Synthesis, structural, biological applications, DFT, molecular docking studies on Fe(III), Co(II), and Ni(II) complexes incorporating 2‐(pyridin‐2‐yl)phenol and 1H‐benzimidazole‐2‐carboxylic acid

Abstract

This study provides a detailed investigation into the synthesis, characterization, and biological activities of the coordination compounds FePPHBZC, CoPPHBZC, and NiPPHBZC. These compounds were synthesized with high yields by reacting chloride salts of Iron, Cobalt, or Nickel with 2‐(pyridin‐2‐yl)phenol (PPH) and 1H‐benzimidazole‐2‐carboxylic acid (BZC) in a 1:1:1 ratio. Various techniques including spectroscopic (IR, UV–vis, mass spectra), elemental analysis, conductivity, magnetic, and thermal analyses confirmed the formation and structure of these coordination compounds. Density functional theory (DFT) calculations were used to study their electronic structure, stability, and reactivity. 3D modeling revealed hexacoordinated geometries for Fe and Co complexes and a tetrahedral coordination for the Ni complex. Analysis of the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and other reactivity parameters indicated changes in reactivity upon metal coordination. Molecular Electrostatic Potential (MEP) diagrams identified electron‐rich areas prone to nucleophilic attack, important for protein interactions during docking studies. Biological evaluations demonstrated that metal–ligand complexes exhibit enhanced antimicrobial, antioxidant, and anti‐inflammatory activities compared to individual ligands, with larger inhibition zones and higher inhibitory activity. Molecular docking studies showed strong interactions between metal–ligand complexes and target proteins, suggesting potential therapeutic applications. Among them, FePPHBZC exhibited the strongest interactions, followed by CoPPHBZC and NiPPHBZC, characterized by hydrogen bonding, ionic interactions, and other non‐covalent interactions, contributing to their enhanced stability and binding affinity.