一例多钒酸盐杂化材料的制备及高效催化烯烃环氧化

以2-(2-吡啶基)咪唑(pIM)、Co²⁺和NaVO₃为原料,在水热条件下,制备了新的钒氧簇化合物[Co(pIM)V₂O₆] (1)。采用X射线单晶衍射、粉末X射线衍射、傅里叶变换红外光谱和元素分析等方法对化合物进行了表征。单晶解析表明,该化合物由VO₄四面体和CoO₃N₂四方锥通过氧原子共边、共角连接成二维结构。基于钒氧簇在催化氧化体系中的高效活性,1作为非均相反应的催化剂,在以H₂O₂为氧化剂的催化烯烃环氧化反应中表现出优秀的催化性能,催化剂能够多次重复使用且活性基本保持不变。此外,磁化率研究表明1中存在反铁磁相互作用。     

基于H3PW12O40·xH2O和3，5-二氨基-1，2，4-三氮唑的POMOF的合成、表征及催化氧化碘离子性能

采用水热法合成了一例结构新颖且罕见的Keggin型多金属氧酸盐基金属有机骨架化合物,即[Cu₄（3,5-datrz）₄][PW^Ⅵ₉W^Ⅴ₃O₃₉]·H₂O （1）,其中3,5-datrz=3,5-二氨基-1,2,4-三氮唑,并通过单晶X射线衍射、傅里叶变换红外光谱、热重分析、粉末X射线衍射和元素分析进行了表征。单晶X射线衍射分析表明：化合物1属于单斜晶系,空间群为C2/c,不对称结构包含2个Cu⁺、2个3,5-datrz配体、0.5个Keggin型磷钨酸阴离子和1个水分子,除结晶水外各组分之间通过共价键连接成Keggin型多金属氧酸盐基金属有机骨架化合物。以化合物1为非均相催化剂,在温度为55℃时催化H₂O₂氧化碘离子反应。结果表明,1催化下的碘单质生成速率为6.11×10^-7 mol·L^-1·s^-1,且重复使用次数达到6次时转化率仍能高达99.6%。     

基于H3PW12O40·xH2O和3，5-二氨基-1，2，4-三氮唑的POMOF的合成、表征及催化氧化碘离子性能

采用水热法合成了一例结构新颖且罕见的Keggin型多金属氧酸盐基金属有机骨架化合物，即[Cu₄(3，5 - dtrz)₄][PW^Ⅵ₉W^Ⅴ₃O₃₉]·H₂O (1)，其中3，5-dtrz=3，5-二氨基-1，2，4-三氮唑，并通过单晶X射线衍射、傅里叶变换红外光谱、热重分析、粉末X射线衍射和元素分析进行了表征。单晶X射线衍射分析表明：化合物1属于单斜晶系，空间群为C2/c，不对称结构包含2个Cu⁺、2个3，5-datrz配体、0.5个Keggin型磷钨酸阴离子和1个水分子，除结晶水外各组分之间通过共价键连接成Keggin型多金属氧酸盐基金属有机骨架化合物。以化合物1为非均相催化剂，在温度为55℃时催化H₂O₂氧化碘离子反应。结果表明，1催化下的碘单质生成速率为6.11×10^-7 mol·L-1·s^-1，且重复使用次数达到6次时转化率仍能高达99.6%。     

单核钌催化剂化学催化和光催化水氧化反应

合成了一系列含有不同对位取代基团的吡啶轴向配体的单核钌化合物Ru(bda)(pic)₂ (H₂bda=2,2''-联吡啶-6,6''-二羧酸; pic=对甲基吡啶),对化合物的结构进行了核磁、质谱和X射线单晶衍射表征,并在中性和酸性条件下研究了这些化合物的电化学性质.以硝酸铈铵为氧化剂,对催化剂的催化活性进行了测试,并以[Ru(bpy)₃]²⁺为光敏剂,S₂O₈^2-为电子牺牲剂,在三组分体系中考察了这些化合物的光催化活性.研究发现,在化学法水氧化反应中,化合物1由于其轴向配体4,4''-联吡啶在酸性条件下能够发生质子化,从而增强了吸电子效应,因此表现出最高的催化活性,催化循环数达到4000.在光催化水氧化反应中,化合物2因其轴向配体具有最强的吸电子能力而表现出最高的催化活性,反应2h的催化循环数达到270.结果表明,轴向配体的吸电子能力明显提高了这类Ru催化剂催化水氧化反应活性.     

PdCl2-CuCl2/Al2O3催化剂低温催化CO氧化的失活机理

采用X射线衍射、N₂吸-脱附、X射线光电子能谱分析、氢气-程序升温还原和原位红外漫反射等方法对新鲜和失活的PdCl₂-CuCl₂/Al₂O₃低温催化CO氧化催化剂进行表征,研究了高相对湿度(100%)下催化剂的失活机理.结果表明,催化剂表面沉积的水使得活性铜物种容易从催化剂表面向载体孔道内部迁移,由于Pd、Cu相互作用弱化从而减弱了Pd与Cu物种间的相互作用,使得催化剂的氧化还原性能受到影响,抑制了Pd⁰再氧化为Pd²⁺的过程,从而因CO氧化反应中催化剂氧化还原循环受阻而导致失活.     

水杨醛肟和乙酰氧肟酸钛氧簇合物的合成及光电性质

通过溶剂热合成方法,以水杨醛肟(H₂Saox)和乙酰氧肟酸(H₂Ahox)为染料敏化功能配体,分别以异丁酸(HiBuac)和苯基膦酸(PhPO₃H₂)为辅助配体,与钛酸四异丙酯(Ti (OⁱPr)₄)反应,合成了六核钛氧簇配合物[Ti₆(μ₃-O)₄(Saox)₂(ⁱBuac)₄(OⁱPr)₈](1)和八核钛氧簇配合物[Ti₈(μ₃-O)₂(Ahox)₂(PhPO₃)₄(OⁱPr)₁₆](2)。配合物1和2均通过红外光谱、元素分析和单晶X射线衍射进行了结构表征。光谱性质表明,配合物1和2在可见光区均有吸收,其带隙分别为2.43和2.61 eV。配合物2是首个基于乙酰氧肟酸的钛氧簇,具有光催化析氢性能且速率可达140.2 μmol·g^-1·h^-1。     

三核钨簇合物-V2O5催化剂对苯乙烯氧化反应的催化

本文研究了三核钨簇合物［W₃O₂(CH₃CO₂)₆(H₂O)₃］Br₃·2H₂O与一些物质组成的二元催化剂对苯乙烯氧化反应的催化作用,结果表明：钨簇合物-V₂O₅催化剂对苯乙烯氧化反应的催化效果特别显著,而且在反应前后其重量、结构及催化活性基本不变,可以多次回收重复使用。对影响钨簇合物-V₂O₅催化剂催化性能的几个因素进行了讨论,测定了催化剂及其吸附氧气的红外光谱,说明钨簇合物及V₂O₅可以与O₂形成分子氧配合物及超氧(O^-₂)配合物。     

焙烧与预处理条件对 Co3O4 催化氧化 CO 性能的影响

采用沉淀法制备了 Co₃O₄, 考察了焙烧和预处理条件对其结构、低温催化氧化 CO 性能的影响. 热重分析表明, 未经焙烧的样品以 Co(OH)₂CO₃ 的形式存在, 150~400 ^oC 空气气氛中焙烧后, 样品以立方相 Co₃O₄ 的形式存在. N2 吸附-脱附法、X 射线衍射、透射电镜及活性测试结果表明, 以纳米颗粒物存在的 Co₃O₄ 的比表面积、颗粒尺寸、催化氧化 CO 活性与焙烧温度密切相关. 正电子湮没寿命谱、O₂-程序升温脱附与定温条件下 CO 氧化测试结果表明, 合适温度 (150~250 ^oC) 下 N₂ 预处理有利于 Co₃O₄ 表面氧空穴团的形成, 它在吸附活化分子氧以及 CO 催化氧化反应中起到关键作用. 同时讨论了预处理作用下Co₃O₄表面氧空穴的再构机制.     

K3Na5(H2NCH2CH2NH3)2{(VO)12O6[B3O6(OH)]6}(H2O)•12H2O的合成与晶体结构

利用水热合成技术成功制备出一种新型多钒硼氧化合物， 用X射线单晶衍射分析技术对其晶体结构和分子结构进行了确定。结果表明在该化合物中多钒硼氧阴离子具有一个新颖的三明治结构。上下两个结构单元都是由六个VO₅四角锥交替地通过顺式和反式共边的方式连接起来构成的一个钒氧三角形结构。中间的结构单元是由BO₃平面三角形和BO₄四面体以共角的方式相互连接形成的一个折叠型的B₁₈O₃₆(OH)₆环。三明治结构中层与层之间通过桥氧相连。一个水分子处于它的核心位置上，与每个VO₅四角锥中的钒原子都保持几乎相等的距离。该化合物及其晶体中存在着丰富的化学结构和成键信息，同时也有作为氧化还原反应催化剂的潜能。     

可见光辐射下活性炭-铁酸镍杂化催化剂光催化氧化氨氮

铁酸镍（NiFe₂O₄）中的镍原子抑制其光芬顿催化活性. 然而,活性炭（AC）能激活其光芬顿催化活性,结果导致复合催化剂AC-NiFe₂O₄在过氧化氢存在时可见光辐射下也可催化氧化氨氮. 用X射线衍射（XRD）,透射电镜（TEM）,傅里叶变换红外（FTIR）光谱,紫外-可见漫反射光谱（UV-Vis DRS）,比表面积和振动样品磁强计对催化剂进行了表征. 光催化降解氨氮的实验表明,该复合催化剂在10 h内氨氮的降解率可达到91.0%,而同样条件下没有催化剂时氨氮的去除率只有24.0%. 对照实验表明,裸铁酸镍在可见光辐射下,氨氮的降解率只有30.0%. 这表明活性炭加速了氨氮的氧化速率. 动力学研究表明,氨氮的氧化遵循一级反应动力学规律,其表观反应动力学常数为3.538×10^-3 min^-1. 机理研究表明,氨氮的氧化是通过生成HONH₂ 中间体,然后转化为NO₂^- .8次循环实验表明该复合催化剂容易分离、可循环使用、且催化活性十分稳定. 因此,该催化剂具有潜在的应用价值.     

A novel oxovanadate structural type – Synthesis,single crystal structure and magnetic properties of a mixed-valence polyoxovanadate formed by {V17O40(Cl)} and {V15O36(Cl)} clusters

A novel polyoxovanadate structural type, with an average nuclearity of V₁₆, formed by a mixture of two different polyoxovananadates: {V₁₅O₃₆(Cl)} and{V₁₇O₄₀(Cl)} has been synthesized and characterized. The title compound, formulated as [Ni(phen)₃]₂{[V₁₅O₃₆(Cl)]_0.5[V₁₇O₄₀(Cl)]_0.5} · H₂O (1) (phen = 1,10′-phenanthroline), presents two different polyoxovanadate architectures: {V₁₅O₃₆(Cl)} and {V₁₇O₄₀(Cl)}, with the last one representing a new framework type in polyoxovanadate chemistry. Here, we present the synthesis of this novel polyoxovanadate under hydrothermal conditions and its characterization by IR and XPS spectroscopies, elemental and thermogravimetric analysis, redox titration, magnetic measurements and single-crystal X-ray diffraction.     

A novel polyoxometalate chain constructed from sandwich lanthanide-containing polyanions [Pr(PW<Subscript>11</Subscript>O<Subscript>39</Subscript>)<Subscript>2</Subscript>]<Superscript>11−</Superscript> and sodium cation linkers

A novel sandwich-type lanthanide polyoxometalate [(CH₃)₄NH]₄Na₃[Pr(PW₁₁O₃₉)₂] · 12H₂O (1) has been synthesized by conventional method and characterized by cyclic voltammetry, IR spectroscopy and single crystal X-ray diffraction. X-ray diffraction result reveals that the sandwich type polyanions are linked by sodium cations to form a structure of zigzag chains, and the chains are further connected into an extensive two-dimensional (2D) framework depending on hydrogen bond. The emission spectrum result shows weak photoluminescence of compound 1. The magnetic studies of compound 1 demonstrate an antiferromagnetic interaction in 1.     

A new decavanadate polyoxovanadate nanocluster: synthesis,characterization and rapid adsorption of methylene blue

A new decavanadate polyoxovanadate nanocluster, [2-ampH]₆[V₁₀O₂₈]?2H₂O (1), was synthesized through reaction between ammonium vanadate and 2-aminopyridine at pH = 2. Nanocluster 1 was characterized by IR, elemental analysis, and X-ray crystallography. 1 was found to adsorb and desorb dyes and may have widespread application in wastewater treatment. The utility of 1 for adsorption of methylene blue was studied. The adsorbed dyes can be easily desorbed, and 1 has full efficiency after five cycles.     

A Self-Assembled 3D Hydrogen Bonded Network Constructed from Polyoxovanadate and Protonated Organic Substrate With a Solvent Hydrolysis Reaction

A self-assembled 3D hydrogen bonded network constructed from polyoxovanadate and organic substrate [V₁₀O₂₈][(CH₃)₂NH₂]₄(imidazolium)₂ (1) has been synthesized at room temperature and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The structure of 1 can be regarded as being linked by the dimethylammonium cations of the decavanadate clusters to produce an interesting 3D network with a 4¹²6³ topology. In the resulting network, there exist one-dimensional channels along the a-axis, in which the imidazolium cations filled the channels. These imidazolium cations are involved in intermolecular hydrogen bonds of the types N–H···O and C–H···O, which seem to be main forces to stabilize the holistic structure.     

A cubane-like [Ni4O4] cluster and a chloro-bridged dinuclear copper complex incorporating a hydroxyl-rich ligand: syntheses and crystal structures

A tetranuclear cubane-like cluster [Ni₄(HL)₄(DMSO)₂]?·?2DMSO?·?H₂O (1) and a dinuclear compound [Cu₂Cl₂(H₂L)₂]?·?1.5MeOH (2) (H₃L?=?3-(2-hydroxy-benzylideneamino)propane-1,2-diol) have been prepared and characterized by X-ray single crystal diffraction, IR, and elemental analysis. The X-ray diffraction analysis indicated that the four metals of 1 showed a Ni₄O₄ cubane arrangement, and two of the six faces of the Ni₄O₄ cubane were capped by DMSO. Complex 1 is the first reported DMSO capped Ni₄O₄ cubane cluster. Complex 2 contains a u ₂-Cl bridged dinuclear core with each Cu^II ion exhibiting pseudo square pyramidal geometry.     

Hydrothermal synthesis and crystal structure of a new two-dimensional zinc citrate complex

A new two-dimensional compound C₁₂H₁₄O₁₆Zn₃ (1), containing seven-coordinate zinc atoms was prepared by the hydrothermal technique. The compound obtained was characterized by TG-DTA, single crystal X-ray diffraction, elemental analysis and FT-IR analysis. Single-crystal X-ray diffraction analysis shows that compound 1 crystallizes with monoclinic symmetry in the space group P2₁/c, a?=?6.1552(13)?Å, b?=?14.546(3)?Å, c?=?9.581?Å, β?=?102.66(2)°, V?=?836.9(4)?ų, Z?=?2, R1?=?0.0311, wR2?=?0.0830.     

基于1,10-邻菲罗啉-5,6-二酮和Keggin型多金属氧化物的化合物的水热合成及性质

在水热条件下,用1,10-邻菲罗啉-5,6-二酮(Do)作为中性配体合成了3个基于Keggin型多金属氧化物的化合物(HDo)₆(PW₁₂O₄₀)₂·H₂O(1),[Cu(Do)₂(H₂O)]₂[Cu(Do)₂(PW₁₂O₄₀)(H₂O)](PW₁₂O₄₀)(2)和[Pb(Do)₂(PW₁₂O₄₀)](HDo)(3),并对其进行了元素分析、红外光谱、电感耦合等离子体分析、Ｘ射线光电子能谱、热重分析以及荧光光谱等表征。单晶X射线衍射分析表明化合物1和2为零维结构,化合物3是一维链状结构。     

Hydrothermal synthesis,crystal structure and fluorescence of a 3D organic–inorganic hybrid coordination network [CuI(4,4′-bipy)]4[ δ -Mo8O26] exhibiting an interesting polymorphism

A new three-dimensional (3D) extended solid [Cu^I(4,4′-bipy)]₄[δ-Mo₈O₂₆] (1) built on {Cu(4,4′-bipy)}⁺ (bipy?=?bipyridine) and isopolymolybdate anion [δ-Mo₈O₂₆]^4? has been synthesized and characterized by elemental analysis, IR, TG, X-ray powder diffraction and single-crystal X-ray diffraction analysis. Compound 1 shows six coppers bonded to [δ-Mo₈O₂₆]^4? to form inorganic planes which are linked by 4,4′-bipy into a 3D network, the first example of [δ-Mo₈O₂₆]^4? six-connected linkage based on an organic-inorganic coordination polymer. A polymorphism of compound 1 was found which has an identical molecular formula but absolutely different structure. The influence of the synthesis conditions of 1 has been studied. Furthermore, the fluorescence of 1 is reported.     

Hydrothermal synthesis and crystal structure of (H2bpp)3[Mo5P2O23]·H2O: a twofold interpenetrating 3D supramolecular architecture constructed of Standberg-type polyoxometalate

A novel three-dimensional (3D) supramolecular assembly of Standberg-type polyoxometalate and flexible organic molecule (H₂bpp)₃[Mo₅P₂O₂₃]·H₂O (1) [bpp = 1,3-bis(4-pyridyl)propane] has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis and thermogravimetric analysis (TGA). X-ray analyses show that compound 1 represent a twofold interpenetrating 3D supramolecular architecture constructed of Standberg-type polyoxometalate and bpp molecular through the hydrogen bonds as well as electrostatic interactions.