Synthesis, crystal structures, and bioactivities of NiII and ZnII complexes with pyridine-3-carbaldehyde thiosemicarbazone

The Ni-II and Zn-II complexes with pyridine-3-carbaldehyde thiosemicarbazone (HL) have been synthesized and characterized by X-ray diffraction. In the [NiL2] (1), the Ni-II atom was four-coordinated to form a square geometry by two nitrogen atoms and two sulfur atoms from two different deprotonated ligands. In [Zn(HL)(2)(C2H2OH)(2)(H2O)(2)](NO3)(2) (2), the Zn-II atom was in a distorted octahedral geometry coordinated by two neutral ligands, two ethanol molecules, and two water molecules. The binding of the two complexes with calf thymus DNA has been investigated by absorption, luminescence titrations. The results suggest that both the two complex intercalates into DNA base pairs. Antimicrobial activities of the free ligand and the two complexes against Staphylococcus Aureus, beta-hemolytic streptococcus, Streptococcus Pneumontae, Bacillus Anthracis shows that the free ligand and 1 did not inhibit the growth of the test microorganisms and 2 showed weak activities against the three former tested microorganisms.