DFT Study on the Reactive Species of Metalloporphyrin Catalytic Oxidation

Metalloporphyrin species such as metal porphyrin (PMII, PMIIICl), metal(III)-peroxo(PMII-O2), metal(III)-hydroperoxo(PMII-OH), and metal(IV)-oxo(PMIV = O) are key intermediates in the catalytic activation of dioxygen by metalloenzymes. It has been difficult to elucidate changes in the structure of the metal centre during catalysis and factors that control their chemical reactivity with substrates. The intermediates of metaloporphyrins catalytic circle were investigated to give insights into the detailed geometric and electronic structure, thus enhancing the understanding of redox metaloenzymes and their highly selective roles in biological process. The intermediates of metalloporphyrins (M = Fe, Mn and Co) including PMII, PMIIICl, PMII-O2, PMIV = O and PMIIIOH have been investigated using density functional theory method. The ground state of the intermediates was determined on assessment of relative energy and the results were are in line with expectations. Geometric structures of the ground state further confirmed the energetic assessment. The Mulliken charge and frontier molecular orbitals revealed the behavior of the intermediates in the catalytic process.