In abstract:

Synthetic mimics of methane activation enzymes

Methane hydroxylation is a challenging process in nature and very few enzymes are able to catalyse this reaction efficiently. In particular, a very efficient heme monoxygenase in our body, namely cytochrome P450, catalysis a range of aliphatic hydroxylation reactions in the liver as a means to detoxify the body from drugs and xenobiotics; however, it is not known to hydroxylate methane. Recently, the Sorokin group established methane hydroxylation by a synthetic porphyrin model system that shows structural analogy to the active site of P450 enzymes.

Researchers at The University of Manchester have conducted a detailed computational study on methane hydroxylation by synthetic and enzymatic iron-porphyrin complexes and rationalised the origins of the rate changes. It shows that the key difference in methane hydroxylation by µ-nitrido-bridged diiron(IV)-oxo complexes with respect to P450 Compound I stems from the differences in orbital reorganisation energies upon breaking of the Fe-O bond, which costs considerably less energy in the synthetic complex than in P450 Compound I. These observations may further explain the differences in activity of heterogeneous versus homogeneous catalysts in methane to methanol conversion.

Click here to read the full article: https://doi.org/10.1021/acscatal.5b02720

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