Spectroscopic, DFT, biological, DNA-binding, and antioxidant studies of some metal chelates with a novel thiazole-derived Schiff base

Abstract

Thermal reactions of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ru(III) metal ions with a novel Schiff base ligand (HL) derived from the condensation of 2-aminothiazole and 2-hydroxy-1-naphthaldehyde resulted in the formation of a series of metal complexes, [Co(L) 2 (H 2 O) 2 ]·2H 2 O (1), [Ni(L)(CH 3 COO)(H 2 O) 2 ] (2), [Cu(L) 2 (H 2 O) 2 ] (3), [Zn(L) 2 ] (4), [Cd(L)(CH 3 COO)]·2H 2 O (5), and [Ru(L) 2 (H 2 O) 2 ]Cl (6). The ligand and its complexes were characterized by means of elemental and thermal analyses, molar conductance, and magnetic moment measurements along with different spectroscopic techniques. The structure of the ligand was determined by X-ray crystal structure analysis and revealed that it crystallized in the orthorhombic space group P2 1 cn with a Z value of 4. Theoretical calculations based on accurate DFT approximations were used to verify the structures of ligand and complexes. The relative reactivities were estimated using chemical descriptors analysis. The biological activities of the compounds were examined. The antioxidant activity against DPPH radical was evaluated in vitro by using spectrophotometric methods; the experiments showed potent antioxidant activity. Also, the interaction of the reported compounds with calf-thymus DNA (CT-DNA) by different techniques revealed that the complexes could bind to CT-DNA by intercalative mode.