Crystal structure, spectroscopic studies, DFT calculations, cyclic voltammetry and biological activity of a copper (II) Schiff base complex

Herein we describe the chemical synthesis of a novel tetradentate Schiff base ligand (H2L), bridged with a pyridine, and its corresponding mononuclear copper complex (Cu(II)L). H2L, derived from the condensation of 2,3-diaminopyridine and 5-bromosalicylaldehyde, and Cu(II)L were structurally confirmed by routine spectral techniques, UV-Vis, FT-IR, H-1 NMR, MS and elemental analysis. Single crystal X-ray diffraction analysis of Cu(II)L complex showed a monoclinic system with P2(1)/C space group and Z = 4 molecules per unit cell. The characterization data of the complex revealed strong coordination via azomethine nitrogen (N) and bromo-phenolate oxygen (O). Moreover, the experimental parameters were found in line with the theoretical parameters. The conductivity measurement showed a non-electrolytic nature of the complex and the electrochemical behavior exhibits two quasi reversible redox processes. In-vitro antimicrobial studies on the synthesized compounds revealed a significant activity of the complex on some bacteria strains than the free ligand. DFT calculations were fully optimized using B3LYP and confirmed practical electrochemical and antibacterial results. (C) 2019 Elsevier B.V. All rights reserved.