Magnetic field effects on the yields of dyes in sensitized transformation of diphenylamine in micellar systems

A strong influence (an increase in the rate of formation of the diphenylbenzidine dication by up to three times) of an external magnetic field on the yields of colored products was observed when micellar solutions of benzophenone and diphenylamine derivatives were UV irradiated in the presence of acids. A mechanism of the phenomenon was suggested. The mechanism by based on the concept of the simultaneous occurrence of two processes, (1) geminate recombination of ketyl and aminyl radicals with the formation of triarylmethane dye and (2) bulk recombination of two radical cations produced in the protonation of aminyl radicals with the formation of the diphenylbenzidine dication. Magnetic field is a factor determining the rate of the triplet-singlet conversion of radical pairs formed in the photoreduction of the ketone by amine and, therefore, the ratio between the stationary concentrations of aminyl radicals and radical cations. The influence of the structure of ketones, the ratio between the reagents and surfactant, and the pH value on the dye yield and the scale of magnetic-spin effects were analyzed.