Intercalation of Azo Compounds into Layered Aluminium Dihydrogentriphosphate and a Layered Double Hydroxide

The inner surfaces of inorganic layered compounds such as aluminium dihydrogen-triphosphate (ADHP) and layered double hydroxide (LDH) were modified by azo compounds. Upon intercalation of 4-phenylazoaniline and 4,4-azodianiline into ADHP, the interlayer spacing increased from 6.4 to 21.5 Å and 20.6 Å, respectively. The intensity of IR peaks due to P-–OH of ADHP and amino groups of guests decreased by the thermal treatment of the intercalates. The interlayer spacings also decreased to 16.9 Å and 16.7 Å, respectively, indicating a dehydration reaction between P–-OH and amino groups. The LDH inner surface was modified by the reaction with trans-p-phenylazobenzoylchloride (PAB-Cl). Upon surface modification, the interlayer spacing increased from 7.6 Å to about 27 Å. The absorption of this surface-modified LDH near 410 nm increased upon irradiation with UV light and decreased upon irradation with visible light, indicating the occurrence of trans–cis isomerization of PAB-Cl between the layers.     

层状水滑石对吡啶二甲酸异构阴离子的选择性插层行为

本文采用焙烧复原法研究了镁铝水滑石与吡啶二甲酸异构阴离子单体及其混合体的插层反应，实验发现镁铝水滑石对吡啶二甲酸异构阴离子存在着明显的选择性，有机酸异构体优先进入层间的顺序是：2,3-吡啶二甲酸>2,5-吡啶二甲酸>2,4-吡啶二甲酸>3,5-吡啶二甲酸>3,4-吡啶二甲酸>2,6-吡啶二甲酸。利用XRD、IR和TG测试技术对样品进行了表征，同时采用Gaussian-98软件包中ab initio 分子轨道法（HF/6-31G）计算了吡啶二甲酸异构阴离子的分子结构，理论结合实验探讨了阴离子在水滑石层间可能的空间构型，分析了其结构与插层行为的关系。研究表明镁铝水滑石层状材料插层过程中具有分子识别能力，可用于分离有机异构阴离子。     

基于主-客体相互作用的插层水滑石光敏特性研究

本文基于水滑石类插层材料(LDHs)特有的超分子结构及其功能可调控性,采用离子交换法成功合成了邻、间、对硝基苯甲酸阴离子(o-、m-、p-NBA-)插层的锌铝水滑石,并研究了插层产物的光敏性能。插层后这3种异构体化合物都在紫外光照射下表现出不同的光响应程度,即光敏作用:m-NBA-LDHo-NBA-LDH≈p-NBA-LDH。用PXRD、FTIR、UV/Vis和理论计算研究了光敏性能,并提出了可能的光敏机理,为其应用于新型感光材料提供了一定的理论基础。     

插层组装超分子结构有机物柱撑阴离子层状材料

通过改变插层组装条件对有机物柱撑阴离子层状材料(organic pillared layered double hydrox-ide，简称organo-LDHs)进行调控，可获得在光化学、电化学、催化、控制释放等方面具有广阔应用前景的新型无机—有机功能性超分子结构复合材料。本文以插层组装概念及超分子结构为理论基础，介绍了超分子结构organo-LDHs的插层组装方法、表征手段、层间有机物客体的定位及应用研究。     

Using NMR in Structural Studies of Aluminum Hydroxide Intercalation Compounds with Lithium Salts

The effect of the anion charge on the structure of [LiAl₂(OH)₆]_nX (X = Cl^-, Br^-, I^-, SO₄ ^2-, C₆H₈O₄ ^2-) intercalation compounds and the water effect on the structure of [LiAl₂(OH)₆]Cl·nH₂O have been studied using ¹H, ⁷Li, and ²⁷Al NMR. A change in the charge on the anion leads to significant changes in the asymmetry parameter for the lithium and aluminum nuclei with relatively small changes in the quadrupolar coupling constant and the broadening factor. The structure of the intermediate [LiAl₂(OH)₆]Cl·0.5H₂O hydrate can be represented as a derivative of the structure of the anhydrous [LiAl₂(OH)₆]Cl intercalate with a slightly increased layer thickness and a minor orthorhombic distortion of the hexagonal cell; the water molecules partially fill the interlayer voids and participate in the diffusion process. Further hydration of the intercalate (x 1) leads to a minor (0.2) increase in the layer thickness and is accompanied by disordering of chloride ions and water molecules in the interlayer space.     

Preparation and Characterization of Cu(II) Phthalocyanine Tetrasulfonate Intercalated and Supported on Layered Double Hydroxides

The aim of the present work was to synthesize and characterize layered doublehydroxides (LDHs), in the magnesium/aluminum form, intercalated with copper(II)phthalocyanine tetrasulfonate (CuPcTs). The metal complex was immobilized intothe LDH gallery region through the reconstitution method and this material wascharacterized by X-ray diffraction (XRD), surface area and porosity measurements,elementary analysis, thermogravimetry (TGA), vibrational (IR) and electronic(UV-visible) spectroscopies, and electronic paramagnetic resonance (EPR). Thecatalytic performance of CuPcTs intercalated and supported on the LDH wasevaluated by carrying out the hydrogen peroxide dismutation. The CuPcTs wassuccessfully intercalated into the LDH layers according to XRD data (the basalspacing of the carbonate precursors increases by approximately 15Å inthe intercalated samples). The surface area and porosity analysis suggested thatthe CuPcTs intercalated materials are not microporous solids. Samples containingthe metal complex confined between the LDH layers have an appreciable thermalstability: decomposition is not observed at least up to 400 °C. TGA experiments also show that the weight-loss curves of the CuPcTs supported samples superimpose those recorded for the CuPcTs complex and the LDH-carbonate while the curves for theintercalated materials are unique. CuPcTs intercalated or supported on LDHs is notactive in the hydrogen peroxide dismutation although the free form shows activity at pH above 8.     

锂铝水滑石对水杨酸及其异构体的选择性插层研究

[LiAl_2(OH)_6]Cl·yH_2O was prepared by co-precipitation. The competitive intercalation of geometric isomers of hydroxybenzoic acid into the interlayer of layered double hydroxides (LDHs) was studied by the reaction of [LiAl_2(OH)_6]Cl·yH_2O with various mixtures of o-hydroxybenzoic acid, m-hydroxybenzoic acid and p-hydroxybenzoic acid. Powder X-ray diffraction (XRD) results confirmed the intercalation of the isomers, and high performance liquid chromatography (HPLC) was used for the quantitative study. The order of the preferential intercalation of the three isomers was found to be: o-hydroxybenzoic acid (1,2-C_7H_6O_3)》 p-hydroxybenzoic acid (1,4-C_7H_6O_3) > m-hydroxybenzoic acid (1,3-C_7H_6O_3).     

Preparation of New Layered Double Hydroxide,Co-TiLDH

Layer double hydroxide (LDH) is well known for its ability to intercalate anionic compounds. Most popular LDH is prepared only conventionally with bivalent and trivalent cations. In this study, Co-Ti LDH consisting of bivalent and tetravalent cations was prepared and characterized by chemical analysis, X-ray diffraction, IR spectra, thermal analysis and Scanning Electron Microscope (SEM). The experimental results indicate that the ageing procedure plays a vital role in the formation of Co-Ti LDH. The insertion of a cyanate anion into LDH was confirmed by chemical analysis and IR spectra. XRD patterns of the prepared LDH (Co-Ti-CNO) showed that the interlayer spacing of the LDH was 0.79 nm. The spacing was similar to that of usual LDH in which chloride or bromide anion is the guest. SEM images show that the morphology of Co-Ti LDH was a plate-like structure or a fibrous structure depending on the preparation conditions.This revised version was published online in July 2005 with a corrected issue number.     

New Layered Double Hydroxide, Zn–Ti LDH : Preparation and Intercalation Reactions

The layered double hydroxide (LDH) well known for its abilityto intercalate anionic compounds has been prepared conventionallyonly with bivalent and trivalent cations. In this study, Zn–Ti LDH consisting of bivalent and tetravalent cations was prepared, andreacted with organic monocarboxylic, dicarboxylic and aromatic acidsat high or room temperature. XRD patterns of the prepared LDH(Zn–Ti-CO₃) showed that interlayer spacing of the LDH was 0.67 nm. The value was small compared to the usual LDH (Zn–Al–CO₃)of 0.76 nm in the case of carbonate anion as the guest. Also, DTA,TG and DTG analysis indicated that the electrostatic force betweenthe layers and carbonate anions increased where the carbonate anionsin Zn–Ti LDH decomposed at 255 °C while those inZn–Al–CO₃ decomposed at 230–240 °C.     

Controllable Modulation of Defects for Layered Double Hydroxide Nanosheets by Altering Intercalation Anions for Efficient Electrooxidation Catalysis

Hydrazine (N₂H₄) is considered as one of the most potential energy storage materials in liquid fuel cells, as it contains high energy and power density, and the high-efficiency oxidation of N₂H₄ in fuel cells has drawn great attention. However, the most used catalysts are expensive noble metal catalysts, thus the development of highly efficient non-noble metal catalysts is crucial to reduce the cost of hydrazine oxidation in practical industry. Herein, we synthesized a series of CoFe-layered double hydroxides (CoFe-LDHs) intercalated with different anions via a simple one-step co-precipitation method for the electrooxidation of hydrazine. Through altering the intercalated anions of CoFe-LDHs, the defects and the electronic structure can be well controlled, and the catalytic performance for the electrooxidation of hydrazine were well promoted by using NO₃⁻ intercalated into CoFe-LDH compared with other anions (like Cl⁻, BO₃³⁻, CO₃²⁻). This work developed a series of hydrazine electrooxidation catalysts and established the relationship between the intercalated anions, the fine structure of the catalyst and the electrocatalytic performance.     

A comparative study of thermal decomposition behaviour of Zn-Cr,Zn-Cr-Al and Zn-Al type layered double hydroxides

Hydrolysis of ZnO in acidic pH provides a facile route for synthesis of layered double hydroxides (LDH) bearing Zn²⁺ with Cr³⁺ and Al³⁺ without having carbonate ion in the inter-layer position. The thermal decomposition of the prepared LDH show that with the increase of Cr³⁺ content in the system there is an increase in the thermal stability of the compounds. In case of Zn-Cr LDH there is a non-mass loss transition around 420°C. Segregation of parent LDH structure to a bivalent oxide and a spinel takes place in both Zn-Cr and Zn-Al LDH only at temperatures above 550°C.Authors are grateful to Director R. R. L. Jorhat for his kind permission to publish the work, as well as acknowledgement is due to Prof. Herbert Poellmann of University of Halle, Germany for some powder XRD runs. Also, acknowledgement is due to Ministry of Environment and Forests, Govt. of India for some financial assistance.     

Highly Dispersed TiO6 Units in a Layered Double Hydroxide for Water Splitting

A family of photocatalysts for water splitting into hydrogen was prepared by distributing TiO₆ units in an MTi‐layered double hydroxide matrix (M=Ni, Zn, Mg) that displays largely enhanced photocatalytic activity with an H₂‐production rate of 31.4 μmol h^?1 as well as excellent recyclable performance. High‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) mapping and XPS measurement reveal that a high dispersion of TiO₆ octahedra in the layered doubled hydroxide (LDH) matrix was obtained by the formation of an M²⁺‐O‐Ti network, rather different from the aggregation state of TiO₆ in the inorganic layered material K₂Ti₄O₉. Both transient absorption and photoluminescence spectra demonstrate that the electron–hole recombination process was significantly depressed in the Ti‐containing LDH materials relative to bulk Ti oxide, which is attributed to the abundant surface defects that serve as trapping sites for photogenerated electrons verified by positron annihilation and extended X‐ray absorption fine structure (EXAFS) techniques. In addition, a theoretical study on the basis of DFT calculations demonstrates that the electronic structure of the TiO₆ units was modified by the adjacent MO₆ octahedron by means of covalent interactions, with a much decreased bandgap of 2.1 eV, which accounts for its superior water‐splitting behavior. Therefore, the dispersion strategy for TiO₆ units within a 2D inorganic matrix can be extended to fabricate other oxide or hydroxide catalysts with greatly enhanced performance in photocatalysis and energy conversion.     

无机层状复合氢氧化物中顺铂-DNA模型分子的选择性插入

药物分子的选择性包裹和控制释放是药物研究领域中具有挑战性的研究方向。本文研究表明:顺铂-DNA模型分子cis-[Pt(NH₃)₂(5′-GMP)₂](5′-GMP 5′-单磷酸鸟苷)可插入无机层状复合氢氧化物[Zn_0.68Al_0.32(OH)₂](NO₃)_0.32·mH₂O。但另一种层状复合氢氧化物[LiAl₂(OH)₆]Cl·H₂O由于其阳离子层中正电荷密度较高、阳离子层与层间阴离子之间静电作用较强,因而顺铂-DNA模型分子不能通过离子交换方式插入其层间。光谱数据证实插入层间的顺铂-DNA模型分子结构不变。这可能为铂-DNA分子的传递提供新的方法。     

Hydrothermal Synthesis of Glutamic Acid/Layered Double Hydroxide Compounds

In this article, glutamic acid (Glu) was intercalated into the Zn-Al layered double hydroxides (Zn-Al LDHs) by hydrothermal method. The influence of the molar ratio of Zn/Al/Glu (R values for short), the aging time, and the pH value of the washing solution was systematically studied. The resulting Glu-LDH compounds were characterized by x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron micrograph (SEM). The XRD results showed that the relative diffraction intensity first increased then decreased as the R value and the pH value of the washing solution increased. Moreover, the crystallinity degree decreased gradually with the increase of the aging time. The absorption peaks attributed to the stretch of (R-COO^?) were observed in the FTIR spectra. SEM graphs indicated that the morphology of the particles was largely influenced by the synthesis conditions.     

Intercalation of Norfloxacin into Layered Double Hydroxides by Delamination/Restacking Process and its Controlled-Release Property

Norfloxacin (NFX)-layered double hydroxide (LDH) intercalated nanocomposite was synthesized by delamination/restacking process. In this method, LDH particles were first delaminated to well-dispersed two-dimensional nanosheets in formamide, and then the LDH nanosheets and NFX anions co-assembled into NFX-LDH nanocomposite. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetry revealed that the product had an expanded LDH structure. This finding indicated that NFX was successfully intercalated into LDH layers, and NFX had both horizontal and vertical orientation in the interlayers of NFX-LDH nanocomposite. Additionally, the delamination/restacking method displayed various remarkable advantages such as simple procedure, short reaction time, and mild conditions compared with the conventional methods of ion exchange, co-precipitation, and reconstruction. Results further showed that the thermal stability of NFX greatly improved after intercalation into LDH layers and that NFX release of the NFX-LDH nanocomposite was gradual, suggesting potential use as an effective drug delivery system.     

Mg-Al-NO_3层状双氢氧化物的制备及性能研究

制备了带正电荷的Mg-Al-NO_3层状双氢氧化物（LDH）,并对其组成、形貌、 电性能、离子交换性能等各种性质进行了表征。实验结果表明,所制备的正电纳米 颗粒具有可调控的层间自由空间。该方法为进一步研究聚合物/纳米复合材料提供 了一个合成前驱体的方法。     

层板剥离水滑石的制备及影响因素

采用阴离子表面活性剂N-月桂酰基谷氨酸(LG)为插层分子，研究了烷烃-LG-水(O/W)微乳液中烷烃量的变化对插层水滑石层间距的影响，同时研究了烷烃分子大小和水滑石层板阳离子不同对水滑石剥离难易程度的影响。实验表明，随着微乳液中烷烃含量的增加，制备得到了由插层到层板剥离的水滑石，并且烷烃的链长越长，水滑石的剥离越容易实现。层板化学组成对剥离难易程度也有影响，难易程度依次是Mg/Al-LDH，Zn/Al-LDH和Ni/Al-LDH。     

谷氨酸柱撑水滑石超分子结构层柱材料的插层组装

用返混沉淀方法实现了谷氨酸柱撑水滑石超分子结构层柱材料的插层组装,得到结晶度高、晶相单一且谷氨酸在层间有序排列的超分子结构层柱材料.用X射线衍射、原子光谱、元素分析、红外光谱及热重-差热分析表征了超分子结构层柱材料的结构,给出其结构模型.     

Fourier Transform Infrared Spectra of Naphthalene Disulfonates between Layers of Mg and Al double Hydroxide: Intercalation by Means of Coprecipitation and Direct Observation of Coordination from the Interlayer Anion to the Metal Cation in the Layer

A Mg/Al-layered double hydroxide with interlayernaphthalene-2,6-disulfonate having a basal spacing of1.68 nm was prepared by means of the coprecipitationmethod. The results of powder X-ray diffractionare compared with those of other intercalates whichhave interlayer naphthalene disulfonates. Fouriertransform infrared spectra of the LDH intercalatedcompounds reveal that the organic molecules located inthe interlayer region are stable. Coordinationfrom the oxygen atom in the –SO₃ ^- group of the interlayer molecules to the metal cation in the layeris observed.     

超分子结构姜黄素插层镁铝水滑石的组装、结构及缓释性能

以镁铝水滑石为主体, 以中药提取物姜黄素为客体, 由共沉淀法、离子交换法和焙烧复原法三种不同方法组装得到超分子结构复合材料——姜黄素插层镁铝水滑石. 并用XRD, IR, HPLC等手段对该材料进行了表征. 结果表明, 共沉淀法和离子交换法成功组装得到两种不同结构的姜黄素插层产物, 使材料的层间距扩大为0.82～1.36 nm, 层间客体姜黄素阴离子是以平行或者单层垂直的定位方向排列于层间的. 考察了该材料在不同pH值的磷酸盐缓冲溶液中的缓释性能, 其缓释历程为客体阴离子与介质中 的离子交换过程. 该研究指出了阴离子层状材料——水滑石在中药释释剂领域的应用潜力.