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

A polyvinylpyridine (PVP) polymer with covalently incorporated viologen groups was synthesized. The viologen substitution level of the polymer was determined to be 1-2 viologen groups per 10 vinylpyridine units. This polymer was used to immobilize, and electrically connect, the low-potential iron-sulfur enzyme hydrogenase at a glassy carbon electrode. The electrode catalyzed the oxidation of H-2 to H+ with the electrons being transferred by the viologen groups to the electrode. The activation energy of this process was 46 kJ mol(-1) at pH 7, The redox potential (E(o)') of the viologen groups in the polymer was -180 mV vs SHE for the first reduction step. Charge transfer properties of the polymer are discussed.