Ming-Xue Li

A Nine-Coordinated Bismuth(III) Complex Derived from Pentadentate 2,6-Diacetylpyridine Bis(4N-methylthiosemicarbazone): Crystal Structure and Both in Vitro and in Vivo Biological Evaluation

Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Few in vivo biological studies have been carried out in comparison to the plentiful in vitro data. Here, an interesting nine-coordinated bismuth(III) complex, [Bi(H2L)(NO3)2]NO3 [1; H2L = 2,6-diacetylpyridine bis((4)N-methylthiosemicarbazone)], has been synthesized and structurally characterized. The analytical data reveal the formation of 1:1 (metal/ligand) stoichiometry. In vitro biological studies have indicated that the bismuth complex 1 has shown much higher antibacterial and anticancer activities than its parent ligand, especially with MIC = 10.66 μM against Bacillus cereus and Salmonella typhimurium and IC50 = 26.8 μM against K562 leukemia cells, respectively. More importantly, it also evidently inhibits H22 xenograft tumor growth on tumor-bearing mice (10 mg/kg; inhibitory rate = 61.6%). These results indicate that coordination to bismuth(III) might be an interesting strategy in the discovery of new anticancer drug candidates.

Synthesis, crystal structures, in vitro biological evaluation of zinc(II) and bismuth(III) complexes of 2-acetylpyrazine N(4)-phenylthiosemicarbazone.

Two metal complexes formulated as [Zn(L)(2)](2)·H(2)O (1) and [Bi(L)(NO(3))(2)(CH(3)OH)] (2), where HL=2-acetylpyrazine N(4)-phenylthiosemicarbazone, have been synthesized and characterized by elemental analysis, IR, MS, NMR and single-crystal X-ray diffraction studies. Biological studies, carried out in vitro against selected bacteria and the K562 leukemia cell lines, respectively, have shown that the free ligand and its two complexes may be endowed with important biological properties, especially HL with MIC=3.90 μg/mL against Pseudomonas aeruginosa, the zinc(II) complex 1 with IC(50)=1.0 μM against K562 leukemia cell lines, respectively. The compounds HL and 1 may exert their cytotoxicity activity via induced loss of mitochondria membrane potential (MMP).

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.

Synthesis, crystal structure and biological evaluation of a main group seven-coordinated bismuth(III) complex with 2-acetylpyridine N4-phenylthiosemicarbazone.

Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Here, a main group seven-coordinated bismuth(III) complex [Bi(L)(NO3)2(CH3CH2OH)] (1) (HL = 2-acetylpyridine N(4)-phenylthiosemicarbazone) has been synthesized and characterized by elemental analysis, IR, (1)H NMR and single-crystal X-ray diffraction studies. The cytotoxicity data suggest that 1 exhibits higher in vitro antiproliferative activity in four human cancer cells tested. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Compound 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).

Cytotoxic activity of iron(III), cobalt(III), nickel(II), zinc(II), and cadmium(II) complexes of 2-acetylpyrazine thiosemicarbazone: crystal structure of the cobalt(III) complex

Transition metal complexes [Fe(HL)2]Cl3 ⋅ 1.5H2O (1), [Co(L)2] ⋅ ClO4 ⋅ H2O (2), Ni(HL)2(ClO4)2 ⋅ 2H2O (3), Zn(HL)L ⋅ BF4 ⋅ 2H2O (4), and Cd(HL)2(ClO4)2 ⋅ 2H2O (5), where HL = C7H9N5S, 2-acetylpyrazine thiosemicarbazone, have been synthesized. Complex 2 was characterized by elemental analysis, infrared spectra, mass spectra, and single-crystal X-ray diffraction. Preliminary in vitro screening showed that 1, 4, and 5 exhibit higher antitumor activity than 2 and 3 against K562 leucocythemia cancer cell line.

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.

Synthesis, crystal structures, and cytotoxicity of 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone and its zinc(II) and diorganotin(IV) complexes

[Zn(L)2] (1) and [(Ph)2Sn(L)(CH3COO)] (2), where HL = 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone, have been synthesized and characterized. The complexes show different coordination depending on their coordinating preferences. Biological studies carried out in vitro against human leukemia K562 cells show that the diorgantin(IV) complex, 2, has significant cytotoxicity with IC50 = 3.3 ± 0.5 μM.

Synthesis, Characterization, Crystal Structure, and Cytotoxicity of a Diorganotin(IV) Complex with 2-Acetylpyridine N 4-Phenylthiosemicarbazone

A new diorganotin(IV) complex formulated as [(Me)2Sn(L) (CH3COO)] (1), where HL = 2-acetylpyridine N(4)-phenylthiose micarbazone, has been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction studies. Schiff base in its deprotonated form coordinates to tin(IV) via pyridine nitrogen atom and the nitrogen atom and sulfur atoms of the thiosemicarbazone moiety. The tin(IV) ion is seven-coordinated and adopts a distorted pentagonal bipyramidal geometry. Biological studies, carried out in vitro against the K562 leukemia cells, have shown that the coupling of HL to Me2Sn(IV) leads to an enhancement of the cytotoxicity of the free ligand.

Electrostatic polypyridine–ruthenium(II)⋯decatungstate dyads: structures, characterizations and photodegradation of dye

Two hybrids, [Ru(bpy)2(CH3CN)2]2[W10O32]·2CH3CN (RuW-1) and [Ru(bpy)3]2[W10O32] (RuW-2) (bpy = 2,2′-bipyridine), were synthesized by the reaction of (2,2′-dipyridyl)ruthenium complexes and decatungstate, under hydrothermal conditions, and characterized by IR, UV, fluorescence and transient absorption spectroscopy. The influences of the coordination environment of the centre ion, Ru(II), are compared and discussed in detail on the basis of analyzing their photophysical and photochemical properties. Kinetics experiments for the photodegradation of Rhodamine B (RhB) dye were followed with spectrophotometric analysis showing an absorbance decrease at 544 nm resulting from the cleavage of the aromatic ring of RhB. UV spectroscopy indicated that the degradation proceeds with a pseudo-first-order rate constant in the range of 10−3 to 10−2 s−1. These results demonstrate that the hybrids have effective activity and reusability for the photodegradation of RhB.

Synthesis and adsorption properties of [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites

Multifunctional [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 (HL = pyridine-2-carboxamide) nanocomposites were successfully synthesized by combining [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O and Fe3O4 nanoparticles. The characterization was performed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray powder diffraction (XRD) and ultraviolet-visible light absorbance spectrometry (UV-vis). The XRD and TEM analyses reveal that the nanocomposites possess high crystallinity with an average particle size of ∼19.43 nm. The VSM and UV-vis demonstrate excellent superparamagnetic behavior and two well-behaved absorption bands of the nanocomposites. The adsorption activity of the nanocomposites was investigated using methylene blue, gentian violet, safranine T, fuchsin basic, methyl orange and Sudan red (III) as probe molecules, and the results reveal that the [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have selective adsorption behavior for organic dyes. The recycling performance was observed using basic fuchsin, and the results demonstrate that the nanocomposites exhibit good recyclability and high stability. The [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have a promising future for magnetic, optical and biomedical applications.