New Metal Complexes Incorporating Schiff Base Ligand Based on Pyridine Moiety: Synthesis, Spectral Characterization, DFT, Biological Evaluation, and Molecular Docking

Abstract

A new Schiff base ligand, HNMPC, was prepared and reacted with some metal ions, including Cu(II), Ni(II), Co(II), Mn(II), and VO(IV). The infrared, electronic, mass, electron spin resonance, nuclear magnetic resonance, thermal and elemental analysis, molar conductance, and magnetic susceptibility measurements were used to characterize the metal complexes. The HNMPC ligand acts as a monoanionic tridentate ONO donor in all complexes, and the coordinating sites are C=Opyridone, C=N, and the phenolate anion. All metal complexes exhibit octahedral configurations, and the results showed that the metal ion:ligand ratio was 1:2. The molecular structural parameters of the ligand and its metal complexes were determined based on the DFT level implemented in the Gaussian 09 program B3LYP/GENECP method at the 6-311G(d,p) basis set for C, H, N, and O atoms and the SDD (Stuttgart/Dresden) basis set for the metal atoms. The theoretical data were correlated with the experimental results. Gram-positive bacteria, Gram-negative bacteria, yeast, and fungi were used to test the current compounds' antimicrobial activity. Investigating the antitumor activity of the ligand and its complexes against the HepG2 cell lines showed encouraging IC50 values that were on par with those of cisplatin. In order to determine the affinity and binding pattern for the synthesized compounds toward the VEGFR-2 active site, molecular docking studies were conducted, and the results were correlated with antitumor data. Based on the obtained results, future work aimed to synthesize a new category of Schiff bases and their metal complexes derived from the current aminopyridine derivative with diverse aldehydes and ketones.