Synthesis, structure and superoxide dismutase-like activity of two mixed-ligand Cu(II) complexes with N , N ′-bis(2-pyridylmethyl)amantadine

Abstract Two mixed-ligand Cu(II) complexes, [Cu(L 1 )(L 2 )](ClO 4 ) 2 ·H 2 O ( 1 ) and [Cu(L 1 )(L 3 )](ClO 4 ) 2 ·H 2 O·CH 3 OH ( 2 ) (L 1  =  N , N ′-bis(2-pyridylmethyl)amantadine, L 2  = 5,5′-dimethy-2,2′-bipyridine, and L 3  = 1,10-phenanthroline), were synthesized and characterized by elemental analysis, UV–Vis, infrared spectra and single crystal X-ray diffraction. Copper ions in 1 and 2 behave the slightly distorted tetragonal pyramid configuration provided by CuN5 coordination set. Both complexes exhibit the quasi -reversible Cu(II)/Cu(I) one-electron redox waves determined by the cyclic voltammetry. Moreover, the frontier molecular orbital energies were obtained by DFT calculations with B3LYP method at LanL2DZ basis. Furthermore, by using NBT assay at pH 7.8, the superoxide dismutase (SOD)-like activity (IC 50 ) of 1 and 2 were measured to be 0.167 and 0.242 μM, respectively. The difference in SOD-like activities of two complexes could be ascribed to the rigidity of the auxiliary ligands.