Iron(II) polypyridyl amine complexes, e.g., [Fe(II)(N4Py)(CH3CN)](ClO4)2 (1), have proven to be effective mimics for the anti-cancer drug Bleomycin with similar efficiency in DNA cleavage with O2 as terminal oxidant. Recently, the cleavage activity of these complexes was shown to be enhanced dramatically by irradiation with visible light, due to light acceleration of the reaction of 1 with O2. In methanol, irradiation of 1 leads to the formation of a “pink” photo-product. Here we show that the photoreaction is accelerated under basic conditions in methanol and the product is spectroscopically similar to the enzyme methane monooxygenase (MMO) and assigned to a [Fe(III)2(μ-O)2] diamond core structure. Importantly the primary photoproduct undergoes a second photochemically driven reaction to produce a green intermediate. A combination of time dependent UV−vis absorption, Raman, and EPR spectroscopy, and cyclic voltammetry are employed to elucidate the photochemical pathways involved.

Light driven activation of O2 with iron(II) polypyridyl complexes

253rd National Meeting (2017)

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