A wide range of important enzyme-catalyzed reactions including the biosynthesis of natural products and metabolism of xenobiotics involve the generation of high valent iron species (i.e. FeIII-OOH, FeIII-(OO) and FeIV=O etc.) formed primarily by direct reaction of iron(II) and iron(III) based enzymes with oxygen. The transient nature of these intermediates, in particular those involving non-heme enzymes, frustrates efforts to observe them and elucidate mechanistic details. It is in this aspect that functional models for biological systems are essential. In recent years we have explored the activation of oxygen by Fe(II) polypyridylamine complexes, in particular to understand the factors that determine their activity in achieving substrate oxidation (such as the oxidative cleavage of double strand DNA). In this contribution, we explore, in a combined experimental and theoretical study, the reaction of these complexes with oxygen and the pathways which are involved in achieving substrate oxidation. The major focus will be on the generation of superoxide radical from the reaction of Fe(II) polypyridylamine based complexes and oxygen and in particular the enhancement in reaction rates observed by irradiation with visible and UV light. This will be complemented by state-of-the-art density functional studies using methods that have been proven to work well for spin-state properties that play a major role here.

Elucidation of the mechanism of activation of oxygen by iron(II)polypyridylamine complexes in water

253rd National Meeting (2017)

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