Magnetic field effects due to the relaxation mechanism observed for the photo-induced electron transfer reaction of zinc(II) tetraphenylporphyrin and 2-methyl-1,4-naphthoquinone

The magnetic field effects (MFEs) on the photo-induced electron transfer (PET) reaction of zinc(II) tetraphenylporphyrin (ZnTPP) with 2-methyl-1,4-naphthoquinone (2MNQ) in a mixed solvent of cyclohexanol and 2-propanol were investigated at 293 K by a nanosecond laser flash photolysis technique. Upon irradiation of ZnTPP, the electron transfer from ZnTPP to 2MNQ occurred and the corresponding cation and anion radicals were generated. The relative yield of the escaped 2MNQ anion radical, R(B), showed appreciable MFEs. The R(B) values increased between 0 and 0.1 T, then decreased again between 0.1 and 1.65 T. The observed MFEs can be explained in terms of the relaxation mechanism.