Crystal structure and superoxide dismutase activity of a six-coordinate manganese(III) complex

A six-coordinate manganese(III) complex [Mn(bpb)(H2O)Cl], where H2bpb is N,N′-(1,2-phenylene)bis(pyridine-2-carboxaminde), was prepared and characterized by X-ray crystallography. It crystallizes in the monoclinic system, space group P 2(1)/c with a=6.735(1) Å, b=22.910(4) Å, c=11.647(2) Å, β=102.20(1)°, Z=4 and V=1756.5(5) Å3. Mn (III) in the complex adopts an octahedral coordination geometry. The cyclic voltammetry of the complex recorded in DMF indicates a reversible one-electron redox reaction. The complex has been shown to catalyze effectively the dismutation of superoxide (O2−) in the riboflavin–methionine–nitro blue tetrazolium assay with an IC50 value of 2.93 μM.