ELECTROCHEMICAL POTENTIALS, CHARGE-TRANSFER AND COMPLEXATION PROPERTIES OF QUINOID SYSTEMS

The application of electroanalytical methods (generally polarography) to studies of charge-transfer complexes derived from different types o f organic molecules (acceptor part-quinone or quinone imine; donor par t-aromatic amine) is discussed. Intramolecular charge transfer has a m ore pronounced effect on the electro-oxidation of the donor moiety tha n on the electroreduction of the acceptor moiety of the molecule. In t he case of intermolecular charge transfer a cathodic shift of the elec troreduction potential of up to .90 mV has been observed; in the case of intramolecular charge transfer the effect of complexation may be ob scured by other effects. The polarographic method has been found to be a useful technique for determining the electron affinity values of qu inoid molecules. The mechanism of interaction between quinone imines a nd 1,4-dihydropyridine can be interpreted using data for the electrore duction mechanism of quinone imines and the electro-oxidation mechanis m of the 1,4-dihydropyridines. Possible applications to biologically a ctive quinones are discussed.