Structural Evolution and Antibacterial Activity of Nickel (II) Coordination Compounds Engineered With Pyrazine Derivatives

Abstract

Three nickel (II) coordination compounds with progressively dimensional structures were successfully constructed using a newly synthesized organic ligand, 2′,6′-di (pyrazin-2-yl)-2,4′-bipyridine (dpb), together with aromatic carboxylate coligands. They are a zero-dimensional mononuclear complex [Ni (dpb)₂](NO₃)₂ (1), a one-dimensional chain [Ni (dpb)(m-bdc)]_n (2) (m-H₂bdc = 1,3-benzenedicarboxylic acid), and a two-dimensional layered network [Ni₃(dpb)₂(btc)₂(H₂O)₂]_n (3) (H₃btc = 1,3,5-benzenetricarboxylic acid). Single-crystal X-ray diffraction confirmed their structures and revealed that increasing the carboxyl group number in the auxiliary ligands effectively drives the dimensionality evolution from 0D to 2D, highlighting the key role of carboxylate donors in tuning topology. Hirshfeld surface analysis quantified intermolecular interactions contributing to crystal stability. Antibacterial tests showed that all compounds exhibit significant activity against Escherichia coli and Staphylococcus aureus, with compound 3 displaying the largest inhibition zone. Molecular docking indicated that compound 1 binds strongly to the active site of E. coli DNA gyrase B through van der Waals forces, hydrogen bonds, and π–π stacking, suggesting a potential antimicrobial mechanism. Cytotoxicity assays revealed no significant harm to human embryonic kidney cells at tested concentrations, confirming good biocompatibility. This work provides a rational strategy for designing dimensionally varied coordination compounds with promising antibacterial properties.