Magnetic field effects on the reaction of the photoexcited triplet of 2-methyl-1,4-naphthoquinone in SDS micellar solution containing the 4-(lauroylamino)-TEMPO radical

A study has ben made of magnetic field effects (MFEs) on the reaction of the photoexcited triplet of 2-methyl-1,4-naphthoquinone (MNQ) in SDS micellar solution containing the 4-lauroylamino-TEMPO radical (L-R-.) under magnetic fields below 1.75 T by a nanosecond laser flash photolysis technique. The triplet MNQ mainly underwent the hydrogen abstraction from an SDS molecule to give a radical pair. The lifetime of the radical pair increased with increasing magnetic field from 0 to 0.62 T. The escaped radical yield also increased from 0 to 1.75 T. The qualitative features of these MFEs were similar to those observed for the photoreduction of MNQ in SDS micellar solution without L-R-., and these MFEs can be explained by the relaxation mechanism. However, it was found that L-R-. affected the MFEs for this reaction in two ways: first, L-R-. reacted with the triplet MNQ through H abstraction and/or electron transfer, and second, the spin relaxation of the radical pair was enhanced through the spin-spin interactions of the individual radical with L-R-..