Novel Cu(II) and Ni(II) complexes of nicotinamide based Mannich base: Synthesis, characterization, DFT calculation, DNA binding, molecular docking, antioxidant, antimicrobial activities

Abstract Nicotinamide incorporating Mannich base ligand (L), Cu(II) and Ni (II) complexes of [CuLCl2].2H2O (1) and [NiLCl2].2H2O (2) were synthesized and characterized by elemental analysis, FT-IR, UV–Visible, ESR and mass spectrometric methods. The square planar geometry of the complexes (1 and 2) were confirmed from analytical and diverse spectroscopic methods. Cyclic votammetric behaviors of complexes (1 and 2) were studied. The optimized geometry of L, complexes (1 and 2) were obtained by Density Functional Theory (DFT) calculations. DNA binding ability of complexes (1 and 2) were studied by electronic absorption and fluorescence techniques. Both the spectroscopic results show that complex 1 (9.64 × 104 M−1) has good binding affinity than complex 2 (6.07 × 104 M−1). The interaction of complexes (1 and 2) with CT-DNA was explored by Molecular docking analysis revealed that an efficient interaction of complexes (1 and 2) with the DNA. The results indicate that prepared complexes (1 and 2) have better binding ability with DNA double helix. Antioxidant activities of complexes (1 and 2) have studied by DPPH method and results suggest that prepared complexes (1 and 2) have better radical scavenging ability. Antimicrobial activities of ligand (L) and complexes (1 and 2) were tested against selected bacterial and fungal pathogens results shows that prepared compounds have higher antimicrobial activity against E. coli and A. niger antimicrobial species than others.