Hydrothermal synthesis of nanocrystalline BaSnO3 using a SnO2·xH2O sol

A BaSnO₃ powder with a crystallite size of 27.6 nm has been prepared through a hydrothermal reaction of a peptised SnO₂·xH₂O and Ba(OH)₂ at 250 °C and the following crystallization of this hydrothermal product at 330 °C. The peptisation of the SnO₂·xH₂O gel is dependent on the pH value. Through peptisation the mean particle size of SnO₂·xH₂O in the aqueous solution has been decreased by a factor of 100 to 8 nm. A limited agglomeration in the sol-prepared powder has been observed under the microscope. The structure evolution and crystallisation behaviours of the sol-prepared powders were investigated by TG-DTA, IR and XRD. The BaSn(OH)₆ phase in the as-prepared powder transforms into an amorphous phase at 260 °C, from which the BaSnO₃ particles nucleate and grow with an increase in temperature. The single-phase BaSnO₃ powder has been obtained at a temperature as low as 330 °C. This sol-prepared powder is more sinter-reactive than the gel-prepared powder and can be sintered to a ceramic with 90.7% of the theoretic density.     

Five and six-coordinate silicon complexes with an O,N,O′-chelating ligand derived from o-hydroxyacetophenone–N-(2-hydroxyethyl)imine

The reaction of o-hydroxyacetophenone–N-(2-hydroxyethyl)imine, 1, with suitable chlorosilanes in the presence of triethylamine gives access to five and six-coordinate silicon complexes. The molecular structures of TBPY-5–34-[2-oxy-κO-acetophenone–N-(2-oxy-κO-ethyl)iminato-κN]diphenylsilane, C₂₂H₂₁NO₂Si, 2, and OC-6–22′-bis[2-oxy-κO-acetophenone–N-(2-oxy-κO-ethyl)iminato-κN]silicon · chloroform, C₂₀H₂₂N₂O₄Si · CHCl₃, 3, have been determined as representative examples.     

Synthesis,characterization and kinetics properties of chromium(III) complex [Cr(3-HNA)(en)2]Cl · H2O · CH3OH

The reaction of chromium(III) chloride, 3-hydroxy-2-naphthoic acid (3-HNA) and ethylenediamine (en) led to the formation of complex [Cr(3-HNA)(en)₂]Cl · H₂O · CH₃OH, Bis(ethylenediamine-κ²N,N′)(3-hydroxy-2-naphthoic acid-κ²O,O′) chromium(III) monochloride monohydrate monomethanol. The kinetics of transfer of Cr(III) from the title compound to the low-molecular-mass chelator EDTA and to the iron-binding protein apoovotransferrin (apoOTf) were carried out by means of UV–Visible (UV–Vis) and fluorescence spectra in 0.01 M Hepes at pH 7.4. The second-order rate constants were calculated, respectively. The results show that Cr(III) can be transferred from the complex to apoovotransferrin.     

Self-organized nano-crystallisation of BaF2 from Na2O/K2O/BaF2/Al2O3/SiO2 glasses

In glasses with the compositions (100 ? x)(2Na₂O·16K₂O·8Al₂O₃·74SiO₂)xBaF₂ (with x = 0 to 6), the glass transition temperature decreases with increasing BaF₂-concentration. Samples with x = 6 were thermally treated at temperatures in the range from 500 to 600 °C for 5–160 h. This leads to the crystallisation of BaF₂. The quantity of crystalline BaF₂ increases with increasing time of thermal treatment, while the mean crystallite size remains constant within the limits of error. The glass transformation temperature of partially crystallised samples increases with increasing crystallisation time and approaches a value equal to the temperature, at which the samples were treated. This is explained by the formation of a highly viscous layer enriched in SiO₂ which is formed during crystallisation. This layer acts as a diffusion barrier and hinders further crystal growth.     

pH-controlled the formation of 4-sulfocalix[4]arene-based 1D and 2D coordination polymers

Three manganese/4-sulfocalix[4]arene complexes, namely, {H[(C₂₈H₂₀O₁₆S₄)Mn(H₂O)₄Mn_0.5(H₂O)₂]}_n ·6nH₂O (1), {NH₄[(C₂₈H₂₀O₁₆S₄)Mn(H₂O)₄Mn_0.5(H₂O)₂]}_n · 5nH₂O (2), [(C₂₈H₂₀O₁₆S₄)Mn₂(H₂O)₈]_n · 6nH₂O (3), have been synthesized under different pH conditions. Complex 1, which exhibits a one-dimensional (1D) structure, is formed at [H⁺] = 2.0 mol L⁻¹. Reaction at pH 4 leads to another one-dimensional (1D) coordination polymer of 2. At pH 5, a two-dimensional (2D) coordination polymer of complex 3 is formed, showing clearly structural effects on pH response.     

Synthesis,characterizations, and crystal structure of a novel 2D metal phosphonate: Na2[Cd2(H2O)3(O3PCH(OH)CO2)2] · 2H2O

A novel cadmium phosphonate compound Na₂[Cd₂(H₂O)₃(O₃PCH(OH)CO₂)₂] · 2H₂O (1) has been synthesized by hydrothermal reaction at 120 °C and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, elemental analysis and thermogravimetric analysis. The structure of compound 1 comprises CdO₆ octahedra and CdO₇ pentagonal bipyramid connected by [O₃PCH(OH)CO₂]³⁻ to form a 2D layered structure with a one-dimensional channel system and the charge-compensating Na⁺ cations being located between two adjacent layers.     

Nitrosyl cis-dichlorodiammine ruthenium complex with bridging H3O2− ligand

The ruthenium complex with bridging H₃O₂⁻ ligand was obtained and the crystal structure was determined. The compound cis-[{RuNO(NH₃)₂Cl₂}₂(μ₂-H₃O₂)]Cl crystallizes in the monoclinic space group P2₁/n with cell parameters a = 15.0651(5), b = 6.3624(2), c = 15.3813(6) Å, β = 94.9690(10)°, Z = 4 and R = 0.0185. The hydroxide hydrate anion is coordinated to the ruthenium atoms of the identical cis-{RuNO(NH₃)₂Cl₂} fragments. The protonation of the starting cis-[RuNO(NH₃)₂(NO₂)₂OH] complex leads to the required coordinated aqua/hydroxide ratio if the specific amount of hydrochloric acid is used. The DFT calculations confirm the formation of the dimer structure in the gas phase. However, the presence of water molecules dramatically reduces the dimerization efficiency.     

Direct H2-to-H2O2 oxidation over highly active/selective Br–F–Pd/Al2O3 catalyst in aqueous acidic medium: Influence of process conditions on the H2O2 formation

The influence of the O₂/H₂ mole ratio in the gaseous feed and also those of other reaction conditions [viz. concentration of H₃PO₄ (0–5 mol/dm³), temperature (5–50 °C), gas (H₂ and O₂) space velocity (5.8–23.4 h^?1) and reaction time (0.1–8 h)] on the H₂O₂ formation in the H₂-to-H₂O₂ oxidation over the Br(1 wt%)–F(1 wt%)–Pd(5 wt%)/Al₂O₃ catalyst in an aqueous acidic (H₃PO₄) medium have been thoroughly investigated. The effects of the O₂/H₂ ratio, reaction temperature and acid concentration on the destruction of H₂O₂ by its decomposition and/or hydrogenation reactions over the catalyst in the acidic reaction medium have also been studied. The net H₂O₂ formation (H₂O₂ yield) over the catalyst passed through a maximum with increasing the acid concentration, the temperature or the O₂/H₂ feed ratio. However, it decreased markedly with increasing the gas space velocity or the reaction period. The H₂O₂ decomposition and hydrogenation activities of the catalyst increased appreciably with increasing the reaction temperature and decreased with increasing the acid concentration. The H₂O₂ destruction during the H₂-to-H₂O₂ oxidation increased with increasing the concentration of H₂ (relative to that of O₂) due to the increased H₂O₂ hydrogenation rate over the catalyst. The net H₂O₂ formation in the H₂-to-H₂O₂ oxidation decreased sharply with increasing the initial amount of H₂O₂ present in the reaction mixture. The presence of H₂O₂ and the higher H₂/O₂ ratios have detrimental effects on the net formation of H₂O₂.     

Decavanadate with a novel coordination complex: Synthesis and characterization of (NH4)2[Ni(H2O)5(NH3)]2(V10O28)·4H2O

A new compound (NH₄)₂[Ni(H₂O)₅(NH₃)]₂[V₁₀O₂₈]·4H₂O (1) containing a {V₁₀O₂₈} ⁶⁻ anionic cluster and a novel complex cation, [Ni(H₂O)₅(NH₃)]^2 +, has been synthesized and fully characterized by single crystal X-ray crystallography, spectroscopy and thermogravimetric analysis. The presence of the ammonia ligand in the complex cation in 1 was established unambiguously by X-ray crystallography and variable temperature (200–400 °C) thermogravimetric analyses in combination with FTIR spectroscopic studies. The formation of the novel complex species {Ni(H₂O)₅(NH₃)}^2 + during the synthesis of 1 can be rationalized in terms of ligand substitution involving {Ni(H₂O)₆}^2 +.     

A novel paradodecatungstate-B compound decorated by transition metal copper,Na2Cu5(H2O)24(OH)2[H2W12O42]·10H2O: Synthesis,structure and antitumor activities

A new paradodecatungstate-B compound decorated by transition metal copper, Na₂Cu₅(H₂O)₂₄(OH)₂[H₂W₁₂O₄₂]·10H₂O (1), has been synthesized by convenient aqueous solution method and structurally characterized by single-crystal X-ray diffraction, IR spectrum, elemental analysis and TGA. The compound crystallizes in the triclinic P-1 space group with a = 10.7140(8) Å, b = 12.9476(9) Å, c = 13.6696(10) Å, α = 73.56°, β = 75.73°, γ = 67.69°, V = 1661.8(2) ų and Z = 1. In compound 1, polyanion of [H₂W₁₂O₄₂]^10 − acts as a dodecadentate ligand that links copper and sodium cations, forming a remarkable three-dimensional framework. The experiment of antitumor activities in vitro shows that the title compound exhibits remarkable inhibitory actions on human cervical carcinoma HeLa cells, ovarian carcinoma SKOV-3 cells, hepatoma HepG2 cells and neuroblastoma SHY5Y cells.     

A new binuclear Cr(III) citrate anion: Synthesis,characterization and crystal structure of [Cr(CO(NH2)2)6]2[Cr2(CO(NH2)2)2(C6H4O7)2]3

The new anion [Cr₂(CO(NH₂)₂)₂(C₆H₄O₇)₂]^2 − has been isolated in the complex [Cr(CO(NH₂)₂)₆]₂[Cr₂(CO(NH₂)₂)₂(C₆H₄O₇)₂]₃. The crystals of this complex were obtained by a one-pot synthetic method using 1:1 molar ratio of hexaureachromium(III) chloride and trisodium citrate in aqueous medium. It was characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction analysis. The compound crystallizes in space group R‾3 of the trigonal system with three formula units in a cell of dimensions a = b = 24.7461(4) Å, c = 13.7204(3) Å and γ = 120°. The crystal structure comprises the columns consisting of [Cr(CO(NH₂)₂)₆]^3 + cations surrounded by a cylinder of complex anions, [Cr₂(CO(NH₂)₂)₂(C₆H₄O₇)₂]^2 − which are packed in a honeycomb-like manner. This supramolecular architecture is formed and stabilized by inter- and intramolecular NH⋯O hydrogen bonds.     

High Li-ion conductivity of Al-doped Li7La3Zr2O12 synthesized by solid-state reaction

Li₇La₃Zr₂O₁₂ (LLZO) has cubic garnet type structure and is a promising solid electrolyte for next-generation Li-ion batteries. In this work, Al-doped LLZO was prepared via conventional solid-state reaction. The effects of sintering temperature and Al doping content on the structure and Li-ion conductivity of LLZO were investigated. The phase composition of the products was confirmed to be cubic LLZO via XRD. The morphology and chemical composition of calcined powders were investigated with SEM, EDS, and TEM. The Li-ion conductivity was measured by AC impedance. The results indicated the optimum sintering temperature range is 800–950 °C, the appropriate molar ratio of LiOH·H₂O, La(OH)₃, ZrO₂ and Al₂O₃ is 7.7:3:2:(0.2–0.4), and the Li-ion conductivity of LLZO sintered at 900 °C with 0.3 mol of Al-doped was 2.11×10⁻⁴ S cm⁻¹ at 25 °C.     

Synthesis,structure and magnetic properties of spinel ferrite (Ni,Cu, Co)Fe2O4 from low nickel matte

Spinel ferrite (Ni, Cu, Co)Fe₂O₄ was synthesized from the low nickel matte by using a co-precipitation-calcination method for the first time. The influences of the added amount of NiCl₂·6H₂O, calcination temperature and time on the structure and magnetic properties of the as-prepared ferrites were studied in detail by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, and Vibrating sample magnetometer (VSM). It is indicated that pure (Ni, Cu, Co)Fe₂O₄ with cubic phase could be obtained under the experimental conditions (NiCl₂·6H₂O added amount of 3.0: 100 g mL⁻¹, calcination temperature from 800 to 1000 °C and calcination time from 1 to 3 h). With increasing calcination temperature and time, saturation magnetization (M_S) of the synthesized (Ni, Cu, Co)Fe₂O₄ increased and the coercivity (H_C) decreased. Under the optimum conditions (i.e. NiCl₂·6H₂O added amount of 3.0: 100 g mL⁻¹, 1000 °C, 3 h), the M_S and H_C values of the product were approximately 46.1 emu g⁻¹ and 51.0 Oe, respectively, which were competitive to those of other nickel ferrites synthesized from pure chemical reagents. This method explores a novel pathway for efficient and comprehensive utilization of the low nickel matte.     

Synthesis and crystal structures of two new inorganic–organic hybrid polyoxomolybdate complexes: [Himi]4[{Co(imi)2(H2O)2}Mo7O24] · 4H2O and [Zn(imi)4]2[(imi)2Mo8O26] · 6H2O

The two new inorganic–organic hybrid polyoxomolybdate complexes [Himi]₄[{Co(imi)₂(H₂O)₂}Mo₇O₂₄] · 4H₂O (1) and [Zn(imi)₄]₂[(imi)₂Mo₈O₂₆] · 6H₂O (2) (imi = imidazole) have been prepared by conventional aqueous solution synthesis. Compound 1 consists of heptamolybdate anions [Mo₇O₂₄]⁶⁻ covalently linked by [CoN₂O₄]²⁺ octahedra into one-dimensional zigzag-shaped chains. The zigzag-shaped chains are further linked together via the hydrogen-bonding interactions to form a 2D supramolecular framework. Compound 2 is build up of an imidazole-coordinated octamolybdate anion, two imidazole coordinating zinc cations and lattice water molecules to form a three-dimensional framework via complex hydrogen-bonding.     

A novel 3D silver(I) coordination polymer exhibiting unprecedented μ3- and μ4-bonding modes of 2-aminopyrazines

The unprecedented μ₃- and μ₄-bonding modes of NH₂pyz (NH₂pyz = 2-aminopyrazine) are observed for the first time in a novel 3D Ag(I) coordination polymer [Ag₇(NHpyz)₆(ClO₄)]_n (1) which was obtained by reaction of Ag₂O, NH₂pyz and NaClO₄ in H₂O/CH₃OH/NH₃ media under ultrasonic treatment. Compound 1 is a 3D framework with infinite 1D Ag belts incorporating diverse Ag···Ag interactions. Moreover, 1 exhibits photoluminescence maximized at 494 nm upon 300 nm excitation at room temperature, which may be mainly assigned to ligand-to-metal charge transfer (LMCT) mixed with metal-centered (d-s/d-p) transitions. Semiconducting behavior of 1 was also measured at room temperature with σ value of 6.78 × 10^?6 S cm^?1.     

A tetranuclear oxofluorovanadium(IV) cluster encapsulating a Na(H2O)n+ subunit

Hydrothermal reactions of sodium vanadate, methylenediphosphonic acid, hydrogen fluoride and the appropriate organoamine yielded the vanadium(IV)-oxyfluoride compounds [NH₃(CH₂)₂(NH₂)(CH₂)₂NH₃]₃[{Na(H₂O)} ⊂ {V₄O₄F₂(O₃PCH₂PO₃)₄}]·8H₂O (1·8H₂O) and [NH₃(CH₂)₂(NH₂)(CH₂)₂(NH₂)(CH₂)NH₃]₂[{Na(H₂O)} ⊂ {V₄HO₄F₂(O₃PCH₂PO₃)₄}]·7H₂O (2·7H₂O). The vanadium-oxyfluoride cationic unit {V₄O₄F₂(O₃PCH₂PO₃)₄}^10 − of the compounds consists of pairs of fluoride bridged {VFO₅} octahedra linked through η⁴-diphosphonate ligands into a three polyhedra thick band. The {Na(H₂O)_n}⁺ groups occupy the interior of the band but are displaced from the centroid toward one face so as to project the aqua ligands into the extra-annular domain. The fluoride ligands bridge two vanadium sites as well as coordinating to the sodium cation.     

A sinusoidal chain constructed from decorated Keggin clusters and {Cu(enMe)2}2+ bridging groups in [Cu(enMe)2(H2O)] [{Cu(enMe)2}{Cu(enMe)2(H2O)W12O40(H2)}] · nH2O

A novel organic–inorganic hybrid material, [Cu(enMe)₂(H₂O)][{Cu(enMe)₂}{Cu(enMe)₂(H₂O)W₁₂O₄₀(H₂)}] · nH₂O (n = 0.33, enMe = 1,2-diaminopropane), has been prepared under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR and magnetic susceptibility measurements. It is revealed that the one-dimensional [{Cu(enMe)₂}{Cu(enMe)₂(H₂O)W₁₂O₄₀(H₂)}]²⁻ chain in the structure shows a unique sinusoidal ruffling, which is constructed from decorated Keggin clusters and {Cu(enMe)₂}²⁺ bridging groups through sharing one terminal and one doubly-bridging oxygen atoms of a cluster. The magnetic measurements show that the compound possesses well-separated Cu²⁺ centers. It was indicated that the hybrid exhibits a good catalytic activity in H₂O₂ decomposition.     

Synthesis,characterization and catalytic properties of a copper complex containing decavanadate nanocluster,Na2[Cu(H2O)6]2{V10O28}·4H2O

A copper complex containing decavanadate nanocluster, Na₂[Cu(H₂O)₆]₂{V₁₀O₂₈}·4H₂O, was prepared by reaction of Cu(NO₃)₂·4H₂O and NH₄VO₃ in an aqueous solution at pH = 4 and its structure was characterized using IR, CV and X-ray crystallography. It was found to be a highly efficient and effective catalyst for the azide alkyne cycloaddition and one-pot three-component (A³) coupling of aldehydes, amines, and alkynes to produce 1,2,3-triazoles and propargylamines respectively in high yields without any co-catalyst or activator.     

Low-fire processing of microwave BaTi4O9 dielectric with crystalline CuB2O4 and BaCuB2O5 additives

The effects of interfacial reaction of CuB₂O₄ (CB)/BaTi₄O₉ (BT4) and BaCuB₂O₅ (BCB)/BaTi₄O₉ (BT4) on densification, phase development and dielectric properties of BaTi₄O₉ (BT4) have been investigated. With BaO present, the wetting of BCB/BT4 improves significantly in comparison to CB/BT4 at temperatures below 925 °C. However, the enhancement in densification becomes less significant for BCB+BT4 than that of CB+BT4 at reduced temperatures. The above results are attributed to a chemical reaction taking place at the interface of CB/BT4 and BCB/BT4 during firing, which becomes less extensive with BaO present in the sintering promoter. For both CB+BT4 and BCB+BT4 systems, the resulting composites have a dielectric constant of 36–40, product (Q·f_r) of quality factor (Q) and resonant frequency (f_r) of 13,000–21,000 GHz, and a temperature coefficient of resonant frequency (τ_f) of 20–40 ppm/°C in the temperature range of 25–80 °C.     

Synthesis,characterization and sinterablity of 10 mol% Sm2O3-doped CeO2 nanopowders via carbonate precipitation

A carbonate coprecipitation method has been used for the facile synthesis of highly reactive 10 mol% Sm₂O₃-doped CeO₂ (20SDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE³⁺ (RE = Ce + Sm) molar ratio (R) and the reaction temperature (T) affect significantly the final yield and precursor properties, including chemical composition and particle morphology. Suitable processing conditions are T = 60 °C and R = 5.0–10, under which precipitation is complete and the resultant precursors show ultrafine particle size, spherical particle shape, and good dispersion. Thus, the processed precursors are rare-earth carbonates with an approximate formula of Ce_0.8Sm_0.2(CO₃)_1.5·1.8H₂O, which directly yield oxide solid-solutions upon thermal decomposition at a low temperature of ∼440 °C. The 20SDC solid solution powders calcined at 700 °C show excellent reactivity and have been densified to ∼99% of the theoretical via pressureless sintering at a very low temperature of 1200 °C for 4 h.