Effect of Substituents on the Oxidation Potential of Phthalocyanines and Electrocrystallization

A series of tetra- or octasubstituted phthalocyaninatocobalt derivatives were prepared and their oxidation behaviors were examined in relation to the nature of substituents. The oxidation potentials of phthalocyanines, especially those of rings were affected by the nature of both substituents and axial ligands. These oxidation potentials were in a linear relation with the Hammett’s constants for substituents or axial ligands. The electrocrystallization proceeded when an oxidation potential higher than that for the phthalocyanine ring was given to the solution. This potential shift was therefore revealed to be an important factor to control the electrocrystallization of these phthalocyanines.