New Cu(II), Ni(II), Co(II), and Mn(II) complexes of the gabapentin (Gpn) bidentate drug ligand were synthesized and studied using elemental analyses, melting temperatures, molar conductivity, UV–Vis, magnetic measurements, FTIR, and surface morphology (scanning (SEM) and transmission (TEM) electron microscopes).The gabapentin ligand was shown to form monobasic metal:ligand (1:1) stoichiometry complexes with the metal ions Cu(II), Ni(II), Co(II), and Mn(II). Molar conductance measurements in dimethyl-sulfoxide solvent with a concentration of 10⁻³ M correlated to a non-electrolytic character for all of the produced complexes. A deformed octahedral environment was proposed for all metal complexes. Through the nitrogen atom of the –NH₂ group and the oxygen atom of the carboxylate group, the Gpn drug chelated as a bidentate ligand toward the Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ metal ions. This coordination behavior was validated by spectroscopic, magnetic, and electronic spectra using the formulas of the [M(Gpn)(H₂O)₃(Cl)]·nH₂O complexes (where n = 2–6).Transmission electron microscopy was used to examine the nanostructure of the produced gabapentin complexes. Molecular docking was utilized to investigate the comparative interaction between the Gpn drug and its four metal [Cu(II), Ni(II), Co(II), and Mn(II)] complexes as ligands using serotonin (6BQH) and dopamine (6CM4) receptors. AutoDock Vina results were further refined through molecular dynamics simulation, and molecular processes for receptor–ligand interactions were also studied. The B3LYP level of theory and LanL2DZ basis set was used for DFT (density functional theory) studies. The optimized geometries, along with the MEP map and HOMO → LUMO of the metal complexes, were studied.

Eight polymer-metal complexes were synthesized from complexation of divalent Mn(II), Ni(II), Co(II), and Cu(II) metal ions with modified polystyrene-alt-(maleic anhydride) (PSMAP and PSMAM) ligands. The structures of these new complexes were characterized using a variety of techniques, including magnetic moment susceptibility, conductance measurements, FT-IR spectroscopy, ultraviolet-visible (UV-VIS), thermogravimetric analysis (TGA), as well as scanning electron microscopy (SEM). All metal-polymer complexes have a non-electrolytic nature based on conductance measurements. The polymer molecule behaves as neutral bidentate NO ligand through O atoms of carbonyl (C=O) and N atoms of amide (O=C-NH). Divalent Mn²⁺, Ni²⁺, Co²⁺ and Cu²⁺ complexes have an octahedral geometry based on their electronic spectra and magnetic values. Based on thermal analysis data, those new complexes are more thermally stable than the ligands. SEM and TEM are manipulated to give the surface structure and the particle size measurements where they give different shapes and sizes of the synthesized complexes.

Three new transition-metal complexes were produced by refluxing azodicarbonamide (ADCA) with nickel(II), copper(II), and zinc(II) solutions in a mixture of 50% (v/v) methanol and water. The magnitude of chelation between metal ions and ligand molecules was assessed by FT-IR, UV, elemental analysis, TGA, conductivity, mass, and magnetic susceptibility measurements. FT-IR analysis suggested a bi-dentate chelation in all complexes, which takes place through the N-azo and O-carbonyl groups. Based on the measurement of magnetic moments and spectral analysis, a distorted octahedral geometry was proposed for Ni(II) and Cu(II) complexes, whereas zinc complex showed a hexa-coordinated geometry. The optical band gaps of the nickel(II), copper(II) and zinc(II) complexes were found to be 1.91, 2.50, and 1.96 eV, respectively, which means that they can be employed as semiconductors and that they are in the same range as highly effective photovoltaic materials. The Urbach energy parameters were also estimated from other optical parameters. The biological activity of azodicarbonamide and its synthesized complexes has been screened against the selected gram bacteria (+ve) and fungi.