A Novel 3D Extended Network Cobalt Paradodecatungstate:Synthesis,Characterization and Crystal Structure of [Co(H_2O)_5]_2[Co(H_2O)_4]_3[H_2W_(12)O_(42)]·11H_2O

1 INTRODUCTION Polyoxometalates are the unique metal-oxygen clusters composed of transition metals in groups V and VI (Mo, W, V, Nb, Ta) in a high oxidation state showing a large structural varieties as well as inte- resting physical and chemical properties in diverse fields including catalysis, analytical chemistry, nanotechnology, chemical sensing, biochemical and geochemical processes, medicine and materials science[1～5]. Recently, there has been increasing interest in the synthesis…     

多金属氧酸盐四硫富瓦烯衍生物荷移盐超薄导电膜(英)

0IntroductionThecharge鄄transfer(CT)saltsbasedplanarπ鄄electrondonorETasaclassofmolecule鄄basedmate鄄rialshavebeenstudiedextensivelyinthepasttwentyyears,becauseoftheirmetallicconductivityandevensuperconductivity[1~6].Inrecentyears,polyoxometalateshaveatt     

Synthesis,Characterization and Crystal Structure of an Inorganic-organic Composite Metatungstate:[Co(4,4′-bipy)_2(H_2O)_4](4,4′-H_2bipy)_2[H_2W_(12)O_(40)]·5.5H_2O

A novel hybrid compound [Co(4,4'-bipy)2(H2O)4](4,4'-H2bipy)2[H2W12O40]·5.5H2O has been synthesized from an acidified aqueous solution and characterized by elemental and thermal analyses,IR and UV spectroscopy,and single-crystal X-ray structure determination. Structure analysis indicates that the title compound is of monoclinic,space group C2/c,with a=21.315(9),b=15.303 (7),c=24.139(10),β=105.170(5)o,V=7599(6)3,Mr=3706.99,Z=4,F(000)=6616,Dc=3.231,μ=18.395 mm-1,R=0.0652 and wR=0.1594. X-ray crystallographic study shows that the title compound consists of one [Co(4,4'-bipy)2(H2O)4]2+ cation,two diprotonated 4,4'-bipyridine molecules,5.5 water molecules of crystallization,and one metatungstate polyoxoanion [H2W12O40]6-,which approaches an effective Td point symmetry. TG-DTA analysis indicates that the framework of the metatungstate polyoxoanion is collapsed at 587.0 ℃.     

两种砷钼杂化多酸盐的合成、 结构及变色性质

分别以2种V形羧酸[1,3-苯二甲酸(H₂BDC)和5-羟基-1,3-苯二甲酸(H₂OIP)]与钼酸铵进行反应, 得到了 2种有机酸根与无机酸根缩合构成的杂化砷钼酸盐： (NH₄)₁₇H₄[(AsMo₆O₂₁)₂(AsMo₆O₂₃)(BDC)₄]·28H₂O(1)和 (NH₄)₅Cs₈H₆[(AsMo₆O₂₁)₃(OIP)₅]·40H₂O(2). 利用单晶X射线衍射对2种化合物进行了结构分析, 发现二者均为三聚结构. 对2种化合物的光致变色及热致变色性质进行了研究, 发现在氙灯照射下2种化合物均可在5 min内变色. 当将2种化合物的样品加热到373 K时, 均出现颜色变化, 并随着温度升高颜色逐渐加深. 光致变色与热致变色过程前后的EPR检测结果均提示化合物的颜色变化与Mo^VI转化为Mo^V有关.     

介孔磷钨酸铯盐的液相组装及酸性研究

以磷钨酸(H₃PW₁₂O₄₀)和氯化铯(CsCl)为原料, 两亲型三嵌段共聚物F127为模板剂, 按不同的Cs/P比制备了一系列介孔磷钨酸铯盐(Cs_xH_3-xPW₁₂O₄₀, m-CsPW). 通过X射线粉末衍射(XRD)、 场发射扫描电子显微镜(FESEM)、 场发射透射电子显微镜(FETEM)、 N₂吸附-脱附测试和小角X射线散射(SAXS)等手段对所得样品进行了表征. 结果表明, 样品是由纳米微晶组装而成的晶态介孔材料. 以三甲基膦为探针分子, 通过³¹P魔角旋转固体核磁共振波谱(³¹P MAS NMR)测定了样品酸处理前后的酸密度和酸强度. 以5,7-二羟基-4-甲基香豆素的Pechmann缩合反应为模型反应, 考察了样品的酸性质与催化活性之间的关系.     

Morphology Engineering of BiVO4 with CoOx Derived from Cobalt-containing Polyoxometalate as Co-catalyst for Oxygen Evolution

Bismuth vanadate (BiVO₄) as a metal oxidation semiconductor has stimulated extensive attention in the photocatalytic water splitting field. However, the poor transport ability and easy recombination of charge carriers limit photocatalytic water oxidation activity of pure BiVO₄. Herein, the photocatalytic activity of BiVO₄ is enhanced via adjusting its morphology and combination co-catalyst. First, the Cu-BiVO₄ was synthesized by copper doping to control the growth of {110} facet of BiVO₄, which is regarded for the separation of photo-generated charge carriers. Then the CoO_x in-situ generated from K₆[SiCo^II(H₂O)W₁₁O₃₉] ⋅ 16H₂O was photo-deposited on Cu-BiVO₄ surface as co-catalyst to speed up reaction kinetics. Cu-BiVO₄@CoO_x hybrid catalyst shows highest photocatalytic activity and best stability among all the prepared catalysts. Oxygen evolution is about 34.6 μmol in pH 4 acetic acid buffer under 420 nm LED irradiation, which is nearly 20 times higher than that of pure BiVO₄. Apparent quantum efficiency (AQE) in 1 h and O₂ yield are 1.83% and 23.1%, respectively. O₂ evolution amount nearly maintains the original value even after 5 cycles.     

The Old Polyoxometalates in New Application as Molecular Resistive Switching Memristors

The coming big-data era has created a huge demand for next-generation memory technologies with characters of higher data-storage densities, faster access speeds, lower power consumption and better environmental compatibility. In this field, the design of resistive switching active materials is pivotal but challengeable. Polyoxometalates (POMs) are promising candidates for next-generation molecular memristors due to their versatile redox characters, excellent electron reservoirs and good compatibility/convenience in microelectronics processing. In this review, five kinds of POM-based active materials in nonvolatile memories (inorganic POMs, crystalline organic-inorganic hybrid POMOFs, polymer modified POMs, POM/transition metal oxides composites and the deposition of POM on metal surfaces) were described. The components of POMs active materials, device fabrications, device parameters, and resistive switching mechanisms relative to their structures were summarized. Finally, challenges and future perspectives of POMs-based memristors were also presented.     

Organoboron‐Functionalization Enables the Hierarchical Assembly of Giant Polyoxometalate Nanocapsules

The aggregation of molecular metal oxides into larger superstructures can bridge the gap between molecular compounds and solid‐state materials. Here, we report that functionalization of polyoxotungstates with organo‐boron substituents leads to giant polyoxometalate‐based nanocapsules with dimensions of up to 4 nm. A “lock and key” mechanism enables the site‐specific anchoring of aromatic organo‐boronic acids to metal‐functionalized Dawson anions [M₃P₂W₁₅O₆₂]^9? (M=Ta^V or Nb^V), resulting in unique nanocapsules containing up to twelve POM units. Experimental and theoretical studies provide initial insights into the role of the organo‐boron moieties and the metal‐functionalized POMs for the assembly of the giant aggregates. The study therefore lays the foundations for the design of organo‐POM‐based functional nanostructures.     

含Keggin类型多酸单元和2-吡啶甲酸的杂化材料的合成、结构及表征

合成了2例基于2-吡啶甲酸（2-PA）和Keggin类型[SiW₁₂O₄₀]^4-、[PMo₁₂O₄₀]^3-多酸单元的有机-无机杂化材料：H₂[（CH₃）₄N]₆[Cu（2-PA）₂（SiW₁₂O₄₀）₂]（1）和（H₃O）[Cu₆（2-PA）₉（PMo₁₂O₄₀）（NO₃）]（2）,并用红外光谱以及X射线衍射对其进行了表征。单晶衍射结构分析表明化合物1为单斜晶系,空间群为P2₁/c,不对称单元中包含1个二价铜离子、2个2-吡啶甲酸配体以及2个Keggin类型[SiW₁₂O₄₀]^4-多酸单元并组成零维结构。循环伏安测试表明化合物1在扫速为100 mV·s^-1时,3组半波电位分别为-270、-516、-708 mV。化合物2为三方晶系,空间群为R3c,不对称单元中包含2个晶体学独立的二价铜离子并且具有2种不同的配位模式,是含六核簇合物单元的二维网络结构。     

三维超分子化合物(H2bimb)2(SiW12O40)的水热合成与晶体结构

利用水热合成方法合成了1个新的Keggin基质的超分子化合物(H2bimb)2(SiW12O40),并通过元素分析、红外光谱、热重分析和X射线单晶衍射方法确定了该化合物的晶体结构.结构分析表明该化合物属于三斜晶系,P-1空间群,晶胞参数a=1.122 6(5)nm,b=1.563 5(5)nm,c=1.892 7(5)...