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, 1H NMR, MS and elemental analysis. Single crystal X-ray diffraction analysis of Cu(II)L complex showed a monoclinic system with P21/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. [Display omitted] •A Schiff base ligand and the corresponding copper complex Cu(II)L are synthetized with good yields.•Structural features are confirmed by different spectroscopic techniques.•Copper complex was revealed by single crystal X-ray diffraction; the geometry was calculated and confirmed by DFT.•Cyclic voltammetry study of the Cu(II)L complex indicated two quasi reversible processes.•The antimicrobial activity of the copper complex Cu(II)L shows a better activity than the ligand (H2L).