A binuclear copper(II) complex based on hydrazone ligand: Characterization, molecular docking, and theoretical and antimicrobial investigation

A new binuclear copper(II) complex [Cu2L2(mu-SO4)(dmf)] with the 2-acetylpyridinebenzoylhydrazone (HL) ligand was synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis), single-crystal X-ray diffraction, density functional theory (DFT), and molecular docking studies. The crystal structure revealed each copper(II) atom coordinated to the NNO chelating system of the anionic hydrazone ligand and a sulfate bridged. The copper ions are connected by a sulfate bridge, which keeps a distance of 3.292(3) angstrom between the two copper(II) centers. Additionally, only one of the copper(II) atoms is coordinated to the oxygen atom of the N,N-dimethylformamide (dmf) solvent molecule, resulting in two different geometry to each metal center. Cu center dot center dot center dot O interactions are observed for the secondary coordination sphere of Cu1 and Cu2 atoms with distances of 2.545(2) and 2.821(3) angstrom, respectively. Theoretical studies with DFT were performed to optimize the geometry of the complex and investigate its spectroscopic properties supporting the experimental results. Two different approaches were used in computational calculations, the plane wave using Perdew-Burke-Ernzerhof (PBE) functional and the localized basis set using the following functionals: B3LYP, B3PW91, CAM-B3LYP, LC-wPBE, M06-2X, omega B97-XD, PBE1PBE, and HSEH1PBE. The in vitro antibacterial potential of the new complex was evaluated against pathogenic bacteria and fungi and compared with the free ligand. The molecular docking was used to predict the inhibitory activity of the ligand and complex against one Gram-positive bacteria (Enterococcus faecalis), one Gram-negative bacteria (Enterobacter aerogenes), and one fungi (Candida albicans) species.