Electrocatalytic properties of meso-tetraphenylporphyrin cobalt for nitric oxide oxidation in methanolic solution and in Nafion® film

Coordination of nitric oxide (NO) to meso-tetraphenylporphyrin cobalt in solutions containing methanol and in Nafion® film has been studied by cyclic voltammetry, visible spectroscopy, ESR and FTIR. Formation of CoIITPP(NO) has been observed in the alcoholic solutions of both CoII- and CoIII-complexes in the presence of NO. The same reductive nitrosylation has been observed only for CoIIITPP+ distributed in the hydrophobic part of the Nafion® film. The electrochemical oxidation of the resulting NO-complex in the methanolic solution and in Nafion® film has been monitored, and demonstrated the catalytic character under an excess of NO. A reaction scheme for the catalytic process, which includes reductive nitrosylation followed by oxidation of CoIITPP(NO) has been suggested. A possible role of trace amount of alcohols in the Nafion® film has been discussed.