The new O,O and N,O type ligands and their Cu(II) and Ni(II) complexes: Crystal structure, absorption-emission properties and superoxide dismutase mimetic studies

In this study, two new O,O type azo-aldehydes (HL 1 and HL 2 ), their N,O type salicylaldoxime derivatives containing azo chromophore group (HL 3 and HL 4 ) and Cu(II) and Ni(II) complexes were synthesized and characterized by elemental analysis, 1 H- 13 C NMR, FT-IR, mass spectroscopies. Solid state structures of the HL 3 and HL 4 were also determined by single crystal X-ray diffraction method. Absorption and photoluminescence behaviours of the ligands and their metal complexes were investigated in DMF solution. Superoxide dismutase (SOD) activity of the Cu(II) and Ni(II) complexes were compared with the literature values. The K cat values for SOD activity show that the complexes possess significant catalytic activity for the dismutation of superoxide compared to the data of some complexes and natural SOD enzymes given in the literature. The K cat values for SOD activities of the complexes were found to be lower than natural enzymes. The complex [Cu(L 3 ) 2 ] is the SOD mimic amongst the tested complexes with K cat of 1.4 × 10 7 M −1 s −1.