VIOLOGEN-BASED REDOX POLYMER FOR CONTACTING THE LOW-POTENTIAL REDOX ENZYME HYDROGENASE AT AN ELECTRODE SURFACE

A polyvinylpyridine (PVP) polymer with covalently incorporated viologe n groups was synthesized. The viologen substitution level of the polym er was determined to be 1-2 viologen groups per 10 vinylpyridine units . This polymer was used to immobilize, and electrically connect, the l ow-potential iron-sulfur enzyme hydrogenase at a glassy carbon electro de. The electrode catalyzed the oxidation of H-2 to H+ with the electr ons being transferred by the viologen groups to the electrode. The act ivation energy of this process was 46 kJ mol(-1) at pH 7, The redox po tential (E(o)') of the viologen groups in the polymer was -180 mV vs S HE for the first reduction step. Charge transfer properties of the pol ymer are discussed.