Ternary transition metal complexes of nitrilotriacetic acid and valine or leucine: Synthesis and biological applications

Abstract

Ternary complexes of Ni(II), Cu(II), and Zn(II) with nitrilotriacetic acid HNTA² as a primary ligand and valine or leucine as a secondary ligand were synthesized in slightly acidic medium. The new complexes were characterized by elemental analysis, FTIR, UV-Vis spectroscopy, thermal analysis, magnetic measurements and mass spectroscopy. The results indicate that the ternary complexes are isolated in M:HNTA: valine (or leucine) ratio of 1:1-1, and the molecular structures are suggested to be [M(HNTA)(valine)(H<inf>2</inf>O)<inf>2</inf>] · 1.5H<inf>2</inf>O and [M(HNTA) (leucine)(H<inf>2</inf>O)<inf>2</inf>]·1.5H<inf>2</inf>O, where M=Ni(II) or Cu(II) and H<inf>2</inf> [Zn(NTA)(valine)(H<inf>2</inf>0)] H<inf>2</inf>0. The suggested geometry of our ternary metal complexes is an octahedral symmetry. The antimicrobial activities of prepared complexes against Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillus flavus (isolates from Microanalytical Center, Faculty of Science, Cairo University) were also investigated. The complexes were tested in vitro to assess growth inhibitory activity against the bacterial and fungal species with standard antibacterial and antifungal agents according to the recommended known method.