Tailored bimetallic Zn/Ni complex of 2, 2’-bipyridine 4,4’-dicarboxylic acid: spectral characterization and demonstrated the potential biological activities

Abstract

Bimetallic complexes have garnered significant attention in the scientific community due to their versatile applications, such as antibacterial, antifungal, antitubercular, antimalarial, antioxidant, antidiabetic, anti-inflammatory, and anticancer activities. This study reports the synthesis and characterization of a bimetallic Zn/Ni complex derived from 2,2’-bipyridine-4,4’-dicarboxylic acid (BPyCOOH) as a multifunctional coordination compound with effective antimicrobial impact. This complex ensured efficient coordination of the ligand with both Zn(II) and Ni(II) ions due to its bifunctional groups in a single ligand structure. Structural elucidation was achieved through UV–Vis, FTIR, and elemental analyses. The UV–Vis spectrum displayed two distinct absorption bands at approximately 280 nm and 400 nm, attributed to π–π* transitions and metal-to-ligand charge transfer (MLCT), confirming the successful formation of the bimetallic coordination framework. The Zn/Ni(BPyCOOH)₂ complex was evaluated for its antimicrobial potential against selected Gram-positive and Gram-negative bacterial strains, also demonstrating minimum inhibitory concentration (MIC) activity. The Gram-positive bacteria, P. mirabilis, showed the highest zones of inhibition (27.7±0.9) at (20 mg/ml) of Zn/Ni(BPyCOOH)₂ complex. Therefore, Zn/Ni(BPyCOOH)₂ complex shows concentration (dose) dependent antimicrobial activity. It is most effective against Proteus mirabilis (P. mirabilis), gram-negative, and least in Staphylococcus aureus (S. aureus), gram-positive, by calculating the diameter of the zone of inhibition. No inhibition in the control proves the results are valid.