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Changwen Hu

Publications and source records attributed to Changwen Hu.

At least 19 recordsLinked to original sources
PubMed2006

From layered double hydroxide to spinel nanostructures: facile synthesis and characterization of nanoplatelets and nanorods.

Mg-Al spinel (MgAl2O4) nanorods and nanoplatelets transformed from Mg-Al layered double hydroxide (Mg-Al-LDHs) were synthesized via a combined hydrothermal method and calcination route using Al(NO3).9H2O and Mg(NO3)2.6H2O as raw materials. The nanorods and nanoplatelets were characterized by means of physical techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microcopy (HRTEM), selected-area electron diffraction (SAED), Fourier transform infrared spectra (FT-IR), thermogravimetric (TG), and nitrogen adsorption-desorption isotherms. XRD patterns reveal that the Mg-Al-LDHs nanostructures were obtained under a hydrothermal reaction temperature of 200 degrees C and Mg-Al spinel nanostructures were fabricated via calcination of the Mg-Al-LDHs nanostructures at 750 degrees C. It can be seen from TEM that the sizes of the Mg-Al-LDHs nanoplatelets were about 20-40 nm and the diameters of the MgAl2O4 nanorods were ca. 6 nm. The HRTEM images indicate that the crystal lattice spaces of the MgAl2O4 nanorods and nanoplatelets are 0.282 and 0.287 nm, respectively.

Aluminum Oxide↗
PubMed2006

Transformation from a low-dimensional framework to a high-dimensional architecture based on different metal ions: syntheses, structures, and photoluminescences.

Five novel metal pamidronates (3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate, APD) formulated as Ni2(C3NH10P2O7)4.4H2O (1), M(C3NH9P2O7).H2O (M = Co (2), Mn (3), Zn (4)) and Cu3(C3NH8P2O7)2.2H2O (5) have been hydrothermally synthesized under similar conditions. Compound 1 is a molecular binuclear nickel cluster. Compounds 2 and 3 exhibit similar one-dimensional ladderlike structures. Compound 4 possesses a novel two-dimensional gridlike framework. Compound 5 shows an unusual three-dimensional architecture, in which two-dimensional layers with a parquet motif are pillared by {CuO4} planar squares. Different dinuclear secondary building units (SBUs) are observed in compounds 1-5, depending on the different coordination modes of APD. They also exhibit different photoluminescence properties.

Journal Article↗
PubMed2006

Microemulsion-mediated solvothermal synthesis and morphological evolution of MnCO3 nanocrystals.

The morphology- and size-controlled synthesis of MnCO3 nanocrystals was successfully achieved by cationic surfactant-CTAB-microemulsion-mediated solvothermal method. Various comparison experiments with different reactant concentrations and molar ratios between water and CTAB, showed the evolvement law of the morphology and size of the as-synthesized MnCO3 nanocrystals. With slowly increasing the concentration of reactants and/or molar ratio between water and CTAB, the morphology of MnCO3 nanocrystals changed gradually from cube to parallelepiped, and then rhombohedron, whereas the size decreased a little. The effect of the experimental parameters on the shapes and sizes of samples, such as the source of carbonate salts, reaction time, and temperature, were also discussed. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products.

Carbonates↗
PubMed2005

Microemulsion-mediated solvothermal synthesis of SrCO3 nanostructures.

The controlled synthesis of SrCO3 nanostructures with different morphologies, such as rodlike, whiskerlike, ellipsoidlike, and spherelike, were successfully achieved by the cationic surfactant-CTAB-microemulsion-mediated solvothermal method. Various comparison experiments showed that fundamental experimental parameters, such as the molar ratio of H2O to CTAB and the concentration of reactants, played important roles in the morphological control of SrCO3 nanostructures. A lower molar ratio of H2O to CTAB favors rodlike products, whereas a higher molar ratio generally leads to the formation of spherical products. A rational mechanism based on fusion, aggregate, and coalescence of microemulsion droplets is proposed for the selective formation of various morphologies. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and field-emission scanning electron microscope (FE-SEM) were used to characterize the products.

Journal Article↗
PubMed2005

Shape-controlled synthesis of Prussian blue analogue Co3[Co(CN)6]2 nanocrystals.

Prussian blue analogue Co3[Co(CN)6]2 nanostructures with morphologies of truncated nanocubes (polyhedra), cubes and rods, were synthesized in large quantities by a direct dissociation of the single-source precursor K3[Co(CN)6] in a microemulsion system; the molar ratio of H2O to surfactant and the concentration of K3[Co(CN)6] both played important roles in determining the shape of the product.

Cobalt↗
PubMed2005

Synthesis and characterization of Dy(OH)3 and Dy2O3 nanotubes.

Dy(OH)3 nanotubes with high aspect ratios of up to about 50 were synthesized in the presence of poly(ethylene glycol) via a hydrothermal method. Poly(ethylene glycol), as a nonionic surfactant, plays an important role in the formation of morphologies. Subsequent thermal treatment of Dy(OH)3 nanotube precursors at 450 degrees C for 6 h led to Dy2O3 nanotubes, during which the precursor tubular morphology was maintained. Selected-area electron diffraction and high-resolution transmission electron microscopy reveal the single-crystal nature of the Dy(OH)3 and Dy2O3 nanotubes. The morphologies and crystalline structure of the as-obtained products were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, respectively. By this method, we can obtain a mass of products.

Crystallization↗
PubMed2004

Syntheses, structures, and photoluminescence of a novel class of d10 metal complexes constructed from pyridine-3,4-dicarboxylic acid with different coordination architectures.

Two novel d(10) metal coordination polymers [Zn(PDB)](n)() (1) and [Cd(3)(PDB)(2)(OH)(2)(H(2)O)(2)](n)() (2) (H(2)PDB = pyridine-3,4-dicarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction. Crystal data for 1: C(7)H(3)NO(4)Zn, orthorhombic Pna2(1), a = 8.423(17) A, b = 6.574(13) A, c = 12.899(3) A, Z = 4. Crystal data for 2: C(14)H(12)N(2)O(12)Cd(3), monoclinic C2/c, a= 20.130(4) A, b = 6.692(13) A, c = 13.081(3) A, beta = 102.78(3) degrees, Z = 4. Both compounds exhibit novel three-dimensional frameworks. Compound 1 not only possesses a one-dimensional rectangular channel but also contains infinite double-stranded helical chains. Compound 2 has two different types of channels, one being built up from pyridine rings and [CdO(5)N] and [CdO(6)] building units and the other being constructed from pyridine rings and [CdO(5)N] building units. Furthermore, both compounds show strong photoluminescence properties at room temperature.

Journal Article↗
PubMed2004

Surfactant-assisted synthesis of Keggin-type polyoxometalates nanorods.

It was demonstrated that Keggin-type polyoxometalates nanorods (POMs-nanorods) were prepared from a solution containing a surfactant polyethylene glycol (PEG), when heteropolyanions [X(n+)M12O40](-(8-n)) (X(n+) = P5+ and Si4+; M = W and Mo) were precipitated by ammonia ion obtained by hydrolysis of urea at 373 K. In this method, PEG was used as a template and ammonia ion (NH4+) was a counterion. In an oil bath kept at 373 K without stirring, three kinds of ammonium salts of POMs, i.e., (NH4)3PW12O40, (NH4)4SiW12O40, and (NH4)3PMo12O40 nanorods were obtained. The POMs-nanorods were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), infrared spectra (IR), inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray powder diffraction (XRD). TEM showed that nanorods were 0.5-1.5 microm in length, and 50-150 nm in diameter. The results of IR, ICP-AES and XRD proved the existence of Keggin structure. The formation process of POMs-nanorods, (NH4)(8-n) [X(n+)M12O40](-(8-n)) (X(n+) = P5+ and Si4+; M = W and Mo) in a H2O/PEG system was discussed.

Electrons↗
PubMed2004

Shape and size control of ZnO nanostructures via a simple solution route.

ZnO nanostructures with different morphologies were synthesized by condensing the Zn(OH)4(2-) precursors under hydrothermal conditions in the presence of a surfactant, cetyltrimethylammonium bromide (CTAB). Shape and size control of ZnO nanostructures was achieved by relatively simple variations of molar ratio of CTAB to Zn(OH)4(2-). With a higher molar ratio, ZnO nanotubes were obtained, whereas with a lower molar ratio, ZnO nanorods were formed; furthermore, with a moderate w value, the coexistence of ZnO nanorods and nanotubes was also observed. The photoluminescence of ZnO nanorods and nanotubes was also investigated.

Cetrimonium↗
PubMed2004

A simple route towards CuO nanowires and nanorods.

CuO nanowires and nanorods were synthesized through a novel controllable solution-phase hydrothermal method using a nonionic surfactant polyethylene glycol (PEG) as the structure-directing template. The lengths of obtained 1D CuO nanostructures could be successfully controlled through choosing different molecular weights of PEG. The phase structures and morphologies were investigated by XRD, TEM, HRTEM and SAED. The formation mechanisms of the nanorods and nanowires were investigated and discussed on the basis of the experimental results.

Bromides↗
PubMed2003

A new type of single-helix coordination polymer with mixed ligands [M2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (M=Co and Ni; phen=1,10-phenanthroline; chdc=cyclohexanedicarboxylate).

A new family of single-stranded helices coordination polymers with mixed ligands, [M2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (1, M=Co; 2, M=Ni; chdc=cyclohexanedicarboxylic acid; phen=1,10-phenanthroline), were prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, TG analysis, and single-crystal X-ray diffraction analysis. X-ray crystal structural analyses reveal that 1 and 2 are isomorphic and belong to the monoclinic system. C40H36Co2N4O10, P2(1)/c, a=10.0566(5) A, b=8.8843(5) A, c=20.2912(14) A, beta=100.052(3) degrees, Z=2 for 1; and C40H36Ni2N4O10, P2(1)/c, a=9.8921(6) A, b=9.0151(4) A, c=20.1628(17) A, beta=100.31(2) degrees, Z=2 for 2. In the structures of 1 and 2, the 1,4-chdc ligand possesses only one kind of e,a-cis-conformation although there are both cis- and trans-conformations in the raw material. Two oxygen atoms of one carboxyl in 1,4-chdc ligand and another oxygen atom of contraposition carboxyl link adjacent Co or Ni atoms into an infinite 1-D zigzag chain. The most attractive structural feature of 1 and 2 is that they both exhibit an infinite chiral chainlike structure with 2(1) helices along the b axis. In addition, the right-handed and the left-handed chains are alternate. Meanwhile, the adjacent chains of 1 and 2 are linked via hydrogen bonds into 2-D network structures, which further form 3-D frameworks via pi-pi interactions of 1,10-phen.

Journal Article↗
PubMed2003

Synthesis, crystal structure, and photochromism of novel two-dimensional supramolecular networks based on Keggin-type polyoxoanion and lanthanide coordination cations.

Three new compounds [Ln(NMP)(4)(H(2)O)(4)][H(x)()GeMo(12)O(40)].2NMP.3H(2)O (Ln = Ce(IV) (1), Pr(IV) (2), x = 0; Ln = Nd(III) (3), x = 1; NMP = N-methyl-2-pyrrolidone) have been prepared in aqueous solution and characterized by elemental analyses, IR, UV-vis, and TG analyses. The single crystal X-ray diffraction shows that all three compounds are isostructural. In their structures, an interesting two-dimensional supramolecular network is constructed by the [GeMo(12)O(40)](4)(-) anion and [Ln(NMP)(4)(H(2)O)(4)](3+/4+) cation building blocks via hydrogen-bonding interactions, exhibiting the porous structure. Upon irradiation with UV light, the crystals of 1-3 show photochromic behavior.

Journal Article↗
PubMed2003

Two novel vanadium tellurites covalently bonded with metal-organic complex moieties: M(phen)V(2)TeO(8) (M = Cu, Ni).

Two novel two-dimensional organic-inorganic hybrid vanadium tellurites M(phen)V(2)TeO(8) (M = Cu (1), Ni (2)) have been hydrothermally synthesized and characterized by the elemental analyses, IR spectra, EPR spectrum, XPS spectra, TG analyses, and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, with a = 9.2193(18) A, b = 7.9853(16) A, c = 21.401(4) A, beta = 97.54(3) degrees, and Z = 4. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 9.2163(18) A, b = 7.9897(16) A, c = 21.386(4) A, beta = 97.52(3) degrees, and Z = 4. Compounds 1 and 2 are isostructural, and both exhibit interesting two-dimensional networks with [V(2)TeO(8)]( infinity ) double-chain-like ribbons bridged by metal-organic complex moieties [M(phen)](2+) (M = Cu and Ni). Furthermore, the three-dimensional supramolecular architectures of compounds 1 and 2 are formed by pi-pi stacking interactions of phen groups between adjacent layers.

Journal Article↗