Tj. Mafatle et T. Nyokong, ELECTROCATALYTIC OXIDATION OF CYSTEINE BY MOLYBDENUM(V) PHTHALOCYANINE COMPLEXES, Journal of electroanalytical chemistry [1992], 408(1-2), 1996, pp. 213-218
Chemically modified electrodes, constructed by incorporating oxomolybd
enum(V) phthalocyanine (OMo(V)(OH)Pc, Pc = phthalocyanine dianion) int
o graphite powder were used to catalyse the oxidation of cysteine. Sol
ution catalysis of cysteine by oxomolybdenum(V) tetrasulfophthalocyani
ne, [OMo(V)(OH)TSPc](4-), was also investigated. A considerable reduct
ion in overpotential for cysteine oxidation was observed. Cysteine oxi
dation occurred at 0.26 and 0.28 V vs. Ag\AgCl for catalysis by OMo(V)
(OH)Pc and [OMo(V)(OH)TSPc](4-) respectively as opposed to 0.77 V vs.
Ag\AgCl observed on CoPc chemically modified electrodes. The anodic pe
ak currents vary linearly with cysteine concentration in the range 0.0
2 to 0.08 mol dm(-3) and 0.008 to 0.02 mol dm(-3) for [OMo(V)(OH)TSPc]
(4-) and OMo(V)Pc respectively.