An Unprecedented 1D Zigzag Chain Alkaline Earth Metal Derivative {[Ba（DMF）3（H20）2][Ba（DMF）4]2（PzWl8O662）}n Containing Dawson Heteropolyanion

An unprecedented 1D zigzag chain alkaline earth metal derivative, {[Ba（DMF）3 （H20）2][Ba（DMF）412（P2W18O62）}n, （DMF=N, N-dimethyl formamide） containing Dawson hetero- polyanion has been successfully synthesized and characterized by X-ray crystallography. Two barium cations bridged by three DMF ligands in parallel combination with the Dawson-type heteropolyanion [P2W18O62]^6- and then the resulting subunits {[Ba（DMF）4]2（P2WlsO62）}^2＋ are alternately linked together via another [Ba（DMF）3（H2O）2]^2＋ ions, constructing a 1D zigzag chain architecture.     

Synthesis and Crystal Structure of a New Cadmium（Ⅱ） Supramolecular Network Containing Chelating Imidazole-4-carboxylate Ligand

A new complex, [Cd（Himc）2（H2O）2] 1, obtained from imidazole-4-carboxylatic acid （H2imc） and Cd（ClO4）2·6H2O, has been synthesized. The crystal structure was determined by X-ray diffraction. The title compound crystallizes in the orthorhombic system, space group Pccn, with a = 7.4886（11）, b = 11.9667（18）, c = 13.550（2） A, V= 1214.3（3） A3, Z = 4, Mr= 370.60, Dc = 2.027 mg/m3, F（000） = 728,μ （MoKa） = 1.829 mm^-1, the final R = 0.0243 and wR = 0.0591 for 1150 unique reflections with I 〉 2σ（I）. The cadmium（II） center in the title complex is coordinated with two oxygen and two nitrogen atoms from two bidentate chelated imidazole-4-carboxlate ligands together with two water molecules, giving a distorted octahedral coordination geometry. A one-dimensional hydrogen bonding chain is formed via intermolecular O-H...O hydrogen bonds, and such adjacent chains are further stacked through intermolecular π-π and hydrogen bonding interactions to form a 3D supramolecular framework. Complex 1 exhibits a fluorescent emission band at 290 nm （λex = 236 nm） in the solid state.     

Hybrid Tungstocuprate [ Cu（2,2＇-bpy）3]2 H4 [ CuW12O40 ]· 6H2O Based on Keggin Polyoxoanion [CuW12O40]^6- with Cu^Ⅱ as Heteroatom

A novel hybrid tungstocuprate （ Ⅱ ） [ Cu （2,2＇-bpy） 3 ] 2 H4 [ CuW12O40 ] · 6H2O （ 2,2＇-bpy = 2,2＇-bipyfidine） was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [ CuW12O40 ]^6- and a pair of chiral complex cations [ Cu（2,2＇-bpy） 3 ]^＋ together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [ Cu （2,2＇-bpy）3 ]^＋v/a multiple C-H…O hydrogen bonds resulting in a dimer.     

Syntheses and Structures of Two New Oxalate-bridged Transition-metal Supramolecular Polymers of [ M （ 2-NH2 py） 2 （ox）

Two new supramoleeular polymers [ M （2-NH2 py）2 （ox） ] [ M = Co （1）, Ni （2） ; 2-NH2py = 2-aminopyridine; ox = oxalate ] were hydrothermally synthesized and characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. The isomorphic compounds 1 and 2 both possess one-dimensional zigzag chain structures, which are composed of [ M （2-NH2 py）2 ]^2＋ units bridged by tetradentate oxalate ligands to form three-dimensional supramolecular network v/a the C-H…O hydrogen bonds and π-π stacking interactions. Compound 1 displays antiferromagnetie interaction.     

Synthesis and Structure of a Novel Supramolecular Compound E Co（ 2,2＇-bipy） （ H20 ） 4] E trans-1,4-chdc ] and Separation of Isomer of 1,4-Cyclohexanedicarboxylic Acid

A supramolecular compound, [ Co（2,2＇-bipy） （ H2O）4 ] [ trans-1,4-chdc ] （ compound 1 ） （ 2,2＇-bipy = 2,2＇- bipyridine, 1,4-chdcH2 = 1,4-cyclohexanedicarboxylic acid）, was synthesized and characterized by single-crystal Xray diffraction analysis, IR spectrometry, TG analysis, and elemental analyses. Single-crystal X-ray diffraction analysis revealed that [ Co（ 2,2＇-bipy） （ H2O）4 ]^2＋ units and adjacent 1,4-chdc^2- formed a single layer by hydrogen bonding and electrostatic interactions along the ac-plane, and two symmetry-related single layers interacted with each other by hydrogen bonding, resulting in a double layer, which further formed a 3-D structure by π-π stacking. The most attractive structural feature of compound 1 is that 1,4-chdc2- possesses only tram-conformation although there are both c/s- and tram-conformations in the raw material.     

Syntheses,Structures,and Properties of Two New Coordination Polymers Based on Tetracarboxylate and 2,2′-Bipyridine Mixed Ligands

Two new coordination polymers {[Zn2L1(2,2'-bpy)2(H2O)2]·4H2O}n(1) and [Zn2L2(2,2'-bpy)2(H2O)2]n(2)(H4L1 = terphenyl-2,2',4,4'-tetracarboxylic acid, H4L2 = quarterphenyl-2,2',4,4'-tetracarboxylic acid, and 2,2'-bpy = 2,2'-bipyridine) have been synthesized and characterized by elemental analysis, IR and X-ray single-crystal diffraction studies. Complex 1 displays 2D wavelike networks, which are further joined together through O–H···O hydrogen bonds to give a 3D supramolecular network. Complex 2 exhibits 1D ladder-like chains, and they are further joined together by π-π stacking and O–H···O hydrogen bonding interactions to form a 3D supramolecular network. The results indicate that the backbone of carboxylate ligands has significant effects on the formation and structure of the resulting functional coordination polymers. Additionally, thermal stability and photoluminescent properties of 1 and 2 are also investigated in detail.     

Two New Mn(Ⅱ)/Co(Ⅱ) Complexes Assembled by 2,5-Dihydroxy-1,4-benzenedicarboxylic Acid and Phenanthroline or Derivative

Two new complexes [Mn(DHTA)(PLQ)]n(1) and{[Co2(DHTA)(phen)2(H2 O)6]· DHTA}n(2)(H2 DHTA = 2,5-dihydroxy-1,4-benzenedicarboxylic acid, PLQ = 1,10-phenanthroline-5,6-quinone, phen = 1,10-phenanthroline) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, fluorescence spectrum, single-crystal and power X-ray diffraction. Complex 1 exhibits a two-dimensional(2 D) network, which was stabilized through O–H···O hydrogen bonding interactions. Complex 2 shows a zero-dimensional structure, which was further extended into a three-dimensional supramolecular structure through O–H···O hydrogen bonds and π-π interactions.     

Hybrid Tungstocuprate [Cu(2,2′-bpy)_3]_2H_4[CuW_(12)O_(40)]·6H_2O Based on Keggin Polyoxoanion [CuW_(12)O_(40)]~(6-) with Cu~Ⅱas Heteroatom

A novel hybrid tungstocuprate(Ⅱ) [Cu(2,2′-bpy)3]2H4[CuW12O40]·6H2O(2,2′-bpy=2,2′-bipyridine) was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [CuW12O40]6- and a pair of chiral complex cations [Cu(2,2′-bpy)3] together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [Cu(2,2′-bpy)3] via multiple C—H…O hydrogen bonds resulting in a dimer.     

Hybrid Tungstocuprate [Cu(2,2'-bpy)3]2H4[CuW12O40]·6H2O Based on Keggin Polyoxoanion [CuW12O40]6-with CuⅡas Heteroatom

A novel hybrid tungstocuprate(Ⅱ) [Cu(2,2'-bpy)3]2H4[CuW12O40]·6H2O(2,2'-bpy=2,2'-bipyridine) was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [CuW12O40]6- and a pair of chiral complex cations [Cu(2,2'-bpy)3] together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [Cu(2,2'-bpy)3] via multiple C-H…O hydrogen bonds resulting in a dimer.     

Crystal structure of a novel two-dimensional supramolecular network based on polyoxoanion and yttrium~Ⅲcoordination cation

A novel compound (NH4)2Y(H2O)8[PMo10V2O40]·10H2O has been prepared in an aqueous solution and characterized by elemental analysis, IR, and TG-DTG analysis. X-ray diffraction analysis was carried out on (NH4)2Y(H2O)8 [PMo10V2O40]·10H2O single crystal, which crystallizes in the monoclinic system of a space group P21/C with a=0.9871(3) nm,b=1.5424(5) nm,c=2.7924(9) nm,β=94.183(5)°and Z=2. In the compound, a two-dimensional network is constructed by the PMo10V2O405- anion and the Y(H2O)83 cation building blocks via hydrogen bonding exhibiting the porous structure.     

Dawson型钒代磷钼酸在酮/醇缩合中的催化性能

合成了Dawson型磷钼酸和钒取代磷钼酸, 用UV-Vis、 IR和XRD表征了结构, 用pH计考察了在不同介质中的酸性. 以苯乙酮和醇的缩合反应作为探针反应, 考察了磷钼酸中钒含量、磷钼酸用量及醇用量等因素对磷钼酸催化性能的影响. 结果表明, 钒取代钼后使Dawson型磷钼酸在有机介质中的酸性减弱. 当H_6P_2Mo_(18)O_(62)∶苯乙酮∶乙二醇的物质的量比为6∶1000∶2000, 回流反应6 h时, 缩酮收率为89.2 %. 在合成缩酮的反应中, 磷钼酸的"假液相"性使其催化活性明显增强, 但随着钒取代数增加, 钒取代磷钼酸的催化性能减弱;醇分子的空间位阻增大, 磷钼酸的催化活性也降低.     

过渡元素Dawson结构的钨钒磷四元杂多配合物的合成与表征

制备了两个系列１２种尚未见文献报道的过渡金属Ｄａｗｓｏｎ结构的钨钒磷四元杂多配合物。经元素分析和热重分析确定配合物通式为Ｋ９，１０［Ｐ２Ｍ（Ｈ２Ｏ）Ｗ１５Ｖ２Ｏ６１］．ｘＨ２Ｏ和Ｋ１０，，１１［Ｐ２Ｍ（Ｈ２Ｏ）Ｗ１４Ｖ３Ｏ６１］．ｘＨ２Ｏ）（Ｍ＝Ｆｅ＾３＾＋，Ｃｏ＾３＾＋，Ｎｉ＾２＾＋，Ｍｎ＾２＾＋，Ｃｕ＾２＾＋，Ｚｎ＾２＾＋＿），采用ＩＲ，ＵＶ，ＮＭＲ，ＥＳＲ和ＸＲＤ等方法进行了结构表征。     

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.     

A 3-D Wells–Dawson phosphotungstate hybrid material modified by Na+ and a bi-copper organic complex linker,and its photo-/electro-catalytic properties

An inorganic–organic hybrid material based on Dawson polyoxometalates, [Na₂{Cu^I₂(bim)₂}₂(P₂W₁₈O₆₂)]·2H₂O (bim = biimidazole) (1), has been hydrothermally synthesized and fully characterized. In 1, each {P₂W₁₈} cluster as a hexa-node ligand connects to six adjacent Dawson clusters via six Na1 ions to generate a pure inorganic 2-D layer, further joined by bimetal–organic segments [Cu₂(bim)₂]²⁺ to form a 3-D inorganic–organic hybrid framework with channels. The structure can be simplified to 3,8-connected 3-D networks with (4³)(4¹⁸·6²⁴·8³) topology, which shows bifunctional electrocatalytic performance for oxidation of ascorbic acid (AA) and reduction of nitrite (NO₂^?), and high-efficient degradation ability for three typical dyes under UV light irradiation.     

Pilaring of Zn_2Al Layered Double Hydroxide by Dawson Polyoxometalate Anions

ＰｉｌａｒｉｎｇｏｆＺｎ２ＡｌＬａｙｅｒｅｄＤｏｕｂｌｅＨｙｄｒｏｘｉｄｅｂｙＤａｗｓｏｎＰｏｌｙｏｘｏｍｅｔａｌａｔｅＡｎｉｏｎｓ＊＊ＳｕｐｐｏｒｔｅｄｂｙｔｈｅＮａｔｉｏｎａｌＮａｔｕｒａｌＳｃｉｅｎｃｅＦｏｕｎｄａｔｉｏｎｏｆＣｈｉｎａａｎｄｔ...     

Hydrothermal synthesis and structural characterization of two 1-D and 2-D Dawson-based phosphotungstates

Two new Dawson-based phosphotungstates (H₂en)_0.5H[Cu(en)₂(H₂O)]₂{[Cu(en)₂](α₁-P₂W₁₇CuO₆₁)}·8H₂O (1) (en=ethylenediamine) and [4,4′-H₂bpy]₂{[Cu(4,4′-bpy)₃][Cu(4,4′-bpy)₄(H₂O)₂]₂[Cu(4,4′-bpy)][α-P₂W₁₈O₆₂]₂}·6H₂O (2) (4,4′-bpy=4,4′-bipyridine) have been hydrothermally synthesized and structurally characterized. 1 crystallizes in the triclinic space group P−1 with a=11.7626(17), b=13.246(2), c=29.350(5) Å, α=87.355(5), β=79.583(5), γ=66.993(3)°, V=4138.3(11) Å³, Z=2, GOF=1.089, R₁=0.0563 and wR₂=0.1505, whereas 2 belongs to the orthorhombic space group Iba2 with a=22.277(8), b=47.04(2), c=22.153(8) Å, V=23215(17) Å³, Z=4, GOF=1.051, R₁=0.0627 and wR₂=0.1477. 1 consists of a 1-D linear chain structure constructed from monocopper^II-substituted Dawson polyoxoanions, while 2 represents the first 2-D sheet-like structure with a (4,4)-connected topological net built up from plenary Dawson-type polyoxoanions and Cu^II-4,4′-bpy complex cations in polyoxometalate chemistry.     

Ammonia sorption by Dawson acid studied by IR spectroscopy and microbalance

Using in-situ microbalance and infrared spectroscopy techniques the double ammonia proton complexation was traced. The results confirm the formation of N₂H₇⁺ dimer in solid Dawson acid H₆P₂W₁₈O₆₂, previously reported only for N₂H₇I and for (N₂H₇)₄SiW₁₂O₄₀. The formation of such dimers was evidenced by the microbalance results, the molar ratio of ammonia to proton was measured as 2:1 at 10.7 kPa and 298 K. The formation of NH₄⁺ monomer (band at 1410 cm⁻¹) and N₂H₇⁺ dimer (1460 cm⁻¹) was revealed by IR spectroscopy. Enthalpy of ammonia sorption on Dawson structure was calculated to be −127.9 kJ mol⁻¹, indicating the lower acid strength of Dawson-type compared to that of the Keggin-type heteropolyacids, like H₄SiW₁₂O₄₀.     

Studies on the Synthesis and Properties of K_8[TiP_2W_17O_62]·12H_2O

The present paper covers a salt of 2:18 heteropoly complex of tungstotitanophosphate prepared with the method of improved sequence preparation. The title compound was characterized by elemental analysis, 31P NMR spectra, polarography, cyclic voltammetry, IR, UV, X-ray powder diffraction , X-ray photoelectron spectra and TG-DTA analysis. The results show that the complex with the formula K8[TiP2W17O62]·12H2O has Dawson structure. Its properties such as spectra, redox behavior and thermal stability are discussed.     

Synthesis and Characterization of Heteropoly Coordination Compounds Containing Optical Ligands

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Hydrothermal Combination of Trilacunary Dawson Phosphotungstates and Hexanickel Clusters: From an Isolated Cluster to a 3D Framework

Three novel hexa‐Ni‐substituted Dawson phosphortungstates [Ni₆(en)₃(H₂O)₆(μ₃‐OH)₃(H₃P₂W₁₅O₅₆)] ? 14 H₂O ( 1 ), [Ni(enMe)₂(H₂O)][Ni₆(enMe)₃(μ₃‐OH)₃(H₂O)₆(HP₂W₁₅O₅₆)] ? 10 H₂O ( 2 ), and [Ni(enMe)₂]₃[Ni(enMe)₂(H₂O)][Ni(enMe)(H₂O)₂][Ni₆(enMe)₃(μ₃‐OH)₃(Ac)₂(H₂O)(P₂W₁₅O₅₆)]₂ ? 6 H₂O ( 3 ) (en=ethylenediamine, enMe=1, 2‐diaminopropane, Ac=CH₃COO^?) have been made under hydrothermal conditions and were characterized by IR spectroscopy, elemental analysis, diffuse reflectance spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. The common structural features of compounds 1 – 3 contain the similar hexa‐Ni‐substituted Dawson polyoxometalate (POM) units that can be viewed as a [Ni₆(μ₃‐OH)₃]⁹⁺ cluster capping on a [P₂W₁₅O₅₆]^12? fragment. Compounds 1 and 2 are two isolated clusters, whereas compound 3 is the first 3D POM framework constructed from hexa‐Ni‐substituted Dawson POM units and Ni(enMe) complex bridges. The preparations of compounds 1 – 3 not only indicate that triangle coplanar Ni₆ clusters are very stable fragments in both trivacant Keggin and trivacant Dawson POM systems, but also offer that the hydrothermal technique can act as an effective strategy for making novel Dawson‐type high‐nuclear transition‐metal cluster substituted POMs by combination of lacunary Dawson precusors with transition‐metal cations in the tunable role of organic ligands. In addition, magnetic measurements illustrate that there exist overall ferromagnetic interactions in compound 3 .