Synthesis, characterization, electrochemical application, and antibacterial activity investigation of 2,2-bipyridineditartaratemanganese (II) complex

Abstract We synthesized and investigated a novel manganese(II) complex containing 2,2′-bipyridine and hydrogen tartrate ligands using physicochemical, spectroscopic, electrochemical, and antibacterial methods. The precursor Na₂[Mn(HTA)₂Cl₂] and the final complex [Mn(HTA)₂(2,2-bpy)] were characterized by testing solubility, melting/decomposition behavior, molar conductance, chloride testing, gravimetric manganese analysis, FTIR, and UV–Vis spectroscopy. The available data support coordination of the tartrate-derived ligand through oxygen donor atoms and 2,2′-bipyridine through nitrogen donor atoms, and an octahedral coordination environment is proposed rather than confirmed. The precursor and final complex showed molar conductance values of 255 and 299 S cm² mol⁻¹, respectively; these values indicate substantial ionic conductivity in water but do not by themselves establish a definite electrolyte stoichiometry for the neutral final complex. Electrochemical characterization showed that poly([Mn(HTA)₂(2,2-bpy)])/GCE increased the electroactive surface area from 0.15 to 0.44 cm² and decreased the charge-transfer resistance from 6266 to 273 Ω. The modified electrode shifted guanine oxidation from 705 to 623 mV. Antibacterial testing at 1000 ppm showed no measurable inhibition zones for the synthesized complexes; however, the DMSO control also produced inhibition zones, so the antibacterial findings are considered preliminary and require confirmation using a solvent concentration that is itself inactive. Overall, the electrochemical results support further investigation of the polymerized manganese complex as an electrode-modifying material, while the proposed molecular structure and antibacterial behavior require additional validation.