Preparation of PO4^3-, P2O7^4- Anion-Pillared Nanocrystalline Mg-Al and Zn-Al Layered Double Hydroxides in Microwave Fields

Using nanocrystalline [Mg-Al-CO3] and [Zn-Al-CO3] as precursors, [Mg-Al-PO4],[Zn-Al-PO4], [Mg-Al-P2O7] and [Zn-Al-P2O7] have been successfully synthesized by a direct reaction with the free PO4^3- or P2O7^4- using the microwave techniques and the anion-exchange method. And the samples thus obtained were characterized by TEM, FT-IR and XRD. The results show that the initial interlayer carbonate ions can be completely replaced by the free PO4^3- or P2O7^4- under controlled microwave conditions employed for a short time.     

Synthesis,Structure and Photoluminescence of a Binuclear Zinc（Ⅱ） Coordination Polymer Based on 2-Carboxycinnamic Acid and Dipyrido [3,2-a： 2＇,3 ＇-c]-phenazine

A binuclear zinc（Ⅱ） complex with 2-carboxycinnamic acid （2-ccm） and dipyrido- [3,2-a：2＇,3＇-c]phenazine （DPPZ）, {[Zn2（2-ccm）2（DPPZ）2]·2H2O}n, was synthesized and characterized by elemental analysis, IR, single-crystal X-ray diffraction, thermal gravimetry and fluo- rescent emission. It crystallizes in monoclinic, space group P21/c with a = 13.409（4）, b = 25.530（7）, c = 13.952（4） A, β = 99.554（3）°, V= 4710（2） A3, Z= 4, C56H36N8O10Zn2, Mr= 1111.67, Dc = 1.568 g/cm3, μ（MoKα） = 1.093 mm^-1, F（000） = 2272, R = 0.0422 and wR = 0.0895. In the crystal, the basic unit of 1 is a binuclear Zn2 entity which is linked by 2-ccm ligand to form a 1D double chain along the a axis. The O-H...O hydrogen bonding and π-π interactions lead to a 3D supramolecular motif. In addition, thermal and luminescent properties of complex 1 have also been investigated.     

Synthesis and Structure of Vanadium—barium Complex of 2, 4, 6—Tripicolinato with 20—Member Macrocyclic Cavities

Recently, the thermal decomposition of heteronuclear complexes has become apromising method for the preparation of di- or tri-metallic oxides because the complex as precursor has the special microstructure, the controlled stoichiometry of the metals and lower decomposition temperature 1. In order to investigate Ba-V-O system, which has the special magnetic behavior 2, we synthesized the title complex as the precursor of this material. On the other hand, microporous constructions existing in…     

Synthesis,Crystal Structure and Photoluminescence of a Three-dimensional Zinc(Ⅱ) Coordination Polymer with(20~3)_2(20)_3 Topology

The title compound,[Zn2(H2C4BIm)(ox)2]·2H2O(1,H2C4BIm = 2,2'-(1,4-bu-tanediyl)bis(1H-benzimidazole),has been synthesized by the hydrothermal reaction of Zn(NO3)2·6H2O with H2C4BIm and Na2C2O4 in water solution.It crystallizes in the triclinic system,space group P1 with a = 9.445(9),b = 9.598(9),c = 14.962(14) ,α = 72.160(10),β = 79.905(12),γ = 83.680(11)°,Mr = 633.18,V = 1269(2) 3,Z = 2,Dc = 1.657 g/cm3,F(000) = 644,μ = 1.953 mm-1,the final R = 0.0671 and wR = 0.1689.X-ray crystal structure analysis revealed that 1 is a 3D network with(203)2(20)3 topology in which the ZnII atom can be considered as a 3-connected node and both ox2-and H2C4BIm serve as the linear linkers.     

Synthesis and Structure of Zinc 3-Hydroxy-2-mercaptopyridine Complex,Zn(C_5H_4NOS)_2

1 INTRODUCTION The zinc-thiolate complexes have been widely studied due to their comprehensive applications[1～3]. In an attempt to synthesize polynuclear zinc-thiolate complexes, we used a substituted pyridine contain- ing two substituent groups, 3-hydroxy-2-mercapto pyridine, as a potential tridentate ligand to react with Zn(NO3)2 in the MeONa-MeOH solution at room temperature, obtaining a new mononuclear zinc-complex, Zn(C5H4NOS)2. In this case, the pro- totropy under basic cond…     

Synthesis,Structure, and Luminescent Property of a 3-D Strontium Complex [Sr_3(pda)_2(Hpda)_2(H2O)_2]_n·2nH_2O

The title complex [Sr3(pda)2(Hpda)2(H2O)2]n·2nH2O(H2pda = pyridine-2,6-dicar- boxylic acid) has been prepared under solvothermal conditions. It has been characterized by X-ray single-crystal diffraction, IR and elemental analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 10.3795(8), b = 9.2225(7), c = 18.5726(14) , β = 104.377(2)o, V = 1722.2(2) 3, C28H22N4O20Sr3, Mr = 997.36, Z = 2, Dc = 1.923 g/cm3, μ = 4.722 mm-1, F(000) = 984, the final R = 0.0269 and wR = 0.0538. This complex possesses a 3-D structure which is constructed from 1-D chain motifs linked by carboxylate groups. The luminescent property of the title complex has been investigated.     

Synthesis,Structure, and Luminescent Property of a 3-D Zinc Complex { [ZN8II（4-APha）8（CH3COO）8] （CH3CH2OH）2}n①

The title complex [ZnⅡ8(4-APha)8(CH3COO)8(CH3CH2OH)2]n(1, 4-APha = 4-aminophenylhydroxamic acid) has been prepared under solvothermal conditions. It has been characterized by X-ray single-crystal diffraction, IR and elemental analysis. The crystal belongs to the monoclinic system, space group C2/c with a = 39.074(4), b = 9.9645(8), c = 38.846(3) A, β = 136.438 o, V = 10423.1(14) A3, C84H118N16O39Zn8, Mr = 2498.90, Z = 4, Dc = 1.592 g/cm3, μ = 1.900 mm-1, F(000) = 5144, the final R = 0.1036 and wR = 0.2953. This complex possesses a 3-D structure which is constructed from 1-D chain motifs linked by the 4-APha- ligands. The luminescent property of the title complex has been investigated.     

Synthesis,X—Ray Structure and Characterization of a Triruthenium Cluster Complex Ru^Ⅲ3（μ3—O）（μ—CH3COO）6（py）2Cl with Four Steps One—electron Redox Processes

The synthesis and crystal structure of oxo-centered carboxylate-bridge trinuclear ruthenium complex,Ru3O(CH3OO)6(py)2Cl(py=pyridine)(1),are reported herein.The complex 1 has been characterized by IR,cyclic voltammetry (CV),UV-Vis and X-ray crystal analysis.The complex 1 in 0.1 mol/L (n-C4H9)4HPF6-CH2Cl2 solution at room temperature shows four oneelectron redox processes at E1/2=-1.38,1.20,-0.17 and 1.07V vs. Ag/AgCl.     

Synthesis,Structure and Photoluminescence of （CH_3-4,4＇-H_2bipy）-（HgCl_4） with CH_3-4,4＇-H_2bipy Generated in Situ

A novel viologen(4,4'bipyridinium)-based complex (CH3-4,4'-H2bipy)(HgCl4) (1),in which the CH3-4,4'-H2bipy (MQ2+) was generated in situ,has been synthesized via hydrothermal reaction and structurally characterized. Complex 1 crystallizes in the space group P21/c of monoclinic system with four formula units in a cell:a = 8.1848(6),b = 21.809(2),c = 9.0285(6) ,β = 107.377(1)°,V = 1538.0(2) 3,C11H11Cl4HgN2,Mr = 513.61,Dc = 2.218 g/cm3,S = 1.009,μ(MoKα) = 10.685 mm-1,F(000) = 956,R = 0.0360 and wR = 0.0812. The crystal structure analysis reveals that the title complex features an isolated structure based on a CH3-4,4'-H2bipy moiety and a mercury atom terminally bound by four chlorine atoms. Photoluminescence investigation reveals a strong emission in blue region,which may originate from π→π* charge-transfer interaction of the CH3-4,4'-H2bipy moiety.     

Hydrothermal Synthesis of Nanorods and Nanowires of Mg/Al Layered Double Hydroxides

Layered double hydroxides (LDHs) are a class of synthetic anion clays, characterized by the formula[MⅡ1-xMⅢx (OH)2]x (An- )x/n·yH2O (where M =metal and A = anion, usually carbonate)[1-3]. A large number of LDHs with a wide variety of M Ⅱ-M Ⅲ cation pairs including M Ⅰ-M Ⅲ ( e. g. , Li-Al ) and M Ⅱ-MⅣ( e. g. , Co-Ti) have been reported. Thus the identities of the cations(MⅠ , MⅡ , MⅢ and MⅣ) and the interlayer anion (An-) together with the value of the stoichiometric coefficient (x) may vary widely, giving rise to a large class of isostructural materials.     

Synthesis of Nordstrandite and Nordstrandite-Derived Layered Double Hydroxides of Li and Al: A Comparative Study with the Bayerite Counterpart

The layered double hydroxides (LDHs) of Li and Al can be synthesized from the four polymorphs of Al(OH)₃, namely gibbsite, bayerite, nordstrandite, and doyleite. The crystal structure of this class of compounds depends on the type of the precursor used due to their topotactic reaction mechanism. While the LDHs derived from gibbsite and bayerite yield different crystal structures, the incorporation of Li into nordstrandite was expected to yield new LDH structures different from those derived from gibbsite and bayerite. The structure of nordstrandite derived LDHs were however identical to that derived from the bayerite counterpart. The absence of symmetry in the interlayer of nordstrandite (C₁) makes it unsuitable to accommodate the intercalating anions with different molecular symmetries. To make the interlayer gallery suitable for the anions, the metal hydroxide layers of the nordstrandite translate, transforming nordstrandite to bayerite. The bayerite with site symmetries O_h and C₂ stabilizes the anions in the interlayer by hydrogen bonding. The transformation of nordstrandite to bayerite, when soaked in lithium salt solution is, therefore, a manifestation of the intercalating anions.     

Single-atom Catalysts Based on Layered Double Hydroxides

Single-atom catalysts(SACs) have attracted much attention for their superior catalytic performance in various fields. It has been widely accepted that the selection of appropriate substrates is crucial to the fabrication and application of SACs. Layered double hydroxides(LDHs) have been developed as one of the promising substrates for single-atoms due to their unique adjustable supramolecular structures. In this review, we comprehensively sort out the research of SACs based on LDHs. By analyzing the characteristics of LDHs and the single-atoms, respectively, the preparation strategies of SACs by using LDHs are summarized. Their applications as efficient catalysts in electrocatalysis, photocatalysis and thermal catalysis are then discussed. Finally, we summarize the opportunities and challenges for the rational design and application expansion of SACs based on LDHs in the future.     

层状双金属氢氧化物的剥离方法及其应用

层状双金属氢氧化物(LDHs)是由带结构正电荷的片层和层间阴离子有序组装而成的层状无机化合物, 近期其剥离研究受到关注. 剥离后的LDHs纳米片可被看做“无机高分子”, 具有纳米尺度的开放结构, 既可作为理论研究模型, 又可作为新型基元组装功能复合纳米结构或材料, 具有显著的应用潜力. 本文对LDHs的剥离方法、剥离产物的表征方法及其应用研究现状进行了综述, 并对今后的研究方向进行了展望.     

Studies on Synthesis and Properties of Mg-Al-nitrate Layered Double Hydroxides

Layered double hydroxides (LDHs), or the so-called hydrotalcite-like compounds, are important clay materials owing to their intercalation ability of anionic species and other physicochemical properties for application as anion adsorbents, medicine stabilizers, ion-exchangers, ionic conductors, catalysts and catalyst supports 1-2. The general formula is, [MⅡ1-x MⅢx(OH)2]x+ [Xm-x/m·nH2O]x-, abbreviated by: [MⅡ-MⅢ-X]. The net positive charge, due to substitution of trivalent by divale…     

Synthesis of Ni／Mg／Al Layered Double Hydroxides and Their Use as Catalyst Precursors in the Preparation of Carbon Nanotubes

Ni/Mg/Al layered double hydroxides(LDHs) with different n(Ni) : n(Mg) : n(Al) ratio values were prepared via a coprecipitation reaction. Then Ni/Mg/Al mixed oxides were obtained by calcination of these LDHs precursors. Carbon nanotubes were produced in the catalytic decomposition of propane over the Ni/Mg/Al mixed oxide catalysts. The quality of as-made nanotubes was investigated by SEM and TEM. The nanotubes were multiwall with a high length-diameter ratio and appeared to be flexible. The catalytic activities of these mixed oxides increased with increasing the Ni content. The Ni/Mg/Al mixed oxide with the highest Ni content [ n( Ni)/n( Mg)/n(Al) = 1/1/1 ] showed the highest activity and the carbon nanotubes grown on its surface had the best quality.     

层状双金属氢氧化物微观结构与性质的理论研究进展

总结了近年来理论计算方法在研究层状双金属氢氧化物(LDHs)结构与功能方面的应用现状. 结合LDHs材料的结构特点, 归纳了量子力学、分子力学、几何建模及物理静电模型相结合对LDHs材料进行结构模拟的思路, 比较了各种方法在LDHs结构模拟上的优势及存在的不足. 量子力学方法能够精确获得水滑石材料的层板构成及作用机制、简单阴离子插层水滑石主客体间的超分子作用实质以及电子性质、反应机理等方面的信息. 与量子力学相比较, 分子力学方法可以快速得到插层水滑石材料的层间阴离子排布及取向、水合膨胀特性及宏观力学性质等. 几何模型和物理静电模型能构建直观、形象的数学模型, 大大简化了计算量,因此能计算接近实际LDHs尺寸的体系, 为推测LDHs结构信息提供了可能性. 随着理论方法和计算机硬件水平的发展, 使得计算机模拟技术逐渐成为获得LDHs材料微观结构参数、电子性质和动力学性质的一种有效手段.     

Layered Double Hydroxides as Catalytic Materials: Recent Development

This report surveys the recent development of layered double hydroxides (LDHs) as catalytic materials, which have attracted considerable attention in the past decade. A major challenge in the rapidly growing field is to improve the functionalities of these materials. Therefore, this article is mainly focused on the lately reported design and synthesis strategies for LDH materials and their catalytic applications as actual catalysts, catalyst precursors and catalyst supports.     

直接脱碳酸化制备有机离子插层的层状双氢氧化物

层状双氢氧化物(Layered double hydroxide, LDH)是一种具有阴离子可交换性质的层状无机材料, 由于其具有多种功能性质, 已被广泛应用于催化^[1~3]、酸吸附剂^[4]、传感器^[5]及聚合物填料^[6~8]等领域. 传统的共沉淀法制备的LDH结晶度低、尺寸小(直径通常小于100 nm). 1998年, Costantino等^[9]采用均匀沉淀法制备出了高结晶度、大尺寸(微米量级)且层间具有CO₃^2-的LDH(LDH-CO₃), 引起了人们的极大兴趣. 为解决LDH-CO₃难于交换和剥离的难题, Iyi等^[10,11]采用两步法制备了层间具有NO₃^- 或有机阴离子的LDH, 即首先采用 HCl-NaCl混合溶液将LDH-CO₃转化成为LDH-Cl, 然后再采用过量的阴离子进行交换制备LDH-NO₃或有机阴离子插层的LDH.     

铜镁铝三元水滑石的姜-泰勒效应

采用密度泛函理论(DFT),用CASTEP程序模块,对类水滑石(CuxMg3-xAl-LDHs,x=0-3)周期性模型进行几何全优化,通过分析各体系的结构参数、电子排布、氢键、Mulliken电荷布居、结合能,总结出体系中的姜-泰勒效应和结构稳定性规律.结果表明,姜-泰勒效应不仅存在于d轨道未排满的Cu2+中,在p轨道未排满的Mg2+中也可能存在,且未饱和的d、p轨道共同影响着金属离子姜-泰勒畸变的大小.在CuxMg3-xAl-LDHs(x=0-3)中,铝八面体和镁八面体分别以稳定的拉长的八面体形式存在.而随着Cu2+的增加,铜八面体逐渐从压扁的八面体向稳定的拉长的八面体形式转变,体系获得了逐渐增多的姜-泰勒稳定化能.总体上,随着Cu2+的增加,体系中姜-泰勒效应导致的畸变使主客体间的氢键和静电作用力均有减弱趋势,且体系的结合能绝对值逐渐减小,故体系稳定性下降.这有助于从理论上进一步认识含铜水滑石的姜-泰勒效应.