Syntheses and crystal structures of two new hydrated borates, Zn8[(BO3)3O2(OH)3] and Pb[B5O8(OH)]·1.5H2O

Two new hydrated borates, Zn₈[(BO₃)₃O₂(OH)₃] and Pb[B₅O₈(OH)]·1.5H₂O, have been prepared by hydrothermal reactions at 170 °C. Single-crystal X-ray structural analyses showed that Zn₈[(BO₃)₃O₂(OH)₃] crystallizes in a non-centrosymmetric space group R32 with a=8.006(2) Å, c=17.751(2) Å, Z=3 and Pb[B₅O₈(OH)]·1.5H₂O in a triclinic space group P1¯ with a=6.656(2) Å, b=6.714(2) Å, c=10.701(2) Å, α=99.07(2)°, β=93.67(2)°, γ=118.87(1)°, Z=2. Zn₈[(BO₃)₃O₂(OH)₃] represents a new structure type in which Zn-centered tetrahedra are connected via common vertices leading to helical ribbons _∞¹[Zn₈O₁₅(OH)₃]¹⁷⁻ that pack side by side and are further condensed through sharing oxygen atoms to form a three-dimensional _∞³[Zn₈O₁₁(OH)₃]⁹⁻ framework. The boron atoms are incorporated into the channels in the framework to complete the final structure. Pb[B₅O₈(OH)]·1.5H₂O is a layered compound containing double ring [B₅O₈(OH)]²⁻ building units that share exocyclic oxygen atoms to form a two-dimensional layer. Symmetry-center-related layers are stacked along the c-axis and held together by interlayer Pb²⁺ ions and water molecules via electrostatic and hydrogen bonding interactions. The IR spectra further confirmed the existence of both triangular BO₃ and OH groups in Zn₈[(BO₃)₃O₂(OH)₃], and BO₃, BO₄, OH groups as well as guest water molecules in Pb[B₅O₈(OH)]·1.5H₂O.     

Electron microscopy studies of W18O49. 1. Crystals formed by gaseous reduction of WO3

W₁₈O₄₉ samples were prepared by reduction of WO₃ crystals at various temperatures (at about 1170, 1270, and 1370K) by equilibration with a gaseous buffer of controlled oxygen pressure. The samples were studied by high-resolution electron microscopy. The results show that an amorphous phase is an intermediary step in the formation of W₁₈O₄₉. Defects are very rarely observed in as-reduced W₁₈O₄₉, which differs in this respect from other tungsten oxides. Apart from twinning, however, three types of extended defects have been observed occasionally, and these are interpreted and discussed.     

W18O49 nanorods decorated with Ag/AgCl nanoparticles as highly-sensitive gas-sensing material and visible-light-driven photocatalyst

A novel gas-sensing material and photocatalyst was successfully obtained by decorating Ag/AgCl nanoparticles on the W₁₈O₄₉ nanorods through a clean photochemical route. The as-prepared samples were characterized using combined techniques of X-ray diffractometry, electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. Gas-sensing measurements indicate that the Ag/AgCl/W₁₈O₄₉ NRs sensors exhibit superior reducing gas-sensing properties to those of bare W₁₈O₄₉ NRs, and they are highly selective and sensitive to NH₃, acetone, and H₂S with short response and recovery times. The Ag/AgCl/W₁₈O₄₉ NRs photocatlysts also possess higher photocatalytic performance than bare W₁₈O₄₉ NRs for degradation of methyl orange under simulated sunlight irradiation. Possible mechanisms concerning the enhancement of gas-sensing and photocatalytic activities of the Ag/AgCl/W₁₈O₄₉ NRs composite were proposed.     

Ln2BaZnO5 and Ln2BaZn1−xCuxO5: A series of zinc oxides with zinc in a pyramidal coordination

A series of zinc oxides Ln₂BaZnO₅ has been synthesized for Ln = Sm, Eu, Gd, Dy, Ho, and Y. Theses phases are orthorhombic and isostructural with the copper compounds Ln₂BaCuO₅ previously described, as shown from the structural study of one member Y₂BaZnO₅. In this structure, whose framework is built up from edge- and face-sharing LnO₇ polyhedra, the Zn²⁺ ions exhibit an unusual pyramidal coordination ZnO₅. The solid solution Y₂BaZn_1?xCu_xO₅ has been studied by infrared spectroscopy and electron spin resonance (ESR). The distorted square-based pyramidal configuration of Zn²⁺ and Cu²⁺ is confirmed. The ESR spectra of diluted samples exhibit a hyperfine structure and are typical of individual Cu(II) ions. For higher Cu(II) contents, they exhibit an anisotropic broad signal which is interpreted in terms of CuCu interactions.     

Oligonukleare Benzylthiolat‐Zinkkomplexe

Oligonuclear Benzylthiolate Zinc Complexes From solutions of zinc nitrate and sodium benzylthiolate crystallize, depending on the reaction conditions, tetraalkylammonium salts of the zinc complexes [Zn₂(SBz)₆]^2—, [Zn₄(SBz)₁₀]^2—, and [Zn₈(S)(SBz)₁₆]^2—. In each complex the zinc ions are tetrahedrally coordinated by sulfur atoms. [Zn₄(SBz)₁₀]^2— has an adamantane framework. The bridging thiolate sulfur atoms in [Zn₈(S)(SBz)₁₆]^2—, unlike those in icosahedral reference compounds, form a cuboctahedral framework.     

一维纳米材料Cs0.2WO3和W18O49长度与红外吸收关联性的Mie散射理论推导及实验验证

研究表明二元、三元钨基氧化物的红外吸收性能具有尺寸和形貌依赖性,但还没有普适性的物理学机理及计算方法。本工作基于Mie散射理论,推导了一维材料的长度与光吸收性能之间的关系,通过理论推导计算和实验验证,探究了纳米钨基氧化物的红外吸收性能与颗粒长度的关联性。首先,基于Mie散射理论的推演和计算,揭示了增加纳米Cs_(0.2)WO_3和W_(18)O_(49)材料长度可适度提高其近红外吸收性能的规律。其次,测试了合成的不同长度Cs_(0.2)WO_3纳米棒和W_(18)O_(49)纳米线的红外吸收性能,结果与理论计算及模拟相吻合。其中在2 500～20 000 nm波长范围内Cs_(0.2)WO_3纳米棒和W_(18)O_(49)纳米线随长度的变化趋势不同,Cs_(0.2)WO_3纳米棒的红外吸收性能随长度的增加而增加,而W_(18)O_(49)纳米线的红外吸收性能随长度的增加而减弱。Cs_(0.2)WO_3纳米棒和W_(18)0O_9纳米线的光热效应均随长度的增加而增加,增幅分别达18.5%和12.7%,再次验证了长度效应。     

Dawson型磷钨杂多阴离子P2W18O626-的电化学性质和对O2还原的电催化作用

用循环伏安、交流伏安和交流阻抗法对Dawson型磷钨杂多阴离子P₂W₁₈O₆₂^6-的电化学性质进行了详细研究, 循环伏安结果显示, P₂W₁₈O₆₂^6-在pH 2.52的0.1 mol·L^-1 Na₂SO₄+NaHSO₄溶液中有两对可逆的单电子还原-氧化波和两对可逆的双电子还原-氧化波. 单电子波的峰电位和电流与溶液的pH无关, 双电子波的峰电位则随溶液pH的增加而负移, 峰电流降低, 表明双电子电极过程有H⁺参与, 其数目为2. 交流阻抗谱表明P₂W₁₈O₆₂^6-的电极过程完全受扩散控制, 实验测定其扩散系数(D_O)为2.5×10^-6 cm²·s^-1. 循环伏安结果表明P₂W₁₈O₆₂^6-的第III对波对O₂还原为H₂O₂具有显著的电催化作用, 催化效率约达300%. 将P₂W₁₈O₆₂^6-应用于PW₁₁O₃₉Fe(III)(H₂O)^4-构成的类电-芬顿过程, 使该过程对硝基苯的降解效率显著提高.     

H_6P_2W_(18)O_(62)/SiO_2:用模板剂制备及光催化降解二甲酚橙的性能

分别采用非离子表面活性剂(C_3H_6OC_2H_4O)_x(P123),阴离子表面活性剂C_(12)H_(25)NaO_4S(SDS)和C_(18)H_(29)NaO_3S(SDBS)作为模板剂,通过溶胶-凝胶再结合程序升温溶剂热一步法制备了一系列固载杂多酸光催化材料-H_6P_2W_(18)O_(62)/SiO_2。通过傅立叶-红外光谱(FTIR)、X-射线衍射(XRD)、电感耦合等离子体原子发射光谱(ICP-AES)、氮气吸附-脱附测定、透射电子显微镜(TEM)以及扫描电子显微镜配合X-射线能量色散谱仪(SEM-EDS)等测试手段对不同模板剂作用下合成产物进行了对比表征分析。结果表明,不同模板剂作用下的系列固载杂多酸-H_6P_2W_(18)O_(62)/SiO_2产物中母体多酸的Dawson基本结构均未发生明显变化,但固载后比表面积显著不同,其中,经模板剂P123和SDS作用合成的H_6P_2W_(18)O_(62)/SiO_2(P123)和H_6P_2W_(18)O_(62)/SiO_2(SDS)的比表面积高达916和634m~2·g~(-1),且显示为有序介孔材料。以二甲酚橙为模型分子,在微波场作用下,该系列固载多酸光催化性能研究结果显示,它们的光催化活性可被微波显著增强,其中,采用P123作用合成产物的光催化活性最高,60 min内对二甲酚橙的降解率达99%以上。     

Crystal Chemistry and Magnetic Properties of SeCu1−xZnxO3(0≤x≤1) Perovskites

The effects of zinc substitution in the structural and magnetic properties of the orthorhombic solid solution SeCu_1−xZn_xO₃ have been studied. Rietveld refinements of the X-ray diffraction patterns indicate that the zinc ions occupy the copper sites. This replacement induces some changes in the Cu-O bond lengths and 〈Cu-O-Cu〉 bond angles. Magnetization vs temperature measurements show a fast decrease in the Weiss constant that reveals a direct quadratic relationship with the increase of the average 〈Cu-O-Cu〉 bond angle. Besides, the introduction of a non-magnetic cation in the B-positions in the structure of SeCu_1−xZn_xO₃ system, progressively decreases the ferromagnetic interactions.     

Synthesis and characterization of hybrid materials based on 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid and Dawson-type tungstophosphate K7[H4PW18O62]·18H2O and K6[P2W18O62]·13H2O

In this study, we synthesized hybrid materials using well-Dawson polyoxometalates (POMs), K₇[H₄PW₁₈O₆₂]·18H₂O or K₆[P₂W₁₈O₆₂]·13H₂O and a room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]). K, W, P and CHN elemental analysis showed that one mole of [H₄PW₁₈O₆₂]⁷⁻ reacts with 6 moles of BMIM⁺ and one mole of [P₂W₁₈O₆₂]⁶⁻ reacts with 4 moles of BMIM⁺ to form, respectively, K[BMIM]₆H₄PW₁₈O₆₂ and K₂[BMIM]₄P₂W₁₈O₆₂. X-ray diffraction illustrated amorphous structure of the hybrid materials. FT-IR spectra showed the presence of both 1-butyl-3-methylimidazolium cation and the Dawson anion. TG analysis displayed a relative thermal stability of the hybrid materials compared to the parents Dawson POMs. Cyclic voltammetry showed that the reduction peak potentials of the Dawson anion in the hybrid materials shift towards negative values and the shift is more pronounced for K[BMIM]₆H₄PW₁₈O₆₂ compared to K₂[BMIM]₄P₂W₁₈O₆₂. This was attributed to a decrease in the acidity of the Dawson POM anion in the hybrid material.     

The synthesis and characterization of a new 3-D inorganic-organic hybrid framework porous material Zn3(bbdc)3(4,4′-bpy)·2(DMF)·4(H2O)

A new 3-D inorganic-organic hybrid framework microporous material Zn₃(bbdc)₃(4,4′-bpy)·2(DMF)·4(H₂O) (1), which is constructed by coordination of zinc ions with 4,4′-bibenzene-dicarboxylic acid (H₂bbdc) and 4,4′-bipyridine (4,4′-bpy), was obtained at mild synthesis condition. Crystallographic data for the compound (1), C₅₈H₅₄N₄O₁₈Zn₃, orthorhombic, space group Pbcn, a=14. 532(3) Å, b=25.037(5) Å, c=18.184(4) Å, Z=4, V=6616(2) Å³.     

Lumineszenz und sensibilisierte Emission der dreiwertigen Seltenen Erden in Sr3La2W2O12

By activation of the new host lattice Sr₃La₂W₂O₁₂ with the trivalent rare earth ions Nd, Eu, Ho, Er, Tm, Yb an intense emission in the visible and/or infrared region is obtained. Energy transfer from Er³⁺ to Tm³⁺ and Nd³⁺ to Yb³⁺ has been found to occur. The excitation, emission, and diffuse reflectance spectra are analyzed for Sr₃La₂W₂O₁₂: Ln³⁺ (Ln = Nd, Sm, Eu, Dy, Ho, Er, Tm, Yb).     

Zinc oxide clusters encapsulated by organozinc phosphazenate assemblies

Phosphazenes (ⁱBuNH)₆P₃N₃ and (BzNH)₆P₃N₃ were combined with 1.5 equivalents of water and 7.5 equivalents of diethylzinc resulting in the formation of zinc oxide phosphazenate complexes Zn₃O₂[(ⁱBuN)₆P₃N₃(EtZn)₅]₂ (6) and Zn₂O₂[(BzN)₆P₃N₃(EtZn)₆]₂ (7), respectively. X-ray structure analysis showed that in both complexes the organozinc phosphazenate moieties encapsulate the zinc oxide clusters, Zn₃O₂ (in 6) and Zn₂O₂ (in 7), which were generated in situ by hydrolysis of Et₂Zn. The geometry and nuclearity of the encapsulated zinc oxide clusters is largely controlled by the steric bulk of the host phosphazenate arrangement, which offers well-defined arrays of Lewis acidic Zn and Lewis basic N sites for coordinating both zinc and oxide ions.     

氧化钨纳米棒团簇的制备及电催化性能

以氯化钨为前驱体,通过溶剂热法制备了WO₃和W₁₈O₄₉并将其应用在染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)和电解水析氢反应(hydrogen evolution reaction,HER)中。通过X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)对WO₃和W₁₈O₄₉的结构和形貌进行表征。结果表明：WO₃和W₁₈O₄₉均为单斜相,其形貌表现为定向排列的纳米棒组成的团簇。X射线光电子能谱(XPS)和电子顺磁共振(EPR)表明W₁₈O₄₉中含有丰富的氧空位。基于氧空位优异的电化学特性,W₁₈O₄₉对电极组装的DSSC获得了7.41%的光电能量转换效率(power conversion efficiency,PCE),高于WO     

Three-dimensional five-connected coordination polymer [M2(C3H2O4)2(H2O)2(μ2-hmt)]n with 46 topologies (M=Zn, Cu; hmt=hexamethylenetetramine)

Two novel three-dimensional five-connected coordination polymers [M₂(C₃H₂O₄)₂(H₂O)₂(μ₂-hmt)]_n with 4⁴6⁶ topologies (M=Zn, Cu; hmt=hexamethylenetetramine) were synthesized and characterized by elemental analysis, crystal structure, IR, thermal gravimetric analyses. Both [Zn₂(C₃H₂O₄)₂(H₂O)₂(μ₂-hmt)]_n and [Cu₂(C₃H₂O₄)₂(H₂O)₂(μ₂-hmt)]_n all crystallize in the orthorhombic system, space group Imm2, and with Z=2. Metal ions have all octahedral geometry coordinated by four oxygen atoms from three malonates, one oxygen atom from a water molecule and one nitrogen atom of hmt ligand. Each malonate binds a metal ion with its two oxygen atoms in a chelating mode and connects to adjacent two metal ions with another two oxygen atoms to form an infinite wavy layer. The layers are bridged by μ₂-hmt molecules to form a three-dimensional framework with channels. The magnetic susceptibility data show there is a weak antiferromagnetic exchange interaction in the complex [Cu₂(C₃H₂O₄)₂(H₂O)₂(μ₂-hmt)]_n.     

Syntheses,Structures and Spectral Properties of Mononuclear CuII and Dimeric ZnII Complexes Based on an Asymmetric Salamo‐type N2O2 Ligand

The asymmetric Salamo‐type N₂O₂ ligand H₂L and its corresponding Cu^II and Zn^II complexes [CuL] and [{ZnL}₂]·2CH₃CN were synthesized and structurally characterized. Crystallographic data of the Cu^II complex revealed that the Cu^II ion is tetracoordinate with a slightly distorted square planar arrangement forming a 2D supramolecular plane structure by hydrogen bonding and π···π stacking interactions. In the Zn^II complex, the Zn^II ions are pentacoordinate in N₂O₂ tetradentate fashion and intermolecular contacts between Zn^II and oxygen atoms result in a head‐to‐tail dimer. The Zn^II ions were found to have slightly distorted square pyramidal and trigonal bipyramidal arrangements, respectively. Hydrogen bonding interactions stabilized the Zn^II complex to facilitate self‐assembly to a 1D linear chain. The Cu^II and Zn^II complexes show intense photoluminescence with maximum emissions at approx. 426 and 411 nm upon excitation at 360 and 350 nm, respectively.     

An organic-inorganic polymer with Dawson-type polyoxometalates as building blocks: synthesis, characterization and crystal structure of [{Pr(DMF)6} {Pr(DMF)7}(P2W18O62)] n

Abstrtact  An organic-inorganic polymer of [Pr(DMF)₆Pr(DMF)₇(P₂W₁₈O₆₂)] _n has been synthesized in acetonitrile-water (5 : 2, volume ratio) mixed solvent. Single-crystal X-ray structural analysis indicates that the title compound crystallizes in a monoclinic lattice, P2₁/C, with a = 1.8574(4), b=2.3907(5), c=2.4222(5) nm, β=99.48(3)°, Z = 4, ∨=10.609(4) nm³, D _c =3.501 Mg/m³, F(000)=9972, R₁=0.0654 and wR ₂= 0.1098. The result of crystal structure analysis reveals that Pr³⁺(1) complex ion is eight-coordinated with a distorted bicapped trigonal prismatic environment, which is combined with the heteropolyanion by terminal oxygen atom, whereas Pr³⁺(2) complex ion is also eight-coordinated with a distorted square antiprismatic environment, which is linked to the heteropolyanion by terminal oxygen atom. Adjacent structure units of [Pr(DMF)₆Pr(DMF)₇(P₂W₁₈O₆₂)] are bridged through W-O-Pr1-O-W links to form an unprecedented one-dimensional zigzag linear chain by alternate polyanions and cationic units in the polymer. Thermal analysis reveals that the framework of the title polyanion decomposes at 613.8°C.     

Fine-Tuning Electrolyte Concentration and Metal–Organic Framework Surface toward Actuating Fast Zn2+ Dehydration for Aqueous Zn-Ion Batteries

Functional porous coating on zinc electrode is emerging as a powerful ionic sieve to suppress dendrite growth and side reactions, thereby improving highly reversible aqueous zinc ion batteries. However, the ultrafast charge rate is limited by the substantial cation transmission strongly associated with dehydration efficiency. Here, we unveil the entire dynamic process of solvated Zn²⁺ ions’ continuous dehydration from electrolyte across the MOF-electrolyte interface into channels with the aid of molecular simulations, taking zeolitic imidazolate framework ZIF-7 as proof-of-concept. The moderate concentration of 2 M ZnSO₄ electrolyte being advantageous over other concentrations possesses the homogeneous water-mediated ion pairing distribution, resulting in the lowest dehydration energy, which elucidates the molecular mechanism underlying such concentration adopted by numerous experimental studies. Furthermore, we show that modifying linkers on the ZIF-7 surface with hydrophilic groups such as −OH or −NH₂ can weaken the solvation shell of Zn²⁺ ions to lower the dehydration free energy by approximately 1 eV, and may improve the electrical conductivity of MOF. These results shed light on the ions delivery mechanism and pave way to achieve long-term stable zinc anodes at high capacities through atomic-scale modification of functional porous materials.     

The role of anhydrous zinc nitrate in the thermal decomposition of the zinc hydroxy nitrates Zn5(OH)8(NO3)2·2H2O and ZnOHNO3·H2O

The steps associated with the thermal decomposition of Zn₅(OH)₈(NO₃)₂·2H₂O and ZnOHNO₃·H₂O are re-examined. Previous reports have suggested that Zn₅(OH)₈(NO₃)₂·2H₂O decomposes to ZnO via two intermediates, Zn₅(OH)₈(NO₃)₂ and Zn₃(OH)₄(NO₃)₂ whereas ZnOHNO₃·H₂O has been reported to decompose to ZnO via a Zn₃(OH)₄(NO₃)₂ intermediate. In this study, we demonstrate using TG, mass spectral analysis of evolved gases and in situ variable temperature powder X-ray diffraction analysis that, in fact, in the decomposition of Zn₅(OH)₈(NO₃)₂·2H₂O an anhydrous zinc nitrate intermediate is also involved. We, additionally, show that the decomposition of ZnOHNO₃·H₂O to ZnO also involves the formation of an anhydrous zinc nitrate intermediate. The anhydrous zinc nitrate formed in both cases is poorly crystallised and this observation may explain why this phase could not be observed by PXRD analysis in the previous studies.     

Cu-ZnO-Al2O3复合催化剂上甘油选择氢解合成丙二醇

分别采用均匀共沉淀法、沉积-沉淀法和传统的共沉淀法制备了3种具有相似组成的Cu-ZnO-A1₂O₃催化剂（CZA-HP,CAZ-DP和CZA-CP）Ε同时还采用均匀共沉淀法制备了Cu-ZnO催化剂（CZ-HP）以用于比较.X射线衍射表征结果表明,以上方法制备的Cu-Zn-Al碱式碳酸盐前体中Cu²⁺,Zn²⁺和Al³⁺的混合均匀程度的顺序为CZA-DP3+分散程度的提高和A1₂O₃与ZnO的紧密接触使得Cu-ZnO-A1₂O₃催化剂中金属Cu和ZnO具有更小的粒径.但ZnO-A1₂O₃间紧密接触也阻隔了Cu-ZnO-A1₂O₃催化剂中金属Cu与ZnO之间的相互作用.因此A1₂O₃的添加使得CZA-HP样品上的Cu粒子表现出最强的氧化还原能力.在473 K和6.0 MPa H₂的反应条件下,以上三种Cu-ZnO-A1₂O₃催化剂均高选择性地催化甘油氢解为丙二醇（30%甘油转化率下的选择性>90%）.Cu-ZnO-A1₂O₃催化剂表面单位Cu原子的本征活性顺序为CZA-DP2O₃的添加还显著地抑制了Cu粒子在反应过程中的聚集,提高了催化剂的稳定性.经6次循环使用后,CZ-HP中Cu粒子的粒径从13.2增至45.2 nm,活性相应下降了45%:而CZA-HP中Cu粒子的粒径从8.3增至19.0 nm,活性仅下降了10%.