ELECTROCHEMICAL AND SPECTROELECTROCHEMICAL CHARACTERIZATION OF COVALENTLY-LINKED DONOR-ACCEPTOR MODEL-COMPOUND

Redox properties of a covalently linked porphyrin-anthraquinone model compound -(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 spec troelectrochemical methods. Three reduction steps and one oxidation st ep are observed in the available potential range. The first of these r eduction processes is a one electron reduction of the anthraquinone (A Q) moiety, occurring at -1.118 V vs Ag+/Ag. The second reduction occur s at -1.675 V and involves an overlap of the first reduction of the po rphyrin ring and the second reduction of the AQ moiety. The third redu ction is assigned as a one-electron reduction of the porphyrin ring. T he 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 W -visible spectroelectrochemistry affirm the above conclusions. (C) 199 8 Elsevier Science Ltd. All rights reserved.