A Water-Soluble Iron Porphyrin as a Highly Efficient and Recyclable Catalyst for Peroxynitrite Decomposition

Abstract

Peroxynitrite can be highly efficient catalyzed to harmless products with a turnover frequency 34.5 s-1by micromolar concentration of water-soluble iron porphyrin, 5, 10, 15, 20-tetrakis-(4-carboxyphenyl)-porphyrin-Fe(III)-chloride (T(p-COOH)PPFe(III)Cl). Then we used spectroscopic and kinetic to study its decomposition mechanism and rate in bionic environment (25 mM sodium bicarbonate). The data reveal that this catalytic reaction is a recyclable reaction. Peroxynitrite is decomposed to nitrate (NO3-) and nitrite (NO2-) through forming [oxoFe(IV)]+intermediate. Moreover, the [oxoFe(IV)]+intermediate is reduced back to the starting porphyrin. It is noted that the oxidized iron porphyrin can be reduced by the reducing agent in the solution. In addition, we also find the catalytic rate constant is higher in the presence of sodium bicarbonate than the absence of sodium bicarbonate. They are 1.26×106M-1s-1and 1.17×106M-1s-1, respectively.