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排序方式: 共有131条查询结果,搜索用时 31 毫秒
1.
Bassil BS Nellutla S Kortz U Stowe AC van Tol J Dalal NS Keita B Nadjo L 《Inorganic chemistry》2005,44(8):2659-2665
The 15-cobalt-substituted polyoxotungstate [Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}](5-) (1) has been characterized by single-crystal XRD, elemental analysis, IR, electrochemistry, magnetic measurements, and EPR. Single-crystal X-ray analysis was carried out on Na(5)[Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}].37H(2)O, which crystallizes in the hexagonal system, space group P6(3)/m, with a = 19.8754(17) A, b = 19.8754(17) A, c = 22.344(4) A, alpha= 90 degrees, beta = 90 degrees, gamma = 120 degrees, and Z = 2. The trimeric polyanion 1 has a core of nine Co(II) ions encapsulated by three unprecedented (beta-SiW(8)O(31)) fragments and two Cl(-) ligands. This central assembly {Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}(17-) is surrounded by six antenna-like Co(II)(H(2)O)(5) groups resulting in the satellite-like structure 1. Synthesis of 1 is accomplished in a simple one-pot procedure by interaction of Co(II) ions with [gamma-SiW(10)O(36)](8-) in aqueous, acidic NaCl medium (pH 5.4). Polyanion 1 was studied by cyclic voltammetry as a function of pH. The current intensity of its Co(II) centers was compared with that of free Co(II) in solution. Our results suggest that 1 keeps its integrity in solution. Magnetic susceptibility results show the presence of both antiferro- and ferromagnetic coupling within the (Co(II))(9) core. A fully anisotropic Ising model has been employed to describe the exchange-coupling and yields g = 2.42 +/- 0.01, J(1) = 17.0 +/- 1.5 cm(-1), and J(2) = -13 +/- 1 cm(-(1). Variable frequency EPR studies reveal an anisotropic Kramer's doublet. 相似文献
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3.
Reconstitution of Nucleosome Demethylation and Catalytic Properties of a Jumonji Histone Demethylase
Carrie Shiau Michael J. Trnka Alen Bozicevic Idelisse Ortiz Torres Bassem Al-Sady Alma L. Burlingame Geeta J. Narlikar Danica Galonić Fujimori 《Chemistry & biology》2013,20(4):494-499
Highlights? Catalytic domain of JMJD2A (cJMJD2A) removes methyl marks in a distributive manner ? Homogeneously methylated nucleosomes were used as substrates ? Quantitative assay for nucleosome demethylation has been developed 相似文献
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A synthetic route to a series of 4-alkyl- or arylquinolines, bearing in 2- and 3-position fluorinated and phosphonate functions at the same time, is reported for the first time. These compounds are synthesized via regioselective heterocyclization of XCF2-alkynylphosphonates (X=F, Cl, Br, H, CF3) with ortho-aminoaryl ketones (R=CH3, CF3, Ph) in the presence of K2CO3 or Li2CO3/TMEDA as mediators. 2-Fluoro- and 3-phosphorus-containing 4-Me, 4-CF3 or 4-Ph quinolines are obtained in good to excellent yields. The influence of substituents in the aromatic ketone, the XCF2-group in the alkyne as well as mediators and the reaction medium on the reactivity and specificity of the reaction is also investigated. 相似文献
6.
Israël-Martyr Mbomekallé Bassem S. Bassil Andreas Suchopar Bineta Keita Louis Nadjo Malika Ammam Mohamed Haouas Francis Taulelle Ulrich Kortz 《Journal of Cluster Science》2014,25(1):277-285
We report on an improved synthesis and structural characterization of the cyclic 48-tungsto–8-arsenate(V) [H4As8W48O184]36? (1). The mixed lithium–potassium salt of this polyanion, K26.5Li9.5[H4As8W48O184]·90H2O (KLi-1), has been studied in the solid state by IR, single-crystal X-ray diffraction, and elemental analysis, and in solution by 183W NMR spectroscopy. 相似文献
7.
Ghada Al-Kadamany Bassem S. Bassil Farah Raad Ulrich Kortz 《Journal of Cluster Science》2014,25(3):867-878
The oxalato-titanium(IV)-containing, dimeric 18-tungsto-2-phosphate [Ti8(C2O4)8P2W18O76(H2O)4]18? (1) and the 32-tungsto-4-phosphate [Ti6(C2O4)4P4W32O124]20? (2) are formed upon reaction of the oxalato-titanium complex [TiO(C2O4)2]2? with the trilacunary Keggin precursor [A-α-PW9O34]9? and the hexalacunary Wells–Dawson precursor [H2P2W12O48]12?, respectively. Polyanion 1 consists of two {PW9} units encapsulating eight titanium centers and connected to each other via two Ti–O–Ti bridges, and crystallizes as a mixed potassium-sodium-lithium salt in the triclinic space group $P{\bar{1}}$ . Polyanion 2 comprises two {P2W16} units containing each two titanium atoms, and the two half-units are connected via two titanium atoms decorated by two oxalate groups each, and crystallizes as a mixed potassium-lithium salt in the rhombohedral space group $R{\bar{3}}c$ . Polyanions 1 and 2 were characterized in the solid state by single-crystal XRD, FT-IR, and TGA, whereas polyanion 2 was also investigated by 31P and 183W NMR. 相似文献
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9.
NaAgPbP2O7 was prepared with a solid-state reaction. The electrical properties were investigated by using impedance measurements in
the frequency range from 200 Hz to 5 MHz with the TEGAM 3550 ALF automatic bridge monitored by a microcomputer between 581 K
and 703 K. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit model. The conductivity data obey the universal power law.
The conductivity in the material is due to the hopping of monovalent ions parallel to (001) plane. 相似文献
10.
Habib Ammari Hyeonbae Kang Eunjoo Kim Hyundae Lee Kaouthar Louati 《Studies in Applied Mathematics》2009,122(1):85-104
The vibration behavior of structures can be characterized in terms of resonance frequencies and mode shapes, which describe properties of the tested object in a global way but do not, in general, provide information about structural details. Following an asymptotic formalism, in much the same spirit as the work in [ 3 ] and recent text [ 1 ], we develop an efficient method to address the inverse problem of identifying an internal corrosive part of small Hausdorff measure in a two-dimensional structure by vibration analysis. The viability of our reconstruction method is documented by a variety of numerical results from synthetic, noiseless and noisy data. 相似文献