Synthesis, Characterization, and in Silico ADMET Evaluation of Transition Metal Complexes Based on Ortho-Phenylenediamine and Its Derivatives

Abstract

A series of cobalt (II), nickel (II), and zinc(II) complexes were synthesized using ortho-phenylenediamine and its two substituted derivatives (methyl- and nitro-ortho-phenylenediamine) as ligands. These complexes were isolated and characterized using various analytical techniques, including Elemental analysis, infrared (IR) and UV-Visible spectroscopy, gravimetry, and conductimetry. Conductimetric analysis revealed that all the complexes exhibit a non-electrolytic behavior in solution, indicating the absence of free ions in the medium. IR spectroscopic studies allowed the identification of the coordination modes of the ligands to the metal centers. Comparison of the IR spectra of the complexes with those of the free ligands highlighted the involvement of the amine (-NH₂) groups in coordination with the metal, confirming their role as the primary coordination sites. UV-Visible spectroscopic analysis was used to determine the geometry of the complexes. The observed absorption bands are characteristic of an octahedral coordination around the metal ions, which is consistent with the expected electronic transitions for these systems. In recent years, the integration of computational methodologies has considerably enhanced the ability to predict the toxicity and pharmacokinetic behavior of bioactive compounds, thereby streamlining the early stages of drug discovery. Within this framework, the present study investigates the ADMET profiles - Absorption, Distribution, Metabolism, Excretion, and Toxicity as well as the drug-likeness properties of the synthesized ligands and their corresponding transition metal complexes.