Redox properties of porphycenes and metalloporphycenes. A comparison with porphyrins

Porphycenes exhibit two reversible one-electron reduction steps while the porphyrins reduce in four distinct redox steps. The redox behavior of porphycenes is similar to that of bacteriochlorin. Metalloporphycenes, in which the metal is an electroactive site, revealed a potential difference between the first oxidation and the first reduction higher than that of the porphycene. Symmetry is vital in modulating the redox and optical properties of porphycene and the substituents effects are not additive.