Skeletal Reorganization of Mercaptoacetaldehyde Dialkyl Acetal in Acid: Formation of Disulphide, 1,2-Bis(mercapto)ethylene and 1,1,2-Tris(mercapto)ethane Derivatives

The reaction of mercaptoacetaldehyde dialkyl acetals 1 a-c in the presence of sulfuric acid, polyphosphoric acid and zinc chloride is described. Other than the disulfide reported previously, new compounds 1,2-bis-(mercapto)ethylene, 1,2,3-tris-(mercapto)ethane and 1,2-bis-(mercapto)methane have been isolated for the first time.     

亚硝基R盐和乙基紫高灵敏度分光光度法测定铋

乙基紫在酸性体系中作为显色剂已有不少报道,而在碱性中未曾见过.本法表观摩尔吸光系数7.73×10~6 L·mol~(-1)·cm~(-1),操作简便,用于试样分析,结果满意.     

限域化学：碳基功能材料从基础研究到应用

限域化学研究的是对象在纳米尺度限域空间内的化学行为。限域空间内的化学环境不同于常规本体溶液,因而会出现许多奇特的现象,如反应选择性增强、活性增加、稳定性提高。本文结合笔者课题组近年来的工作,对限域化学领域碳基功能材料的限域策略,包括限域界面诱导、限域化学组装印刷及三维多孔受限体系作简要介绍,并阐述了其在催化、储能方面的应用。最后提出了限域化学未来发展面临的主要挑战,期望能为此领域研究提供参考。     

Asymmetric borane reduction of prochiral ketones catalyzed by phosphinamides prepared from L‐serine

Synthesis of several new chiral phosphinamide catalysts with a proximal hydroxyl group from L ‐serine was described. These compounds have been successfully used in the asymmetric catalytic borane reduction of prochiral ketones. The optically active secondary alcohols were obtained with an enantiomeric excess (ee) up to 81% and excellent yields. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:288–291, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10145     

Remarkable synergistic effect in cobalt-iron nitride/alloy nanosheets for robust electrochemical water splitting

Design and synthesis of noble-metal-free bifunctional catalysts for efficient and robust electrochemical water splitting are of significant importance in developing clean and renewable energy sources for sustainable energy consumption.Herein,a simple three-step strategy is reported to construct cobalt-iron nitride/alloy nanosheets on nickel foam(CoFe-NA/NF)as a bifunctional catalyst for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The electrocatalyst with optimized composition(CoFe-NA2/NF)can achieve ultralow overpotentials of 73 mV and 250 mV for HER and OER,respectively,at a current density of 10 mA cm^-2 in 1 M KOH.Notably,the electrolyzer based on this electrocatalyst is able to boost the overall water splitting with a cell voltage of 1.564 V to deliver 10 mA cm^-2 for at least 50 h without obvious performance decay.Furthermore,our experiment and theoretical calculation demonstrate that the combination of cobalt-iron nitride and alloy can have low hydrogen adsorption energy and facilitate water dissociation during HER.In addition,the surface reconstruction introduces metal oxyhydroxides to optimize the OER process.Our work may pave a new pathway to design bifunctional catalysts for overall water splitting.     

Novel Polymer Clusters with a Uniform Chain Density

The thermal decomposition of polystyrene clusters prepared by using 4‐methacryloyloxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl as a branching agent was studied. The weight‐average molar mass (M̄_w) and the radius of gyration (R_g) of the resultant clusters can be scaled as M̄_w ∝︁ R_g^{3.0 ± 0.1}, revealing that these clusters have a uniform chain density. Moreover, the dynamic properties of such clusters converge unexpectedly faster than the static properties as the molar mass decreases.     

Synthesis of chiral 2‐oxo‐ and 2‐thio‐1,3,2‐oxazaphospholidines via the asymmetric cyclization of l‐serinoates with (thio)phosphoryl dichlorides

In this article, we have described the asymmetric cyclization of L‐serinoates and N‐benzyl L‐serinoate with phosphoro(no‐)dichloridates or their thio‐analog, respectively, and we have investigated the asymmetric induction effect of the chiral carbon center on the forming of a chiral phosphorus center. The diastereomeric excess percentages (de%) of the desired products 2‐oxo‐ and 2‐thio‐1,3,2‐oxazaphospholidines, are obtained based on their ³¹P NMR data. In some cases, the cyclization products have been separated as pure diastereomers by column chromatography. Their configuration is preliminarily discussed. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:187–191, 2000     

Surface studies of polyethers with well‐defined segmental length

Two series of polyethers were synthesized by the polymerization of 1, n‐dibromoalkane (n = 4, 6, 8, 10, 12, 14 and 18) with bisphenol‐A (BA) and 4, 4'‐(hexafluoroisopropylidene) diphenol‐A. The length of the flexible aliphatic segment changes from 4 Å to 21 Å (corresponding to 4 to 18 CH₂ groups). X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and atomic force microscopy (AFM) were used to characterize the surfaces of the polyethers. The influence of the length of the flexible aliphatic segments on the surface composition of the BA and 6FBA polyethers was investigated. The intensity ratios of the characteristic SIMS peaks of the flexible segments to those of the rigid segments were related to the length of the flexible segments and the XPS results confirmed that the SIMS intensity ratios can be used to determine the surface compositions. AFM was utilized to investigate the crystallization process of the BA polymer with n = 8. The appearance of nuclei, the generation of primary lamellae and the formation of spherulites were observed dynamically. Nuclei appeared first as 10 nm dots, some disappeared and a few could grow into lamellae. The lamellae that developed from the nuclei bred more lamellae, which in turn induced secondary nucleation and branching of lamellae and finally led to a spherical appearance.