Futoshi Matsumoto

Mediated electron transfer of polyethylene oxide-modified superoxide dismutase by methyl viologen

Abstract Methyl viologen was found to efficiently mediate the electron transfer between polyethylene oxide-modified superoxide dismutase and the electrode in dimethyl sulphoxide media. Based on the potential-step chronoamperometric experiments, the rate constant for the mediated electron transfer was estimated to be ≈ (1−2) × 10 3 M −1 s −1 .

Electroreduction of oxygen in quinoline and isoquinoline

Abstract The thermodynamic and kinetic parameters (the formal potential, E °′, the standard rate constant, k °, and the cathodic transfer coefficient, α c ) of the reduction of oxygen to superoxide ion (O 2 − ) at glassy carbon electrode in quinoline and isoquinoline solutions have been evaluated using cyclic and normal pulse voltammetry. Tetrabutylammonium perchlorate (0.1 M) was used as supporting electrolyte. The obtained values of E °′ (V vs. Ag/AgClO 4 (0.01 M)), k ° (cm s −1 ) and α c are as follows: −0.85±0.01, (6.9±0.5)×10 −3 and 0.44±0.05 in quinoline, and −1.00±0.01, (3.4±0.3)×10 −3 and 0.42±0.03 in isoquinoline. They are compared with the previous data obtained for the O 2 /O 2 − couple in the commonly used aprotic solvents, demonstrating that quinoline and isoquinoline are newly included in solvents which are suitable for examining the electrode reaction of O 2 /O 2 − couple as well as various reactivities of O 2 − .