INTRAMOLECULAR ELECTRON-TRANSFER WITHIN A WATER-SOLUBLE, FERROCENE-LABELED POLYACRYLATE

A water-soluble polyanionic polyacrylate was rendered electroactive by the covalent attachment of (on average) one ferrocene molecule to eac h polymer chain. Electro-oxidation of the ferrocene labels produced fe rricinium groups that could not be electro-reduced in dilute supportin g electrolyte solutions (less than 0.1M). However, Ru(NH3)(6)(3+) coun terions bound electrostatically to the oxidized polyanion could be ele ctro-reduced and the resulting, bound Ru(NH3)(6)(2+) counterions rapid ly reduced the ferrocenium groups on the same polyanionic chain by int ramolecular electron transfer. These phenomena are demonstrated by mea ns of cyclic voltammetry. Experimental and numerically simulated cycli c voltammetric responses are compared to support the mechanism propose d to account for the observed results which may be relevant to long ra nge electron transfers in redox enzymes and across molecular monolayer s on surfaces.