Synthesis, characterization and anti-fungal evaluation of Ni(II) and Cu(II) complexes with a derivative of 4-aminoantipyrine

Transition metal complexes of Ni(II) and Cu(II) metal ions with the general stoichiometry [M(L)X]X and [M(L)SO4], where M = Ni(II) and Cu(II), L = (1E)-N-((5-((E)-(2,3-dimethyl-1-phenyl-4-pyrazolineimino)methyl)thiophen-2-yl)methylene)-2,3-dimethyl-1-phenyl-4-pyrazolineamine and X = Cl−, NO3− and SO42−, have been synthesized and characterized. The synthesized ligand and metal complexes were characterized by 1H NMR, IR, mass spectrometry, UV-Vis spectra and EPR. In molecular modelling, the geometries of the Schiff's base and metal complexes were fully optimized with respect to the energy using the 6-31g(d,p) basis set. The nickel(II) complexes were found to have octahedral geometry, whereas the copper(II) complexes were of tetragonal geometry. The covalency factor (β) and orbital reduction factor (k) suggest the covalent nature of the complexes. To develop broad spectrum new molecules against seed-borne fungi, the minimum inhibitory concentration (MIC) of the ligand and its metal complexes was evaluated by the serial dilution method.