O2／EAHQ／[C5H5NC16H33]3PW4O16体系对苯乙烯选择性催化环氧化

考察了O2／2－乙基蒽氢醌（EAHQ）[C5H5NC16H33]3PW4O16催化体系对苯乙烯选择性环氧化中的溶液效应和催化剂稳定性等,发现在邻苯二甲酸和二甲酯和磷酸三丁酯的混合溶剂中,由于邻苯二甲酸二甲酯的配位作用较强,对催化剂的活性有抑制作用;若以甲苯取代部分邻苯二甲酸二甲酯,催化剂有较好的活性、较高的选择性及很好的稳定性,当催化剂的摩尔用量从2－乙基蒽氢醌的1／100减少到1／800时,反应结果基本保护不变。该体系对环氧苯乙烷的选择性达92％,催化剂的转化数达500。     

PW86–PW91 density functional calculation of vertical ionization potentials: Some implications for present‐day functionals

A total of 181 vertical ionization potentials (VIPs) of 41 molecules were calculated by density functional theory (DFT) employing the Perdew–Wang 1986 (PW86) exchange and Perdew–Wang 1991 (PW91) correlation functionals and using the aug‐cc‐pV5Z basis and experimental ground‐state geometries. The overall average absolute deviation (AAD) from experiment was found to be 0.55 eV and only 0.31 eV for linear molecules but 0.86 eV for nonplanar molecules. A number of VIPs were in error by over 2 eV. In particular, DFT performed most poorly when ionization was from an orbital with highly varying density gradients (which arise from the orbital's shape or compactness or through its density being distributed over a number of atoms). Indications are that many or all present‐day functionals suffer from the same failings. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 34–52, 2001     

O_2/EAHQ/[C_5H_5NC_(16)H_(33)]_3PW_4O_(16)体系对苯乙烯选择性催化环氧化

考察了 O2 / 2 -乙基蒽氢醌 (EAHQ) / [C5 H5 NC1 6 H33]3PW4O1 6 催化体系对苯乙烯选择性环氧化中的溶剂效应和催化剂稳定性等 .发现在邻苯二甲酸二甲酯和磷酸三丁酯的混合溶剂中 ,由于邻苯二甲酸二甲酯的配位作用较强 ,对催化剂的活性有抑制作用 ;若以甲苯取代部分邻苯二甲酸二甲酯 ,催化剂有较好的活性、较高的选择性及很好的稳定性 .当催化剂的摩尔用量从 2 -乙基蒽氢醌的 1/ 10 0减少到 1/ 80 0时 ,反应结果基本保持不变 .该体系对环氧苯乙烷的选择性达 92 % ,催化剂的转化数达 5 0 0     

AuCl_3催化2-丙炔基-苯胺和丙炔反应机理的研究

采用密度泛函理论方法B3PW91研究了AuCl3催化剂作用下2-丙炔基-苯胺和丙炔环加成生成吲哚衍生物的反应机理。研究结果表明,吲哚衍生物的生成需要经过六个步骤,其中氢迁移过程具有最高的活化自由能为214.22 kJ/mol,是反应的速率控制步骤。整个反应是强放热的,AuCl3催化下反应能够顺利进行,而且AuCl3易于从产物上离去,所以,对于该反应AuCl3是一种有效的催化剂。     

微波增强H3PW12O40／TiO2光催化降解染料和水杨酸的研究

以孔雀石绿为模型分子, 考察了微波无极灯的形状、微波功率和溶液初始浓度对光催化降解效果的影响. 并且在最佳微波反应条件下, 考察了通过溶胶-凝胶再结合程序升温水热法制备的复合材料H3PW12O40/TiO2对刚果红、酸性黑、酸性品红和水杨酸的光催化降解情况. 结果表明, 微波无极灯具有更好地增强H3PW12O40/TiO2光催化降解有机污染物的作用.     

超临界流体状态下的异构烷烃与烯烃烷基化反应

成功地应用固体酸催化剂在超临界反应条件下进行了异构烷烃与丁烯的烷基化反应。在超临界反应条件下,固体酸催化剂在１４００ｈ的反应以后,仍保持１００％的烯烃转化率。探索出一个解决固体酸催化剂在烷基化反应中极易失活的有效方法。探讨了超临界流体抑制固体酸催化剂结炭失活的机制和烷基化反应中选择超临界反应条件的规律。     

Systematic trends in (0 0 1) surface ab initio calculations of ABO3 perovskites

By means of the hybrid exchange–correlation functionals, as it is implemented in the CRYSTAL computer code, ab initio calculations for main ABO₃ perovskite (0 0 1) surfaces, namely SrTiO₃, BaTiO₃, PbTiO₃, CaTiO₃, SrZrO₃, BaZrO₃, PbZrO₃ and CaZrO₃, were performed. For ABO₃ perovskite (0 0 1) surfaces, with a few exceptions, all atoms of the upper surface layer relax inward, all atoms of the second surface layer relax outward, and all third layer atoms, again, inward. The relaxation of (0 0 1) surface metal atoms for ABO₃ perovskite upper two surface layers for both AO and BO₂-terminations, in most cases, are considerably larger than that of oxygen atoms, what leads to a considerable rumpling of the outermost plane. The ABO₃ perovskite (0 0 1) surface energies always are smaller than the (0 1 1) and especially (1 1 1) surface energies. The ABO₃ perovskite AO and BO₂-terminated (0 0 1) surface band gaps always are reduced with respect to the bulk values. The B–O chemical bond population in ABO₃ perovskite bulk always are smaller than near the (0 0 1) and especially (0 1 1) surfaces.     

Mixed Matrix Membrane with Penetrating Subnanochannels: A Versatile Nanofluidic Platform for Selective Metal Ion Conduction

Biological ion channels penetrated through cell membrane form unique transport pathways for selective ionic conductance. Replicating the success of ion selectivity with mixed matrix membranes (MMMs) will enable new separation technologies but remains challenging. Herein, we report a soft substrate-assisted solution casting method to develop MMMs with penetrating subnanochannels for selective metal ion conduction. The MMMs are composed of penetrating Prussian white (PW) microcubes with subnanochannels in dense polyimide (PI) matrices, achieving selective monovalent metal ion conduction. The ion selectivity of K⁺/Mg²⁺ is up to 14.0, and the ion conductance of K⁺ can reach 45.5 μS with the testing diameter of 5 mm, which can be further improved by increasing the testing area. Given the diversity of nanoporous materials and polymer matrices, we expect that the MMMs with penetrating subnanochannels could be developed into a versatile nanofluidic platform for various emerging applications.     

Eco‐friendly synthesis of benzoxazepine and malonamide derivatives in aqueous media

A special, efficient and reusable heterogeneous catalytic system is reported for the one‐pot three‐component synthesis of a series of malonamide and 2,3,4,5‐tetrahydrobenzo[b][1,4]oxazepine derivatives in the presence of a heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ in aqueous media and at room temperature. The products were identified using physical data (melting points) by comparison with those reported in the literature. Also, the structures of the new compounds were characterized by means of infrared, ¹H NMR, ¹³C NMR and CHN analyses. Copyright © 2016 John Wiley & Sons, Ltd.     

Thiophene hydrodesulfurization activity of alumina supported heteropoly compounds: nickel effect

Summary Hydrotreating nickel tungsten catalysts have been prepared by impregnation of g-alumina with solutions of H₃PW₁₂O₄₀ acid and its Ni salt. It is shown that the initial heteropolyanion, its lacunar analog, nickel substituted heteropolyanion and other new formed phases are present on the surface. The thiophene conversion is related to the presence of mixed NiWS phase and to the close cooperation between WS₂ and NiS_x phases.     

On the NH3+HCO3H→HCOOH+H3NO mechanism: a density functional theory study

The B1LYP, B3LYP and MPW1PW91 density functional theory methods combined with the 6-311G(2d, 2p) basis set were used to carry out a density functional theory study of the NH₃+HCO₃H→HCOOH+H₃NO reaction. The purpose of this work is to study the reaction mechanism from the viewpoint of bond order transformations throughout the course of the reaction, and propose the reasons for the apparent differences in activation barriers.     

Second‐order elastic constants of hexagonal hydroxylapatite (P63) from ab initio quantum mechanics: Comparison between DFT functionals and basis sets

Three very popular Hamiltonians in the density functional theory framework, PBE, PBEsol, and B3LYP, and different basis sets (Gaussian‐type orbitals and plane waves) were employed to simulate the hydroxylapatite unit cell and its second‐order elastic constants. Dispersive interactions were included in the quantum‐mechanical treatment via the DFT‐D2 and Tkatchenko‐Scheffler schemes. The calculated bulk, shear, and Young's moduli were in the range of 82‐117 GPa, 42‐51 GPa, and 107‐134 GPa, respectively. The axial moduli, K_a and K_b, were instead in the range of 277‐322 GPa and 506‐509 GPa. The theoretical data, especially those from plan waves simulations, are in good agreement with available results in literature and further extend the knowledge of the mechanical and vibrational properties of hydroxylapatite.     

SBA-15 supported HPW: Effective catalytic performance in the alkylation of phenol

SBA-15 was synthesized using non-ionic surfactant as the structure directing agent at 40 °C. It was then impregnated with different loadings (10, 30, 50 and 70%) of phosphotungstic acid. They were characterized by XRD, N₂ adsorption, FT-IR and DRIFT techniques. The physicochemical characterization revealed that SBA-15 could accommodate discrete phosphotungstic acid due to its large pore volume and high surface area. The catalytic activity of these materials was examined in the vapour phase tert-butylation of phenol using tert-butyl alcohol as the alkylating agent. The influence of reaction parameters such as reaction temperature, reactant feed ratio, WHSV and time on stream was studied, and the results were correlated with physicochemical characteristics of the catalysts. 4-tert-Butyl phenol was observed as the major product with high selectivity. Among the catalysts, 30% phosphotungstic acid supported SBA-15 showed high phenol conversion under optimum conditions, which is significantly higher than either phosphotungstic acid loaded mesoporous AlPO or AlMCM-41.     

光致变色的PW12/1,10DAD自组装超晶格多层膜

本文报道了在固体基底表面上用PE方法连续自组装沉积PW₁₂和1,10-DAD分子,构建了PW₁₂/1,10-DAD自组装多层膜.紫外-可见吸收、X射线衍射等分析结果表明此多层膜有好的超晶格结构,层间距为3.19nm.与真空蒸镀WO₃薄膜相比,PW₁₂/1,10-DAD自组装多层膜表现出更好的光致变色特性.     

磷钨杂多化合物催化H2O2氧化十八醇制十八酸

合成了磷钨杂多化合物,考察了其对十八醇经过氧化氢催化氧化制十八酸的反应活性,探讨了温度,催化剂用量、反应时间以及Ｈ２Ｏ２与底物的摩尔比等一系列条件对反应的影响,确定了最佳反应条件。通过ＩＲ,ＩＣＰ,ＵＶ和ＮＭＲ等技术对催化剂进行了表征,考察了反应前后催化剂的变化情况,讨论了活性中心。     

磷钨酸钾模板法制备高活性二氧化钛空心微球

TiO2空心微球因具有低密度、高活性、易分离而有利于多次重复使用的优点而广受关注.本文介绍一种无氟制备TiO2空心微球的简单方法——磷钨酸钾(K3PW12O40)模板法.首先,将H3PW12O40和KCl溶液混匀,得到白色牛奶状的K3PW12O40模板(式(1)),然后在磁力搅拌下加入一定量的Ti(SO4)2粉末,加热至大约125oC开始回流.回流8 h后,过滤洗涤.滤饼分散在强NaOH溶液中,原位除去K3PW12O40模板(式(2)).最后,将催化剂洗涤到滤液为中性,干燥后即得到TiO2空心微球.3KCl + H3PW12O40= K3PW12O40ˉ+3HCl (1) K3PW12O40+24NaOH =12Na2WO4+ K3PO4+12 H2O (2) Ti(SO4)2+2H2O = TiO2+2H2SO4(3)我们将所制备的TiO2空心微球,采用X射线衍射、透射电子显微镜、扫描电子显微镜、傅立叶红外光谱、固体粉末漫反射和X射线光电子能谱等进行了表征.采用紫外光催化降解阴离子染料(活性嫣红X3B)来评价催化剂的性能.实验结果显示：(1)所制TiO2空心微球直径在0.5–1.0μm;(2)磷钨酸钾模板剂充当晶核,有利于空心微球的晶化;(3)加入的高浓度硫酸钛,水解产生大量的硫酸,抑制硫酸钛水解,不利于TiO2空心微球的晶化(式(3));(4)催化剂的活性随着硫酸钛量的增加而先增后降.4 mmol硫酸钛用量的TiO2空心微球具有最高的光催化活性,是TiO2颗粒样品(无磷钨酸钾模板法制备)的2.1倍.用该方法制备的TiO2空心微球活性高可归因于以下主要原因：(1)TiO2空心微球独特的孔结构;(2)良好的晶化程度(TiO2样品晶化度越高,越有利于光生载流子的分离,抑制复合);(3)样品残余磷钨酸钾模板和TiO2之间存在光生电子转移,有利于空心微球TiO2活性的提高.该法具有操作简单、重复性好、易于批量制备的等优点,有望广泛应用于(光)催化、电化学、分离与纯化以及药物缓释等领域.     

Eco‐friendly synthesis of 3,4‐dihydroquinoxalin‐2‐amine,diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives with the aid of MCM‐48/H5PW10V2O40

A heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ was produced and used as an efficient, eco‐friendly and highly recyclable catalyst for the one‐pot and multicomponent synthesis of 3,4‐dihydroquinoxalin‐2‐amine, diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives in aqueous media and at room temperature with high yields in short reaction times (40–60 min). The recoverable catalyst was easily recycled at least five times without any loss of catalytic activity. The structures of obtained products were confirmed using ¹H NMR and ¹³C NMR spectra.