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Two new 1D helical coordination polymers based on polyoxometalate were synthesized by self-assembly of Keggin-type POMs and copper salts in the presence of triangular N-heterocyclic derivatives or long-chain N-containing carboxylate ligand, that are, (H3O)[{Cu(H2tpim)2}{SiMo12O40}] · 0.5H2O [Htpim = 2,4,5-tri(4-pyridyl)-imidazole] ( 1 ) and [Cu2(Hcpp)3(cpp)(H2O)][PMo12O40] · 2H2O [Hcpp = 1-(4-cyanobenzyl)-3–2-yl)pyrazole] ( 2 ). Their structures were determined by single-crystal X-ray diffraction and further characterized by elemental analyses and TG analyses. Compounds 1 and 2 exhibit (1D→2D) interdigitated architectures assembled from 1D helical chains. In compound 1 , the achiral 2D interdigitated nets containing left- and right-handed helixes are further interdigitated with each other to form a 3D supramolecular framework. In compound 2 , adjacent 2D interdigitated layers with opposite chirality are further extended by supramolecular interactions into a 3D supramolecular network, in which non-coordinating Keggin-type POMs as guests are encapsulated. 相似文献
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AbstractThrough using a S-containing ligand 2,2’-dimethyl-4,4’-bithiazole (dbt), a series of Wells-Dawson and Keggin-based compounds, {Zn(dbt)3}{Zn(dbt)2(H2O)}2{HP2WVWVI17O62}·4H2O (1), {Cd(dbt)2(H2O) (HP2WVWVI17O62)}{Cd(dbt)3}{Cd(dbt)2(H2O)}·13H2O (2), {Cd2(dbt)4Cl} {PW12O40} (3) and {Cd2(dbt)4}{SiW12O40} (4), were synthesized under hydrothermal conditions and structurally characterized. In 1, there are three dissociated subunits: Wells-Dawson anion, {Zn(dbt)3}2+ and {Zn(dbt)2(H2O)}2+. In 2, the mono-supporting Wells-Dawson anions exhibit abundant hydrogen bonding interactions with discrete {Cd(dbt)3}2+ and {Cd(dbt)2(H2O)}2+ mononuclear coordination complexes, constructing a supramolecular layer. Compound 3 has a binuclear Cd cluster {Cd2(dbt)4Cl}4+ with a Cl as a bridging atom. The Keggin anions link these binuclear Cd clusters alternately to build a 1D chain. In 4, a pair of {Cd(dbt)2}2+ subunits connect adjacent Keggin anions and a 1D chain is formed. In these four compounds, only the N donors coordinate with Zn or Cd and the S atoms are uncoordinated. These compounds show good fluorescence sensing performance to Hg2+. We also studied the electrochemical and photocatalytic properties of 1–4. These compounds also can act as electrochemical sensors for the detection of nitrite. 相似文献
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A spectroscopic study on the reaction-controlled phase transfer catalyst in the epoxidation of cyclohexene 总被引:3,自引:0,他引:3
Jinbo Gao Yangying Chen Bo Han Zhaochi Feng Can Li Ning Zhou Shuang Gao Zuwei Xi 《Journal of molecular catalysis. A, Chemical》2004,210(1-2):197-204
The epoxidation of cyclohexene with hydrogen peroxide in a biphase medium (H2O/CHCl3) was carried out with the reaction-controlled phase transfer catalyst composed of quaternary ammonium heteropolyoxotungstates [π-C5H5N(CH2)15CH3]3[PW4O16]. A conversion of about 90% and a selectivity of over 90% were obtained for epoxidation of cyclohexene on the catalyst. The fresh catalyst, the catalyst under reaction conditions and the used catalysts were characterized by FT-IR, Raman and 31P NMR spectroscopy. It appears that the insoluble catalyst could degrade into smaller species, [(PO4){WO(O2)2}4]3−, [(PO4){WO(O2)2}2{WO(O2)2(H2O)}]3−, and [(PO3(OH)){WO(O2)2}2]2− after the reaction with hydrogen peroxide and becomes soluble in the CHCl3 solvent. The active oxygen in the [W2O2(O2)4] structure unit of these soluble species reacts with olefins to form the epoxides and consequently the corresponding W---Ob---W (corner-sharing) and W---Oc---W (edge-sharing) bonds are formed. The peroxo group [W2O2(O2)4] can be regenerated when the W---Ob---W and W---Oc---W bonds react with hydrogen peroxide again. These soluble species lose active oxygen and then polymerize into larger compounds with the W---Ob---W and W---Oc---W bonds and then precipitate from the reaction solution after the hydrogen peroxide is consumed up. Part of the used catalyst seems to form more stable compounds with Keggin structure under the reaction conditions. 相似文献
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Jian Liu Jia-Ning Xu Ya-Bing Liu Yu-Kun Lu Jiang-Feng Song Xiao Zhang Xiao-Bing Cui Ji-Qing Xu Tie-Gang Wang 《Journal of solid state chemistry》2007,180(12):3456-3462
A novel polyoxometalate [Cu(phen)2]3{PW4VIW5VV3IVO40(VIVO)3[Cu(en)2]}4H2O 1 (en=ethylenediamine, phen=1,10-phenanthroline) has been synthesized hydrothermally and characterized by elemental analysis, IR, XPS, TG, EPR and single-crystal X-ray diffraction analysis. The crystal structure analysis shows that compound 1 contains a novel highly reduced tri-capped and mono-supported pseudo-Keggin-type heteropolyanion, {PW4VIW5VV3IVO40(VIVO)3[Cu(en)2]}6−, three [Cu(phen)2]2+ cations and four lattice water molecules. They are further linked to form three-dimensional supramolecular networks through extensive hydrogen bonding and π–π stacking interactions. Interestingly, the water dimer and terminal oxygen of the cluster polyanion constitute a beautiful supramolecular helix chain. The heteropolyanion is the first example of tri-capped and mono-supported pseudo-Keggin-type tungstovanadophosphate and the pH value is crucial for obtaining compound 1 in synthetic procedure. 相似文献
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《Journal of Coordination Chemistry》2012,65(23):3970-3979
AbstractThree inorganic materials based on Strandberg polyoxoanion, Na10[Ag(P2Mo5O23)]2·8H2O (1), Na8[{Cu(H2O)4}(HP2Mo5O23)2]·8H2O (2), and Na8[{Co(H2O)4}(HP2Mo5O23)2]·6H2O (3), were hydrothermally synthesized and characterized by elemental analyses, IR, TG, and single crystal X-ray diffraction analyses. The compounds are based on the [P2Mo5O23]6? cluster and transition metal linkers. Compound 1 is a 1-D wave-like chain connected by Ag+ bridges. Compounds 2 and 3 are isostructural dimers bonded by {Cu(H2O)4} or {Co(H2O)4} linkers. The 1-D chain and dimeric clusters of 1-3 are further extended to 3-D supramolecular networks via hydrogen bonds and supramolecular interactions. Channels with different sizes are observed in 1-3, in which isolated Na+ and lattice water molecule fill the channels via intermolecular interactions. Weak interactions play important roles in stabilizing the three 3-D networks. Electrochemical and electrocatalytic properties of 1-3 have been investigated. 相似文献
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A stochastic technique based on genetic algorithms was implemented to develop new force fields by optimizing molecular mechanics (MM) parameters. These force fields have been optimized for inorganic compounds such as polyoxometalates (POMs) and especially for type‐I polymolybdate and polytungstate clusters. Focussing on the methodology of the development of the force fields, they were tested for the prediction of structural parameters, comparing the MM optimized structures with the geometry obtained after an optimization based on density functional theory. Results show that the genetic algorithm converges toward an optimum combination of parameters which successfully reproduces POMs structures with a high degree of accuracy. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
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Chu Wu Jinghua Lv He Zhang Chunmei Wang Chunxiao Wang 《Journal of Coordination Chemistry》2017,70(11):1862-1871
A chain based on the Keggin polyoxoanions, (H2bipy)2(Hbipy) [AsW11CoO39]·H2O (bipy = 4,4′-bipyridine) (1) has been hydrothermally synthesized and characterized by elemental analysis, IR, UV, TG, and single-crystal X-ray diffraction. In 1, substituted cobalt atoms share half occupancy sites with two W atoms on two asymmetric positions of opposite W3O13 trimers forming mono-substituted Keggin arsenotungstate. The Keggin clusters of two different arrays are alternately connected to generate unique wave-like chains in –A–B–A–B– ways via Co–O–W bridge. Compound 1 exhibits bifunctional electrocatalytic behavior for oxidation of ascorbic acid (AA) and reduction of hydrogen peroxide (H2O2), and good degradation ability for three typical dyes under UV light. 相似文献
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Pr对K7MgBW11O39配合物的化学热扩渗及其导电性的研究 总被引:3,自引:0,他引:3
Praseodymium Chemistry-Heated Diffused Permeation is used to treat K7MgBW11O39 for the first time. ICP, IR, XRD, TG-DTA, have been used to characterize K7MgBW11O39·15H2O and treated sample, indicating that Pr can be permeated into the body of this sample. The results of AC impedance spectra and DC four-probe show that the value of conductivity is 104 times higher than that of sample before permeation at room temperature. At the range of 301~576K,the conductivity of permeated sample almost keep constant and its thermal stability improved more than 150K, which imply that this material is promising. 相似文献
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