New complexes of α-amino nitrile with VO(II), Cr(III), Fe(II), Fe(III), and Cd(II) metal ions: Synthesis, characterization and anti-bacterial activity

Few studies have been illustrated in the field of α-amino nitrile complexes, a new series of metal ion complexes for VO(II), Cr(III), Fe(II), Fe(III) and Cd(II) were derived from α-aminonitrile ((E)-2-(2-hydroxyphenyl)-2-((4-(phenyldiazenyl)phenyl)amino)acetonitrile) ligand (HL). The complexes have been characterized using conventional techniques such as Fourier transform infra-red (FT-IR) and ultraviolet visible (UV-VIS) spectroscopy, elemental and metal analysis (C.H.N.S.M), thermal analysis (TGA), and molar conductivity. Octahedral geometries were suggested for the new complexes, except that the vanadium complex was a square pyramid, and they were observed to be electrolytic. The coordination behavior of the ligand was bidentate, of the NO-type, through hydroxyl and amine groups, forming a 6-membered ring and releasing the nitrile group freely. Generally the suggested formula of complexes A1-A5 are: [VO(HL)2]SO4.2H2O, [Cr(HL)2(H2O)2]Cl3.4H2O, [Fe(HL)2Cl(H2O)]Cl.H2O, [Fe(L)2(H2O)2]Cl.2H2O, [Cd(HL)2(H2O)2]Cl2.5H2O respectively, considering the ligand is deprotonated (L-1) in A4 complex. Hence, the coordination sphere of each complex includes two ligands and one or two aqua molecules, except the oxovanadium (IV) complex, which is without aqua coordinating. Antibacterial activity has been evaluated for the synthesized compounds against Pseudomonas, Escherichia coli, Proteus, and Staphylococcus aureus; the results were promising, considering the presence of a free nitrile moiety and metal ions, which influenced the structure-activity relationship. KEY WORDS: α-Aminonitrile, Bi-dentate ligand, Anti-bacterial activity Bull. Chem. Soc. Ethiop. 2026, 40(2), 443-453 DOI: https://dx.doi.org/10.4314/bcse.v40i2.13