Highly ordered mesoporous La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 as a very efficient nanocatalyst for green aerobic oxidative coupling of thiols to disulfides

Selective aerobic oxidative coupling of thiols that are catalyzed by La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 (SBA-15@Glp–La; SBA = Santa Barbara amorphous) was studied. Using SBA-15@Glp–La, the complete conversion was achieved at room temperature in the presence of air without producing any over-oxidized yields. SBA-15@Glp–La was prepared by post-grafting technique. 5-Oxopyrrolidine-2-carboxylic acid (Glp) condensation followed by La(III) impregnation caused this La(III)-grafted 5-oxopyrrolidine-2-carboxylic acid (Glp) to immobilize on SBA-15. This SBA-15@Glp–La catalyst shows excellent catalytic activity in the selective aerobic oxidative coupling of thiols. Effects of amount of the catalyst, polarity of the solvent, effects of substrate, and catalyst reusability were investigated. It has been observed that seven repetitive reaction cycles did not cause any appreciable loss in the catalytic activity of this catalyst. The catalyst characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy, inductively coupled plasma, elemental mapping, and N₂ adsorption–desorption is reported. The procedure developed is heterogeneous and environmentally benign.     

可充锂空气电池多孔纳米催化剂

可充锂空气电池是当前化学电源研究热点和重点, 近年来取得了重要进展. 简要介绍了该领域在空气电极多孔纳米催化材料的设计与应用方面的最新研究成果, 讨论了碳、贵金属、氧化物三类催化材料的特征及性能, 展望了新型高效氧还原/氧析出双功能阴极纳米催化剂的发展方向.     

N-Doped porous carbon supported palladium nanoparticles as a highly efficient and recyclable catalyst for the Suzuki coupling reaction

A new catalyst, Pd particles supported on the N-doped porous carbon(PC) derived from Zn-based metal–organic frameworks(zeolitic imidazolate framework: ZIF-8), was successfully prepared for the first time.The as-prepared catalyst was designated as N-doped PC-Pd, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscope, N_2 adsorption and inductively coupled plasma atomic emission spectroscopy. The N-doped PC-Pd composite exhibited high catalytic activity toward the Suzuki–Miyaura cross-coupling reactions. The yields of the products were in the range of 90%–99%. The catalyst could be readily recycled and reused at least 6 consecutive cycles without a significant loss of its catalytic activity.     

纳米孔炭负载 MnOx 催化剂上苯甲醇氧化反应性能

 以纳米孔炭 (NC) 为载体, 采用浸渍法制备了一系列 MnOx/NC 催化剂, 并用于以空气为氧源的苯甲醇液相氧化反应. 通过 X 射线衍射、X 射线光电子能谱、N2 吸附-脱附和 H2-程序升温还原等手段对催化剂进行了表征, 考察了催化剂中 Mn 负载量和焙烧温度, 以及反应条件等对反应性能的影响. 结果表明, 10%MnOx/NC 催化剂的活性较高, 反应 4 h 后苯甲醇转化率可达 80.4%; 明显高于活性炭负载的 MnOx 催化剂. 这主要归因于其表面存在大量高分散、且易于还原的 Mn 物种.     

二维纳米空洞方格:诺氟沙星锰(Ⅱ)配合物

The reactions of norfloxacin (H-Norf) with Mn(ClO₄)₂·6H₂O and Mn(OH)₂ yield Mn(H-Norf)(ClO₄)₂·2H₂O (1) and [Mn(Norf)₂·4H₂O]_n (2) , respectively. 1 is monomeric while 2 has a novel 2D neutral square grid with an antibacterial drug as building block. Crystal data for 1: triclinic, space group P1 (No.2), a=9.0939(3), b=9.4395(3), c=12.7182(3)?, α=111.447(2), β=90.340(2), γ=112.357(1)°, V=926.34(5)?³, Z=1, ρ_cacl=1.664g·cm^-3. MoKα radiation (λ=0.71073?), T=293(2)K, μ=0.595mm^-1, R₁=0.0692, wR₂=0.1482 for 2320 observed reflections from 4390 independent reflections, GOF=0.940; Crystal data for 2: Monoclinic, P2₁/c, a=5.7530(12), b=21.865(4), c=13.343(3)?, β=98.25(3)°, V=1661.1(6)?³, Z=2, ρ_cacl=1.527g·cm^-3, T=293(2)K, μ=0.477mm^-1, R₁=0.0531, wR₂=0.1552 for 2070 observed reflections from 2870 independent reflections, GOF=1.384. CCDC: 140819; 151063.     

Bicontinuous Nanoporous Frameworks: Caged Longevity for Enzymes

The preparation of bicontinuous nanoporous covalent frameworks, which are promising for caging active enzymes, is demonstrated. The frameworks have three‐ dimensionally continuous, hydrophilic pores with widths varying between 5 and 30 nm. Enzymes were infiltrated into the bicontinuous pore by applying a pressured enzyme solution. The new materials and methods allowed the amount of caged proteins to be controlled precisely. The resulting enzyme‐loaded framework films could be recycled many times with nearly no loss of catalytic activity. Entropic trapping of proteins by a bicontinuous pore with the right size distribution is an unprecedented strategy toward facile in vitro utilization of biocatalysts.     

Ultra‐small and highly dispersed Pd nanoparticles inside the pores of ZIF‐8: Sustainable approach to waste‐minimized Mizoroki–Heck cross‐coupling reaction based on reusable heterogeneous catalyst

The rapid development of nanomaterials, particularly advanced hybrid nanoparticles, has made new opportunities for the design and fabrication of high‐performance metal‐based catalysts. However, generating metal nanoparticles of desired size without aggregation is an important challenge for enhancing the catalytic activity of metal nanoparticles supported in the host matrix. In this work, a hybrid nanoporous material, namely Pd nanoparticles@N‐heterocyclic carbene@ZIF‐8, with a high internal surface area was successfully prepared using a dispersed anionic sulfonated N‐heterocyclic carbene–Pd(II) precursor inside the cavities of zeolitic imidazolate framework (ZIF‐8) using an impregnation approach followed by reduction with NaBH₄. The anionic sulfonated N‐heterocyclic carbene was found to be a superb ligand for the stabilization of Pd nanoparticles in the pores of ZIF‐8. The resulting system was applied to the Mizoroki–Heck cross‐coupling reaction, in which the catalyst showed high catalytic activity under mild reaction conditions.     

生物凝胶电镀法制备铜纳米多孔膜

采用生物凝胶电镀法制备铜纳米多孔膜。 电镀电压为5 V,阳极为铜片,实验探究了电镀液成分、电镀时间、阴极衬底及沉积电压对电镀层表面形貌的影响。 采用扫描电子显微镜(SEM)和X射线衍射(XRD)对样品形貌和晶型进行表征,得出制备铜膜的最佳条件。 结果表明,电镀的铜膜颗粒尺寸在100 nm左右,晶粒平均尺寸为25 nm,存在较强的(111)织构,而且XRD结果表明,附着的壳聚糖凝胶对铜膜有保护作用,防止其被氧化。 同时采用电化学工作站对其过程中的电镀电流进行实时测量,电流变化曲线表明电镀进行到一定时间后,电流趋于一个很小的稳定值,壳聚糖凝胶阻止了镀液中铜离子的进一步沉积。     

An Ordered Nanoporous Monolith from an Elastomeric Crosslinked Block Copolymer Precursor

Summary: An ordered nanoporous monolith was prepared from a poly(isoprene‐b‐dimethylsiloxane) (PI‐PDMS) hexagonally packed cylinder precursor. The PDMS cylinders were macroscopically aligned, the PI was crosslinked with dicumyl peroxide, and the PDMS was removed using tetrabutylammonium fluoride. The stability of the pores depended on the modulus of the matrix. At high crosslink density the pores were stable, but they collapsed at a low crosslink density. The nanoporous materials could be swollen in toluene.

A scanning electron micrograph of the end‐on view of crosslinked degraded poly(isoprene‐b‐dimethylsiloxane).     

Time-Resolved Spectroscopic Studies of the Photoluminescence of Nanoporous Silicon: Effects of Lewis Acid/Base Exposure

Visible light emission emanating from nanostructured porous silicon is sensitive to adsorption of a number of small molecules, suggesting its utility as a chemical sensor. In this work we investigate the mechanistic origin of the diminution of the luminescence by n-propyl amine adsorption and restoration by trifluoroacetic acid, most sensitively by an examination of the changes in observed lifetime of the porous Si luminescence. This is quantified in terms of a stretched exponential model that is consistent with a distribution of luminescent centers in this nanophase material.     

Capacitance characteristics of nanoporous carbon materials in ionistors based on RbAg<Subscript>4</Subscript>I<Subscript>5</Subscript> solid electrolyte

Characteristics of solid-state ionistors developed on the basis of nanoporous carbon synthesized by chlorination of metal carbides are presented. It is shown that the energy storage density in this type of devices reaches 150 J/g when they are operated in the hybrid mode.     

先驱体聚合物粘结法制备SiC纳米多孔陶瓷

采用SiC纳米粉体与聚碳硅烷(PCS)为原料低压成型低温烧结制备SiC纳米多孔陶瓷,研究了PCS含量对烧成纳米多孔陶瓷性能的影响。SEM和AFM微观形貌分析表明,PCS裂解产物将SiC纳米颗粒粘结起来,烧成陶瓷内部有大量的纳米孔存在。烧成SiC纳米多孔陶瓷孔径分布呈单峰分布、孔径分布范围窄,随着PCS含量的增大烧成多孔陶瓷强度增大,但孔隙率降低、烧结过程中坯体尺寸线收缩率增大。PCS含量为20wt%时三点弯折强度为36.8MPa,孔隙率为39.5%,平均孔径为49.3 nm。     

Highly efficient protection of alcohols as trityl ethers under solvent-free conditions,and recovery catalyzed by reusable nanoporous MCM-41-SO3H

An efficient method was developed for the protection of alcohols as trityl ethers using triphenylmethanol in the presence of nanoporous MCM-41-SO₃H as a heterogeneous catalyst under solvent-free ball-milling at room temperature. Low catalyst loading, high efficiency, reusability are among the advantages of this new solvent-free and environmentally friendly method. The deprotection of the produced trityl ethers was also efficiently achieved using the same catalyst in wet acetonitrile.     

Humidity Sensing Properties of the Sensor Based on V‐doped Nanoporous Ti0.9Sn0.1O2 Thin Film

Vanadium doped nanoporous Ti_0.9Sn_0.1O₂ thin film has been prepared on an alumina substrate by sol‐gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V‐doped nanoporous Ti_0.9Sn_0.1O₂ thin film shows good humidity sensing properties, and impendence of it decreases more than four orders of magnitude in the relative humidity (RH) range of 11%–95% at 25°C. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is suggested to explain the humidity sensitive properties.     

纳米孔金膜电极：合金化/去合金化法制备及电化学性能

采用合金化/去合金化法在金电极表面制备出一层具有纳米孔结构的金膜，其孔径约为15 nm。该方法首先在金电极表面电沉积一层锌，再通过热处理形成合金层，最后利用化学去合金化法去除合金中的锌。X射线衍射(XRD)结果表明在合金化过程中，锌扩散进入金基体并形成了金-锌合金层。利用场发射扫描电子显微镜(FESEM)对去合金化得到的纳米孔金膜进行了形貌的表征，结果表明合金化条件对样品的纳米结构有明显的影响。电化学测试结果表明，经合金化/去合金化处理的金电极，其表面粗糙度有明显的提高。这种金电极对甲醇具有较高的催化氧化活性，在0.3 mol·L^-1甲醇的KOH溶液中，甲醇的氧化峰电流密度高达2.02 mA·cm^-2。     

漆酶在纳米多孔金上的固定化及其酶学性质研究

利用纳米材料为载体对酶等生物大分子进行固定化近年来引起人们的浓厚兴趣. 以Au/Ag合金为原料, 通过控制浓硝酸的腐蚀时间再辅以退火处理得到了不同孔径的纳米多孔金(NPG), 利用扫描电镜(SEM)和N2气体吸附仪对孔性质进行了表征. 以NPG为载体, 用α-硫辛酸和N-乙基-N’-(3-二甲基氨基丙基)碳酰二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)对金表面进行活化, 通过化学共价偶联的方法对产自Trametes versicolor的漆酶进行了固定化. 比较了孔径大小对酶固定化量及比活力的影响. 发现小孔径更有利于对该漆酶的固定化. 与游离酶相比, 固定化酶的最适pH没有改变, 但最适温度却从原来的40 ℃升到了60 ℃. 固定化后, 漆酶的pH和热稳定性都明显提高了. 重复使用8次仍能保持初始活力的65%, 且在4 ℃下保存1个月几乎观察不到酶活力的下降. 此外, 失活的固定化酶经浓硝酸处理后, NPG载体可重复利用. 本结果初步显示出了NPG在生物技术领域中的应用潜力.     

Nanoporous Networks of Si-, Al-, P-Oxygen Tetrahedra with Encapsulated Dyes as New Composite Materials

Microporous and mesoporous molecular sieves like zeolite faujasites, AlPO₄-5 and Si-MCM-41 are obtained by polycondensation of oxygen containing tetrahedra of the metal aluminium, the semimetal silicon and the non-metal phosphorus by conventional or microwave-assisted hydrothermal synthesis. The encapsulation of dyes after different methods is described. Monomolecular distribution of dyes in the framework of the hosts is obtained. The encapsulated dyes show high absorption and fluorescence intensities which is interesting for photochromic switches, optical sensors and lasing. The location of a dye is identified after single molecule spectroscopy.     

不同Co含量对纳米多孔Ni-Co结构及析氢催化性能的影响

通过真空熔炼和快速凝固的方法制备了不同Co含量的Ni-Co-Al合金,经脱合金化后得到纳米多孔Ni-Co。采用XRD、SEM、TEM、N2吸附-脱附研究了所得纳米多孔Ni-Co结构特征,以线性扫描伏安法(LSV)、交流阻抗(IMP)等手段对纳米多孔NiCo/GCE电极析氢性能进行了测试。结果表明:纳米多孔Ni-Co合金骨架表面存在尺寸更为细小的5～10 nm的小孔,Co含量(质量分数)在40%～60%时,析氢催化性能较好。     

TiO_2/CdS/Ru(bpy)_2(NCS)_2作为太阳电池光阳极的探讨

将 Cd S纳米粒子复合在 Ti O2 纳米多孔膜上 ,用染料 Ru( bpy) 2 ( NCS) 2 对此复合半导体纳米膜电极进行敏化 ,测量了不同 Cd S复合量的 ITO/Ti O2 /Cd S/Ru( bpy) 2 ( NCS) 2 光阳极组成光电池的能量转换效率 .实验证明 ,ITO/Ti O2 /Cd S/Ru( bpy) 2 ( NCS) 2 作为太阳电池光阳极的能量转换效率与 Ti O2 /Cd S复合半导体中 Cd S的含量有关 .当 Cd S复合时间为 5 min的电池的短路电流为 5 .2 3A/m2 ,开路电压为 0 .71 6 V,能量转换效率为 0 .77% .     

硫化物/Ru(Ⅱ)结合物复合敏化TiO_2纳米多孔膜

用光电化学方法研究了Cds、Pbs和RuL2（NCS）2（L＝2.2′-bipydine-4.4′-dicarboxylicacid）复合敏化TiO2。纳米晶电极的光电化学行为．结果表明，采用复合敏化比用rul（Ⅱ）络合物单独敏化TiO2。纳米晶电极效果好，大大提高了光电转换效率．主要原因是采用复合敏化，可防止TiO2导带上由光注入产生的电子的反向转移，避免了电子的损失．