Electrochemical study with cavity microelectrode containing clay-supported Mn(III)salen complex – Dioxygen activation with cytochrome P450 model

MnIIICl–salen complex of tetradentate Schiff base ligand was incorporated into layers of clay montmorillonite by using an in situ flexible ligand method. The obtained modified clay was examined by X-ray diffraction, FT-IR and by using a cavity microelectrode (CME) to perform the electrochemical studies of the catalyst in the supported solid phase. Experiments show a well-defined and chemically reversible redox system of the manganese complex incorporated into the clay, similar to that observed in solution but with apparent diffusion coefficient around 2.3 × 10−9 cm−2 s−1. Dioxygen activation in catalytic conditions that was found to be efficient in the modified material is studied with the CME. It demonstrates the absence of formation of μ-oxo dimers and peroxo-bridged compounds and a good penetration of the different reactants into the clay. Moreover, this analysis illustrates the interest of CME as a powerful tool for the study of similar supported catalyst implying the biomimetic activation of molecular oxygen.