Syntheses, characterizations, X-ray crystal structures, and antibacterial activities of Co(II), Ni(II), and Zn(II) complexes of the Schiff base derived from 5-nitro-2-hydroxybenzaldehyde and benzylamine

Abstract

Three new complexes, [Co^IIL₂(bzln)₂] (1), [Ni^IIL₂(DMF)₂] (2), and [Zn^IIL₂] (3), with the bidentate (NO) Schiff base HL = 2-((E)-(benzylimino)methyl)-4-nitrophenol have been synthesized and characterized. [Co^IIL₂(bzln)₂] (1) was initially formed from the reaction of H₂L¹ (N,N′-bis(5-nitrobenzaldehyde)-2-aminobenzylamine = H₂L¹), with Co^II(CH₃COO)₂·4H₂O in the presence of benzylamine. The X-ray crystal structure of 1 revealed that HL was formed from the hydrolysis of H₂L¹ and the recondensation of benzylamine with 2-hydroxy-5-nitrobenzaldehyde produced in H₂L¹ hydrolysis. The Schiff base HL was then prepared by direct reaction of 2-hydroxy-5-nitrobenzaldehyde and benzylamine. Complexes 1–3 were also directly synthesized and their crystal and molecular structures determined by X-ray crystallography. The ligand and its metal complexes were also screened for in vitro antibacterial activity.

Keywords:

• Co(II)
• Ni(II), and Zn(II) complexes
• Unsymmetrical Schiff base
• Crystal structure
• Antibacterial activity

Acknowledgments

Partial support of this work by the Isfahan University of Technology Research Council is gratefully acknowledged. The X-ray center of the Vienna University of Technology is acknowledged for providing access to the single-crystal diffractometer.