Collect. Czech. Chem. Commun. 1981, 46, 457-461

EPR study of reduction of vanadyl tetrasulphophthalocyanine by ascorbic acid

Dana M. Wagnerováa, Pavel Stopkaa, Horst Reinb and Jörg Friedrichb

a Institute of Inorganic Chemistry, Czechoslovak Academy of Sciences, 160 00 Prague 6, Czechoslovakia
b Central Institute of Molecular Biology, Academy of Sciences of the German Democratic Republic, 1115 Berlin-Buch, GDR


Based on the EPR spectra, vanadyl tetrasulphophthalocyanine (VOTSP) was found to be reduced by ascorbic acid in alkaline medium to the vanadium(III) complex. The hyperfine structure of the spectra indicates that after re-oxidation, the equilibrium between the dimeric and the monomeric forms of VOTSP is shifted in favour of the latter as compared with the initial state, obviously owing to the formation of adducts of VOTSP with the oxidation products of ascorbic acid. The formation of the adducts prevents dimerization.