沉积-沉淀-微波干燥法制备金属氧化物负载的金簇合物及其在CO氧化和 硫化物氧化反应中的催化性能

采用沉积-沉淀法再辅以微波干燥和焙烧制备了金属氧化物负载的金簇合物和小的金纳米粒子.干燥方法影响了金颗粒尺寸.在炉干燥过程中Au(III)因部分还原而致使Au聚集.相反,在微波干燥下,因快速和加热均一而使Au(III)得以保持,在Al2O3上负载的Au颗粒尺寸小至1.4 nm.该法可用于具有几种不同微波吸收效率的金属氧化物载体,如MnO2,Al2O3和TiO2.这些催化剂在低温CO氧化和硫化物选择有氧氧化反应中的催化活性比常规方法制备的更高.     

聚合物稳定的金簇合物上卤素吸附质:质谱检测及其对催化的影响（英文）

聚(N-乙烯基-2-吡咯烷酮)稳定的金簇合物(Au:PVP)的质谱结果表明,来源于合成前驱体的Cl吸附质主要存在于Au_(34)和Au_(43)簇合物上.金簇合物上Cl吸附质的数量不影响其催化有氧苯甲醇氧化性能,表明Cl原子与Au簇合物间存在较弱的键合作用.相反,用Br替代Au_(34)和Au_(43)簇合物上Cl显著抑制了其催化活性,但对其电子结构没有任何影响.这表明,Br原子与金簇合物的键合较强,在空间上堵塞了活性位.因Br吸附质而导致活性显著下降表明,Au_(34)和Au_(43)簇合物对Au:PVP催化活性起主要贡献.     

聚合物稳定的金纳米簇催化：理论计算与实验的相互影响

平均粒径为2–10 nm的聚合物稳定的Au纳米簇(NCs)表现出独特的催化性能。多个研究表明,影响聚合物稳定的Au NCs催化活性的主要因素为： Au NC尺寸的控制、聚合物的选择以及反应条件的优化。这是由于聚合物稳定的Au NCs在多个催化反应中表现出明显的尺寸效应,其催化活性也因所采用的聚合物和反应条件的不同而不同。为了阐明影响聚合物稳定的Au NCs催化活性的内在原因,众多研究者关注于聚合物稳定的Au NCs催化中的理论计算与实验的相互影响。本文主要总结了聚合物稳定的Au NCs中这种相互影响的研究进展。     

大孔交联酰胺类聚合物对苯酚氢键吸附机理的研究

大孔交联酰胺类聚合物是一类同时能提供氢键的给体(—NH—)和氢键的受体(—C O)的功能高分子材料。将D392乙酰化制得大孔交联聚(N-对乙烯基苄基乙酰胺)(PS-CH2NHCOCH3),并对其化学结构进行表征;测定了它在非水体系中对苯酚的吸附等温线,计算出不同吸附量时对应的吸附焓。结果表明,合成的大孔交联PS-CH2NHCOCH3在环己烷中对苯酚的吸附量大,吸附选择性高,排除了吸附过程的疏水作用及范德华力的影响因素,证明其吸附机理为氢键吸附。     

连二-2-吡啶酮三核钴簇合物的溶剂热合成及其晶体结构

用二-2-吡啶酮作为配体与羧酸钴在溶剂热中反应,得到两个新型连二-2-吡啶酮三核钴簇合物--Co3(Py2CO2H)2(PhCO2)5]·MeCN(1)和Co3(Py2CO)2(PhCO2)6(2),其结构经XRD, IR和元素分析表征.1属单斜晶系,P(2)1空间群,晶胞参数:a=1.068 7(3) nm, b=2.258 0(5) nm, c=1.163 9(3) nm, α=90.000°, β=104.805(5)°, γ=90.000°, V=2 715.6(4) nm3, Z=2, Dc=1.497 g·cm-3.2属三斜晶系,P-1空间群,晶胞参数:a=1.133 5(3) nm, b=1.140 8(3) nm, c=1.181 8(3) nm, α=85.59 8(6)°, β=75.973(5)°, γ=69.519(5)°, V=1 388.8(2), Z=1, Dc=1.521 g·cm-3.     

线性簇合物SC_(2n)S~(2-)(n=1～12)电子吸收光谱

应用密度泛函理论,在B3LYP/6-31G水平上优化了线性簇合物SC2nS2-(n=1～12)的基态平衡几何结构,并计算了它们的谐振动频率.在基态平衡构型下,通过TD-B3LYP/cc-pvTZ和TD-B3LYP/cc-pvDZ计算,确定了簇合物SC2nS2-(n=1～10)X1Σ g→11Σ u电子跃迁的垂直激发能和对应的振子强度.基于计算结果,导出了X1Σ g→11Σ u电子跃迁吸收波长与体系大小n的解析关系式,以及SC2nS2-体系第一电离能与体系大小n的解析表达式,并讨论了不同端位原子对碳链体系激发态性质的影响.     

2-巯基苯并噻唑直接键合硅胶的制备及其对Cu(Ⅱ)的吸附性能研究

采用一种简单有效的方法合成了2-巯基苯并噻唑(MBT)直接键合硅胶.将键合硅胶用于水中Cu(Ⅱ)的吸附,考查了溶液pH值的影响.结果表明当pH为6时,键合硅胶的吸附量最大.通过分批实验,研究了278K、293K和308K 3个温度条件下的吸附平衡.应用Langmuir和Freundlich两个双参数等温线模型进行拟合,MATLAB软件的误差分析表明,Freundlich模型与实验数据更加吻合.计算得到吸附过程的热力学参数△G°、△H°和△S°的值分别为-21.90kJ/mol(293K)、14.57kJ/mol和124.61J/(mol·K).结果表明,键合硅胶对Cu(Ⅱ)的吸附是一个自发进行的吸热过程.     

双核铜簇合物[Cu2(dmpytaa)4(CH3OH)2]·3CH3OH的合成、结构及其表征

合成了一个新的4,6-二甲基-2-嘧啶硫乙酸与铜的双核簇合物[Cu2(dmpytaa)4(CH3OH)2]·3CH3OH(Hdmpytaa=4,6二甲基2嘧啶硫乙酸),通过X射线衍射、红外光谱、紫外光谱、热重分析对其进行了结构表征。该晶体属于三斜晶系,空间群P1-,晶胞参数:a=509(3),b=13.526(3),c=15.396(3),α=70.68(3)°,β=68.82(3)°,γ=88.73(3)°,V=2460.3(9)3,μ=1.100mm-1,Dc=1.453gcm3,F(000)=1120,R=0.0537,wR=0.1227(I>2σ(I)),6942个可观察衍射点。该双核分子中两个中心金属Cu原子均处于扭曲的八面体构型中心,并分别与来自四个不同羧酸配体上的羧基氧原子,一个溶剂甲醇分子中的氧原子,以及相邻的一个Cu原子配位。     

二氯·双(N,N-二乙基-2-辛硫基乙酰胺)合钯(Ⅱ)配合物的合成及其结构

在有机溶剂中合成了反式-[Pb(DEOTA)_2Cl_2],C_(28)H_(58)N_2O_(2)Cl_2S_2Pd,对配合物进行了组成分析、摩尔电导、差热-热重、紫外、红外等测试,并经X射线单晶结构分析,确定了配合物的结构.配合物晶体属单斜晶系,空间群C2/ca=32.513(9)(?),b=12.174(3)(?),c=9.798(4)(?),β=106.27(3)°,V=3722(1)(?)~3,Z=4,D_c=1.24g·cm~(-3).     

汞（Ⅱ）在螫合树脂聚[对乙烯苄基-（2-羟乙基）硫醚]上的吸附机理

研究了Hg^2 在自合成的新型含硫螯合树脂-聚[对乙烯苄基-(2-羟乙基)硫醚](PSME)上的吸附机理。静态吸附结果表明：吸附属于液膜扩散控制机理；树脂对Hg^2 的等温吸附过程可以用Freundlich方程描述；在吸附过程中存在着明显的氧化还原现象。在较低浓度下，Hg^2 主要被还原成Hg2^2 和Hg^0；而在较高浓度下Hg^2 则主要被还原成Hg2^2 。在两种情况下，-S-均被氧化成-SO2-键。     

One pot synthesis of polymer protected gold nanoparticles and nanoprisms in glycerol

Uniform and stable polymer protected spherical gold nanoparticles were synthesized using glycerol as reducing agent. Further it was observed that the morphology of the particles varied from spherical to triangular prismatic gold nanoparticles when the reaction was changed from normal mode of reflux condition to microwave mode (MW) of heating. Further a brief mechanism relating the formation of prisms with the orientation of polymer and nucleation period has been discussed. Formation of triangular prismatic and spherical gold nanoparticles were characterised using UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis.     

Controlled Synthesis of PCL/PVP Copolymer by RAFT Method and Its Hydrophilic Block-Dependent Micellar Behaviors

A range of poly(ε-caprolactone)/poly(N-vinyl-2-pyrrolidone) amphiphilic block copolymers with well-de ned hydrophilic chain length were synthesized by the living/controlled reversible addition fragmentation chain transfer polymerization method. The composition and struc-ture of the targeted resultants were characterized with ¹H NMR, ¹³C NMR, FT-IR spec-troscopy and gel permeation chromatography. The various block copolymers were success-fully employed to fabricate the spherical micelle with core-shell morphological structure. The poly(N-vinyl-2-pyrrolidone) block-dependent characteristics of the copolymeric micelles were investigated by uorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The solubilization of the hydrophobic ibuprofen as a model drug in the micelle solution was also explored. It was found that the drug loading contents are related to the micellar morphology structure determined by hydrophilic chain length in the copolymer.     

高容量锂离子电池核壳型硅/碳复合电极材料的制备与性能

通过自组装方式采用一步法制备了锂离子电池硅碳复合电极材料.使用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等对样品结构进行表征.结果表明,聚乙烯吡咯烷酮(PVP)包覆的纳米硅颗粒(Si@PVP)均匀嵌入到具有三维网络纳米孔结构的导电石墨化炭黑(GCB)骨架中,形成核壳复合型(Si@PVP-GCB)纳米颗粒,既提高了该复合电极材料的导电性能,又改善了材料的机械强度.在纳米级GCB颗粒内部存在的中空石墨环结构和包覆在纳米Si颗粒外面的PVP包覆层都有效缓冲了纳米Si颗粒在充放电过程中较大的体积变化,从而使纳米Si颗粒更加稳定.电化学测试结果表明,Si@PVP-GCB电极材料在电流密度为50 m A/g时,经过100次循环后其可逆容量仍达到545 m A·h/g时,远高于商品化的石墨微球(GMs)电极材料的容量(理论容量为372 m A·h/g).     

Thermal- and dispersion-stable lipase-installed gold colloid: PEGylation of enzyme-installed gold colloid

Gold colloid possessing both lipase and PEG-tethered chains on the surface was prepared by the adsorption of lipase, followed by the immobilization of the PEG/polycation block copolymer on the colloid surface. The obtained colloid showed high dispersion stability up to 0.3 M NaCl concentration. The enzymatic activity of the lipase on the colloid complex was equivalent to the native enzyme. Surprisingly, more than 95% of the initial enzymatic activity was retained after repeated thermal treatments (five times) at 58 °C for 10 min. The PEG condensed layer between the immobilized enzyme on the gold colloid may prevent the denaturation of the enzyme at high temperature. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

用聚(L-蛋氨酸)/纳米金修饰玻碳电极同时灵敏检测多巴胺和尿酸简

A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine) (PMT)-modified glassy carbon electrode (GCE) to form a nano-Au/PMT composite-modified GCE (nano-Au/PMT/GCE). Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode. The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH = 7.00). Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0×10^-8 to 10^-6 mol/L for DA and 7.0×10^-8 to 10^-6 mol/L for UA. The detection limits were 3.7×10^-8 mol/L for DA and 4.5×10^-8 mol/L for UA at a signal-to-noise ratio of 3. According to our experimental results, nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.     

Reaction cycles and poisoning in catalysis by gold clusters: A thermodynamics approach

In heterogeneous catalysis, a catalytic process takes place at finite temperature and at finite pressure of the atmosphere of the reactant gases. By applying ab initio atomistic thermodynamics to the model case of free Au₂ and clusters in an atmosphere of O₂ and CO, we derive all the thermodynamically possible reaction paths for the oxidation of CO to CO₂. This analysis lets us explain how gold clusters enable oxidation reactions without breaking the spin‐conservation rule. Furthermore, we identify special cluster + ligands compositions such as reaction intermediates and poisoned species. In particular, a thermodynamically driven poisoning is identified for the catalytic system containing free Au₂, and the experimental (p, T) conditions that avoid its formation are suggested. This implies that for some systems a catalytic cycle can be established, on thermodynamics grounds, only in a defined range of temperatures and pressures. In addition, our predictions for provide the so far most complete interpretation of the available experimental data (Socaciu et al, J. Am. Chem. Soc. 2003). © 2013 Wiley Periodicals, Inc.     

Separation of pinhole and tunneling electron transfer processes at self-assembled polymeric monolayers on gold electrodes

Self-assembled monolayers of poly(3-alkylthiophene) on gold electrodes are examined by cyclic voltammetry in solutions containing electroactive species. Two well-separated electron transfer processes, namely, electron tunneling through the monolayer and electron exchange at pinholes (defects) of the monolayer are observed. The voltammetric responses of the pinhole electron transfer process take place around the standard potential of the electroactive species and resemble those of a nanoelectrode ensemble of independent individual nanoelectrodes. The voltammetric characteristics of the electron tunneling agree well with predictions of the Marcus theory. Satisfactory values of tunneling coefficient, standard rate constant and organization energy are derived from the voltammetric data.     

Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer–inorganic hybrid catalyst for the Suzuki–Miyaura cross-coupling reaction

Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc)₂ by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV–vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki–Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki–Miyaura cross-coupling reaction.