Cation-directed synthesis of tungstosilicates. 1. Syntheses and structures of K10A-alpha-[SiW9O34].24H2O,of the sandwich-type complex K10.75[Co(H2O)6]0.5[Co(H2O)4Cl]0.25A-alpha-[K2(Co(H2O)2)3(SiW9O34)2].32H2O and of Cs15[K(SiW11O39)2].39H2O

The influence of the nature of alkali metal cations on the structure of the species obtained from the trivacant precursor A-alpha-[SiW(9)O(34)](10-) has been studied. Starting from the potassium salt 1, K(10)A-alpha-[SiW(9)O(34)].24H(2)O, the sandwich-type complex 2, K(10.75)[Co(H(2)O)(6)](0.5)[Co(H(2)O)(4)Cl](0.25)A-alpha-[K(2)(Co(H(2)O)(2))(3)(SiW(9)O(34) )(2)].32H(2)O, has been obtained. The crystal structures of these two compounds consist of two A-alpha-[SiW(9)O(34)](10-) anions linked by a set of potassium (1) or cobalt plus potassium cations (2), and the relative orientation of the two half-anions is the same. Attempts to link two A-alpha-[SiW(9)O(34)](10-) anions by tungsten atoms instead of cobalt failed whatever the alkali metal cation. Moreover, the nondisordered structure of Cs(15)[K(SiW(11)O(39))(2)].39H(2)O is described. Two [SiW(11)O(39)](8-) anions are linked through a potassium cation with a "trans-oid" conformation, and the potassium occupies a cubic coordination site.     

Cation-directed synthesis of tungstosilicates. 2. Synthesis, structure, and characterization of the open Wells-Dawson anion alpha-[{K(H2O)2}(Si2W18O66)]15- and its transiton-metal derivatives [{M(H2O)}(mu-H2O)2K(Si2W18O66)]13- and [{M(H2O)}(mu-H2O)2K{M(H2O)4}(Si2W18O66)]11-

The dimer alpha-[{K(H2O)2}(Si2W18O66)]15- (1), synthesized by reacting K10A-alpha-[SiW9O34] with two equivalents of H+ in aqueous solution, has been characterized by polarography and 183W NMR spectroscopy. Nine resonance signals have been observed with the tetrabutylammonium salt in dimethylformamide/acetonitrile solution, in agreement with the crystal structure of the anion which consists of two A-alpha-[SiW9O34]10- associated through two W-O-W junctions. This anion derives from the Wells-Dawson structure by breaking four W-O-W junctions. The pocket between the two-half-anions can be filled by several metal cations. Reaction of transition-metal cations with 1 leads to the formation of [{M(H2O)}(mu-H2O)2K(Si2W18O66)]13- (1M) (M = Co, Ni, Cu) and [{M(H2O)}(mu-H2O)2K{M(H2O)4}(Si2W18O66)]11- (1M2) (M = Mn, Co, Ni) complexes. One potassium is always included in the pocket with one or two transition metals. Because of the shift of the potassium cation to one side of the anion, the coordination modes of the two transition metals are different. Crystals of 1, 1M, and 1Co2 potassium salts are triclinic (P-1, Z = 2) and crystals of 1M2 potassium salts are monoclinic (P2(1)/n, Z = 4). The symmetry of 1Mand 1M2 complexes is C1 and they are present in the crystal as racemate inversion pairs.     

3D-transition metal mono-substituted Keggin polyoxotungstate with an antenna molecule: synthesis, structure and characterization

Three new organic-inorganic hybrid complexes based on 3d-transition metal monosubstituted Keggin polyoxometalates (POMs) with imidazole (Im) as pendant ligands, formulated as (HIm)(6-)[SiW11O39NiIm]0.8[SiW11O39Ni(H2O)]0.2.7H2O (1), (Im)4Na6[SiW11O39MnIm]0.69[SiW11O39Mn(H2O)]0.31.7.5H2O (2) and (HIm)6[SiW11O39CoIm]0.63[SiW11O39Co(H2O)]0.37.7H2O (3), have been synthesized and characterized by IR spectroscopy, UV-visible spectroscopy, elemental analysis, TG analysis, cyclic voltammetry, magnetic properties, EPR and single-crystal/powder X-ray diffraction. The structural analyses indicate that the 3d metal atoms are incorporated into the vacancy of the alpha-[SiW11O39](8-) (SiW11). Complexes 1-3 are the first examples of crystallographically characterized 3d-transition metal mono-substituted POMs with an antenna organic ligand synthesized under normal bench conditions.     

两个新的含铜杂多钨酸盐的合成、晶体结构和电化学行为

采用水热方法合成2个新的含铜杂多钨酸盐[Cu(en)2 (H2O)2][Cu(en)2]4[Cu(en)2 (H2O)]·[Cu4( H2O)2 (SiW9O34)2]·7H2O(en=乙二胺)(1)和[Cu(en)2(H2O)]2[Cu(en)2]4[CuSiW11O39]2·7H2O (2).化合物1是由过渡金属配...     

Keggin三取代型杂多阴离子183W NMR化学位移的特征模式

三空位杂多阴离子ＳｉＷ９Ｏ１０－３４有α和β两种异构体［１］,β－ＳｉＷ９Ｏ１０－３４阴离子钠盐的晶体结构测定表明,它是β－ＳｉＷ１２Ｏ４－４０阴离子的缺位衍生物,是从β－ＳｉＷ１２Ｏ４－４０阴离子中去掉３个ＷＯ６八面体后形成的含３个空位的杂多阴离子...     

过氧钛钨硅杂多配合物的合成、表征及催化活性

合成了过氧钛钨硅杂多酸盐α-M6-mHm[SiW11(TiO2)O39].xH2O和α-M10-mHm[SiW9(TiO2)3O37].xH2O(M=K, TBA), 用IR, UV吸收光谱,极谱-循环伏安, 183W NMR, XPS和XRD等测试方法对其性质、结构进行研究。结果表明, 它们都是具有Keggin结构的过氧杂多配合物,TiO2基的引入将其极谱半波电位提高至-0.3V以上, 它们对顺丁烯二酸的H2O2环氧化反应具有显著高的催化活性。     

过氧杂多阴离子柱撑水滑石的合成、表征及催化性能的研究

通过离子交换法, 将含钛过渡金属离子一、三取代钨硅、钨磷过氧杂多配合物嵌入Zn2Al类水滑石中, 获得了柱撑化合物, 并用XRD, IR, XPS, 元素分析等手段对产物的结构和组成进行了表征。结果表明, 过氧杂多阴离子进入水滑石层间后, 水滑石的层间距从0.92nm增大到1.47nm, 且O2^2^-链没有被破坏。柱撑产物在环己烯氧化反应中显示优良的催化性能。     

过氧杂多阴离子型层柱化合物的合成、表征及催化活性

通过离子交换法,将含Zr过渡金属离子1,3取代钨硅、钨磷过氧杂多酸盐嵌入Zn2Al类水滑石中,获得了层柱化合物,并用XRD,IR,UV等手段对产物的结构进行了表征.结果表明过氧杂多阴离子进入水滑石层间后,水滑石的层间距从0.92增大到1.47 nm,且过氧链没被破坏.层柱化合物在酯化反应中显示优良的催化性能.     

β-K4H3[SiW9O37(CpTi)3]·11H2O环戊二烯钛多酸衍生物与DNA作用研究

某些过渡金属配合物具有特异性催化DNA和RNA断裂的功能, 因而研究过渡金属配合物对DNA和RNA的断链反应对新型抗肿瘤、抗艾滋病化学药物的定向设计及其基因治疗和分子生物学中DNA和RNA的高度专一性定点断裂、 DNA定位诱变和构象识别具有重要意义和应用前景[1,2]. 我们对二茂钛多酸有机金属衍生物合成及抗肿瘤活性研究表明, 环戊二烯钛多氧金属酸盐衍生物具有很高的抗肿瘤活性和较好的水溶性及稳定性, 有潜在的抗肿瘤药用价值[3].     

Phenyltin-substituted 9-tungstogermanate and comparison with its tungstosilicate analogue

Reaction of (C 6H 5)SnCl 3 with Na 10[ A-alpha-GeW 9O 34] in water results in the monomeric, trisubstituted Keggin species [{(C 6H 5)Sn(OH)} 3( A-alpha-GeW 9O 34)] (4-) ( 1), constituting the first organotin derivative of a trilacunary Keggin tungstogermanate. Polyanion 1 could be obtained as two different cesium salts depending on the applied isolation strategy: Cs 3Na[{(C 6H 5)Sn(OH)} 3( A-alpha-GeW 9O 34)].9H 2O ( CsNa-1) and Cs 3[{(C 6H 5)Sn(OH)} 3( A-alpha-HGeW 9O 34)].8H 2O ( Cs-H1). The monomeric phenyltin-containing tungstosilicate [{(C 6H 5)Sn(OH)} 3( A-alpha-SiW 9O 34)] (4-) ( 2) and the dimeric, sandwich-type derivative [{(C 6H 5)Sn(OH)} 3( A-alpha-H 3SiW 9O 34) 2] (8-) ( 3) have also been isolated as the cesium salts Cs 3Na[{(C 6H 5)Sn(OH)} 3( A-alpha-SiW 9O 34)].9H 2O ( CsNa-2), Cs 4[{(C 6H 5)Sn(OH)} 3( A-alpha-SiW 9O 34)].13H 2O ( Cs-2), and Cs 8[{(C 6H 5)Sn(OH)} 3( A-alpha-H 3SiW 9O 34) 2].23H 2O ( Cs-3), respectively. We have investigated in detail the similarities and differences in the reactivity of (C 6H 5)Sn (3+) with [ A-alpha-GeW 9O 34] (10-) vs [ A-alpha-SiW 9O 34] (10-). All five compounds have been characterized in the solid state by means of elemental analysis, infrared spectroscopy, thermogravimetry, and single-crystal X-ray diffraction, representing the first structural analysis for polyanions 1- 3. A full solution characterization of 1 by multinuclear NMR spectroscopy ( (1)H, (13)C, (119)Sn, and (183)W) has also been performed. The monomeric polyanions 1 and 2 are closely associated in the solid state through (Sn)O-H...O t (O t: terminal oxygen atom) hydrogen bonds reinforced by weak C-H...O t contacts to form 2-dimensional ( CsNa-1 and CsNa-2) or 1-dimensional ( Cs-H1) arrangements, and also dimeric entities ( Cs-2) depending on the network of intermolecular interactions.     

About the Keggin isomers: crystal structure of [N(C4H9)4]-gamma-[SiMo2W10O40]n- (n= 4 or 6)

The tetrabutylammonium gamma-dodecatungstosilicate has been crystallized in a 6/1 acetonitrile/water solvent. An X-ray single-crystal analysis was carried out on [N(C4H9)4]4-gamma-[SiW12O40] which crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with a = 19.0881(3) A, b = 21.4435(3) A, c = 26.0799(1) A, V = 10674.9(2) A3, Z = 4, and rho(calcd) = 2.392 g/cm3. The idealized C2v arrangement of the anion results from the rotation of 60 degrees of two trigonal [W3O13] groups in the Keggin anion. Taking as reference the geometrical characteristics of the Keggin anion, it appears that the bond lengths and bonds angles within the four [W3O13] groups are not significantly modified while the mu-oxo junctions between the two rotated groups and those between the two unrotated groups involve more acute and opened W-O-W angles, respectively. The syntheses and 183W NMR characterizations of the mixed gamma-[SiW10Mo2O40]n- compounds corresponding to the oxidized (Mo(VI); n = 4) and to the two electron-reduced (Mo(V); n = 6) anions are reported. Structural analysis by 183W NMR has proved unambiguously that the C2v structure of the gamma-[SiW10O36]8- subunit is retained in both the compounds. The electronic behavior of the series gamma-[SiW10M2E2O36]6- (M = Mo or W; E = O or S) is examined, compared and related to 183W NMR data.     

Si取代Keggin型多酸催化光解水产氢机理

本文采用DFT和TD-DFT方法研究了Keggin型多酸[SiW12O40]4-光催化劈裂水产氢气机理。计算结果显示反应主要包括四个步骤：(i) 光激发,(ii) 电荷转移和生成单电子还原(OER)中间体,(iii) 生成双电子还原(TER)中间体,(iv)氢气从多酸表面解离和催化剂重生。当第一个电子从甲醇转移到多酸后,后续反应存在均为热力学上有利的放热途径,并推动第二个电子从甲醇自由基,H[SiW12O40]4-或[SiW12O40]5-转移到OER中间体H[SiW12O40]4-或[SiW12O40]5-生成TER中间体[SiW12O40]6-,H[SiW12O40]5-或H2[SiW12O40]4-,并伴随着H2产生。耦合的电子和质子转移路径在能量上最有利。甲醇和水分子的参与有利于H2产生。多酸在整个催化循环中,扮演了光敏剂、催化剂、电子的受体和给体。     

Investigation of the pronounced medium effects observed in the voltammetry of the highly charged lacunary anions [alpha-SiW11O39]8- and [alpha-PW11O39]7-

A detailed study is reported of the influence of protons, metal cations, and media on the redox chemistry of lacunary anions [alpha-SiW11O39]8- and [alpha-PW11O39]7- of high formal negative charge. Each anion displayed a single chemically reversible one-electron reduction process in carefully dried aprotic CH3CN solution. This process was detected at very negative potentials just prior to the solvent limit. Addition of 0.3 equiv of acid gave rise to a new reduction process at considerably less negative potentials, which is attributed to formation of the protonated species [SiW11O38(OH)]7- and [PW11O38(OH)]6-. Voltammograms derived from simulations based on a double-square scheme are in excellent agreement with experiment. Previous data reported the presence of several processes in CH3CN and appear to have been influenced by the presence of protons and/or adventitious water. Not surprisingly, protonation reactions coupled to charge transfer contribute significantly to the voltammetry of these lacunary anions in buffered aqueous media over the pH range 2-6. A multi-square-scheme mechanism allowed the essential thermodynamic and kinetic features of this system to be captured and an assessment of the relative significance of possible individual pathways. The high formal anionic charges of [SiW11O39]8- and [PW11O39]7- appear to provide highly basic reduced forms that are able to abstract protons from water to produce protonated species which are reduced at potentials more than a volt less negative than those for the processes [SiW11O39]8-/9- and [PW11O39]7-/8- found in dry aprotic media.     

Two multi-copper-containing heteropolyoxotungstates constructed from the lacunary Keggin polyoxoanion and the high-nuclear spin cluster

Two novel high-nuclear copper-substituted polyoxometalates, Na16[Cu14(OH)4(H2O)16(SiW8O31)4].20.5H2O (1) and K10Na14[Cu10(H2O)2(N3)4(GeW9O34)2(GeW8O31)2].30H2O (2), containing 14 Cu2+ ions and 10 Cu2+ ions, respectively, have been obtained in aqueous solution and characterized by IR, UV, TG, element analysis, electrochemistry, and single-crystal X-ray analyses. The polyoxoanion framework of 1 is composed of four [beta-SiW8O31] units connected by 14 Cu2+ ions to constitute a tetrameric compound. In 2, two [beta-GeW8O31] anions and two [B-alpha-GeW9O34] anions are connected together by a [Cu10(N3)4O32(H2O)2] {Cu10(N3)4} cluster to construct a novel tetrameric compound. The results of the electrocatalytic experiments reveal that the reduced species of 1 and 2 have electrocatalytic activities for nitrate reduction.     

Cation-controlled assembly of Na+-linked lacunary alpha-Keggin tungstosilicates

Two novel salts of lacunary tungstosilicates with guanidinium and alkali metal cations, (CH6N3)7Na[SiW11O39].(CH3)2CO.8H2O (1) and (CH6N3)K6Na[SiW11O39].11.5H2O (2), have been synthesized and their crystal structures have been determined by synchrotron X-ray diffraction. In both crystals, the Na+ cations link the lacunary Keggin-type tungstosilicate anions into linear structures. The neighboring [SiW11O39]8- anions are related by two-fold screw and translational operations in compounds 1 and 2, respectively. Second harmonic generation was observed for compound 1.     

γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物的合成与表征

利用缺位填充法合成了12个γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物K13[Ln(SiW10O36)2]·nH2O(Ln=La3+,Ce3+,Pr3+,Nd3+,Sm3+,Eu3+,Gd3+,Tb3+,Dy3+,Ho3+,Er3+,Yb3+).通过元素分析确定其组成,由红外光谱、紫外-可见吸收光谱、循环伏安及室温磁化率测定结果确认稀土离子与γ-[SiW10O36]8-相配位;183WNMR及荧光光谱结果则表明,稀土离子处于2个γ-[SiW10O36]8-构成的八配位环境中,标题化合物具有夹心型D2d对称性结构.     

含硅多金属氧酸盐的抑菌作用

本文按文献方法合成了α-1,2,3-K6H[SiW9V3O40]、α-1,2-K6[SiW10V2O40]和α-K5[SiW11VO40](以下分别简写为α-SiW9V3,α-SiW10V2,α-SiW11V)3种多金属氧酸盐,并通过紫外和红外光谱对3种多金属氧酸盐化合物结构进行了表征。利用纸片法研究了3种钒取代的硅钨酸盐及硅钨酸（H4SiW12O40?xH2O,简写为SiW12）对大肠杆菌、枯草芽孢杆菌、酵母菌、黑曲霉和青霉的抑菌活性。结果表明：4种物质对大肠杆菌、枯草芽孢杆菌、酵母菌和黑曲霉均有不同程度的抑菌效果,但对青霉的抑菌效果较差。由于引起果蔬腐败的微生物主要有细菌、杆菌、霉菌和酵母菌等,本实验将为多金属氧酸盐作为广谱高效果蔬保鲜剂提供理论依据。     

Selective precipitation of prions by polyoxometalate complexes

The efficacy of a variety of polyoxometalate anions in selectively precipitating the infectious isoform of the prion protein (PrPSc) over the normal, cellular protein (PrPC) was tested as a means of improving the sensitivity of a conformation-dependent immunoassay (CDI). Experiments utilizing neutralized aqueous solutions containing MgCl2.6H2O and Na2H[PW12O40] (1) indicated that use of the former is detrimental to selectivity, while use of the latter gives optimal selectivity at a concentration of 2.48% w/v, much higher than the 0.31% w/v employed in the current CDI protocol. Similar experiments using Na4[SiW12O40] (2), K5[BW12O40] (3), and Na6[H2W12O40] (4) were performed to probe the role of charge density in polyoxometalate anions possessing the Keggin structure. These, coupled with assignment of solution structures via NMR and infrared spectroscopy, revealed the following trend in optimal concentrations: [HBW11O39]8- < [SiW11O39]8- < [PW11O39]7- = [H2W12O40]6-. Interestingly, use of the salts K10[Zn4(H2O)2(PW9O34)2] (5), Na16[Zn4(H2O)2(P2W15O56)2] (6), and Na27[NaAs4W40O140] (7), containing larger polyoxometalate anions, was found to suppress PrPSc precipitation in a concentration-dependent manner. Taken together, the results suggest a precipitation mechanism wherein Keggin-type anions link multiple PrPSc moieties by binding a somewhat hindered cleft featuring one or more positively charged residues.     

Surface modification of mesoporous, macroporous, and amorphous silica with catalytically active polyoxometalate clusters

Transition-metal-substituted polyoxometalates (TMSP) of the type [MII(H2O)PW11O39]5- (M = Co, Zn) and [SiW9O37(CoII(H2O))3]10- have been chemically anchored to modified macroporous (400 nm pores), mesoporous (2.8 nm pores), and amorphous silica surfaces. The materials were characterized by solid-state 31P MAS NMR, UV-vis, FT-IR spectroscopy, and N2 adsorption experiments to verify cluster attachment and the structure of the TMSP on the support. On the basis of the spectroscopic evidence, clusters were attached datively to the surface, and the integrity of the [CoPW11] cluster was maintained for nonaqueous impregnation with TBA5[CoPW11]; partial degradation of the cluster occurred when it was impregnated from aqueous solution using the K5[CoPW11] salt. Both the amine surface groups and the cobalt centers in the clusters were found to be necessary to prevent cluster loss during washing or reaction processes. The catalytic activities of the supported TMSP clusters were tested by the epoxidation of cyclohexene to cyclohexene oxide in the presence of isobutyraldehyde. The percent conversion of the substrate and the amount of product formed per unit time were similar for [CoPW11] clusters on each of the three silica supports, but slightly lower than for purely homogeneous reactions. [SiW9Co3] clusters with three available cobalt centers exhibited higher catalytic activity with nearly identical performance on a silica support or in homogeneous solution.     

Two novel trivacant Keggin-type polytungstates supported manganese carbonyl derivatives synthesized by degradation of metastable [γ-XW10O36]8- (X = Ge(IV), Si(IV))

Two novel trivacant Keggin-type polyoxometallate-based manganese carbonyl derivatives K(8)[(OC)(3)Mn(A-α-H(2)GeW(9)O(34))]·10H(2)O (1) and K(8)[(OC)(3)Mn(A-α-H(2)SiW(9)O(34))]·11H(2)O (2) have been synthesized by degradation of the metastable [γ-XW(10)O(36)](8-) (X = Ge(IV), Si(IV)) in CH(3)CN-H(2)O solvent (1 : 2, vol.) and structurally characterized by elemental analyses, IR spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray diffraction analyses indicate that 1 and 2 are isomorphic and consist of a [(OC)(3)Mn](+) group and a trivacant [A-α-H(2)XW(9)O(34)](8-) fragment, which exhibit the first examples of trivacant Keggin-type metal carbonyl derivatives. Additionally, the electrocatalytic properties of both for NO(2)(-) oxidation have been investigated.