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981.
The synthesis, the spectroscopic and structural characterization of different thiophenolate-capped zinc clusters are reported and described. In particular, different reactions of 4-chlorobenzenethiol with zinc salts yield the clusters [Me4N][Et3NH][Zn4(μ-S-C6H4-Cl)6(S-C6H4-Cl)4] (2a), [Et3NH]2[Zn4(μ-S-C6H4-Cl)6(S-C6H4-Cl)4] (2b), and [Me4N]2[Zn4(μ-S-C6H4-Cl)6(S-C6H4-Cl)4] (2c), and also the thiophenolate derivative [Et3NH]2[Zn4(μ-S-C6H5)6(S-C6H5)4] (1b) was obtained.The nanosized thiophenolate-capped clusters were investigated by 1H and 13C NMR, elemental analysis, and electrospray ionization (ESI) mass spectrometry. NMR experiments provided insights into the dynamic behaviour of the clusters. The thermal decomposition patterns of 2c were analyzed in air as well as in nitrogen, indicating the formation of zinc oxide and metallic zinc, respectively. The X-ray structure of 2a revealed that the cluster core consists of an adamantane-like framework analogous to those realized in many other M4(SR)10 metal complexes. 相似文献
982.
The reactions of O2CH3 radicals with CuII(glycine)2 and CuII(GGG), GGG = glycylglycylglycine, in aqueous solutions were studied.The results demonstrate that the peroxyl radicals oxidize the copper complexes forming relatively stable intermediates of the type LmCuIII-OOCH3. These intermediates decompose via oxidation of the ligands glycine and GGG, respectively. Substituents on the alkyl of the peroxyl radical affect somewhat the kinetics of reaction but not the mechanism of oxidation. It is suggested that analogous reactions are probably contributing to the radical-induced deleterious biological processes. 相似文献
983.
Thomas Riis-Johannessen John C. Jeffery Craig R. Rice 《Inorganica chimica acta》2005,358(9):2781-2798
Reaction of the potentially tetradentate N-donor ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine (L1) with the transition metal dications CoII, NiII, CuII, CdII and HgII results in the formation of mononuclear [M(L1)]2+ complexes, in which a planar ligand coordinates to the metals via all four N-donors. In contrast, reaction of L1 with CuI and AgI monocations, affords dinuclear double stranded helicate species [M2(L1)2]2+ (where M = CuI or AgI), in which partitioning of the ligand into two bis-bidentate pyridyl-thiazole chelating units allows each ligand to bridge both metal centres. X-Ray crystallography, electrospray mass spectroscopy and NMR spectroscopy reveal that the complexes [Mn(L1)m]z+ (where n = 1, m = 1 and z = 2, when M = CoII, NiII, CuII, CdII and HgII; n = 2, m = 2 and z = 2, when M = CuI), retain their solid-state structures in solution. Conversely, whilst 1H NMR studies suggest that combination of equimolar amounts of Ag(X)(where ) and L1 (in either nitromethane or acetonitrile) results in the formation of a helicate in solution, in the solid-state, an anion-templating effect gives rise to either mononuclear or dinuclear helicate structures [Agn(L1)n][X]n (where n = 2 when X = OTf−; n = 1 when ). 相似文献
984.
The reaction of quadruply bonded dimolybdenum complex, [Mo2(μ-OAc)4] (1), with lithiated amidinato, Li[(NiPr)2CR] (R = tBu; 2a, Me; 2b, Ph; 2c), was investigated. The reaction of 1 with 2a afforded the dark-red solid, whereas the product was so highly unstable that the product was not able to be characterized. In the case of acetamidinato 2b, lantern-type mixed-ligand quadruply bonded dimolybdenum complex, [Mo2(μ-OAc){μ-(NiPr)2CMe}3] (3), was obtained as a yellow solid. In the reaction with benzamidinato 2c, symmetrical lantern-type dimolybdenum complex, [Mo2(μ-OAc)2 {μ-(NiPr)2CPh}2] (4), was isolated as a yellow solid. In the latter reaction, intermediary red compound (5), which is considered to be stereoisomer of 4 possessing non-lantern-type skeleton, was formed. However, isolation of 5 as a single component was not successful due to isomerization to 4. Complex 5 readily reacted with dry oxygen to give dimolybdenum(V) complex, [{Mo(η-(NiPr)2CPh)oxo}2 (μ-OAc)2(μ-oxo)] (6), as a red solid. These complexes were characterized spectroscopically as well as, in some cases, by X-ray analyses. 相似文献
985.
The preparation and characterization of organolithium O,C,O-pincer compound [2,6-(tBuOCH2)2C6H3]-Li (1) is described. The X-ray diffraction techniques revealed the dimeric structure of 1 consisting of two lithium atoms Li(1) and Li(2) and two monoanionic chelating aryl ligands in the solid state, where each lithium atom is coordinated by two oxygen atoms of two different ligands. The NMR spectroscopy and cryoscopy measurements established monomer-dimer equilibrium of 1 in concentrated solutions of non-coordinated solvents, while the diluted solutions of 1 consist of monomer only. 相似文献
986.
Tibor J. Sabo Goran N. Kalu?erovi? Tatjana P. Stanojkovi? Zorica D. Jurani? 《Inorganica chimica acta》2005,358(7):2239-2245
Four platinum(IV) complexes, trans,trans-dichlorobis(N,N-dimethylglycinato)platinum(IV), trans,trans-[Pt(dmgly)2Cl2] (1) and trans,trans-dibromobis(N,N-dimethylglycinato)platinum (IV), trans,trans-[Pt(dmgly)2Br2] (2), as well as, trans,trans-dichlorobis(N-methylglycinato)platinum(IV), trans,trans-[Pt(sar)2Cl2] (3) and trans,trans-dibromobis(N-methylglycinato)platinum(IV), trans,trans-[Pt(sar)2Br2] (4) (with configuration index for all complexes OC-6-14), were synthesized and characterized by elemental analysis, infrared and 1H NMR spectroscopy. In the aim to assess the selectivity in the antitumor action of these complexes, the antiproliferative action of these compounds was determined to human adenocarcinoma HeLa cells; to human myelogenous leukemia K562 cells and to normal immunocompetent cells; i.e., on human PBMC. The details of the crystal structure synthesized trans,trans-[Pt(sar)2Br2] complex were also reported here. In the crystal structure of trans,trans-[Pt(sar)2Br2], the Pt(IV) ion had a deformed octahedral coordination with both N-methylglycinates and bromides bonded trans to one another and with the N-Pt-Br bond angles of 84.1(4) and 95.9(4)°. The trans,trans-[Pt(sar)2Br2] complex molecules form 2D-layers with multiple N-H?O and C-H?O hydrogen bonds. 相似文献
987.
Greta De Filippo Alessandra Garau Abdollah Yari Mojtaba Shamsipur 《Inorganica chimica acta》2005,358(3):801-807
The reactions of Ag+ with five mixed donor phenanthroline-containing macrocycles (L1-L5) having N2S3-, N2S2O-, N2S2-, N3S2-, and N4S2-donor sets, respectively, have been studied in MeCN by spectrofluorimetric, spectrophotometric, conductometric and potentiometric methods. All ligands form 1:1 [Ag(L)]+ complexes, and in the case of L4 and L5, formation of 1:2 [Ag(L)2]+ species is also observed. The corresponding formation constants have been evaluated and their values allow a deeper insight into the role played by complexation process in the potentiometric selectivity for Ag+ of membrane electrodes (ISE), and in the selective transport of Ag+ through supported liquid membrane (SLM) systems based on these ligands. The X-ray crystal structure of the complex [Ag(L4)]BF4 is also reported. 相似文献
988.
A novel asymmetric bidentate ligand, 2-(pyrazin-2-yl)naphthoimidazole (PZNI), and its Ru(II) complexes [Ru(bpy)2(PZNI)]2+ (1) and [Ru(phen)2(PZNI)]2+ (2) have been synthesized and characterized by elemental analysis, mass spectra, 1H NMR, and electronic spectroscopy. The electrochemical behaviors of the novel complexes were studied by cyclic voltammetry. The DNA-binding properties of the complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that the complexes 1 and 2 interact with calf thymus DNA by intercalative mode via the terminal naphthyl ring into the base pairs of DNA. The two Ru(II) complexes have also been found to promote the cleavage of plasmid pBR 322 DNA from the supercoiled form I to the open circular form II upon irradiation. 相似文献
989.
The dimethylaminopyridine (DMAP) promoted reaction between [Os(bpy)2(CO)(OTf)]OTf (where ) and methylene chloride is reported. C-Cl bond breaking of a solvent molecule leads to the formation of the [Os(bpy)2(CO)(Cl)]OTf complex. The reactivity and redox properties of [Os(bpy)2(CO)(OTf)]OTf were investigated by means of room- and low-temperature electrochemical experiments. In CH2Cl2, at low temperature, the complex undergoes two 1e electrochemical and chemical reversible reductions (ErEr mechanism), but at room temperature a more complex electrochemical mechanism is observed, leading to the electro-synthesis of [Os(bpy)2(CO)(Cl)]OTf via electrochemical reversible and chemical irreversible reduction processes (ErCi mechanism). The DMAP nucleophilicity was used to produce the new [Os(bpy)2(CO)(Br)]OTf and [Os(bpy)2(CO)(I)]OTf complexes which have been fully characterized. 相似文献
990.
Maaser K Sutter AP Krahn A Höpfner M Grabowski P Scherübl H 《Biochemical and biophysical research communications》2004,324(2):878-886
Specific ligands of the peripheral benzodiazepine receptor (PBR) have been shown to induce both apoptosis and G1/G0 cell cycle arrest in colorectal cancers. The signaling pathways leading to cell cycle arrest are still unknown. Using cDNA array technology, we identified signaling molecules involved in cell cycle arrest induced by the PBR ligands FGIN-1-27 and PK 11195. Differential gene expression was confirmed by semi-quantitative RT-PCR or Western blot analysis of gene products. The PBR ligand-mediated signaling involved the upregulation of the cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1, cdc16, and the cell cycle inhibitors gadd45 and gadd153, the downregulation of the cyclins D1 and B1, as well as the inactivation of ERK1/2. The p21-deficient colorectal cancer cell line HCT116 p21-/- was significantly less sensitive to PBR ligands than the parental HCT116 wild-type cells, demonstrating the functional involvement of p21WAF1/CIP1 in PBR ligand-mediated G1 arrest. This study thus revealed PBR ligand-triggered signaling pathways leading to cell cycle arrest. Moreover, we showed the functional implication and interaction of differentially expressed gene products and provided a model of signaling pathways involved in PBR ligand-induced G1 arrest. These results form the basis for future PBR ligand-mediated therapeutic approaches. 相似文献