Copper(II) trans-bis-(glycinato): an efficient heterogeneous catalyst for cross coupling of phenols with aryl halides

Copper(II) trans-bis-(glycinato) complex, easily prepared by the solid state reaction of copper(II) acetate and glycine (trans-[Cu(glyo)₂·H₂O]) was found to be an efficient, recyclable, and high yielding catalyst for the Ullmann type synthesis of diaryl ethers via the cross coupling of phenols with aryl halides without using any additives at relatively low reaction temperature. The catalyst could easily be recovered by simple filtration and was reused for several runs with consistent catalytic activity.     

Microwave-assisted synthesis of macrocycles via intramolecular and/or bimolecular Ullmann coupling

Microwave-assisted synthesis of macrocyclic diaryl ethers via intramolecular and/or bimolecular Ullmann coupling is described. Using the optimized conditions, a panel of macrocycles, with different substitution patterns, ring sizes, and linkers, has been successfully synthesized using microwave irradiation. To the best of our knowledge, this work represents the first examples of the microwave-assisted synthesis of macrocyclic diaryl ethers via intramolecular and/or bimolecular Ullmann coupling.     

A Sensitive Visible Spectrophotometric Method for Copper Using Bis-Substituted Thiocarbamoyl Trisulfides

Abstract

Bis-substituted thiocarbamoyl disulfides (thiuram disulfides) were investigated as chromogenic reagents for the analysis of copper in trichloroacetic acid solutions. It was found that hydrogen peroxide speeded color development, increased color stability and enhanced color intensity in a trichloroacetic acid-alcohol matrix. In the presence of hydrogen peroxide, all copper complexes had molar absorptivities exceeding 30,000. Bis-pentamethylene thiocarbamoyl disulfide was selected as the best commerically available reagent of those investigated. The procedure is almost interference free, silver and mercury being the most serious interference. The sensitivity is 6 × 10^?3 micrograms/cm².     

Fe(CO)5 promoted C-S bond activation and formation of an unusual C2S3 ligand in [{Fe2(CO)6}2(μ-C2S3)]

Photolysis of a hexane solution containing Fe(CO)₅ and CS₂ leads to desulfurization and formation of a novel cluster [{Fe₂(CO)₆}₂(μ-C₂S₃)] (1). Its molecular structure was determined by single crystal X-ray diffraction methods and shown to consist of two distinct Fe₂(CO)₆ units linked by an unusual C₂S₃ unit.     

基于层状二硫化钼纳米片比色检测亚锡离子

在醋酸/醋酸钠缓冲溶液(pH=4.5)中, 亚锡离子对层状二硫化钼(MoS₂)纳米片催化过氧化氢(H₂O₂)氧化邻苯二胺(OPD)的显色反应有很强的抑制作用, 据此构建了一种检测亚锡离子的比色传感器. 实验结果表明, 与不加MoS₂纳米片的OPD/H₂O₂比色传感体系相比, MoS₂/OPD/H₂O₂体系检测亚锡离子的灵敏度显著提高, 线性范围变宽. 在优化的条件下, MoS₂/OPD/H₂O₂传感体系检测亚锡离子的线性范围为0.02~3.0 μmol/L, 检出限为8 nmol/L (S/N=3). 该传感体系对检测亚锡离子具有高的选择性, 可用于湖水中亚锡离子的检测.     

Defect Engineering of MoS2 and Its Impacts on Electrocatalytic and Photocatalytic Behavior in Hydrogen Evolution Reactions

Molybdenum disulfide (MoS₂) has been regarded as a favorable photocatalytic co‐catalyst and efficient hydrogen evolution reaction (HER) electrocatalyst alternative to expensive noble‐metals catalysts, owing to earth‐abundance, proper band gap, high surface area, and fast electron transfer ability. In order to achieve a higher catalytic efficiency, defects strategies such as phase engineering and vacancy introduction are considered as promising methods for natural 2H‐MoS₂ to increase its active sites and promote electron transfer rate. In this study, we report a new two‐step defect engineering process to generate vacancies‐rich hybrid‐phase MoS₂ and to introduce Ru particles at the same time, which includes hydrothermal reaction and a subsequent hydrogen reduction. Compositional and structural properties of the synthesized defects‐rich MoS₂ are investigated by XRD, XPS, XAFS and Raman measurements, and the electrochemical hydrogen evolution reaction performance, as well as photocatalytic hydrogen evolution performance in the ammonia borane dehydrogenation are evaluated. Both catalytic activities are boosted with the increase of defects concentrations in MoS₂, which ascertains that the defects engineering is a promising route to promote catalytic performance of MoS₂.     

Influence of surface characteristics on carbon disulfide catalytic hydrolysis over modified lake sediment biochar and research on deactivated mechanism

A series of lake sediment biochar (LSB) catalysts modified by metal oxides and basic functional groups were utilized for removal of carbon disulfide (CS₂) in yellow phosphorus tail gas. The influences of preparation and modification conditions for surface characteristics of Fe-KOH/LSB on removal of CS₂ were investigated. Surface area and pore structure analyses indicated that preparation processes were aimed to increase the micropore structure of LSB. Diffuse reflection using transform of Fourier infrared radiation results showed that Fe had high hydrolysis activity for CS₂ and low oxidation activity for H₂S. Thermogravimetric/differential thermal analysis results indicated that low calcination temperature was not conducive to the generation of Fe₂O₃ and high calcination temperature led to the oxidation of LSB. CO₂ temperature programmed desorption results stated that high alkalinity site strength could improve the catalytic hydrolysis performance. High KOH content could enhance alkalinity site strength but led to the block of pore. These modification factors mainly controlled the catalytic hydrolysis ability of Fe-KOH/LSB. X-ray photoelectron spectroscopy results claimed that the deactivation of Fe-KOH/LSB was attributed to the generation of S and sulfate, and the consumption of active component. In the deactivation process, S and sulfate generated and covered the activity sites, and Fe₂O₃ was converted into FeSO₄ or Fe₂(SO₄)₃, which led to the deactivation.     

Chemoselective one-pot synthesis of 2-phenylamino-5-alkylthio-1,3,4-thiadiazole derivatives from phenylthiosemicarbazide and CS2

A novel and fairly efficient chemoselective one-pot method has been developed for the synthesis of both 2-phenylamino-5-alkylthio-1,3,4-thiadiazole and bis-(2-phenylamino-5-alkylthio-)1,3,4-thiadiazole derivatives from phenylthiosemicarbazide and CS₂.     

高质量单层二硫化钼薄膜的研究进展

作为一种新型的二维半导体材料,单层二硫化钼薄膜由于其优异的特性,在电子学与光电子学等众多领域具有潜在的应用价值.本文综述了我们课题组在过去几年中针对单层二硫化钼薄膜的研究所取得的进展,具体包括:在二硫化钼薄膜的制备方面,通过氧辅助化学气相沉积方法,实现了大尺寸单层二硫化钼单晶的可控生长和晶圆级单层二硫化钼薄膜的高定向外延生长;在二硫化钼薄膜的加工方面,发展了单层二硫化钼薄膜的无损转移、洁净图案化加工、可控结构相变与局域相调控的方法,为场效应晶体管等电子学器件的制备与性能优化提供了基础;在二硫化钼异质结方面,研究了二硫化钼薄膜与其他二维材料形成的异质结的电学以及光电性质,为二维材料异质结的构筑和器件特性研究提供了实验参考;在二硫化钼薄膜功能化器件与应用方面,构筑了全二维材料、亚5 nm超短沟道场效应晶体管器件,验证了单层二硫化钼对短沟道效应的有效抑制及其在5 nm工艺节点器件中的应用优势;此外,利用制备的高质量单层二硫化钼和发展的器件洁净加工技术,实现了高性能柔性薄膜晶体管的集成,获得了超高灵敏度与稳定性的非接触型湿度传感器.我们在二硫化钼薄膜的制备、加工以及器件特性研究方面所取得的进展对于二硫化钼及其他二维过渡金属硫属化合物的基础和应用研究均具有指导意义.     

Variation of photoluminescence spectral line shape of monolayer WS2

The origin of the variation of photoluminescence (PL) spectra of monolayer tungsten disulfide (WS₂) is investigated systematically. Dependence of the PL spectrum on the excitation power show that the relatively sharp component corresponds to excitons whereas the broader component at slightly lower energy corresponds to negatively charged trions. PL imaging and second harmonic generation measurements show that the trion signals are suppressed more than the exciton signals near the edges, thereby relatively enhancing the excitonic feature in the PL spectrum and that such relative enhancement of the exciton signals is more pronounced near approximately armchair edges. This effect is interpreted in terms of depletion of free electrons near the edges caused by structural defects and adsorption of electron acceptors such as oxygen atoms.