Crosslinking Reaction in the Formation of Porous Clays

Clay minerals are a class of hydrous layer aluminosilicates of the so-called phyllosilicate^[1] family made up of two basic types of layers, the SiO₄ tetrahedral sheet and the Al₂(OH)₆[or Mg₃(OH)₆] octahedral sheet, many of which posses interlayer cations capable of exchanging reaction with other cations. The preparation of porous clays are based on this reactivity of exchangeable interlayer cations by using the intercalation of polycations such as Al₁₃⁷⁺ oligomers^[2] into the galleries of clay minerals to form a microporous materials^[3] Here we reported a study on the interlayered crosslinking of a 2:1 type montmorillonites with a hydrolysed polycations Al in the formation of porous clays. Na-montmorillonite gel (Na-mont, particle size<2 μ) were purified by using sedimentation of Na-bentonite fines (400 mesh, Zhejiang, China) and subsequent extensively washing to remove any soluble Na⁺. Hydrolysed polycations Al was prepared by NaOH hydrolysis of AlCl₃ solutions in a condition^[2] of OH/Al=2.0 and then aging at 70-90℃ for 4 h by the following process^[3].     

钒钨酸盐/刚果红电致变色复合膜及器件研究

应用Layer-by-Layer自组装技术, 采用聚乙烯亚胺(PEI)阳离子将无机电致变色材料[P₂W₁₅V₃O₆₂]^8?(P₂W₁₅V₃)阴离子与刚果红(CR)阴离子通过静电引力复合, 构筑了复合膜[PEI/P₂W₁₅V₃/PEI/CR]₂₀及对比膜 [PEI/P₂W₁₅V₃]₂₀. 利用扫描电子显微镜、 紫外-可见吸收光谱和电化学工作站研究了复合膜的形貌与电致变色性能. 对比研究表明, 复合膜可实现浅红色-蓝紫色-浅红色的可逆颜色调变, 且保持了[P₂W₁₅V₃O₆₂]^8?阴离子的电致变色性能, 光反差22.55%, 着色效率122.67 cm²/C.复合膜循环测试400圈后透过率(500 nm)处损耗仅为6.94%, 稳定性良好; 由复合膜组装的电致变色器件也实现了由浅红色到蓝紫色的颜色变化. 本研究可为解决多酸电致变色材料颜色变化单一的问题提供参考.     

Second-harmonic generation from monolayer Langmuir–Blodgett films of various push–pull pyridine and terpyridine metal complexes

The new ligands (E)-4-[2-(4-(N-methyl-N-hexadecylaminophenyl)ethenyl]pyridine (L¹) and 4′-(C₆H₄-p-N(Me)(hexadecyl))-2,2′:6′,2″-terpyridine (L²) were prepared along with their complexes [cis-Ir(CO)₂ClL¹], [fac-Os(CO)₃Cl₂L¹], [ZnCl₂L²] and [IrCl₃L²]. Whereas these complexes show a large second-order nonlinear optical (NLO) response at the molecular level, similar to that of related organic alkylated salts as evidenced by the Electric Field Induced Second-Harmonic (EFISH) generation technique, their Langmuir–Blodgett (LB) film susceptibility is lower than that of the salts.     

二苯并噻吩及其氧化物与离子液体相互作用的理论研究

采用密度泛函理论方法比较了DBT/DBTO₂和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-的相互作用。对最稳定的[BMIM]⁺[PF₆]^-、[BMIM]⁺[PF₆]^--DBT、[BMIM]⁺[PF₆]^--DBTO₂、[BMIM]⁺[BF₄]^-、[BMIM]⁺[BF₄]^--DBT、[BMIM]⁺[BF₄]^--DBTO₂进行了NBO和AIM分析。结果表明,DBT和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-中的咪唑环彼此相互平行,NBO和AIM分析表明它们之间发生了π-π相互作用。H1'和H9'形成的F…H氢键有利于π-π堆积作用的形成。DBTO₂倾向于趋近C2-H2和甲基基团形成O…H相互作用;DBTO₂优先吸附在[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-。在模拟油中,[BMIM]⁺[PF₆]^-和[BMIM]⁺[BF₄]^-离子液体对DBTO₂的萃取能力大于DBT,其原因是可能是DBTO₂具有较大的极性和O…H与F…H的氢键作用。     

Crystals Array via Oriented Nucleation and Growth Induced by Smectic E Mesophase of C7-T-BTBT

Long-range order crystalline thin films of organic semiconductors have attracted wide attention owing to their high charge carrier mobility. However, uncontrolled crystal nucleation and growth during the thin film drying process cause the formation of grain boundaries, thereby limiting the long-range order. Herein, we achieved the oriented nucleation and growth of organic semiconductors by off-centre spin-coating at the temperature of the smectic E(SmE) liquid crystal mesophase, and then followed by Ostwald ripening during solvent vapour annealing. The thin film of 2-(5-heptylthiophen-2-yl)[1]benzothieno[3,2-b] [1]benzothiophne (C7-T-BTBT) blended with 40%(mass fraction) poly(methyl methacrylate)(PMMA) was prepared by off-centrespin-coating at SmE mesophase(170℃), followed by solvent vapour annealing in chloroform for 24 h(chloroform is a good solvent for C7-T-BTBT and PMMA). The C7-T-BTBT molecules grew to rod-like crystals, which were mostly arranged parallel to each other. The crystal growth was perfect and resulted in a single crystal. The average length of the crystals was approximately 87 μm. Moreover, the highest charge carrier mobility is 1.62 cm²·V⁻¹·s⁻¹ as against that of the film prepared at 25℃(0.06 cm²·V⁻¹·s⁻¹).     

A New Mechanism for the Formation of the Ozone Hole in the Earth Atmosphere

It is generally accepted that the Earth ozone layer is depleted by chlorine atoms produced via solar photolysis of chlorofluorocarbons (CFCs) in the upper stratosphere^[1]. This photodissociation model predicts an ozone depletion maximum at an altitude between 30 and 40 km and negligible ozone depletion below 20 km^[1]. However, the Antarctic/Arctic ozone hole appearing in each spring is observed to be located at an altitude of about 15 km^[2]. The formation of the ozone hole has been attributed to heterogeneous reactions on the surface of polar stratosphere clouds (PSCs) consisting mainly of condensed water ice:HCl+ClONO₂→Cl₂+HNO₃^[3,4]. Recently, it has been observed that dissociation of CFCs by capture of low-energy electrons is enhanced by several orders of magnitude when CFCs are adsorbed on the surfaces of ice films of polar molecules such as H₂O and NH₃^[5,6]. This enhancement is due to transfer of electrons in precursors of solvated states in polar molecular ice to CFCs that then dissociate^[7]. This effect should be most efficient in the lower stratosphere of about 15 km, where low-energy electrons can be produced by cosmic-ray ionization and localized in precursors of solvated electrons in PSCs^[8]. Strong and straightforward evidence of this new mechanism for ozone depletion has also been found in data obtained from field measurements (satellites, balloons, etc.)^[8]. In this talk, we will present the data from both field and laboratory measurements and discuss the new mechanism for the formation of the ozone hole.     

Nano-organized CdS particles with Quantum Effect on Polyaniline Film

Polyaniline(PANI)/p-aminothiophenol(PATP)/Au film was obtained by electrochemical methods^[1].The CdS nano-particles were electrodeposited according to the method of Baranski etal.^[2].     

The Structure and Properties of Mesoporous TiO2 Film Photocatalyst

As a good photocatalyst, TiO₂ has a promising prospect in environmental purification^[1]. Due to the technical problem for the separation of dispersed TiO₂ nanosized catalyst, TiO₂ film photocatalyst has become a better choice for TiO₂ photocatalyst used in fluid^[2]. Because TiO₂ thin film photocatalyst has small surface area, the catalytical activity was very low. It was an effective way to use mesoporous TiO₂ film with high surface area as photocatalyst. The structure and properties of mesoporous TiO₂ film was studied here.     

Kinetic and mechanistic study of the chlorpromazine-hydrogen peroxide reaction for the catalytic spectrophotometric determination of iodide

Extensive kinetic studies were performed to investigate the mechanism of the chlorpromazine (CP)-hydrogen peroxide reaction utilized in the catalytic determination of iodide. This reaction proceeds by two independent, parallel reactions, one through the formation of a red free radical, another directly to form the colorless product. The red color formation is catalyzed by traces of iodide. The color formation reaction was followed by measuring the increase in absorbance at 525 nm and its kinetic investigations were carried out by the initial rate method. The reaction rate curves for colorless sulfoxide formation were obtained by following the increase in absorbance at 335 nm, and the analysis was carried out by the integration method. The disappearance rate of CP is given by -d[CP]dt = k₃[I⁻[H₂O₂][H⁺] + k₆[CP][H₂O₂][H⁺] + k₉[CP][H₂O₂][H⁺] + k₁₀[CP][H₂O₂], where the first and second terms correspond to the chromogenic reaction and the third and fourth to colorless sulfoxide formation. Mechanisms consistent with each term were proposed and analytical implications of the kinetic studies are discussed.     

激光解吸电离飞行时间质谱下的银簇行为

近年来,对金属簇的研究已成为化学与物理学中最活跃的研究领域之一［１］．金属簇被认为是介于单个原子与固体之间的中间相［２］．深入地研究其结构、形成机理及物理与化学行为,对于寻找新的催化剂［３］,重新认识气相化学与凝聚相化学的关系［４］,都有非常重要的意...     

Temperature-dependent structural changes of[Bmim]FeCl4 magnetic ionic liquid characterized by an in-situ X-ray absorption fine structure

The temperature-dependent structural changes in 1-butyl-3-methylimidazolium tetrafluoride([Bmim]FeCl4)magnetic ionic liquid(MIL)were investigated by using in-situ X-ray absorption fine structure(XAFS)combined with Raman spectroscopy and DFT calculations.XAFS re sults revealed that the coordination number and bond length of Fe-Cl in the anion of[Bmim]FeCl4 MIL decreased with increments in temperature.These results directly reflected the dissociation of tetrahedral structure[FeCl4]^-,and the formation of bridge-chain[Fe2 Cl5]^+,and[FeCl2]^+species in the anion of[Bmim]FeCl4 MIL.These behaviors indicated that[FeCl4]^-dissociation was endothermic,and was promoted by increased temperature.The results obtained through XAFS were in agreement with those obtained through Raman spectroscopy and DFT calculations.     

修饰NADH模拟物的金属-有机三元环光催化制氢

将含有不同还原型烟酰烟腺嘌呤二核苷酸(NADH)活性中心模拟物的有机配体H2L1和H2L2与钴离子配位自组装获得2例具有氧化还原活性且带有正电荷的金属-有机大环Co-L1和Co-L2.选择阴离子型钌基光敏剂[Ru(dcbpy)3]4-(dcbpy=2,2'-联吡啶-4,4'-二羧酸)作为光敏中心,金属-有机大环结构作为...     

Assembly of molecular squares and helical chain polymers of Mo(W)/Cu/S clusters using thiolato ligands as linkers

Reactions between thiomolybdate or thiotungstate [Et₄N]₂[MS₄] (M = Mo, W) and CuSBu^t led to the formation of two novel Mo(W)/Cu/S clusters [Et₄N]₄[{MS₄Cu₂(μ-SBu^t)}₄] (1, M = Mo; 2, M = W). Single-crystal X-ray diffraction studies reveal that 2 is the first example of a molecular square containing CuS₂WS₂Cu building blocks. The reactions of [Et₄N]₂[MS₄] with CuCl followed by the addition of K₂SSS (SSS = 1,3,4-thiadiazole-2,5-dithiolate) yielded novel polymers {[Et₄N]₂[MS₄Cu₂(SSS)]}_n (3, M = Mo; 4, M = W). Crystal structure determination shows that the CuS₂WS₂Cu building blocks in the anion of 4 are bridged by SSS²⁻ ligands to produce a helical chain running down the crystallographic b axis.     

手性赖氨酸基Gemini表面活性剂的表面性能

用表面张力法、电导法和稳态荧光法研究了手性Gemini表面活性剂[C₁₂-m-C₁₂] Na₂（m=2,4,6）和[C₁₂-T-C₁₂] Na₂的表面性能及临界胶束聚集数,并计算胶束形成的热力学参数,用圆二色谱法考察了[C₁₂-2-C₁₂] Na₂在不同浓度下的立体构型. 结果表明,手性Gemini表面活性剂的临界胶束浓度（cmc）和临界表面张力γ_cmc随着连接基链长增加或刚性增强而增大;ΔG_m⁰和ΔH_m⁰为负值,|ΔH_m⁰|比|-TΔS_m⁰|小很多,说明胶束化过程为熵驱动的自发放热过程;随着连接基链长增加或刚性增强,ΔG_m⁰和ΔH_m⁰逐渐增大,ΔS_m⁰和临界胶束聚集数逐渐减小,表明其胶束化能力随之降低;当浓度大于cmc时,手性Gemini表面活性剂可形成手性超分子聚集体.     

阴离子插层镁铝水滑石结构及相互作用的理论研究

采用密度泛函理论(DFT)计算了MgAl-LDHs层板与无机阴离子(F^-、Cl^-、NO₃^-、CO₃^2-、SO₄^2-)和有机阴离子(水杨酸根离子([HO(C₆H₄)COO]^-)、苯甲酸根离子([(C₆H₅)COO]^-)、对二甲氨基苯甲酸根离子([p-(CH₃)₂N(C₆H₄)COO]^-)、十二烷基磺酸根离子[C₁₂H₂₅SO₃]^-、己烷基磺酸根离子[C₆H₁₃SO₃]^-、丙烷基磺酸根离子[C₃H₇SO₃]^-)间的相互作用,获得稳定超分子几何结构及相互作用能。层板主体与客体间存在较强的超分子作用,包括主客体间静电作用和氢键等。主、客体间相互作用能数值大小顺序为CO₃^2- > SO₄^2- > F^-> Cl^-> NO₃^-;[p-(CH₃)₂N(C₆H₄)COO]^-> [(C₆H₅)COO]^-> [HO(C₆H₄)COO]^-和[C₁₂H₂₅SO₃]^-> [C₆H₁₃SO₃]^- > [C₃H₇SO₃]^-。另外,还采用自然键轨道(NBO)计算和分析了LDHs 层板与阴离子间作用机理,从二阶微扰理论计算得到的稳定化能变化趋势与相互作用能数据基本吻合。     

Electrochromic Properties of Rhodium Oxide Films Prepared by Sol-gel Method

Electrochromic materials have been extensively investigated for their significant potential in information display, automotive, sensor and smart windows^[1]. Many studies have been carried out on the inorganic electrochromic materials, such as WO₃, MoO₃, NiO_x and so on^[2]. In this paper, We first report the electrochromic behavior of rhodium oxide film prepared by sol-gel method on transparent conductor substrate. The film exhibited reversible two color (from bright yellow to dark green) electrochromic behavior with satisfactory contrast at anodic and cathodic forms when the applied potential was reversed successively.     

Reactivity of tri- and tetra-nuclear ethylidyne cyclopentadienylcobalt clusters towards protonic acids

The bis(μ₃-ethylidyne) tricobalt cluster [(CpCo)₃(μ₃-CCH₃)₂] (1b) is protonated by trifluoroacetic acid to give the dicobalt edge-protonated cation [H(CpCo)₃(μ₃-CCH₃)₂]⁺ [lb + H]⁺. Protonation of the μ₃-ethylidyne tetracobalt cluster hydride [H(CpCo)₄(μ₃-CCH₃)] (3) takes place in two consecutive steps. At low temperature [H₂(CpCo)₄(μ₃-CCH₃)]⁺ [3 + H]⁺ is formed first, and is then slowly converted into [H₃(CpCo)₄(μ₃-CCH₃)]²⁺ [3 + 2H]²⁺ by an excess of acid. As judged by the ¹H NMR data and the crystal structure of [3 + X]⁺[(CF₃COO)₂X]⁻ (X = H or D) the endo hydrogens in [3 + H]⁺ and [3 + 2H]²⁺ occupy μ₃-(Co₃) face capping hydridic positions. The cations [1b + H]⁺ and [3 + H]⁺ show hydride fluxionality in solution, which in the case of [3 + H]⁺ can be frozen out on the NMR timescale at low temperature (ΔG ^≠ (203 K) = 40.8 kJ/mol). The structure of [3 + X]⁺ [(CF₃COO)₂X]⁻ (X = H or D) was determined by X-ray crystallography. One of the hydrides/deuterides is located on the crystallographic mirror plane, capping a tricobalt face of the cluster cation. The other endo hydrogen atom is believed to be disordered between the other two μ₃-(Co₃) sites, which are related by space group symmetry. Deuteronation of 3 shows a strong normal kinetic deuterium isotope effect. From the temperature independence of the ¹H NMR spectrum of [3 + 2D]²⁺ a non-fluxional solution structure can be inferred. In all the systems studied, hydridic (μ₂- or μ₃-) sites are thermodynamically preferred to possible isomeric agostic CoHC or Co₂HC sites for the endo hydrogens. Agostic interactions cannot, however, be ruled out in transient intermediates during the course of the protonations.     

Optimised hydrothermal synthesis of multi-dimensional hybrid coordination polymers containing flexible organic ligands

In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H₄pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V₂O₂(pmida)₂]⁴⁻ in solution, we have isolated [M₂V₂O₂(pmida)₂(H₂O)₁₀] species (where M²⁺ = Mn²⁺, Co²⁺ or Cd²⁺) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5·(H₂O), [CoVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5, [Co(H₂O)₆][CoV₂O₂(pmida)₂(pyr)(H₂O)₂]·2(H₂O) and [Cd₂V₂O₂(pmida)₂(pyr)₂(H₂O)₄]·4(H₂O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V⁴⁺ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units. A closely related anionic moiety, [Ge₂(pmida)₂(OH)₂]²⁻, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR.     

Electrochemical properties of a ruthenium complex immobilized as thin films and in carbon paste electrodes

The electrochemical properties of mer-[RuCl₃(dppb)(4-pic)] (dppb = Ph₂P(CH₂)₄PPh₂, 4-pic = CH₃C₅H₄N), Rupic, in CHCl₃ are governed by the formation of species such as [Ru₂Cl₅(dppb)₂], [Ru₂(dppb)₂Cl₄(4-pic)] and trans-[RuCl₂(dppb)(4-pic)₂] upon the reduction of “[RuCl₂(dppb)]”. The overall behavior depends on whether Rupic is immobilized in cast or Langmuir–Blodgett (LB) films, or incorporated into a carbon paste electrode (CPE). In cyclic voltammograms, one redox process appears for LB/Rupic films and CPE/Rupic, at E_pa = 0.35 V, E_pc = 0.25 V vs SCE, and E_pa = 0.32 V, E_pc = 0.24 V vs Ag/AgCl, respectively. This redox process was ascribed to the Ru^III/Ru^II charge transfer. For cast films the redox pair was poorly defined, with E_pa = 0.27 V and E_pc = 0.20 V. The reason for the difference lies in the phase separation and formation of aggregates onto ITO for the cast film, in contrast to the LB film. With aggregation, the formation of species occurring in solution is impaired for Rupic in cast films. The electrochemical properties for Rupic in LB films and incorporated into CPE allowed the electrocatalytic activity of Rupic to be exploited in sensors for dopamine and ascorbic acid.     

Electron paramagnetic resonance study of the reactions of tetrathiomolybdate with roussin salts and esters, and with some related iron nitrosyls

The tetrathiomolybdate ion [MoS₄]²⁻ reacts in DMF solution with Roussin esters Fe₂(SR)₂(NO)₄ (R = Me, Et, n-Pr, i-Pr, n-Bu,t-Bu, n-C₅H₁₁) to yield the paramagnetic iron nitrosyls [Fe(NO)₂(SR)₂]⁻ (1), [Fe(NO)₂(S₂MoS₂]⁻ (2) and [Fe(NO)(S₂MOS₂)₂]⁻ (3). The new complexes (2) and (3) have been characterized by EPR spectroscopy and the assignment to them of constitutions based respectively upon tetrahedral and square pyramidal iron is supported by EHMO calculations. Fe₂(SPh)₂(NO)₄ with [MoS₄]²⁻ yields only [Fe(NO)₂(SPh)₂]⁻, and preformed (3) reacts with PhS⁻ to give firstly EPR-silent species, and then [Fe(NO)₂(SPh)₂]⁻. The mononitrosyl (3) can also be formed by reaction of [MoS₄]²⁻ with [Fe₄S₃(NO)₇]⁻, Fe₄S₄(NO)₄, or Fe₂I₂(NO)₄.