The aggregation and reaction with oxygen of the tetrasodium salt of cobalt phthalocyanine-4,4',4'',4'''-tetrasulphonic acid

Abstract

The reversible addition of molecular oxygen to the tetrasodium salt of cobalt phthalocyanine-4,4?,4?,4??-tetrasulphonic acid in aqueous solution has been confirmed. Visible absorption spectra of the monomeric and dimeric species and of the oxygen adduct have been determined. A monomer-dimer system prevails at neutral pH, low ionic strength, and low dye concentrations. The oxygen adduct and the dimeric form of the dye predominate in alkaline solution.

Interactions of cobalt tetrasulfophthalocyanine with thiolate anions in dimethylformamide

“…However, all these results are tempered by the fact that CoTSPc and its reduced forms associate in aqueous solutions [17,18]. CoTSPc association is suggested to play a critical role in reaction (1) [8][9][10][11][12][13][14].…”

Spectroscopic measurements on metal tetrasulphonato-phthalocyanines

“…The spectra-electrochemical measurements in alkaline media were seriously hampered by aggregation of the metal chelate [3,18]. As a result, the diffusion of the complex towards the electrode was very slow and no cyclic voltammogram could be recorded for the complex.…”

The cathodic reduction of oxygen at metal tetrasulfonato-phthalocyanines: influence of adsorption conditions on electrocatalysis

“…This spectrum was recorded immediately after the addition of CoTSPc to the oxygen-free 0.1 M ISOH solution. Two peaks are visible and are ascribed to a monomer (670 nm) and a dimer species (626 nm) [14,15].…”

“…It has been reported [14,15] that increasing the ionic strength of a solution of CoTSPc increases the dimer peak in the UV-vis spectrum. The extra ions most probably compensate the expected large electrostatic repulsion between two CoTSPc4-ions.…”