Spectro-Electrochemistry of Cobalt and Iron Tetrasulphonated Phthalocyanines

摘要

Cobalt and iron derivatives of tetrasulphonated phthalocyanine (TsPc) have been studied by spectro-electrochemistry in aqueous solution at pH 2-10. For CoTsPc, two reduced species are observed: yellow (Co(I)TsPc(-2) (-) and pink (C0(I)TsPc(-3))2(--), over the entire pH range. In acid, oxidation gives a monomeric Co(III)TsPc(-2)+ species; in base, an equilibrium exists between monomeric andimeric forms of Co(III(TsPc(-2)+, whose relative concentration depends upon concentration of CoTsPc, ionic strength, pH and temperature. Reduction of (Fe(III(TRsPC(-2)(+) solutions gives green Fe(III)TsPc(-2)and pink (Fe(I)TsPc(-2(-) over the entire pH range. Oxidation gives a product which appears to be an (Fe(IV)TsPc) 2(++) species. Differences between the spectra of the species and in the species obtaned at different pH values, and aggregation effects are discussed with reference to the nature of axial coordination to the central metal atoms.