Nb2O5·nH2O as a heterogeneous catalyst with water-tolerant Lewis acid sites

Niobic acid, Nb(2)O(5)·nH(2)O, has been studied as a heterogeneous Lewis acid catalyst. NbO(4) tetrahedra, Lewis acid sites, on Nb(2)O(5)·nH(2)O surface immediately form NbO(4)-H(2)O adducts in the presence of water. However, a part of the adducts can still function as effective Lewis acid sites, catalyzing the allylation of benzaldehyde with tetraallyl tin and the conversion of glucose into 5-(hydroxymethyl)furfural in water.     

Synthesis and Crystal Structure of a New Potassium Yttrium Diphosphate Dihydrate KYP2O7·2H2O

The dihydrated potassium yttrium diphosphate, KYP2O7·2H2O, has been synthesized for the first time. Single-crystal XRD study has allowed the determination of its structure and correct formula. It crystallizes in the monoclinic system, space group P21/c, with the cell parameters a = 7.7069（3）, b = 10.5801（4）, c = 10.0204（5）A,β = 93.24（3）A, V= 815.76（6）A^3, Z= 4, Mr = 337.98, F（000） = 656, Dc = 2.752 g/cm^3 and/t = 8.073 mm^-1. The single-crystal structure was solved from 1856 unique reflections with the final R = 0.0365 and wR = 0.0772, refined with 119 parameters. The atomic arrangement of KYP2O7·2H2O is built by the P2O7 groups, the YO7 and the KO10 polyhedrons which are connected by corner and edge-sharing to form a three-dimensional framework. Water molecules are directly bonded to the Y and K atoms, and they are located in channels running along the a direction.     

Synthesis and photocatalytic properties of a new heteropolyoxoniobate compound: K10[Nb2O2(H2O)2][SiNb12O40)·12H2O

The synthesis and photocatalytic properties of a heteropolyoxoniobate, K(10)[Nb(2)O(2)(H(2)O)(2)][SiNb(12)O(40)]·12H(2)O (1), are reported, revealing an important role of Zr(4+) additives in the crystallization. Compound 1 exhibits overall photocatalytic water splitting activity, and its photocatalytic activity is significantly higher than that of Na(10)[Nb(2)O(2)][SiNb(12)O(40)]·xH(2)O (2). Fluorescence lifetime measurements suggest that the enhanced photocatalytic activity of 1 likely results from a larger yield of longer-lived charge trapping states in 1 due to the coordination of one water molecule to the bridging Nb(5+), leading to highly unsymmetrical seven-coordinated Nb(5+) sites.     

Synthesis of calcium titanate from [Ca(H2O)3]2[Ti2(O2)2O(NC6H6O6)2]·2H2O as a cheap single-source precursor

Calcium titanate (CaTiO₃) was conveniently synthesized by thermal decomposition of a single-source precursor [Ca(H₂O)₃]₂[Ti₂(O₂)₂O(NC₆H₆O₆)₂]·2H₂O at low temperature. This single-source precursor was characterized by elemental analysis, IR spectrum, thermal gravimetric analysis and X-ray single crystal diffraction. The calcined products at different temperature were further characterized by powder X-ray diffractions and IR spectra. The morphology, microstructure, and crystallinity of the resulting CaTiO₃ materials have been characterized by SEM and TEM. The BET measurement revealed that the CaTiO₃ powders had a surface area of 14.0 m²/g. In addition, the microwave dielectric properties of the resulting CaTiO₃ material have been measured.     

Parameters of Li2O2 · H2O crystallization from the LiOH-H2O2-H2O ternary system

The decomposition kinetics of peroxide products contained in the liquid phase of the LiOH-H₂O₂-H₂O ternary system were studied, and the applicability of the solubility method to studying this system was demonstrated for hydrogen peroxide concentrations in the liquid phase from 2 to 6 wt % and temperatures of 21–33°C. The stabilizing influence of solid Li₂O₂ · H₂O on hydrogen peroxide decomposition was demonstrated. The temperature and concentration boundaries of existence were determined for the Li₂O₂ · H₂O phase, whose identity was verified by chemical analysis and qualitative X-ray powder diffraction analysis.     

Hierarchical N-doped carbon nanocages/carbon textiles as a flexible O2 electrode for Li–O2 batteries

The conventional Li–O2 battery(LOB)has hardly been considered as a next-generation flexible electronics thus far,since it is bulk,inflexible and limited by the absence of an adjustable cell configuration.Here,we present a flexible Li–O2 cell using N-doped carbon nanocages grown onto the carbon textiles(NCNs/CTs)as a self-standing and binder-free O2 electrode.The highly flexible NCNs/CTs exhibits an excellent mechanic durability,a promising catalytic activity towards the ORR and OER,a considerable cyclability of more than 70 cycles with an overpotential of 0.36 V on the 1 stcycle at a constant current density of 0.2 m A/cm2,a good rate capability,a superior reversibility with formation and decomposition of desired Li2 O2,and a highly electrochemical stability even under stringent bending and twisting conditions.Our work represents a promising progress in the material development and architecture design of O2 electrode for flexible LOBs.     

Direct Synthesis of Acetic Acid from CH4 and CO2 in the Presence of O2 over a V2O5-PdCl2／Al2O3 Catalyst

The possibility of synthesizing acetic acid from CH4 and CO2 in the presence of O2 over a V2O5-PdCl2/Al2O3 catalyst has been explored. The result shows that it is feasible in catalyzing a direct conversion of CH4, CO2 and O2 to acetic acid. It is concluded that both CO2 and O2 are involved in the formation of acetic acid.     

Die Molarverhältnisse CO2∶O2 und N2O∶O2

Ohne Zusammenfassung     

Synthesis and Characterization of a Novel Compound SnDy2O4

In recent years, the research on rare earth became a focus, and a lot of rare earth complex compounds with AB2O4 stoichiometry were prepared1-3. The compound SnDy2O4 is expected to spinel-type phase while it exhibits a new structure type. SnDy2O4 was prepared by the thermal decomposition of the oxalate precursor that was prepared by rheological phase reaction method. SnO(AR), Dy2O3(99.9%) and H2C2O4·2H2O are ground in molar ratio 1:1:4.1, and placed into the reaction apparatus. …     

Synthesis and Crystal Structure of a Macrocycle [Cu(dadm)(mal)(H2O)]2·2H2O

The reaction of 4,4′-diaminodiphenylmethane (dadm), malonic acid (H2mal) and Cu(NO3)2 in aqueous solution results in a discrete binuclear Cu(II) macrocycle: [Cu(dadm)(mal)- (H2O)]2(2H2O. It crystallizes in monoclinic, space group P21/c with a = 15.231(3), b = 11.847(2), c = 9.801(2)A,Z= 106.75(3)o, V = 1693.5(6)A3, Z = 2, C32H40Cu2N4O12, Mr = 799.76, Dc = 1.568 g/cm3, λ(MoK() = 0.71073A, μ = 1.325 mm-1, F(000) = 828, the final R = 0.0531 and Wr = 0.1244 for 3421 observed reflections with I > 2σ(I). Each Cu(II) is coordinated by two oxygen atoms from a mal ligand, two nitrogen atoms from two dadm ligands and a water oxygen atom to form a triangle bipyramidal motif. The title compound possesses a distorted macrocycle enclosed by dadm with approximate dimensions of 8.3A× 5.9A.     

Oxidation of alkanols with a CeIII—LiBr—H2O2 system

Russian Chemical Bulletin -     

Synthesis and Structure of a Novel Compound [Cu2(EDTA)(Py)2(H2O)2]·2H2O

A novel compound [Cu2(EDTA)(Py)2(H2O)2]·2H2O was synthesized by the reaction of CuSO4(5H2O with H4EDTA in pyridine/water (V/V = 1/4) solvent, and characterized by elemental analysis, IR spectrum and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 1.26974(6), b = 0.67949(3), c = 1.48548(3) nm, β = 91.454(2)o, V = 1.28122(9) nm3, Z = 2, Dc = 1.673 g/cm3, Mr = 645.56, F(000) = 664, μ(MoKα) = 1.729 mm-1, the final R = 0.0353 and wR = 0.0832 for 1920 observed reflections (I > 2((I)). The compound is a centrosymmetric binuclear molecule with bridged EDTA group. Each Cu(II) atom is linked to two oxygen atoms and one nitrogen atom of EDTA, one oxygen atom of water and one nitrogen atom of pyridine to form a distorted square pyramidal environment. There exist face-to-face π-π stacking interactions between pyridine rings from neighboring molecule with the interplanar distance of 0.3670 nm and hydrogen bonding between EDTA and water molecules.     

Demonstration of a pulsed photoelectron spectrometer on mass-selected negative ions: O−, O2−, and O4−

A new type of negative ion photoelectron spectrometer which utilizes time-of-flight for both ion mass selection and photoelectron energy analysis is described and demonstrated on the 532 nm photodetachment of the well-known O⁻ and O⁻₂ ions as well as the O⁻₄ cluster ion. Photoelectron spectra of O⁻₄ at 355 and 532 nm depend on laser power, suggesting that photodissociation competes with photodetachment at both wavelengths.     

Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系光谱性质的研究

根据稀土离子能级的特点,对Ga2O3-La2O3-Yb2O3-Er2O3(HO2O3)体系的光谱性质进行了探讨,发现它们有二类发光性质:Stokes发光和反Stokes发光,研究了发光强度和发射波长与掺杂离子的依赖关系,观察到由能量的共振转移引起的荧光浓度猝灭现象,并取得了最大发光强度时的掺杂离子浓度和一些规律性结果.