Synthesis, Structure, Antimicrobial, DNA Binding and DFT Analysis of Bioactive Cu(II), Ni(II) and Co(II) Complexes Obtained from (Thiophene-2-yl)Methanamine Schiff Base Ligands

The synthesis of two Schiff base ligand, 2-(thiophene-2-yl)methylamino)methyl)-6-bromo-chlorophenol (HL1) and 2-((thiophen-2-yl)methyl amino)methyl)-4-methylphenol (HL2) and their cobalt, nickel, and copper complexes (C1-C6) are performed and their characterization was made using elemental analysis such as NMR, IR, UV-Vis ESR, and ESI mass spectrometry. The results of all the characterizations revealed that geometry of square planar was exhibited by copper and nickel complexes, whereas octahedral geometry was observed in cobalt complexes around metal ion. The optimized geometry of ligands their complexes (C1-C6) were obtained by density functional theory (DFT) calculations. The entire tested complexes bind with CT-DNA as result through intercalation mode of binding. The antioxidant activity of compounds C1-C6 were analyzed through a stable free radical and standard antioxidant i.e. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and ascorbic acid respectively. Furthermore these compounds, C1 and C4 showed good antioxidant activity. For the antibacterial and antifungal activities, ligands and their metal complexes were selected and the complexes are noticed to have greater activity than those of free Schiff bases.