Synthesis, Crystal Structure and Antibacterial Activity of Cu(II) Complex with Nitrogen Donor Pyrazolyl Borate Derivatives

Background: Pyrazolyl borate derivatives are versatile ligands that can be coordinated with transition metals and formated a variety of different coordination modes. Copper complexes are highly active in biological applications and have high bioactivity. Because of the above description and applications, in the present work, synthesis and characterization of pyrazolyl borate derivative ligands and their Cu(II) complex were reported. The structure of the synthesized complex was determined by X-ray crystallography. In addition, the antimicrobial activity of the synthesized compounds along with the molecular docking of them was investigated.

Methods: N-donor pyrazolyl borate derivative ligands abbreviated as K[HB(PzMe2)3] and K[H2B(PzMe2)2] and their Cu(II) complex were synthesized and characterized. The synthesized ligands and complex were evaluated for antibacterial activities against the gram-positive (B. subtilis) and the gram-negative (S. enterica) bacteria. Also, their molecular docking with B. subtilis SMC head domain (PDB ID: 5H67) as the possible targets was investigated.

Results: The in vitro and in silico results showed, among the investigated compounds, complex [Cu(H2B(PzMe2)2)(HB(PzMe2)3)] indicated the highest antibacterial activity. Also, the Statistical analysis showed that the difference between the obtained data was significant.

Conclusion: We have synthesized N-donor pyrazolyl borate derivatives and their copper (II) complex. Single X-ray results indicated the Cu(II) complex adopted an N5 environment around the metal center with a distorted square pyramidal geometry. The obtained binding energy of molecular docking studies is in direct correlation with the in vitro antibacterial studies. Briefly, the reported Cu(II) complex may be considered as a potential antibacterial candidate.