Synthesis, characterization, DFT and antimicrobial studies of transition metal ion complexes of a new schiff base ligand, 5-methylpyrazole-3yl-N-(2́-hydroxyphenylamine)methyleneimine, (MPzOAP)

Abstract

A new pyrazole based ‘NNO’ tridentate ligand, 5-methylpyrazole-3yl-N-(2́-hydroxyphenylamine)methyleneimine, (MPzOAP) was synthesized and characterized by elemental analyses, mass, IR, 1H NMR spectral parameters. The versatile coordination mode of the ligand was established by the synthesis of Co(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) metal ion complexes. These complexes were characterized by elemental analyses, conductance and magnetic susceptibility measurements, UV–Vis, IR, 1H NMR spectroscopy, PXRD and thermal analysis. The structures of the ligand and complexes were also investigated using the DFT method. The ligand structure contains the coordination function of the tertiary nitrogen atom of pyrazole ring, the azomethine nitrogen and the phenolic oxygen atom, suitably spaced for chelation with a metal ion and acting as a ‘NNO’ tridentate donor ligand. In vitro antimicrobial activity of the reported ligand and the metal ion complexes were screened and the mode of action was also studied by scanning electron microscopy (SEM) against some pathogenic bacteria.