Synthesis, characterization and fungicidal activity of binary and ternary metal(II) complexes derived from 4,4′-((4-nitro-1,2-phenylene) bis(azanylylidene))bis(3-(hydroxyimino)pentan-2-one)

• Novel ligand, binary and ternary metal complexes were synthesized.
• Characterization of the ligand and metal complexes were carried out by various spectral techniques.
• The complexes displayed either a tetragonal distorted octahedral or a square planar geometry.
• The metal complexes are more potent as fungicides than the ligand and the standard antifungal drug “Amphotericin B”.

Ternary copper(II) and binary copper(II), nickel(II) and cobalt(II) complexes derived from 4,4′-((4-nitro-1,2-phenylene)bis(azanylylidene))bis(3-(hydroxyimino)pentan-2-one) (H2L) were synthesized and characterized by elemental and thermal analyses, IR, UV–Vis. and 1H NMR spectroscopy, conductivity and magnetic moments measurements. The analytical and spectral data showed that, the ligand acts as dibasic tetradentate or dibasic hexadentate bonding to the metal ion via the two-imine nitrogen, two nitrogen and/or oximato oxygen atoms of deprotonated oxime groups forming five and/or six rings including the metal ions. The complexes adopt either tetragonal distorted octahedral or square planar geometry around metal ions. The ESR spectra of the solid copper(II) complexes are characteristic to d9 configuration and having an axial symmetry type of a d(x2−y2) ground state. The g values confirmed the geometry is elongated tetragonal octahedral geometry with considerably ionic or covalent environment. The antifungal biological activity of the prepared compounds was studied using well diffusion method. The obtained results showed that, the ligand is biologically inactive while its metal complexes were more potent fungicides than the ligand and standard antifungal drug (Amphotericin B).

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