Synthesis, crystal structure, and biological activity of a nickel(II) complex of 2-acetylpyridine N(4)-methylthiosemicarbazone

Nickel complex formulated as Ni(L)2 (L = monodeprotonated ligand corresponding to 2-acetylpyridine N(4)-methylthiosemicarbazone, HL) has been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The complex consists of discrete monomeric molecules with octahedral nickel(II) with two anionic 2-acetylpyridine N(4)-methylthiosemicarbazones as NNS tridentate ligands coordinated to nickel via the pyridine nitrogen, azomethine nitrogen, and sulfur. Hydrogen bonds link the different components to stabilize the crystal structure. Biological studies, carried out in vitro against bacteria, fungi, and the K562 leukemic cell line have shown that the free ligand and complex show distinct differences in biological activity.