Exploring diaminomaleonitrile-derived Schiff base ligand and its complexes: Synthesis, characterization, computational insights, biological assessment, and molecular docking

Abstract

A tetra dentate ONNO donor diaminomaleonitrile-based Schiff base ligand along with its four new complexes of Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized. The computational approach has been utilized to provide a theoretical framework for understanding the electronic structure and properties of these complexes. The distorted octahedral geometry of the Schiff base metal complexes indicates that the metal ions are coordinated with the ligand through ONNO donor sites, which is further confirmed by characterization using physiochemical and spectroscopic techniques like elemental analysis, mass, electronic, infrared, 1H, and 13C spectra. In addition, magnetic behavior is analyzed using the Vibrating Sample Magnetometer(VSM). To evaluate the potential modes of biomolecular interactions with the synthesized complexes utilizing Deoxyribo Nucleic Acid(DNA) and to assess the corresponding binding constants, an absorption spectroscopic technique has been utilized. Metal complexes are reported to have a range of binding constant values from 5.45 × 104 M−1 to 4.35 × 105 M−1 with different binding modes, such as intercalation, mixed mode, and electrostatic contact. In addition, in-vitro tests for antibacterial and anti-inflammatory activity have been employed to assess the bioactivities. With an IC50 value of 209.24 µg/mL, the Zn(II) complex is found to show considerable anti-inflammatory action as well as has superior antibacterial activity among all other complexes. The existence of electron-withdrawing CN groups together with other factors can be accounted for biological activity in our reported complexes. Further, molecular docking simulations are conducted to gain insights into the molecular-level interactions and to determine the potential binding energies of inhibitors whose results are in consistent with the in-vitro investigations.