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 Ag+ and Pd2+, show the metal sensing properties of the complexes. (c) 2007 Elsevier B.V. All rights reserved.