Home > Research > Biomimetic Metal-Oxo Intermediates
Metal containing enzymes involved in catalyzing in vivo activation of oxygen uses a reactive metal-oxygen intermediate species (metal-oxo (M=O), metal-superoxo (M-O2·-), metal-peroxo (M-O22-) and metal-hydroperoxo (M-OOH): see figure) to transfer the oxygen atom to the substrate. Further understanding of this biochemistry is obtained and advanced by means of synthesis of biomimetic compounds, as well as investigation into their structures and electronic properties and observation of the reactivities. Metal- containing enzymes that catalyze the reactions are divided into a large protein part and an active site part that directly activates the oxygen. The active site part consists of the central metal and the surrounding ligands, and the research is done with compounds that mimic this active site.

Hence in our lab, we are studying the synthesis of biomimetic metal compounds containing various ligands, their metal-oxo intermediates, substrate oxidation reactivities and reaction mechanisms. Recently in particular, using a series of transition metals, reactive metal-oxygen (M-O2: M = Cr, Mn, Fe, Co, Ni) compounds were synthesized. Systematic results of properties related to their structures, spectroscopic analysis and reactivities can be obtained using macrocyclic ligands (n-TMC: n = 12, 13, 14). Among the notable accomplishments is that the various new reactive metal-oxygen species are found to exist as either end-on metal-superoxo or side-on metal-peroxo species, identified using low-temperature single-crystal structure analysis. In addition, research is done on factors affecting these intermediate reactivities such as solvent effects including its pH, ligand topologies and the presence of redox-inactive metals (Ca2+, Mg2+, Zn2+, Sc3+ etc.).