Methylviologen-Accelerated Photoreduction of Tris(acetylacetonato)cobalt(III) with 1-Benzyl-1,4-dihydronicotinamide

The photoreduction of tris(acetylacetonato)cobalt(III) (Co(acac)3) by 1-benzyl-1,4-dihydronicotinamide (BNAH) was examined with or without methylviologen in the wavelength range of 340–410 nm. The reaction rate of electron transfer from BNAH to Co(acac)3 was considerably enhanced by methylviologen, especially, in lower polar environments; The weaker the hydrophobic interaction between BNAH and the substrate become, the more effectively methylviologen acts as an electron mediator for the above photoreaction. The reaction mechanism is also discussed with particular reference to the participation of the electron mediator in the elementary steps of the present photoinduced reaction.