Chun-Ling Chen

Cytotoxicity and structure–activity relationships of four α-N-heterocyclic thiosemicarbazone derivatives crystal structure of 2-acetylpyrazine thiosemicarbazone

A series of thiosemicarbazone ligands, HL(1) (2-acetylpyrazine thiosemicarbazone), HL(2) (2-acetylpyrazine N(4)-methylthiosemicarbazone), HL(3) (2-benzoylpyridine thiosemicarbazone) and HL(4) (2-benzoylpyridine N(4)-methylthiosemicarbazone), have been synthesized. The crystal structure of HL(1) has been determined by single-crystal X-ray diffraction. Hydrogen bonds link the different components to stabilize the crystal structure. The antitumor activity of the four ligands were tested against K562 leucocythemia and BEL7402 liver cancer cell lines. All the thiosemicarbazones showed significant antitumor activity. Different substituents on the ligands show different levels of antitumor activity. By comparison with the other thiosemicarbazone species studied, HL(4) with substitution at N(4) position in thiosemicarbazone along with 2-benzoylpyridine is the most active thiosemicarbazone ligand with IC(50)=0.002microm in the K562 leucocythemia cell line and 0.138microm in the BEL7402 liver cancer cell line, respectively.

Iron(III) complex of 2-acetylpyrazine thiosemicarbazone: synthesis, spectral characterization, structural studies and antitumoral activity

[Fe(HL)2]Cl3 · 1.5H2O (1), where HL = C7H9N5S, 2-acetylpyrazine thiosemicarbazone, was obtained and fully characterized. X-ray diffraction studies show that complex 1 crystallizes in monoclinic lattice, space group P21 /n, with a = 11.342(6), b = 12.547(6), c = 17.056(9) Å, β = 103.551(7)°, V = 2360(2) Å3, Z = 2, Mr = 1159.46, D Calcd = 1.632 g cm−3, μ(Mo-Kα) = 1.188 mm−1, F(000) = 1184, the final R 1 = 0.0955 and wR 2 = 0.2626. The 2-acetylpyrazine thiosemicarbazone is a tridentate ligand and binds to the metal through the pyrazine nitrogen, the imine nitrogen and the sulfur in the neutral thione form yielding an octahedral geometry. The title iron complex showed significant antitumor activity against the Ec9706 human esophagus cancer cell line with an IC50 value (10.50 µM) in a micromolar range similar to cisplatin.

Antitumor activity of manganese(II) and cobalt(III) complexes of 2-acetylpyridine schiff bases derived from S-methyldithiocarbazate: Synthesis, characterization, and crystal structure of the manganese(II) complex of 2-acetylpyridine S-methyldithiocarbazate

Transition metal complexes [Mn(L)2] (I) and [Co(L)2] · (ClO4) · H2O (II), where HL = 2-acetylpyridine S-methyldithiocarbazate, have been synthesized. Complex I was characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction studies. The manganese(II) atom in complex I adopts a distorted octahedral geometry with the Schiff base coordinated to it as a uninegatively charged tridentate chelating agent via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atom. Biological studies carried out in vitro against K562 leukemia cancer cell line have shown that the free ligand and its metal complexes exhibited significant and different antitumor activity, since they exhibit IC50 values in the μM range.

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.

Biological activity of Co(III) and Ni(II) complexes of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone: Synthesis, characterization, crystal structure of Co(III) complex of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone1

Transition metal complexes formulated as [Co(L)2]ClO4 (I) and [Ni(L)2] · H2O (II), where HL = pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone, have been synthesized. Complex I was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. In complex I, the ligand is N2S tridentate, coordinating to the metal center through pyridine nitrogen, imine nitrogen and sulfur atoms. Hydrogen bonds link the different components to stabilize the crystal structure. Preliminary in vitro screening indicated that the free ligand was active against various bacteria and fungi and all the tested compounds showed significant antitumor activity against K562 leukaemia cell line, and can therefore be candidates for further stages of screening in vitro and/or in vivo.

Biological activities of pyridine-2-carbaldehyde Schiff bases derived from S-methyl- and S-benzyldithiocarbazate and their zinc(II) and manganese(II) complexes. Crystal Structure of the Manganese(II) complex of pyridine-2-carbaldehyde S-benzyldithiocarbazate

Transition metal complexes [Zn(L1)2] (I) and [Mn(L2)2] (II), where HL1 = pyridine-2-carboxaldehyde S-methyldithiocarbazate, HL2 = pyridine-2-carboxaldehyde S-benzyldithiocarbazate, have been synthesized. Complex II was characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction studies. The manganese(II) atom in complex II adopts a distorted octahedral geometry with the Schiff base coordinated to it as a uninegatively charged tridentate chelating agent via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atom. Biological studies carried out in vitro against selected bacteria, fungi, and K562 leukemia cell line, respectively, have shown that the free ligands and their metal complexes exhibited distinctive differences in the biological properties. Ligand HL1 and complex I have the marked and broad antimicrobial activities compared to HL2 and complex II while only HL1 and complex II show significant antitumor activity against K562 leukemia cell line, since they exhibit IC50 values in the μM range.

1,2-Bis(1H-pyrrol-2-ylmethyl­ene)diazane monohydrate

The molecular structure of title compound, C10H10N4·H2O, has an inversion centre located on the mid-point of the N—N bond of the molecule. A twofold rotation axis passes through the water O atom. In the crystal structure, a two-dimensional network is constructed through N—H⋯O and O—H⋯N hydrogen bonds.

2-Acetyl­pyrazine 4-methyl­thio­semi­carbazone

The title compound, C8H11N5S, has been prepared by the reaction of 2-acetylpyrazine with 4-methyl-3-thiosemicarbazide. It exists in the thione form and adopts the E configuration. The molecules are connected by the intermolecular N—H⋯N and N—H⋯S interactions.

Bis(2,2'-bipyridine-κN,N')(thio-cyanato-κN)copper(II) perchlorate.

The asymmetric unit of title compound, [Cu(NCS)(C10H8N2)2]ClO4, contains a bis(2,2′-bipyridine)(isothiocyanato)copper(II) cation and a perchlorate anion. In the cation, the Cu2+ ion is coordinated by four N atoms from two bidentate 2,2′-bipyridine molecules and an N atom from an isothiocyanate anion, resulting in a distorted CuN5 pyramidal configuration. The crystal structure is stabilized by weak intermolecular C—H⋯O and C—H⋯S hydrogen bonds, and weak π–π interactions between 2,2′-bipyridine rings [centroid–centroid distance = 3.908 (4) Å]. The perchlorate counteranion is disordered over two positions in a 0.66:0.34 ratio.

N′-Ferrocenyl-2-hydroxy­benzohydrazide

The title complex, [Fe(C5H5)(C13H11N2O3)], was prepared via self-assembly using ferrocenyl hydrazide and ethyl salicylate. The compound is potentially a tridentate ferrocene-based ligand. The conformation of the molecule allows the formation of an intramolecular N—H⋯O hydrogen bond involving the hydroxyl group. The CONHNHCO unit and the rings bonded to it are nearly coplanar. The crystal structure is stabilized by intermolecular O—H⋯O(carbonyl) and N—H⋯O(carbonyl) hydrogen bonds.