New Zn(II) complexes based on biologically active substituted acetic acid and nitrogen donor ligands: synthesis, crystal structure and biological applications

Abstract

The complexes [Zn(phenylacetato)₂(2-aminopyridin)₂] (3), [Zn(phenylacetato)₂(1,10-phenanthroline)]·H₂O (4), and [Zn(phenylacetato)₂(2,9-dimethyl-1,10-phenanthroline)]·0.5 H₂O (5) were prepared and characterized by IR-, UV–Visible, ¹H and ¹³C NMR spectroscopy, and single crystal X-ray diffraction. BNPP hydrolysis of the complexes and their parent nitrogen ligands showed that the hydrolysis rate of bis-(4-nitrophenyl) phosphate (BNPP) was 1.7 × 10⁵ L mol⁻¹ s⁻¹ for 3, 3.1 × 10⁵ L mol⁻¹ s⁻¹ for 4 and 4.3 × 10⁴ L mol⁻¹ s⁻¹ for 5. Antibacterial activities show the effect of complexation on activity against Gram-positive (S. epidermidis, S. aureus, E. faecalis, M. luteus and B. subtilis) and Gram-negative (K. pneumonia, E. coli, P. mirabilis and P. aeruginosa) bacteria using the agar well diffusion method. Complex 4 showed good activity against G− bacteria except P. aeruginosa, and against G+ bacteria except E. ferabis. Complex 5 showed no activity against G− bacteria, low activity against M. luteus and B. subtilis bacteria and high activity against S. epidemidis and S. aureus. Complex 3 did not show any activity against G− or G+ bacteria.

Keywords:

• Zinc(II) complexes
• nitrogen ligands
• zinc(II) phenylacetate
• phosphate diester hydrolysis
• antibacterial activity