Voltammetric and spectroelectrochemical characterization of porphyrazines: Electrochemical metal sensor

Voltammetric and spectroelectrochemical characterization of the metallo-porphyrazines (M = 2H+, Mg2+, Cu2+, Zn2+ and Co2+) substituted with eight (1-naphthylmethylthio) groups on the peripheral positions are described. Cyclic voltammetry and differential pulse voltammetry studies show that while metal-free, magnesium, zinc, and copper porphyrazine complexes give three ligand-based reductions and one ligand-based oxidation couple having diffusion controlled one-electron reversible character, cobalt porphyrazine gives both metal-based and ligand-based reduction and oxidation couples. Assignments of the redox couples were confirmed by spectroelectrochemical measurements. Distinctive voltammetric and spectroscopic changes during titration of the cobalt porphyrazine with soft metal ions, Ag+ and Pd2+, show the metal sensing properties of the complexes.