Synthesis and electrochemical properties of substituted heteropoly acid with Dawson structure H7[In(H2O)P2W17O61]·23H2O

A new solid high-proton conductor, substituted heteropoly acid with Dawson structure H(7)[In(H(2)O)P(2)W(17)O(61)]·23H(2)O, has been synthesized by the degradation/ion exchange/freezing method. The pH of the synthesis reaction was given. The product was characterized by chemical analysis, IR, UV, XRD and TG-DTA. The determination of conductivity shows that H(7)[In(H(2)O)P(2)W(17)O(61)]·23H(2)O is an excellent solid high-proton conductor with conductivity of 1.34 × 10(-3) S cm(-1) at 18 °C, and 70% relative humidity (RH). Its activation energy is 37.72 kJ mol(-1), which suggests that its mechanism of proton conduction is the Vehicle mechanism.     

Dawson型杂多酸钕盐催化氧化甲苯制备苯甲醛

合成了Dawson型磷钼钒杂多酸稀土(钕)盐,并用红外光谱分析(IR)、X射线衍射(XRD)方法对催化剂进行了表征;以H2O2为氧化剂,进行了甲苯氧化制备苯甲醛的反应研究.由于钕和钒的协同作用,催化剂表现出高的活性.实验结果表明,甲苯的转化率90.1%,苯甲醛的选择性达51.0%,双氧水的转化率89.0%,双氧水的有效利用率43.1%.基于对杂多酸盐结构的研究,对反应机理进行了初步的探讨.     

三缺位Keggin多阴离子[α-A-AsW_9O_（34）]~（9-）到Dawson多阴离子[α-As_2W_（18）O_（62）]~（6-）的结构转变（英文）

以Na8[α-A-HAsW9O34].11H2O,CuCl2.2H2O和乙二胺（en）为原料,在两步水热条件下反应合成了一种有机-无机复合的饱和Dawson砷钨酸盐[H2en]3[α-As2W18O62].0.5en.9H2O（1）,并对其进行了元素分析、红外光谱和单晶X射线衍射表征。在化合物1的形成过程中,首次观察到三缺位Keggin多阴离子[α-A-AsW9O34]9-到饱和Dawson多阴离子[α-As2W18O62]6-的结构转变,这为饱和Dawson多阴离子可以看作由两个三缺位Keggin多阴离子通过共用六个氧原子聚合而成的事实提供了一个有力的实验证据。而且,多金属氧酸盐化学中其它一些不同多阴离子间的转变也被归纳。     

具有Dawson结构的钼钒磷杂多酸的制备和性质研究

本文报道用改良的分步处理合成方法, 直接制备了五种未见报道的2:18系列钼钒磷杂多酸, 详细考察了它们的生成条件. 经元素分析、电位滴定和差热热重分析确定阴离子的组成分别为[P2Mo17VO62]^7^-,[P2Mo16V2O62]^8^-,[P2Mo15V3O62]^9^-, [P2Mo14V4O62H2]^8^-, [P2Mo13V5O62H2]^9^-. 对五种杂多酸的热化学性质和碱度进行了讨论. 根据紫外、红外及X射线衍射结果讨论了它们的结构, 表明都属于具有Dawson结构的杂多化合物.     

A Novel 3D Polyoxotungstate Constructed from Dawson Polyanions and Alkaline Earth Cations

A novel 3D polyoxotungstate [Ca(H2O)2][Ca(H2O)3]H2[P2W18O62]·9H2O(1) has been synthesized by the conventional aqueous solution method and characterized by IR spectrum,elemental analyses,single-crystal X-ray diffraction and electrochemistry.1 crystallizes in triclinic,space group P1 with a = 12.9077(14),b = 14.8593(16),c = 20.023(2),α = 70.1620(10),β = 80.8110(10),γ = 64.3770(10)o,V = 3256.9(6)3,Z = 2,Dc = 4.790 g/cm3,μ = 31.975 mm-1,F(000) = 4080,R = 0.0412,and wR = 0.1039.X-ray single-crystal structural analysis indicates that the molecular structural unit of 1 consists of one saturated Dawson [α-P2W18O62]6-polyanion,one seven-coordinate [Ca(H2O)2]2+ cation,one eight-coordinate [Ca(H2O)3]2+ cation,two protons and nine lattice water molecules.Interestingly,adjacent Dawson [α-P2W18O62]6-polyanions are connected by [Ca(H2O)2]2+ and [Ca(H2O)3]2+ cations and hydrogen bonding interactions to form a 3D infinite framework.The electrochemistry property of 1 has been studied.     

Hydrothermal Synthesis and Characterization of a Novel Organically-templated Tungsten Heteropolyacid with a Microporous Structure

1 INTRODUCTION The synthesis of microporous metal phosphateshas been an area of intense research due to their richstructural chemistry and potential applications incatalysis, separation, and ion exchange processes[1].One of the main goals of this research is to synthe-size zeolite-like materials with large ring sizes so asto perform shape-selective catalysis on reactants. Forthis reason, the phosphor substitution of silicon inzeolites has been intensively investigated. In 1988,Davis et …     

The proton conductivity of heteropoly compounds

Five kinds of molybdovanadophosphoric acid: H7[P2Mo17VO62], H8[P2Mo16V2O62], H9[P2Mo15V3O62], H8[P2Mo14V4O61(H2O)] and H9[P2Mo13V5O61(H2O)] have been synthesized. The salts, K13[Ln(SiW11O39)2] (Ln=La, Ce, Pr, Nd or Gd) have also been prepared. The proton conductivities (C) of all the above compounds have been measured, and are dependent not only on the nature of compound itself, but also on external factors such as temperature and frequency. The general trend of proton conductivity, changing with the hydration number, frequency and temperature is summarized and important conclusions have been drawn based on experimental measurements. The resulting data have not been reported hitherto in the literature.     

BaCe_(0.8-x)Nb_xGd_(0.2)O_(3-δ)(0≤x≤0.45)的制备及性能研究

采用高温固相反应法制备了质子导体BaCe0.8-xNbxGd0.2O3-δ(0≤x≤0.45)。结合XRD、SEM、EIS等技术对其物相、微观形貌、稳定性及电导率进行了研究。结果表明,在1600℃烧结5h制备的质子导体BaCe0.8-xNbxGd0.2O3-δ(0≤x≤0.45)均能保持主相为斜方晶的钙钛矿结构。Nb的加入可明显提高烧结样品的致密性及在CO2和水蒸气气氛下的稳定性。在湿润H2/Ar(0.4%,V/V)气氛中800℃下,x=0.1样品的电导率为5.73mS·cm-1,电导活化能为0.35eV,与x=0的样品相当。     

基于溶剂的结构效应构筑新颖的多金属氧酸盐超分子化合物

摘要 选用不同的溶剂并在水热合成的条件下得到了二个经典Dawson型有机无机杂化的超分子化合物,即(H2BBI)3P2W18O62?H2O (1)和H2(H2BBI)2P2W18O62?2H2O (2), (BBI为1,4-二咪唑基丁烷), 通过单晶X-射线衍射、元素分析、红外光谱、光催化, 对化合物1和2的结构和性质进行了测试和表征. X-射线单晶衍射分析表明化合物1是通过多金属氧酸盐Dawson的端氧, 有机配体BBI的N原子以及游离的水分子构筑成的新颖的三维超分子结构. 化合物2是通过改变化合物1的溶剂来转变有机配体BBI在空间的排布使化合物2结晶在手性的空间群P1. 并对化合物1和2 的光催化性质进行了研究。     

An Unprecedented 1D Zigzag Chain Alkaline Earth Metal Derivative {[Ba(DMF)_3(H_2O)_2][Ba(DMF)_4]_2(P_2W_(18)O_(62))}_n Containing Dawson Heteropolyanion

Most of the polyoxometalates have discrete structures of definite sizes and shapes belonging to well-known structural types, such as the Lindquist, Keggin, Dawson, Strandberg, or Anderson1–2. Linking these discrete entities to build solid-state materials…     

Two Dawson-templated three-dimensional metal-organic frameworks based on oxalate-bridged binuclear cobalt(II)/Nickel(II) SBUs and Bpy linkers

The Dawson anion P 2W 18O 62 (6-) has been used as a noncoordinating polyoxoanion template for the construction of two metal-organic frameworks, namely, [M 2(bpy) 3(H 2O) 2(ox)][P 2W 18O 62]2(H 2-bpy). nH 2O (M = Co(II), n = 3 ( 1); M = Ni(II), n = 2 ( 2)) (bpy = 4,4'-bipyridine; ox = C 2O 4 (2-)). Single-crystal X-ray analysis reveals that both of the structures exhibit 3D host frameworks constructed from the oxalate-bridged binuclear superoctahedron secondary building units (SBUs) and bpy linkers and the voids of which are occupied by Dawson anions, guest bpy, and water molecules. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the transition-metal centers in compounds 1 and 2. Furthermore, a compound 1-modified carbon paste electrode ( 1-CPE) displays good electrocatalytic activity toward the reduction of nitrite.     

铌取代Dawson结构钨磷杂多配合物的合成及其结构表征

本文报道了八种新化合物α2-M7-mHm[P2W17NbO62].xH2O, α-1, 2,3-M9-mHm[P2W15Nb3O62].xH2O (M=K, TMA, TEA, TBA)的合成和表征。红外和紫外光谱表明两种阴离子具有Dawson结构, ^3^1P和^1^8^3W NMR测定结果表明铌原子确系"极位"一、三取代。α-1, 2,3-K7H2[P2W15Nb3O62].30H2O为六方晶系, 晶胞参数为: a=1.9836(4), b=1.9836(9), c=1.5498(6)nm, α=β=90°, γ=120°。此外, 还报道了极谱、XPS和XRD结果。     

Stabilising pentavalent actinides--visible-near infrared and X-ray absorption spectroscopic studies of the utility of the [(Np3W4O15)(H2O)3(MW9O33)3]18- (M = Sb, Bi) structural type

We report the interaction between B-type tri-lacunary heteropolyoxotungstate anions and actinyl(V) cations in aqueous solution, yielding a greater understanding of the stability of the O≡An≡O(1+) linear dioxo actinide moiety. Previously we reported that B-α-[BiW(9)O(33)](9-) and B-α-[SbW(9)O(33)](9-) will react with NpO(2)(1+) to yield [(Np(3)W(4)O(15))(H(2)O)(3)(MW(9)O(33))(3)](18-) (M = Bi, or Sb). Single crystal structural characterisation of salts of these complexes revealed a core in which three Np(V) atoms interact with a central W(VI) atom through bridging oxo groups. These bridging oxygen atoms come from one of the two axial oxygens in O≡Np≡O(1+) and represent a highly unusual interaction for a discrete molecular species. In this study visible/near infra-red spectroscopy indicates that [(Np(3)W(4)O(15))(H(2)O)(3)(BiW(9)O(33))(3)](18-) could be readily stabilized in solution at near neutral pH for several months, with (NH(4))(14)Na(4)[(Np(3)W(4)O(15))(H(2)O)(39)BiW(9)O(33))(3)]·62H(2)O crystallising from solution in high yield. At lower pH and [BiW(9)O(33)](9-) : NpO(2)(1+) ratios additional Np(V) species could be observed in solution. Stabilization of [(Np(3)W(4)O(15))(H(2)O)(3)(SbW(9)O(33))(3)](18-) in solution proved more challenging, with several distinctive Np(V) near infra-red transitions observed in solution. Slow complexation kinetics and reduction to Np(IV) was also observed. High [SbW(9)O(33)](9-) : NpO(2)(1+) molar ratios and careful control of solution pH was required to prepare solutions in which [(Np(3)W(4)O(15))(H(2)O)(3)(SbW(9)O(33))(3)](18-) was the only neptunium containing species. In stark contrast to the NpO(2)(1+) chemistry, [BiW(9)O(33)](9-) readily oxidizes PuO(2)(1+) to PuO(2)(2+) yielding further evidence of the decreased stability of Pu(V)vs. Np(V). Np L(II)-edge XAFS measurement revealed very good agreement with single crystal diffraction data for the Np structural environment for [(Np(3)W(4)O(15))(H(2)O)(3)(MW(9)O(33))(3)](18-) (M = Bi, or Sb) in the solid state. There was also good agreement between coordination shells for [(Np(3)W(4)O(15))(H(2)O)(3)(BiW(9)O(33))(3)](18-) in the solid state and in solution, yielding further confirmation of the high stability of this particular cluster.     

Microwave-assisted construction of ferromagnetic coordination polymers of [W(V)(CN)8]3- with Cu(II)-pyrazole synthons

The microwave-mediated self-assembly of [W(V)(CN)(8)](3-) with Cu(II) in the presence of pyrazole ligand resulted in the formation of three novel assemblies: Cu(II)(2)(Hpyr)(5)(H(2)O)[W(V)(CN)(8)](NO(3))·H(2)O (1), {Cu(II)(5)(Hpyr)(18)[W(V)(CN)(8)](4)}·[Cu(II)(Hpyr)(4)(H(2)O)(2)]·9H(2)O (2), and Cu(II)(4)(Hpyr)(10)(H(2)O)[W(V)(CN)(8)](2)(HCOO)(2)·4.5H(2)O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)(2)(H(2)O)(4)}(2+) ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic-organic 3-D framework (I(1)O(2)). The magnetic measurements for 1-3 reveal a weak ferromagnetic coupling through Cu(II)-NC-W(V) bridges.     

Syntheses and Characterizations of Two New Organic-inorganic Hybrids Based on Heteropolymolybdates and Piperidine Molecules

1 INTRODUCTION The rational design and synthesis of organic-inor- ganic hybrid materials have recently attracted an increasing interest not only from a structural point of view, but also due to their potential applications in different areas such as catalysis, medicine, sorption, electrical conductivity, magnetism and photoche- mistry[1~8]. It should be noted that polyoxometalates (POMs)[9~11], known as their wide applications in many interdisciplinary fields, are an outstanding class o…     

基于[P_2W_(15)O_(56)]~(12-)构筑块的四核铜夹心型化合物的合成、结构表征及其热稳定性

以三缺位型Dawson结构的钨磷酸盐前驱体Na12[α-P2W15O56]·24H2O与CuCl2·6H2O和Na3PO4为原料、水为溶剂,经溶液合成法合成了四核夹心型多金属氧酸盐化合物Na3H13[Cu4(H2O)2(P2W15O56)2]·72H2O(1);利用X射线单晶衍射仪、红外光谱仪、紫外光谱仪、X射线粉末衍射仪等分析了合成产物的结构,采用变温红外光谱测定了其热性质.结果表明,该化合物为三斜晶系,P-1空间群;其晶胞参数为:a=1.318 1(2)nm,b=1.345 1(2)nm,c=2.497 3(4)nm,α=78.149(3)°,β=88.242(3)°,γ=62.087(2)°.该化合物的骨架结构由两个三缺位的Dawson结构单元{P2W15O56}通过一个{Cu4O16}簇连接而成;其在350℃以下表现出一定的热稳定性.     

The lacunary polyoxoanion synthon alpha-P(2)W(15)O(56)(12-): an investigation of the key variables in its synthesis plus multiple control reactions leading to a reliable synthesis

A reliable way to determine the purity of the kinetically precipitated, noncrystalline lacunary polyoxoanion alpha-P(2)W(15)O(56)(12-) has been developed, namely, the conversion of alpha-P(2)W(15)O(56)(12-) into the tri-Nb(5+)- and V(5+)-containing polyoxoanions P(2)W(15)Nb(3)O(62)(9-) and P(2)W(15)V(3)O(62)(9-), respectively, followed by quantitative analysis of their purity by (31)P-NMR prior to recrystallization. With this previously unappreciated, straightforward alpha-P(2)W(15)O(56)(12-) purity-assessment methodology in hand, the five reported literature syntheses of alpha-P(2)W(15)O(56)(12-) are investigated with an emphasis on understanding the effects of the five differing variables within these syntheses (the amount of Na(2)CO(3) base, the rate of addition of the base, the reaction temperature, the reaction scale, and the product drying method). Two methods of Nb(5+) addition (Nb(6)O(19)(8-) and NbCl(5)) to yield P(2)W(15)Nb(3)O(62)(9-) are also evaluated, as is the issue of whether any purification is provided by the normally optimum strategy of first preparing a water-soluble salt and its crystallization from water (here the (CH(3))(4)N(+) salt of the Nb-O-Nb bridged anhydride, P(4)W(30)Nb(6)O(123)(16-)), followed by its conversion to the organic-solvent soluble, but noncrystalline, (n-C(4)H(9))(4)N(+) salt, [(n-C(4)H(9))(4)N](9)[P(2)W(15)Nb(3)O(62)]. The results yield five previously unavailable and unequivocal insights: (1) Only the amount of added Na(2)CO(3) base affects the purity or yield of the desired alpha-P(2)W(15)O(56)(12-); the amount of added base is key, however. (2) Contant's 1990 Inorganic Syntheses procedure provides the highest-purity alpha-P(2)W(15)O(56)(12-) presently available. (3) All prior syntheses calling for the addition of base to P(2)W(18)O(62)(6-) until pH 9 must be abandoned. (4) The purity of even Contant's alpha-P(2)W(15)O(56)(12-) is only 90%. (5) An identifiable impurity is the 16 tungsten polyoxoanion, alpha-P(2)W(16)()O(59)(12-). Also identified and summarized are multiple compounding errors in the observation of, reporting on, and thinking about the synthesis of alpha-P(2)W(15)O(56)(12-) historically, errors which delayed the most reliable synthesis of alpha-P(2)W(15)O(56)(12-) from being identified for 18 years (from the 1983 discovery of alpha-P(2)W(15)O(56)(12-)). However, these errors yield valuable take-home lessons for anyone interested in working in this demanding area of inorganic synthetic chemistry, where direct structural methods for identifying the products and their purity, such as the lacunary polyoxoanion synthon alpha-P(2)W(15)O(56)(12-), sometimes simply do not exist.     

Encapsulation of anion/cation in the central cavity of tetrameric polyoxometalate, composed of four trititanium(IV)-substituted α-Dawson subunits, initiated by protonation/deprotonation of the bridging oxygen atoms on the intramolecular surface

Preparation and structural characterization of a novel polyoxometalate (POM), [(P(2)W(15)Ti(3)O(60.5))(4)(NH(4))](35-) 1, i.e., an encapsulated NH(4)(+) cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR spectroscopy, solution ((15)N{(1)H}, (31)P, (183)W) NMR spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH(4)Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P(2)W(15)(TiO(2))(3)O(56)(OH)(3)](9-) 2, for 3 h in an electric furnace at 200 °C. The encapsulated NH(4)(+) cation in 1 was confirmed by (15)N{(1)H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl(-) anion encapsulated in [{α-1,2,3-P(2)W(15)Ti(3)O(57.5)(OH)(3)}(4)Cl](25-) 3 with the NH(4)(+) cation was attained by neutralizing an aqueous solution containing 3 with the addition of aqueous NH(3) (the initial pH of ca. 2-2.5 was changed to 6.4), followed by adding NH(4)Cl. It has been clarified that the conditions as to whether the anion or the cation is encapsulated in the central cavity of the Dawson tetramer were significantly related to the protonation/deprotonation of the bridging oxygen atoms on the intramolecular surface, Ti-O-Ti/Ti-OH-Ti sites constituting the Dawson subunits.     

Tetrameric,trititanium(IV)-substituted polyoxotungstates with an alpha-Dawson substructure as soluble metal-oxide analogues: molecular structure of the giant "tetrapod" [(alpha-1,2,3-P2W15Ti3O62)4[mu3-Ti(OH)3]4Cl]45-

The preparation and structural characterization of the novel polyoxoanion [(alpha-1,2,3-P(2)W(15)Ti(3)O(62))(4)[mu(3)-Ti(OH)(3)](4)Cl](45-) (1 a; abbreviated to [TiO(6)](16); FW approximately 16 000) which consists of four tri-Ti(IV)-1,2,3-substituted alpha-Dawson substructures, four Ti(OH)(3) bridging groups, and one encapsulated Cl(-) ion, are described. A water-soluble, all-inorganic composition compound of the tetrameric Ti-O-Ti-bridged anhydride form, Na(x)H(45-x)[1 a].y H(2)O (1; x=16-19, y=60-70), which was afforded by the reaction of the tri-lacunary Dawson polyoxotungstate Na(12)[B-alpha-P(2)W(15)O(56)].19 H(2)O with an excess of TiCl(4) in aqueous solution, was obtained as analytically pure, homogeneous colorless crystals. Single-crystal X-ray structure analysis revealed that 1 a was an inorganic, giant "tetrapod"-shaped molecule (inscribed to a sphere with a diameter of approximately 32 A) with approximately T(d) symmetry, in which the 16 edge- and/or corner-shared TiO(6) octahedra were contained. This number of TiO(6) octahedra was larger than that found in other titanium(IV)-substituted polyoxotungstates. Complex 1 was characterized by complete elemental analysis, TG/DTA, FTIR, UV/Vis absorption, and solution ((31)P and (183)W) NMR spectroscopy. The longest wavelength band in the UV/Vis absorption spectra of 1 in water was attributed to the O-->Ti(IV) ligand-to-metal charge-transfer (LMCT) transition: the wavelength of the LMCT band increased linearly as the number of TiO(6) octahedra contained in the Keggin and Dawson polyoxoanions increased. The Ti(n) chromophores formed in the Keggin and Dawson polyoxotungstates are water-soluble analogues of solid TiO(2) or SrTiO(3) as light-semiconductors and photocatalysts.     

Dawson型磷钨钼杂多酸的制备及其对H2O2氧化环己酮制己二酸的催化

采用水热法制备了新型H6P2W9Mo9O62.24H2O催化剂,并用UV-Vis、FT-IR和TG-DTA等测试技术对催化剂进行了表征。以微波促进30%过氧化氢氧化环己酮制备己二酸合成反应为探针,考察了催化剂的催化性能。通过正交实验探讨了几种因素对反应的影响,确定了优化工艺条件为:n(环己酮)∶n(过氧化氢)∶n(草酸)∶n(催化剂)=100∶400∶1.25∶0.25,反应温度100℃,微波辐射功率400 W,反应时间3.5 h,己二酸产品的收率达87.33%,纯度可达99.7%。反应结束后,将反应后含催化剂的溶液浓缩至一定浓度,催化产率降低,重复使用5次收率降低为45.89%。