CATALYTIC BEHAVIOR OF OSMIUM(II), RHODIUM(III) AND RUTHENIUM(II) PHTHALOCYANINES TOWARDS THE ELECTROOXIDATION OF CYSTEINE ON GLASSY-CARBON ELECTRODES

Glassy carbon electrodes (GCE's) modified with phthalocyanine complexe s of Rh, Ru and Os are employed for the catalytic oxidation of cystein e. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)(RhPc)-Pc-III, [(CN)(2)(RhPc)-Pc-III](-), (DMSO)(2)O sPcII, and [(DMSO)(2)Ru(II)Pc]. 2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an inc rease in the catalytic activity of the electrode with repetitive scann ing. This improvement in the catalytic activity of the GCE after the f irst scan is attributed to the formation of dimeric pi cation radical species at the electrode surface.