Magnetic-Field-Dependent Spin Adduct Yield in the Photoreduction of Naphthoquinones in SDS Micellar Solution

Article abstract of DOI:10.1021/j100289a023

A spin trapping method was applied to probe the radical pair model in the magnetic-field-dependent photoreduction of naphthoquinones in a SDS micellar solution.In these systems a spin adduct of the SDS radical was detected, and the adduct yield was strongly dependent on the static magnetic field.The magnetic-field-dependent adduct yield varied with spin traps, quinones, and concentration of the quinones.In addition, quenching of stable nitroxides, added to the system instead of the spin trap, during the photoreduction of a naphthoquinone in a SDS micellar solution was also dependent on the magnetic field.These results were analyzed with a kinetic model of this reaction system.The present method, using ESR spectroscopy with a spin trapping technique, is superior to other methods because with the former method intermediate transient radicals can be accumulated and detected directly under various magnetic fields.Another advantage of our method is that many different kinds of spin traps can be employed to elucidate the detailed behaviors of the transient radicals.A magnetic-field effect of more than 300 percent was obtained.To the best of our knowledge this is the largest magnetic field effect for a final product yield.