Platinum-Imidazolyl Schiff Base Complexes Immobilized in Periodic Mesoporous Organosilica Frameworks as Catalysts for Hydrosilylation

An imidazolyl Schiff base-containing periodic mesoporous organosilica (PMO) was synthesized via co-condensation reactions between a newly prepared bis (imidazolyl)imine-bridged bis silane and tetraethyl orthosilicate in the presence of cetyltrimethyl ammonium bromide as a soft template. The resultant as-synthesized PMO was then employed as a solid support for platinum catalysts. This complex was fully characterized via various techniques including FTIR, solid-state¹³C NMR, and ²⁹Si-NMR spectroscopy, as well as N₂ adsorption/desorption analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. In addition, the catalyst was proven to efficiently mediate hydrosilylation reactions between olefins and hydrosilanes, and it can be reused for at least five cycles without significant loss of activity.     

Synthesis of homoallylic amines and acylhydrazides by tin powder‐promoted multicomponent one‐pot allylation reactions

An efficient process for the synthesis of homoallylic amines and N′‐homoallylic hydrazides is developed from the one‐pot reaction of carbonyl compounds, amines or N‐acylhydrazines, allyllic bromide and tin powder using water as solvent. N‐Acylhydrazines are found to be more reactive than amines in these processes. They can react not only with aldehydes but also with ketones to give the corresponding N′‐homoallylic hydrazides. Copyright © 2016 John Wiley & Sons, Ltd.     

Platinum(II) complexes bearing bulky Schiff base ligands anchored onto mesoporous SBA‐15 supports as efficient catalysts for hydrosilylation

Reported herein is an easy‐to‐prepare novel heterogeneous catalyst of platinum complexes bearing binary ligands of bidentate naphthalenolimine and cyclo‐1,5‐octadiene that are anchored onto mesoporous silica SBA‐15. The presence of the binary ligands not only stabilized the platinum, but also enabled the platinum atoms to form nanoclusters with diameters of ca 1 nm, and led to high platinum loading (8.69 wt%). Moreover, the platinum catalyst exhibited high catalytic activity towards hydrosilylation of terminal alkenes and styrene with silanes under mild and solvent‐free conditions, with excellent regioselectivity.     

Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation

Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.     

Blending Cr2O3 into a NiO–Ni Electrocatalyst for Sustained Water Splitting

The rising H₂ economy demands active and durable electrocatalysts based on low‐cost, earth‐abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over‐coated by a Cr₂O₃‐blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr₂O₃ triphase material exhibits superior activity and stability similar to Pt for the hydrogen‐evolution reaction in basic solutions. The chemically stable Cr₂O₃ is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen‐evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm^?2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. The non‐precious metal catalysts afford a high efficiency of about 15 % for light‐driven water splitting using GaAs solar cells.     

Sn‐mediated one‐pot four‐component allylation of aldimines

A convenient and facile method for the synthesis of homoallylic amines was disclosed. The one‐pot reaction of aldehydes, aromatic amines and allylic bromide with tin powder at room temperature could afford the homoallylic amines in good to excellent yield without any promoter or additive. The method is highly efficient and environmentally benign with low cost and concise manipulation. Copyright © 2014 John Wiley & Sons, Ltd.     

双查尔酮Rhuschalcone Ⅰ的合成

针对Rhuschalcone Ⅰ的结构特征,将其切为2个合成片断：化合物8和化合物10,然后将2个片断连接。 以间苯二酚和对羟基苯甲醛为起始原料,经选择性甲基化、碘代、甲氧甲基化、羟醛缩合、Ullmann反应和脱保护等步骤,完成了Rhuschalcone Ⅰ的合成。 关键中间体与最终产物的化学结构经1H NMR、13C NMR和ESI-MS等表征及分析予以确认。     

滑轮绳索系统中动态节点绳索单元

解除了传统有限元方法中单元节点与物质点固结的假设, 建立了空间点的速度和加速度与相应物质点的速度和加速度之间的数学关系, 强调了虚功率原理中出现的速度和加速度皆为物质速度和物质加速度. 在此基础上构造了单元节点既不与空间坐标固定也不与物质坐标固定的动态节点绳索单元. 根据滑轮绳索系统的特点, 选取绳索出入绳点的弧长坐标、出入绳角、面外摆角以及拉伸应变等空间参数描述了滑轮绳索系统的运动. 将绳索与滑轮以及绳索与卷筒之间的相互作用合理简化为物质速度间的约束条件, 避免了传统方法中接触力计算不收敛、效率低等缺点. 所提方法可精细求解绳索与滑轮间接触边界点位置和卷筒入绳点在卷筒上的运动、滑轮的中心和其连体基的运动、绳索出入滑轮和卷筒时空间方位的变化以及绳索上任意点的拉力变化等细节. 可为含绳索机械系统的力学分析提供新的理论基础. 所用的解除单元节点与物质点绑定的理论具有一定的普适性, 可为有限元方法的理论和应用提供参考.      

全二维气相色谱/飞行时间质谱分析不同产地的川芎挥发油

建立了川芎挥发油的全二维气相色谱/飞行时间质谱(GC×GC/TOF MS)指纹图谱,并结合聚类分析评价了川芎药材的质量。4种萜类和苯酞类物质在DB-Petro×DB-17柱系统上实现了明显的族组分分离。从新都市的1个样品中分离出375种组分,其中相似度、反相似度皆大于800的化合物215个;根据质谱库检索和保留指数验证,或参照标准化合物及文献报道,从中定性了43个化合物。结合偏最小二乘法-判别分析,可以很好地将4个产区的挥发油样品加以区分,并找出20种差异最大的化合物,其中包括4种苯酞类物质。在此基础上,进一步应用正交偏最小二乘法,关联化学成分和抗氧化活性,结果发现,苯酞类物质(如藁本内酯、川芎内酯A和新蛇床内酯)对川芎挥发油样品地区差异的影响最大,其中彭州产川芎样品中苯酞类物质的含量最高。本文通过高分辨色谱技术研究了相邻产地的药物化学组成差异,并将化学指纹及生物学活性相关联,建立了系统的中药质量评价及活性化合物筛选研究模式。     

岩石动态巴西圆盘实验中的过载现象

巴西圆盘实验是国际岩石力学与工程学会（ISRM）推荐的测量岩石静态拉伸强度的方法之一,也是该学会推荐的唯一测量岩石动态拉伸强度的方法。但是巴西圆盘实验得到的静态或者动态拉伸强度往往较真实值偏大,其中一个原因是所谓的过载现象,而且其相应的过载效应在动态巴西圆盘测试中尤为明显。为探究岩石材料动态劈裂拉伸强度的过载效应机理及其率相关性,利用SHPB实验装置开展了不同加载率条件下的动态巴西圆盘实验,对岩石材料劈裂拉伸强度的过载特性进行了定量分析;结合颗粒流程序进行了相关实验的数值模拟,得到了圆盘破裂的微观过程。结果表明:（1）动态巴西圆盘实验得到的岩石拉伸强度存在明显的过载现象,圆盘试样拉伸强度的过载比随加载率增加呈对数形式增加;（2）依据动态拉伸强度实验结果对模型参数引入率相关性后,模拟观察到的过载效应更加贴近实验观测。这些结果表明巴西圆盘实验中拉伸强度的过载现象是客观存在的,其机理与试样的圆盘构型以及测试方法有关。结合实验和数值结果,解释了巴西圆盘实验的过载机理,证明了动态巴西圆盘实验修正的必要性并给出了相应的方案,以获取岩石材料的真实动态拉伸强度。