Electrochemical and spectroelectrochemical characterization of covalently-linked donor-acceptor model compound

Redox properties of a covalently linked porphyrin-anthraquinone model compound 5-(2-anthraquinone)-15-(N,N-dimethyl)aminobenzal-2,8,12,18-tetraethyl-3,7,13,17- tetramethyl porphyrin (D-P-AQ) triad have been studied by cyclic voltammetric and in situ UV-visible thin-layer spectroelectrochemical methods. Three reduction steps and one oxidation step are observed in the available potential range. The first of these reduction processes is a one electron reduction of the anthraquinone (AQ) moiety, occurring at -1.118 V vs Ag⁺/Ag. The second reduction occurs at -1.675 V and involves an overlap of the first reduction of the porphyrin ring and the second reduction of the AQ moiety. The third reduction is assigned as a one-electron reduction of the porphyrin ring. The first oxidation of D-P-AQ occurs at +0.475 V and is ascribed to a one-electron oxidation of the porphyrin ring. The results of in situ UV-visible spectroelectrochemistry affirm the above conclusions.