribution between micellar and aqueous phases. The distribution coefficients and rate constants of intramicellar quenching and PhOH escape from micelles were extracted using global kinetic analysis. A very pronounced internal heavy atom effect was observed for the RP yield and geminate recombination and attributed to the enchanced intersystem crossing within contact RP due to the spin orbital coupling. Application of an external magnetic field results in the of RP decay even in the systems with minor contribution of geminate recombination.