synthesis, characterization and biochemical activity of cobalt(ii), nickel(ii), copper(ii), and zinc(ii) complexes with 1,2,4-triazole based schiff base

The work describes the synthesis and spectral investigation of co (ii), ni(ii), cu(ii), and zn(ii) complexes with (e)-4-((2-pyrrole)amino)-5-(pyridine-4-yl)-4h-1,2,4-triazole-3-thione (l). the new ligand was synthesized through three successive steps, first potassium salt was prepared which is isonazid with an alkaline solution of carbon disulfide, followed by the ring closure of potassium salt with excess hydrazine hydrate, and then the final step was condensation of 2-acetylpyrrole in glacial acetic medium with 4-amino-1,2,4-triazole precursor afforded good yield of the new schiff base, l. the physical and spectroscopic properties of the ligand and its complexes were well studied. the new ligand and its metal complexes were fully characterized by 1h-nmr,13c-nmr, ft-ir, and ms spectra and uv-visible spectra. likewise, the molar conductivity in dmso solvent and magnetic susceptibility measurements were carried out to elucidate the suggested chemical structures. the results observed from experimental methods were consistent with their suggested compositions. based on the spectral data, metal complexes with coordination numbers 6 and 4 were proposed, with l functioning as a bi-dentate ligand. the metal complexes displayed an octahedral geometry around a bivalent cobalt, nickel, and zinc tetrahedral environment. furthermore, the biological activity of ligand and metal complexes solutions in blank dmso solvent were screened against some bacteria and fungi and the data observed encourages us to take these considerations for a future studying about the toxicity of the new based-schiff base and its metal chelates.