Indium(III) complex with NOON-tetradentate Schiff base ligand: Synthesis, crystal structure determination, electrochemical properties, theoretical studies, and molecular docking

In this study, a novel indium(III) complex coordinated to a NOON-type tetradentate Schiff base ligand was synthesized and analyzed using elemental analysis, FT-IR, and 1 H NMR spectroscopy. Single-crystal X-ray diffraction (SC-XRD) revealed a solvated structure in which the Schiff base ligand binds the indium center in a tetradentate manner. The indium(III) atom exhibits a distorted octahedral geometry, being hexacoordinated by four donor atoms from the ligand, one chloride ion, and one water molecule. The water and methanol molecules play a crucial role in stabilizing the crystal lattice through extensive hydrogen bonding. Hirshfeld surface analysis (HSA) was employed to examine molecular-level interactions inside the solid-state assembly. Electrochemical behavior of the ligand and the indium(III) complex was explored using cyclic voltammetry in a pH 7.0 buffered solution, revealing an irreversible process. Geometry optimizations of the ligand and its indium complex were carried out using Density Functional Theory (DFT) with the M06 functional in combination with the Def2-TZVP basis set, offering deeper insight into their molecular geometry and electronic properties. The combined use of NMR data and computational modeling provided a comprehensive understanding of the structural dynamics. Furthermore, molecular docking simulations were performed using AutoDock Vina and AutoDock 4.2 to evaluate the binding interaction. The optimized structures were docked to DNA and bovine serum albumin (BSA), and the binding energies (ΔG) and binding constants (K b ) were determined. The results demonstrated strong binding affinities, with specific interactions identified at the DNA binding site and BSA amino acid residues, indicating promising biological relevance. • SC-XRD shows a distorted octahedral geometry of indium complex stabilized by H-bonded water. • Electrochemical analysis shows an irreversible, adsorption-controlled redox process. • Hirshfeld surface analysis highlights the H···H and H···Cl interactions in the crystal packing. • Indium complex binds DNA and BSA, targeting the DNA groove and key residues of BSA.