Reversible Reduction and Reoxidation of Thin Films of Tetrapyrazinotetraazaporphyrines

The electrochemical properties of Cu‐tetra(pyrazino [2,3])‐[b,g,l,q]‐5,10,15,20‐tetraazaporphyrine, 4 , and Cu‐tetra(5,6‐dicyanopyrazino [2,3]) [b,g,l,q]‐5,10,15,20‐tetraazaporphyrine, 5 , as thin films in contact with an aqueous acid electrolyte were investigated by cyclic voltammetry. The electrodes show stable electrochromic reduction and reoxidation. A strong shift of the redox potentials into the anodic direction could be accomplished in comparison with the analogue compounds Cu‐phthalocyanine, 1 , and Cu‐2,3,9,10,16,17,23,24‐octacyanophthalocyanine, 2 . There is strong evidence for an irreversible structural change of 4 during the first reduction cycle.