Assignment of multiline tungsten-183 NMR spectra of diamagnetic polyoxotungstates from intensity patterns

Measurement of relative integrated intensities and peak heights of multiline one-dimensional 183W NMR spectra of diamagnetic polyoxotungstates can result in complete or partial assignment of chemical shifts, even when 183W-183W spin-coupled satellites are not detectable or well-resolved. The intensity of the center peak of each signal is diminished according to the number and type (corner- vs edge-sharing of WO6 octahedra) of potential spin-couplings. Application of the method is exemplified by analysis of spectra of alpha-[XW11O39]n- and derivatives, alpha2-[P2W17O61]10-, and [As4W40O140]28-. Intensity patterns of the six-line spectra of the beta1 and beta3 isomers of [XW11O39]n- are sufficiently different to allow identification.     

Theoretical study of the relative stabilities of the alpha/beta3-[XW11O39](m-) lacunary polyoxometalates (X = P, Si)

A computational study of the relative stability of the monolacunary Keggin polyoxotungstates alpha and beta 3-[XW 11O 39] ( m- ) (X = P, m = 7; X = Si, m = 8) was performed. The influence of the nature of different grafted cations and of the central anion XO 4 ( n- ) on the relative stabilities of the lacunary isomers was analyzed. From these results, an interpretation of the structural difference in the metallic frameworks of alpha-[PW 11O 39{Ru(DMSO) 3(H 2O)}] (5-), alpha-[PW 11O 39{Ru(C 6H 6)(H 2O)}] (5-), and beta 3-[SiW 11O 39{Ru(DMSO) 3(H 2O)}] (6-) is proposed, and conclusions are drawn as to how to favor the formation of beta 3 derivatives in future syntheses.     

新型层柱微孔材料-XW11Co柱撑Zn-Al型层柱化合物的合成、表征及催化活性研究

采用水热合成与离子交换方法, 将中心原子不同的过渡金属(Co^2^+)取代型Keggin结构杂多阴离子XW11O39Co(H2O)^n^-(X=Ge^4^+, B^3^+和Co^2^+)嵌入Zn-Al型阴离子粘土层间, 合成了底面间距(d001)为1.46±0.01nm的新型层柱化合物Zn2Al-GeW11Co, Zn2Al-BW11Co和Zn2Al-CoW11Co; 通过XRD, IR, XPS和DTA等手段, 研究了它们的结构与性质, 推测了这些杂多阴离子(XW11Co)在层间的空间取向; 考察了这些新型层柱化合物对乙酸与n-丁醇酯化反应的催化活性; 吡啶吸附IR光谱研究结果表明, 它们同时具有B酸与L酸两种酸中心。     

杂多酸/聚乙烯醇复合膜的制备及光催化性能研究

合成了过渡金属取代的硅钨酸盐K₆SiM(H₂O)W₁₁O₃₉(M=Co、Ni、Cu,简称为SiMW₁₁),利用硅钨酸(H₄SiW₁₂O₄₀·nH₂O,简称为SiW₁₂)与SiMW₁₁做母体,分别将它们负载于聚乙烯醇(polyvinyl alcohol,PVA)上,制成一系列杂多酸/聚乙烯醇复合膜光催化剂,利用IR、SEM进行了表征.以高压汞灯为光源,分别研究了SiW₁₂/PVA、SiCoW11/PVA、SiNiW₁₁/PVA、SiCuW₁₁/PVA复合膜对有机染料甲基橙的光催化脱色,它们都具有很高的催化活性,60 min内对甲基橙的脱色率均可达到90%以上,其中SiW₁₂/PVA复合膜效果最好,12 min内脱色率达100%.提高SiW₁₂负载量可有效提高膜的光催化活性,当SiW₁₂与PVA质量比为1:1时催化活性最高.     

Hydrothermal and solid-state transformation of ruthenium-supported Keggin-type heteropolytungstates [XW11O39{Ru(II)(benzene)(H2O)}]n- (X = P (n = 5), Si (n = 6), Ge (n = 6)) to ruthenium-substituted Keggin-type heteropolytungstates

A new pathway for the preparation of mono-ruthenium (Ru)(iii)-substituted Keggin-type heteropolytungstates with an aqua ligand, [PW(11)O(39)Ru(iii)(H(2)O)](4-) (1a), [SiW(11)O(39)Ru(iii)(H(2)O)](5-) (1b) and [GeW(11)O(39)Ru(iii)(H(2)O)](5-) (1c), using [Ru(ii)(benzene)Cl(2)](2) as a Ru source was described. Compounds 1a-1c were prepared by reacting [XW(11)O(39)](n-) (X = P, Si and Ge) with [Ru(ii)(benzene)Cl(2)](2) under hydrothermal condition and were isolated as caesium salts. Ru(benzene)-supported heteropolytungstates, [PW(11)O(39){Ru(ii)(benzene)(H(2)O)}](5-) (2a), [SiW(11)O(39){Ru(ii)(benzene)(H(2)O)}](6-) (2b) and [GeW(11)O(39){Ru(ii)(benzene)(H(2)O)}](6-) (2c), were first produced in the reaction media, and then transformed to 1a, 1b and 1c, respectively, under hydrothermal conditions. Calcination of Ru(benzene)-supported heteropolytungstates, 2a, 2b and 2c, in the solid state produced mixtures of 1a, 1b and 1c with CO (carbon monoxide)-coordinated complexes, [PW(11)O(39)Ru(ii)(CO)](5-) (4a), [SiW(11)O(39)Ru(ii)(CO)](6-) (4b) and [GeW(11)O(39)Ru(ii)(CO)](6-) (4c), respectively. From comparison of their catalytic activities in water oxidation reaction, it was indicated that ruthenium should be incorporated in the heteropolytungstate in order to promote catalytic activity.     

单空位Keggin结构杂多化合物的相转移化学研究(英文)

利用相转移试剂四庚基溴化铵将含过渡金属单空位Ｋｅｇｇｉｎ结构杂多化合物［ＸＷ１１Ｏ３９Ｚ（Ｈ２Ｏ）］ｎ－（Ｘ＝Ｃｒ，Ｍｎ，Ｆｅ；Ｚ＝Ｃｏ，Ｚｎ，Ｃｒ；ｎ＝６，７），从水相转移至非极性溶剂有机相苯中．并根据电子光谱、ＩＲ谱、ＥＳＲ谱的变化，进一步考察了它们在有机相苯中的配位水脱去，形成配位不饱和杂多阴离子的情况，同时详细研究了该类杂多阴离子所含表面配位水与若干无机阴离子及有机配体的取代反应．实验表明，杂多阴离子由水相转移至有机相苯后，较易脱去配位水形成溶剂配位不饱和离子．当加入Ｌｅｗｉｓ碱时，可迅速恢复饱和配位．ＥＳＲ测定给出某些含过渡金属单空位Ｋｅｇｇｉｎ结构杂多阴离子相转移前后价态变化及电子转移情况．     

Photocatalytic Hydrogen Evolution of Keggin-type Polyoxotungstates and their Electrochemical Behaviors

Photocatalytic hydrogen production from water is considered as an approach for conversion of the solar energy into the chemical energy. During the past decades much efforts have been made to exploit the semiconductor photocatalysts working under both UV a…     

复合材料K_8[Fe(H_2O)CdW_(11)O_(39)]/PANI/ZrO_2的制备、表征及光催化性能

采用静电自组装法制备了复合材料K_8[Fe(H_2O)CdW_(11)O_(39)]/PANI/ZrO_2.运用UV,IR,XRD,SEM-EDS和N_2吸附-脱附的检测手段对其进行了表征,并以该化合物作为催化剂,研究了其对孔雀石绿溶液的光降解情况.通过实验确定最佳的光降解条件:孔雀石绿溶液的初始浓度为25mg/L,孔雀石绿溶液的初始pH值为2,K_8[Fe(H_2O)CdW_(11)O_(39)]/PANI/ZrO_2的用量为0.05g.在最佳的条件下,孔雀石绿溶液的脱色率可达98.68%.因此,K_8[Fe(H_2O)CdW_(11)O_(39)]/PANI/ZrO_2是一种光催化性能良好的复合材料.     

杂多阴离子的相转移化学 Ⅰ.取代的Keggin及Dawson结构杂多阴离子在非极性溶剂中的溶剂化行为研究

利用四庚基溴化铵将Keggin结构的杂多阴离子ZW~1~1O~3~9M(H~2O)^n^-(Z=Si,Ge,P,M=Ni^2^+,Cu^2^+,Cr^3^+,Co^2^+,n=4～6)和Dawson结构的杂多阴离子P~2W~1~7O~6~1M(H~2O)^n^-(M=Ni^2^+,Cu^2^+,Cr^3^+,Co^2^+,n=7,8) 从水溶液中转移至非极性溶剂(苯或甲苯)中,并观察到在水溶液中难以进行的配位水的脱去反应,形成配位不饱和的杂多阴离子.当加入Lewis碱如丙酮,吡啶等,可迅速恢复饱和配位,其电子吸收光谱也相应变化,基本恢复到配位饱和时的数值,有ESR信号.实验表明,在非极性溶剂中,配体之间相互进行的取代反应,吡啶的配位能力最强, 发生了取代反应ZW~1~1O~3~9M(L)^n^-+Py→ZW~1~1O~3~9M(Py)^n^-+L(L=丙酮,乙腈等).同时我们也研究了温度,杂多阴离子浓度,惰性气体流量对杂多阴离子在非极性溶剂中的溶剂化行为的影响,得到了相转移的一般规律,为杂多阴离子在非极性溶剂中的催化研究提供了理论依据     

The ruthenium(II)-supported heteropolytungstates [Ru(dmso)3(H2O)-XW11O39]6- (X = Ge, Si)

The novel Ru(II)-supported heteropolytungstates [Ru(dmso)(3)(H(2)O)XW(11)O(39)](6-)(X = Ge, Si) have been synthesized and characterized by single-crystal X-ray diffraction, multinuclear NMR ((183)W, (13)C, (1)H, (29)Si) and IR spectroscopy, elemental analysis and electrochemistry. The novel polyanion structure consists of a Ru(dmso)(3)(H(2)O) unit linked to a monolacunary [XW(11)O(39)](8-) Keggin fragment via two Ru-O-W bonds resulting in an assembly with C(1) symmetry. Polyanions 1 and 2 were synthesized by reaction of cis-Ru(dmso)(4)Cl(2) with [A-alpha-XW(9)O(34)](10-) in aqueous, acidic medium (pH 4.8). Tungsten-183 NMR of 1 leads to a spectrum with 11 peaks of equal intensity, indicating that the solid-state structure is preserved in solution. Electrochemistry studies revealed that 1 and 2 are stable in solution at least from pH 0 to 7, even in the presence of dioxygen. Their cyclic voltammetry patterns show mainly two two-electron reversible W-waves, those of the Si derivative 2 being located at slightly more negative potentials than those of the Ge derivative 1. The observed stability of 1 and 2 might be attributed to a stabilization of the Ru-center both by the strongly bound dmso ligands and the Keggin moiety. This stabilization drives the redox waves of Ru outside the accessible potential range. However, conditions were found to reveal, at least partially, the redox behavior of Ru in 1 and 2.     

Emission Spectra of Some Heteropolytungstates Containing Europium

The emission spectra of some heteropolytungstates containing europium, K.[Eu(XW11 O39)2](X = P, Ge, As, or Ga), K17[EuCAs2W17O61)2] and K16H9EuAs4W40O140 have been investigated and the structures of these compounds are discussed. The emission spectra at room temperature are very similar to each other in terms of both the number of bands and transition frequencies, showing that they have the similar structures to those of K16[Ce(P2W17O61)2] and K12[U(GeW11O39)2].     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11NiO6-39 and SiW11MnO6-39 on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11O39Ni(H2O)6-(SiNiW11) and SiW11O39Mn(H2O)6-(SiMnW11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-3 and NO-2 were comparatively studied.     

异双核X-M之间的磁耦合交换作用: Keggin型杂多酸衍生物[M(H2O)XW11O39]7-(X=FeⅢ, CoⅢ; M=CoⅡ)的密度泛函研究

采用DFT-BS方法研究异双核的Keggin型杂多酸衍生物[M(H2O)XW11O39]7-(Ⅰ: X=FeⅢ, M=CoⅡ; Ⅱ: X=CoⅢ, M=CoⅡ)的磁耦合作用, 计算得到耦合常数(J)为负值, 表明所研究体系具有反铁磁性; J值大小顺序为|J(Ⅰ)|<|J(Ⅱ)|, 说明磁耦合作用增强; 体系Ⅰ与Ⅱ相比, X由FeⅢ变成CoⅢ, M不变, 桥氧原子Ob和Ob2(O′b2)上的自旋密度增大, 进一步从相关BS态的磁轨道比较得出, 体系Ⅱ中轨道重叠程度大于体系Ⅰ, 结果使X-M之间的反铁磁耦合作用加强.     

SiW12、PbS对提高TiO2纳米管光电转换效率的协同效应研究

复合薄膜可以改善TiO2纳米管在光电转换时电子-空穴易复合和吸收光谱范围窄的缺陷。用电沉积法将多酸H4SiW12O40（SiW12）沉积在TiO2纳米管表面形成SiW12/TiO2纳米管复合薄膜,再用连续离子层吸附反应法（SILAR）将PbS吸附到SiW12 /TiO2纳米管复合薄膜表面,形成PbS/ SiW12/TiO2纳米管复合薄膜,所得薄膜的光电转换效率相较于TiO2纳米管提高了57倍。X射线衍射（XRD）和扫描电子显微镜（SEM）表征结果表明,用电沉积法和连续离子层吸附反应法实现了PbS/SiW12/TiO2纳米管复合薄膜的制备;紫外可见（UV-vis）吸收光谱测试表明,复合薄膜的光吸收带边扩展到了可见光区域,电化学阻抗测试（EIS）表明,复合薄膜具有更高的电子转移速率;荧光光谱（PL）测试表明,复合薄膜拥有更小的电子-空穴复合率。以上结果说明,SiW12、PbS与TiO2纳米管复合,很好地抑制了TiO2纳米管电子-空穴的复合,并拓宽了吸收光谱范围,能显著地提高TiO2纳米管的光电性能。本文探索了一种有效提高TiO2纳米管光电转换效率的方法,对TiO2纳米管复合薄膜的制备具有一定的参考意义。     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11 NiO39^6- and SiW11 MnO39^6- on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11 O39 Ni(H2O)^6- (SiNiW11) and SiW11 O39Mn( H2O)^6-( SiMnW11 ) were first immobilized on a 4-aminothiophenol (4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these muhilayer film electrodes for the reduction of BrO3^- and NO2^- were comparatively studied.     

Synthesis and Spectroscopic Characterization of Organothiophosphoryl Polyoxotungstates α- [C6H11P (S) ]2Xn+W11O39(8-n)- (Xn+ = P5+, Si4+, Ge4+, Ga3+)

Organothiophosphoryl polyoxotungstate derivatives α-C6H11P(S)]2Xn W11O39(8-n)- (X=P, Si, Ge, Ga)were obtained by the reactions of the monovacant α-[Xn W11O39](12-n)- (X=P, Si, Ge, Ga) anions with electrophilic C6H11P(S)Cl2 in acetonitrile. These new organic-inorganic hybrid anions were characterized by elemental analyses, IR, 31P and 183W NMR spectrometries. The six-line 183W NMR spectrum indicates that [C6H11P (S) ]2Xn W11O39(8-n)- (X= P, Si, Ge, Ga) anions possess true Cs symmetry in acetonitrile. According to the spectroscopic observation and the chemical analyses, it is known that each of the hybrid anions consists of an α-[XW11O3)] framework on which two equivalent C6H11P(S) groups are grafted through P-O-W bridges.     

Well-ordered self-assembled monolayers created via vapor-phase reactions on a monolayer template

The reaction of vapor-phase alkyl isocyanates (O=C=N-(CH2)n-1CH3) with OH-terminated alkanethiol template monolayers on Au produces well-organized self-assembled monolayers, containing intrachain carbamate linkages (Au/S(CH2)16O(C=O)NH(CH2)n-1CH3, where n = 1-8, 11, and 12). X-ray photoelectron spectroscopy, contact angle goniometry, and reflection absorption infrared spectroscopy suggest that the template surface completely reacts with the isocyanates yielding a monolayer that contains an interchain hydrogen-bonded carbamate network. Spectroscopic data indicates that the alkyl underlayer remains well ordered following reaction with the isocyanates. The order of the overlayer and the hydrogen-bonding interactions between adjacent chains increase as a function of the alkyl isocyanate chain length, n. The overlayer appears to be well ordered for n > or = 5.     

Fabrication and electrochemical investigation of layer-by-layer deposited titanium phosphate/Prussian blue composite films

Composite films of titanium phosphate (TiPS)/Prussian blue (PB) were fabricated by the alternative deposition of TiPS layer and PB nanocrystals. The layer of TiPS was fabricated by adsorption of hydrated titanium from aqueous Ti(SO4)2 solution and subsequent reaction with phosphate groups. The layer of PB nanocrystals was fabricated by sequential adsorption of FeCl3 solution and K4[Fe(CN)6] solution. Regular deposition of TiPS/PB composite films were verified by UV-vis absorption spectroscopy and quartz crystal microbalance measurements. The successful fabrication of the TiPS/PB composite films was further confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Instead of producing films of TiPS layers alternating with PB nanocrystal layers, the TiPS/PB composite films have a structure in which the interstices of the PB nanocrystal films are filled with TiPS component. TiPS/PB composite films show enhanced electrochemical properties and improved stability in comparison with pure PB films prepared by the multiple sequential adsorption process. TiPS/PB composite films have the capability to catalyze the electrochemical reduction of H2O2 and can be used as a biosensor for detecting H2O2.     

紫外光照处理对TiO2膜光伏性能的影响

近年来人们利用纳米晶TiO2电极取代普通的TiO2电极[1],使其太阳能电池的光电转换效率得到很大提高.纳米晶TiO2电极具有大量表面态,在化学上表现为Ti3+或Ti—OH,对于光生电荷的分离过程和迁移过程有重要影响.这些表面化学结构的变化可能会导致TiO2的光伏性能的变化.1997年Fujishima等[2]用紫外光照射TiO2膜使它具有超亲水的性质,结构分析表明,超亲水的原因在于光照使TiO2膜的表面形成Ti—OH[3].因此,在光照处理的同时可能会导致TiO2的光伏性的变化.本文对紫外光照处理TiO2膜的光伏性能进行了研究,并结合光诱导TiO2的亲水性变化对光伏性能变化的原因进行了讨论.