Photo-induced oxidation of [Fe(II)(N4Py)CH3CN] and related complexes.

The photochemistry of the complexes [Fe(N4Py)(CH(3)CN)](ClO(4))(2) (1), where N4Py is 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine and [Fe(MeN4Py)(CH(3)CN)](ClO(4))(2) (2), where MeN4Py is 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethanamine, in water, dichloromethane and methanol is described. Under UV or visible irradiation both 1 and 2 undergo enhancement of the rate of outer sphere electron transfer to (3)O(2) to yield the superoxide radical anion and the complexes in the Fe(III) redox state. Addition of ascorbic acid to the photoproduct leads to a recovery of the initial UV/Vis spectrum of 1 and 2, indicating that ligand oxidation does not occur. The results are discussed within the context of the recent report of the enhancement of the oxidative DNA cleavage activity of 1 under UV and visible irradiation (Inorg. Chem. 2010, 49, 11009).