A New Zinc(II) Complex with N2O2-Tetradentate Schiff-Base Derived from Pyridoxal-S-Methylthiosemicarbazone: Synthesis, Characterization, Crystal Structure, DFT, Molecular Docking and Antioxidant Activity Studies

Abstract

A new unsymmetrical N2O2-tetradentate Schiff-base complex of zinc(II) was synthesized by the template reaction of pyridoxal-S-methylthiosemicarbazone and 2-hydroxy-4-methoxy-benzaldehyde as starting compounds. S-methylthiosemicarbazone (1) and zinc(II) complex [Zn(L)CH3OH] (2) were characterized by elemental analysis, FT-IR, UV–visible, 1H, and 13C NMR spectra. The molecular structure of the complex (2) was determined by single crystal X-ray diffraction technique. The structure consists of a distorted square-pyramidal geometry around the central metal, Zn(II). Quantum chemical calculations were carried out using density functional theory DFT/B3LYP, 6–31G (d), and LanL2DZ basis sets for theoretical characterization of the compounds. The experimental and theoretical data were compared comprehensively. The potential energy distribution (PED) analysis was performed for the assignment of vibration frequencies. In order to support in vitro studies, molecular docking studies have been carried out so that the title compound can be an inhibitor of Epidermal Growth Factor Receptor (1 m17), and the relationship between calculated HOMO energies and docking studies has been examined. In addition, the total antioxidant capacity (as TEAC value) and free radical scavenging activity of the compounds were determined by Cupric Reducing Antioxidant Capacity (CUPRAC) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) methods, respectively. © 2021 Elsevier Ltd