Direct detection of superoxide anion generated in C60-photosensitized oxidation of NADH and an analogue by molecular oxygen

摘要

Visible-light irradiation of poly(vinylpyrrolidone) (PVP)-solubilized C60 in water in the presence of NADHn(dihydronicotinamide adenine dinucleotide) and molecular oxygen (O2) results in formation of superoxide anionn(O2nu0001u0002). Formation of O2nu0001u0002 having a characteristic g| | value of 2.18 was evidenced by the direct observation with usenof a low-temperature EPR technique at 77 K. Photoinduced O2nu0001u0002 formation was also observed for an N-methyl-2-npyrrolidone (NMP) solution of C60 and 1-benzyl-1,4-dihydronicotinamide (BNAH) in the presence of O2, whereasnC60 radical anion (C60nu0001u0002) was formed in the absence of O2 under otherwise the same experimental conditions. Thesenresults suggest that C60n2u0002 formed in the photoinduced electron-transfer reduction of C60 by BNAH acts as an electronndonor to O2 to give O2nu0001u0002 in NMP.