Exploring Schiff base ligand and their transition metal complexes: synthesis, characterization, antimicrobial, ADME and computational insight as cholesterol lowering agents and anticancer activity on HeLa cells

Abstract

This research work includes a detailed investigation of the synthesis, spectroscopic characterization and biological properties of Schiff bases ligand derived from 1,8-diamminonapthalene and 5-bromosalicyaldehyde along with their transition metal complexes. The compounds were meticulously characterized employing sophisticated spectral techniques that are FT-IR (Infra-red), analytical, ¹H-NMR (Proton Nuclear Magnetic Resonance), SEM (Surface morphology analysis), ESI–MS (Electrospray Ionization Mass Spectrometry), PXRD (Powder X-ray Diffraction) and ESR (Electron Spin Resonance). The spectroscopic data reported that the ligand exhibits a tetradentate binding mode, while the metal complexes demonstrate hexa-coordinated geometries. Additionally, DFT investigation was executed employed B3LYP/LanL2DZ as basis set to optimize geometry and evaluate molecular electrostatic potential surfaces. In vitro antimicrobial studies were explored against gram +ve bacteria, gram −ve bacteria and fungal strains. Among these, the copper chloride complex (3) displayed the highest efficacy possessing a minimum inhibitory concentration (MIC) of 0.0094 µmol/mL. Molecular docking investigations were executed to evaluate the binding affinities of the synthesized compounds against a cholesterol lowering agent (2OBD) and HeLa cancerous cells (6I2I). The results indicated that cobalt (1) and nickel chloride (2) complexes exhibit the lowest binding affinities, suggesting higher potency. Additionally, the synthesized compounds demonstrated greater effectiveness against HeLa cancerous cells compared to the 2OBD receptor. The in silico ADME analysis discloses the therapeutic usability of the synthesized compounds.

Graphical abstract