Synthesis, characterization, and biological evaluation of 3-benzoyl-1,5-di-(4-bromophenyl) formazan and its metal complexes: Structural insights and antibacterial activity

Abstract

This paper presents the synthesis, analysis, and biological assessment of a symmetrical N-donor ligand, 3-benzoyl-1,5-di-(4-bromophenyl) formazan (HL), and its transition metal complexes with Co(II), Ni(II), Cu(I), and Pd(II). The compounds were examined using UV–visible (UV–Vis), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), thermogravimetric (TG) analysis, magnetic susceptibility, and elemental composition measurements. The Co(II) complex exhibited paramagnetic properties, while Ni(II), Cu(I), and Pd(II) showed diamagnetic character, as confirmed by density functional theory (DFT) calculations and in silico studies, including molecular docking, oral bioavailability screening, and bioactivity score evaluations. Molecular docking analyses predicted the antibacterial, antifungal, and anticancer potential of the synthesized molecules, revealing strong interactions between bacterial enzymes and cancer-related proteins. The ligand acted as a bidentate monobasic agent, coordinating with terminal nitrogen atoms to form thermally stable complexes. In vitro testing against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) demonstrated promising antibacterial properties, with the Cu(I) complex showing the most potent antimicrobial activity. The experimental outcomes were aligned with the in silico predictions. Drug-likeness and ADMET analyses support the potential of these compounds as therapeutic agents. This study highlights the importance of N-donor ligand complexes in biological processes, encouraging further investigation of these potential medicinal compounds and aiding the evaluation of N-donor ligands and their complexes as prospective therapeutic agents.