951 resultados para Microwave hydrothermal synthesis


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In this work we demonstrate that hexagonal nanodisks of cadmium hydroxide with nanoporous structures could be fabricated by a facile hydrothermal treatment without using any templates or organic additives. With this method, the length of the hexagonal edge and thickness of the nanodisks can be adjusted through controlling the experimental conditions such as the pH value of the mother liquor and the initial concentration of the cadmium ion. On the basis of our experimental observations and understandings of the nanocrystal growth, the formation of the nanodisks is believed to mainly originate from the oriented attachment of small particles. Furthermore, the hexagonal Cd(OH)(2) nanodisks can be converted to CdO semiconductors with similar morphology by calcinations.

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Nanocrystals and powders of KMgF3 doped with Eu2+ were synthesized by the microemulsion method and the solvothermal process, respectively. The emission and excitation spectra of KMgF3:Eu2+ phosphors were measured and compared with those of the samples synthesized through a solid. state reaction, Bridgman-Stockbarger method, and mild hydrothermal technique. The KMgF3: Eu2+ samples synthesized by means of the microemulsion method and the solvothermal process show only a sharp emission peak located at 360 nm, in the emission spectra, which arises from the f -> f(P-6(1/2)-> S-8(1/2)) transition of Eu2+. The broad emission bands appear at 420 nm,,which arises from Eu2+ <- O2- cannot be observed(in the mild hydrothermal and single crystal samples, the emission peak at 420 nm besides the emission of Eu2+ at 360 nm is observed). In the excitation spectrum of the KMgF3: Eu2+ samples synthesized by the microemulsion method and the solvothermal process, the excitation peaks show an intensive blue shift. The blue shift can he attributed to the lower oxygenic content in the KMgF3: Eu2+ samples synthesized by the microemulsion method and the solvothermal process.

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A novel organic-inorganic hybrid compound [Cu(phen)](2)[(VV4As2O19)-V-IV-As-V-O-V].0.5H(2)O 1 has been hydrothermally synthesized. Its structure, determined by single crystal X-ray diffraction, exhibits an unusual two-dimensional arsenic vanadate layered network grafted with the [Cu(phen)](2+) complex. The chelating phen ligands project perpendicularly beyond the inorganic layer. Variable temperature magnetic susceptibility studies indicate that both ferro- and antiferro-magnetic interactions exist in 1.

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A new polyoxometalate derivative {PW9V3O40[Ag(2,2'-bipy)](2)[Ag-2(2,2'-bipy)(3)](2)} 1 has been hydrothermally synthesized and structurally characterized by the single crystal X-ray diffraction. X-Ray analysis showed that both [Ag(2,2'-bipy)](+) and [Ag-2(2,2'-bipy)(3)](2+) units are supported on the alpha-Keggin polyoxoanion [PW9V3O40](6-) via the surface bridging oxygen atoms. 1 represents the first alpha-Keggin type polyoxoanion coordinated with four transition metal complex moieties, which further acts as a neutral molecular units for the construction of an interesting three-dimensional supramolecular framework.

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Three novel supramolecular assemblies constructed from polyoxometalate and crown ether building blocks, [(DB18C6)Na(H2O)(1.5)](2)Mo6O19.CH3CN, 1, and [{Na(DB18C6)(H2O)(2)}(3)(H2O)(2)]XMo12O40.6DMF.CH3CN (X = P, 2, and As, 3; DB18C6 = dibenzo-18-crown-6; DMF = N,N-dimethylfomamide), have been synthesized and characterized by elemental analyses, IR, UV-vis, EPR, TG, and single crystal X-ray diffraction. Compound 1 crystallizes in the tetragonal space group P4/mbm with a = 16.9701(6) Angstrom, c = 14.2676(4) Angstrom, and Z = 2. Compound 2 crystallizes in the hexagonal space group P6(3)/m with a = 15,7435(17) Angstrom, c = 30.042(7) Angstrom, gamma = 120degrees, and Z = 2. Compound 3 crystallizes in the hexagonal space group P6(3)/m with a = 15.6882(5) Angstrom, c = 29.9778(18) Angstrom, gamma = 120degrees, and Z = 2. Compound 1 exhibits an unusual three-dimensional network with one-dimensional sandglasslike channels based on the extensive weak forces between the oxygen atoms on the [Mo6O19](2-) polyoxoanions and the CH2 groups of crown ether molecules, Compounds 2 and 3 are isostructural, and both contain a novel semiopen cagelike trimeric cation [{Na(DB18C6)(H2O)(2)}(3)(H2O)(2)](3+). In their packing arrangement, an interesting 2-D "honeycomblike" "host" network is formed, in which the [XMo12O40](3-) (X = As and P) polyoxoanion "guests" resided.

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Two novel organic-inorganic hybrid compounds, (H(2)enMe)(4)(H3O)[Ni(enMe)(2)].[Na3Mo12O52P8(OH)(10)].5H(2)O (1) and (H(2)enMe)(4)(H3O)[Cu(enMe)(2)].[Na3Mo12O52P8(OH)(10)].5H(2)O (2) (enMe = 1,2-diaminopropane), have been hydrothermally synthesized and characterized by elemental analyses, IR, EPR, XPS, UV-Vis spectra and TG analyses. Single crystal X-ray diffraction shows that 1 and 2 are isostructural compounds. Both the compounds exhibit an unusual two-dimensional (2-D) window-like network consisting of one-dimensional (1-D) chains of sodium molybdenum phosphate anions connected by transition metal coordination complexes cations. Compound 1 and 2 represent the first 2-D molybdenum phosphate skeleton pillared by transition metal complex fragments.

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The synthesis, structural characterization and preliminary magnetic studies of a novel coordination polymer with paddlewheel Co-3 clusters are reported firstly. In the polymer, Co-3 clusters are covalently linked through PO4 tetrahedra and 4-pyridinecarboxylate (4-pya) ligands into interpenetrated three-dimensional network.

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Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

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A new vandylpolymolybdophosphate, [H2N(C2H4)(2)NH2](4)-(H3O)[(PMo2Mo6V4O40)-Mo-V-V-VI-O-IV((VO)-O-IV)(2)].H2O, was hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV-vis, XPS, ESR spectra, mid singe crystal X-ray diffraction analysis. The compound contains an unusual highly reduced pseudo-Keggin type polyoxoanion with nine negative charges and exhibits an interesting phosphorus-centered alternate layer arrangement of molybdenum and vanadium oxides.

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A novel organic-inorganic hybrid complex [(CuCl)(2) (o-phen)](infinity) 1 (o-phen = o-phenanthroline) has been hydrothermally synthesized and structurally characterized by elemental analyses, XPS spectrum, TG analysis, and single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic system, space group P2(1)/n, a = 3.7285(7) Angstrom, b = 19.603(4) Angstrom, c = 16.757(3) Angstrom, beta = 95.83(3)degrees, V = 1218.4(4) Angstrom(3), Z = 4, lambda(MoKalpha) = 0.71073 Angstrom (R(F) = 0.0643 for 2559 reflections). Data were collected on an R-axis RAPID diffractometer at 293 K in the range of 1.60 < θ < 27.48degrees. The title compound exhibits a one-dimensional chain-like scaffolding constructed by the unusual [Cu3Cl3] hexagon motifs by, sharing opposite edges. Only Cu(1) sites of the [Cu3Cl3] hexagon are coordinated with N donors of o-phen groups. Furthermore, the three-dimensional supermolecular architecture is formed by C-H...Cl hydrogen bonds between o-phen groups and CuCl chains.

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A new iron hydrogen phosphate, heptairon bis(phosphate) tetrakis(hydrogenphosphate), Fe-7(PO4)(2)(HPO4)(4), has been prepared hydrothermally and characterized by single-crystal X-ray diffraction. The compound has one Fe atom on an inversion centre and is isostructural with Mn-7(PO4)(2)(HPO4)(4) and Co-7(PO4)(2)(HPO4)(4). The structure is based on a framework of edge- and corner-sharing FeO6, Fe-5 and PO4 polyhedra, isotypic with that found in the mixed-valence iron phosphate Fe-7(PO4)(6). The Fe atoms in the title compound are purely in the divalent state, just like the Co atoms in Co-7(PO4)(2)(HPO4)(4), the necessary charge balance being maintained by the addition of H atoms in the form of bridging Fe-OH-P groups.

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A novel manganese phosphomolybdate, [H3N(CH2)(4)NH3](H3O)(2){[Mn(phen)(2)](4)[(MnMovO30)-O-12(HPO4)(6)(H2PO4)(2)]} . 4H(2)O 1, has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. The crystal data: triclinic, P (1) over bar, a = 14.172(7) Angstrom, b = 16.547(2) Angstrom, c = 16.679(3) Angstrom, alpha = 62.881(12)degrees, beta = 73.83(3)degrees, gamma = 88.81(3)degrees. X-ray crystallography shows that the [Mn(phen)(2)] fragments are covalently bonded to the [Mn(Mo6P4)(2)] dimers leading to a one-dimensional chain with rectangular cavities occupied by tetramethylene-diamine cations and water molecules. (C) 2002 Elsevier Science B.V. All rights reserved.

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An unusual polyoxometalate [H2N(C2H4)(2)NH2](4)(H3O)[(PMO2Mo6V4O40)-Mo-V-V-VI-O-IV((VO)-O-IV)(2)].H2O is hydrothermally synthesized and characterized by IR, UV-VIS, elemental analyses, X-ray photoelectron spectrum, ESR, TG and Single crystal X-ray diffraction. The title compound crystallizes in the orthorhombic space group Pbca with a = 15-227(5), b = 19.491(4), c = 18.737(3) Angstrom, V = 5123(2) Angstrom(3), Z = 4, and R-1 (wR(2)) = 0.0726(0.1416). The compound contains an unusual highly reduced pseudo-Keggin type polyoxoanion and exhibits an interesting phosphorus-centered alternate arrangement of layers of molybdenum and vanadium oxides.

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The crystal structure of the title compound, bis[tris(2,2'-bipyridyl-N,N')nickel(II)] cyclo-tetravanadate undecahydrate, contains a centrosymmetric [V4O12](4-) anion, which has an eight-membered ring structure formed by four VO4 tetrahedra sharing vertices, and two complex cations containing octahedrally-coordinated Ni-II ions. The anion and coordinated Ni-II ions are isolated and make up anion and cation layers, respectively. The Ni-N distances range from 2.077(3) to 2.112(2)Angstrom and the V-O distances range from 1.621(2) to 1.803(2)Angstrom.

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MCM-22 zeolite films have been grown with layers vertical to the substrate under hydrothermal synthesis conditions, and characterized by X-ray diffraction and scanning electron microscopy.