Biomedical subjects
Publications and source records attributed to Changwen Hu.
At 1 atm pressure, high-quality multiwall carbon nanotubes were synthesized directly from graphite in the absence of catalyst by a one-step water-assisted method.
A novel three-dimensional copper molybdate with mixed ligands, [[Cu(II)(2,2'-bpy)][Cu(II)(IN)(2)][Mo(4)O(12)(OH)(2)]] (IN(-) = isonicotinate ion, 2,2'-bpy = 2,2'-bipyridine), 1, has been hydrothermally synthesized and structurally characterized, and this compound is built from an unprecedented tetranuclear molybdenum oxide cluster covalently bonded to two types of copper complex fragments, [Cu(II)(2,2'-bpy)](2+) and [Cu(II)(IN)(2)], via terminal oxygen atoms of [MoO(6)] octahedra. Crystal data for compound 1: monoclinic, space group C2/c, a = 16.4755 A, b = 10.3714 A, c = 17.4382 A, alpha = 90.0000 degrees, beta = 94.8098 degrees, gamma = 90.0000 degrees; V = 2969.24 A(3); Z = 2. Variable temperature magnetic susceptibility indicates that both ferromagnetic and antiferromagnetic interactions exist in 1.
A convenient microemulsion-mediated hydrothermal process was employed for the first synthesis of BaF2 whiskers with lengths up to 50 mum and aspects ratios as high as 1000, each of which is a single crystal with a growth direction of (111). A directed aggregation growth process mediated by the microemulsion droplet building blocks is proposed for the formation of BaF2 whiskers.
Reducing Cu(OH)4(2-) with hydrazine hydrate and glucose in the presence of a structure-directing surfactant at room temperature gave Cu and Cu2O nanotubes/nanorods, respectively, whereas facile hydrothermal treatment of Cu(OH)4(2-) precursor resulted in CuO nanotubes/nanorods.
Multilayer ultrathin films were fabricated from partially doped polyaniline (PAN) and a Keggin-type polyoxometalate [alpha-SiW(12)O(40)](4-) (alpha-SiW(12)) in aqueous solution via the layer-by-layer self-assembly technique and characterized by UV-vis, FTIR, and X-ray photoelectron spectra (XPS), ellipsometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM). UV-vis spectroscopy shows that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of PAN/alpha-SiW(12) bilayers, suggesting that the deposition process is regular and highly reproducible from layer to layer. FTIR and XPS spectra confirm the incorporation of alpha-SiW(12) and PAN into the films. Ellipsometric measurements show that the PAN/alpha-SiW(12) bilayer thickness increases with the increasing PAN solution concentration. SEM and AFM images indicate that the film surface is relatively uniform and smooth. In addition, the electrical conductivities of the multilayer films doped with hydrochloric acid were also measured.
The spherical Lindquist type polyoxometalate, Mo(6)O(19)(2)(-), has been used as a noncoordinating anionic template for the construction of novel three-dimensional lanthanide-aromatic monocarboxylate dimer supramolecular networks [Ln(2)(DNBA)(4)(DMF)(8)][Mo(6)O(19)] (Ln = La 1, Ce 2, and Eu 3, DNBA = 3,5-dinitrobenzoate, DMF = dimethylformamide). The title compounds are characterized by elemental analyses, IR, and single-crystal X-ray diffractions. X-ray diffraction experiments reveal that two Ln(III) ions are bridged by four 3,5-dinitrobenzoate anions as asymmetrically bridging ligands, leading to dimeric cores, [Ln(2)(DNBA)(4)(DMF)(8)](2+); [Ln(2)(DNBA)(4)(DMF)(8)](2+) groups are joined together by pi-pi stacking interactions between the aromatic groups to form a two-dimensional grid-like network; the 2-D supramolecular layers are further extended into 3-D supramolecular networks with 1-D box-like channels by hydrogen-bonding interactions, in which hexamolybdate polyanions reside. The compounds represent the first examples of 3-D carboxylate-bridged lanthanide dimer supramolecular "host" networks formed by pi-pi stacking and hydrogen-bonding interactions encapsulating noncoordinating "guest" polyoxoanion species. The fluorescent activity of compound 3 is reported.
Three novel polyoxometalate derivatives decorated by transition metal complexes have been hydrothermally synthesized. Compound 1 consists of [PMo(VI)(6)Mo(V)(2)V(IV)(8)O(44)[Co (2,2'-bipy)(2)(H(2)O)](4)](3+) polyoxocations and [PMo(VI)(4-)Mo(V)(4)V(IV)(8)O(44)[Co(2,2'-bipy)(2)(H(2)O)](2)](3-) polyoxoanions, which are both built on mixed-metal tetracapped [PMo(8)V(8)O(44)] subunits covalently bonded to four or two [Co(2,2'-bpy)(2)(H(2)O)](2+) clusters via terminal oxo groups of the capping V atoms. Compound 2 is built on [PMo(VI)(8)V(IV)(6)O(42)[Cu(I)(phen)](2)](5-) clusters constructed from mixed-metal bicapped [PMo(VI)(8)V(IV)(6)O(42)](7-) subunits covalently bonded to two [Cu(phen)](+) fragments in the similar way to 1. The structure of 3 is composed of [PMo(VI)(9)Mo(V)(3)O(40)](6-) units capped by two divalent Ni atoms via four bridging oxo groups. The crystal data for these are the following: C(120)H(126)Co(6)Mo(16)N(24)O(103)P(2)V(16) (1), triclinic P1, a = 15.6727(2) A, b = 17.3155(3) A, c = 19.5445(2) A, alpha = 86.1520(1) degrees, beta = 81.2010(1) degrees, gamma = 63.5970(1) degrees, Z = 1; C(120)H(85)Cu(6-)Mo(8)N(20)O(44)PV(6) (2), triclinic P1, a = 14.565(4) A, b = 15.899(3) A, c = 16.246(4) A, alpha = 116.289(2) degrees, beta = 103.084(2) degrees, gamma = 94.796(2) degrees, Z = 1; C(60)H(40)Mo(12)N(10)Ni(3)O(40)P (3), monoclinic P2(1)/c, a = 14.804(3) A, b = 22.137(4) A, c = 25.162(5) A, alpha = 90 degrees, beta = 98.59(3) degrees, gamma = 90 degrees, Z = 4.
Two novel nickel coordination polymers [Ni(2)(2,2'-bipy)(2)(OH)(2)(H(2)btec)](3)(n)(1) and [Ni(2)(1,10'-phen)(2)(H(2)O)(2)(btec)](n)(2) (btec = 1,2,4,5-benzenetetracarboxylate) have been hydrothermally synthesized and characterized by elemental analyses, IR and XPS spectra, TG analysis, X-ray powder diffraction, and single crystal X-ray diffraction. Crystal data for 1: C(90)H(66)N(12)O(30)Ni(6), monoclinic P2(1)/c, a = 10.905(2) A, b = 18.006(4) A, c = 20.551(4) A, beta = 94.91(3) degrees, Z = 2. Crystal data for 2: C(34)H(22)N(4)O(10)Ni(2), monoclinic P2(1)/n, a = 10.122(2) A, b = 9.3106(19) A, c = 15.690(3) A, beta = 92.03(3) degrees, Z = 2. Compound 1 exhibits a novel one-dimensional chainlike structure, in which the dinuclear Ni centers are linked by the btec ligands. Furthermore, the adjacent chains are linked into a 2-D wavelike layer via the strong OH.O hydrogen bonding interactions. Compound 2 possesses an unusual two-dimensional steplike network with interesting rhombic grids. Both compounds exhibit unprecedented metal-organic ligand construction modes in [M/btec/L] (M = transition metal; L = chelate ligands) systems. The magnetic behaviors of compounds 1 and 2 have been studied.
Reaction of Pb(OH)3- with ClO- in the presence of surfactant CTAB under conventional conditions resulted in PbO2 nanorods, whereas the reaction under hydrothermal conditions afforded Pb3O4 nanorods, as confirmed by X-ray powder diffraction and transmission electron microscopy (TEM). Selected area electron diffraction (SEAD) and high-resolution TEM (HRTEM) revealed that both PbO2 and Pb3O4 nanorods are single crystalline. For the formation of Pb3O4 nanorods, it is reasonable that PbO2 slowly decomposes to Pb3O4 under hydrothermal conditions, while retaining the morphology of PbO2.
Three novel supramolecular assemblies constructed from polyoxometalate and crown ether building blocks, [(DB18C6)Na(H(2)O)(1.5)](2)Mo(6)O(19).CH(3)CN, 1, and [(Na(DB18C6)(H(2)O)(2))(3)(H(2)O)(2)]XMo(12)O(40).6DMF.CH(3)CN (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) A, c = 14.2676(4) A, and Z = 2. Compound 2 crystallizes in the hexagonal space group P6(3)/m with a = 15.7435(17) A, c = 30.042(7) A, gamma = 120 degrees, and Z = 2. Compound 3 crystallizes in the hexagonal space group P6(3)/m with a = 15.6882(5) A, c = 29.9778(18) A, gamma = 120 degrees, 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 [Mo(6)O(19)](2)(-) polyoxoanions and the CH(2) groups of crown ether molecules. Compounds 2 and 3 are isostructural, and both contain a novel semiopen cagelike trimeric cation [(Na(DB18C6)(H(2)O)(2))(3)(H(2)O)(2)](3+). In their packing arrangement, an interesting 2-D "honeycomblike" "host" network is formed, in which the [XMo(12)O(40)](3)(-) (X = As and P) polyoxoanion "guests" resided.
Two novel compounds, [Co(4,4'-bipy)(H(2)O)(4)](4-abs)(2).H(2)O (1) and [Mn(4,4'-bipy)(H(2)O)(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)(H(2)O)(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)(H(2)O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C(22)H(30)CoN(4)O(11)S(2), monoclinic P2(1), a = 11.380(2) A, b = 8.0274(16) A, c = 15.670(3) A, alpha = gamma = 90 degrees, 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)(H(2)O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C(22)H(32)MnN(4)O(12)S(2), monoclinic P2(1)/c, a = 15.0833(14) A, b = 8.2887(4) A, c = 23.2228(15) A, alpha = gamma = 90 degrees, beta = 95.186(3) degrees, Z = 4.
The surfactant-encapsulated cluster (SEC) composed of a hydrophobic dimethyl dioctadecyl ammonium (DODA) shell and an encapsulated hydrophilic polyoxoanion core can form casting films. The structure of the casting film is influenced by evaporation rates of organic solvent. When the casting films are prepared by slow evaporation of chloroform, the alkyl chains are considered to possess a partial interdigitation, and the interdigitated length is 1.6 nm. The casting film structure is characterized by scanning force microscopy (SFM), Fourier transformation infrared (FT-IR), wide-angle X-ray diffraction, and differential scanning calorimetry (DSC).
Ultrathin multilayer films of two lanthanide polyoxometalates (LPOMs), K(17)[Eu(P(2)W(17)O(61))(2)] (EPW) and K(13)[Eu(SiW(11)O(39))(2)] (ESW), and poly(allylamine hydrochloride) (PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solutions. UV-vis spectroscopy and ellipsometry respectively show that the absorbance values at characteristic wavelengths and the thicknesses of the multilayer films increase linearly with the number of LPOM/PAH bilayers, suggesting that the deposition process is linear and highly reproducible from layer to layer. Average thicknesses of ca. 3.4 and 2.4 nm were determined for the EPW/PAH and ESW/PAH bilayers by ellipsometry, respectively. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) images provide the surface morphology of the LPOM/PAH films, indicating that the film surface is relatively uniform and smooth. The photoluminescent properties of these films have also been investigated by fluorescence spectroscopy. The LPOM/PAH multilayer film has a good thermal stability as shown by UV-vis, X-ray photoelectron, and fluorescence spectra.