Synthesis, Structural Characterization, and Biological Activity of Two Different Nickel(II) Complexes Derived from N′-[1-(2-pyridyl)ethylidene]morpholine-4-carbothiohydrazide

Abstract

The reaction of Ni(OAc)2 with N′-[1-(2-pyridyl)ethylidene]morpholine-4-carbothiohydrazide (HL) afforded two nickel(II) complexes, [Ni(L)2] (1) and [Ni(L)(OAc)] (2), depending on reaction temperature and starting molar ratio; the former was a 6-coordinate, paramagnetic complex and the latter a 4-coordinate, diamagnetic complex. X-ray analysis of the complex 2 revealed that the ligands, L and OAc, were coordinated to the central metal ion to form a square-planar geometry. The complex 2 showed enhanced antimicrobial activities against selected Gram-positive bacteria, compared with those of the ligand alone, whereas the other complex 1 showed no activity.

Syntheses, crystal structures and antimicrobial activities of monomeric 8-coordinate, and dimeric and monomeric 7-coordinate bismuth(III) complexes with tridentate and pentadentate thiosemicarbazones and pentadentate semicarbazone ligands

“…The coordination number of the zinc(II) ion, solubility and hydrophobicity of the zinc(II) complexes played less significant roles for antimicrobial activities. These features were in contrast to the nickel(II) complexes with the same ligands [17,18]; the latters show selective and effective activities against two Gram-positive bacteria (B. subtilis and S. aureus), only when they take a labile 4-coordinate structure consisting of one tridentate ligand and one replaceable monodentate ligand such as OAc À and Cl À . Thus, the structure factors that govern antimicrobial activities are strongly dependent on the central metal ions.…”

“…We have recently reported the relationship between the structure and antimicrobial activity in the transitionmetal (zinc(II) and nickel(II)) complexes with multidentate thiosemicarbazone and semicarbazone ligands [16][17][18][19]. We have presented that the nickel(II) complexes with thiosemicarbazone and semicarbazone ligands (L1-L3) show selective and effective activities against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), only when they take a labile 4-coordinate structure consisting of one tridentate ligand and one replaceable monodentate ligand such as OAc À and Cl À [18].…”

“…In our continuing studies of the structure-antimicrobial activity relationship of the metal complexes with thiosemicarbazone and semicarbazone ligands [16][17][18][19], we have prepared several novel bismuth(III) complexes with tridentate (Hmtsc; L1) and pentadentate thiosemicarbazone (H 2 dmtsc; L3) and semicarbazone (H 2 dasc; L4b) ligands, i.e. [Bi(dmtsc)(NO 3 2 ], 3b, [Bi(mtsc)Cl 2 ] Á 0.5DMSO Á 2H 2 O, 3c, and cis-[Bi(mtsc)Cl 2 (DMSO)] Á DMSO, 3d.…”

Bonding and structure trends of thiosemicarbazone derivatives of metals—An overview

“…11), the thiosemicarbazone ligand undergoes oxidation at the sulfur center where it changes into sulfone and coordinates to rhodium as dianionic tridentate C, N 3 , S-donor. [189][190][191][192][193][194][195][196][197][198][199][200][201][202][203][204]. In complexes 117-126, the -N 2 H, group deprotonates and the ligands bind via N 4 , N 3 , S-donor atoms, and in complexes 127-132, the of OH group deprotonates, and ligands bind via O, N 3 , S-donor atoms.…”

Syntheses, crystal structures and antimicrobial activities of 6-coordinate antimony(III) complexes with tridentate 2-acetylpyridine thiosemicarbazone, bis(thiosemicarbazone) and semicarbazone ligands

“…Observed results so far lead us to conclude that the structure factors which govern antimicrobial activities are strongly dependent on the central metal ion [19][20][21][22][23]. The structure-activity correlation of nickel(II) complexes with thiosemicarbazone and semicarbazone ligands has been attributed to their ligand-replacement ability because they show selective and effective activities against two bacteria, only when they take a labile 4-coordinate structure having one tridentate ligand and one replaceable monodentate ligand [21].…”