Preparation, Identification, and Antioxidant Activity of Some New Transition Metal Complexes of Curcumin with Mono-and Bidentate Ligands

Eight ternary copper (II) and nickel (II) complexes of curcumin (Cur) [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] as a primary ligand, o-phenylenediamine (OPD), dimethylglyoxime (H2dmg), tryptophan (Tryp), bromoaniline (Br-Ani) or thymine (Thy) as a secondary ligand have been prepared and characterized by melting point, conductivity, infrared and electronic spectra. The complexes obtained are stable powders at room temperature, soluble in DMSO and are non-electrolyte. The IR and UV-vis spectroscopic analysis revealed that the complexes adopt either octahedral, tetrahedral or square planar geometry. All the ligands are bound to the cations Cu(II) and Ni(II) via the nitrogen and oxygen atoms. The synthesized compounds were screened for their in-vitro antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) free radical scavenging. The results obtained show that these complexes have a good antioxidant activity in comparison with ascorbic acid as positive control. These observations suggest the possibility of using the complexes as antioxidant agents to solve the problems linked to the presence of free radicals in living organisms.