Perchlorinated phthalocyanines: spectroscopic properties and surface electrochemistry

Abstract

The electronic spectroscopic data for zinc, cobalt, and iron perchlorinated phthalocyanines in several oxidation states are discussed.The magnetic properties of the iron(II) and cobalt(II) derivatives from ambient temperature to 5 K are reported. The electrochemical behavior of these three species is reported in solution and as surfaces on highly oriented pyrolytic graphite. The pH dependence of the surface data is analyzed in detail. The first clearly defined reduction process corresponds with M'[Cll6Pc(-2)]"/M'[C1|6Pc(-3)]12" for M = Co and Fe. The iron and cobalt species' MnPc(-2)/[M'Pc(-2)]~r edox process are broad or ill-defined on the surface and absent from solution. The FeIII[Cl16Pc(-2)]+/Fe"[Cl16Pc(-2)] redox process has atypical pH dependence. The data are explained in terms of the acceptor nature of the chlorine substitution. Oxygen reduction data, catalyzed by these species, are also reported.to Union Carbide, Parma, for a gift of highly oriented pyrolytic graphite.

Monomeric and Polymeric Tetra-aminophthalocyanatocobalt(II) Modified Electrodes: Electrocatalytic Reduction of Oxygen

“…However, we [23,35] have argued, in line with a much earlier seminal study of the mechanism of CoPc catalysed oxygen reduction [17], that the active species is probably the divalent Co(II)Pc(2-) instead of the Co(I)Pc(2-) species and an intermediate oxygen adduct is involved:…”

“…However in basic conditions, the reduction of O 2 appears at a potential almost 400 mV more positive (Table 2 and Fig. 5) than the Co(II)Pc(2-)/[Co(I)Pc(2-)] -redox couple, which is similar to the behaviour of the CoCl 16 Pc species [35].…”

“…This argument is based on the observation that oxygen reduction, catalysed by the CoCl 16 Pc species [35], appears at a potential almost 400-600 mV more positive than the Co(II)Cl 16 Pc(2-)/Co(I)Cl 16 Pc(2-) couple in strong alkaline condition. In this case the Co(I)Cl 16 Pc(2-) species could not be the active catalyst since such a positive oxygen reduction potential would require an unrealistically high reduction rate.…”

Derivation of metallophthalocyanine redox potentials via Hammett parameter analysis

“…Metal phthalocyanine species exhibit rich electrochemical behavior due to the accessibility of a range of oxidation states centred on the ligand, and, for many transition metal ions, on the metal [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Further, phthalocyanine species have been modified by the use of a wide range of substituents at the peripheral benzene rings [15].…”

Electrocatalytic activity of a graphite electrode coated with hexadecachlorophthalocyanatoiron(II) toward sulfide oxidation, and its possible application in electroanalysis

“…[Traduit par la rCdaction] Perhalogenated metallophthalocyanines have been reported to be effective catalysts for the reduction of dioxygen (1,2). Most recently, we discovered that one of the perhalogenated metallophthalocyanines, hexadecachlorophthalocyanatoiron(I1) (abbreviated as F~"[c~,,Pc(~-)]), when it is coated on a graphite electrode (labelled as Fe"[~l,,Pc(2-)]/c in this paper), displays very high activity toward the oxidation of sulfide ion in basic solutions.…”