Biologically active Cu(II), Ni(II) & Co(II) complexes of a tridentate N, O, O-donor Schiff base from citral and l-alanine: Synthesis, characterization and antimicrobial activity

Abstract

The intramolecular hydrogen-bonded N, O, O-donor Schiff base ligand (L1), which is derived from citral (3,7-dimethyl-2,6-octadienal, C10H16O) and l-alanine, has been used to synthesize a series of Cu(II), Ni(II), and Co(II) complexes (1, 2 &3). Elemental analysis, spectroscopic techniques, magnetic susceptibility tests, and thermal analysis were used to characterize these complexes. Complexes 1 and 3 have a distorted square pyramidal geometry with the N, O, O donor (azomethine nitrogen and μ2-carboxylato oxygen atoms) Schiff base, L1, in which the adjacent M(II) ions are coupled in an equatorial-axial pattern by the carboxylate unit of L1 and display ferromagnetic interaction. However, complex 2 displays distorted octahedral geometry with significant antiferromagnetic interactions between neighboring Ni(II) ions via a bridged carboxylate unit in an equatorial-axial manner. The octahedral geometry of complex 2 is further supported by analyses of ligand field parameters and theoretical magnetic susceptibility studies. The antimicrobial activities of L1 and its complexes were screened against bacteria (AR) and fungus. The findings suggest that M(II) complexes of L1 have the potential to be employed in the development of antibacterial and antifungal drugs.