A study on the reaction of copper complex of dioxotetraamine with superoxide ion by spectrophotometry and pulse radiolysis

The reactions of a dioxotetraamine Cu(II) complex [Cu(H−2L)] (L is 6-(9-fluorenyl)-1,4,8,11-tetraazaandencane-5,7-dione)with radical dotO2 − were investigated by electrochemistry, UV–Vis spectrophotometry and pulse radiolysis, respectively. In DMSO solution, [CuII(H−2L)] was oxidized into [CuIII(H−2L)]+ by radical dotO2 −, a consecutive reaction was observed with [CuIII(H−2L)(O2 2−)] − as intermediates (k1=1.71×103 M−1 s−1, k2=1.2×10−2 s−1). The mechanism of radical dotO2 − dismutation catalyzed by the complex involved alternate oxidation and reduction of Cu(II) by radical dotO2 − and the kcat is 6.07 × 107 M−1 s−1 (pH 7.4).