Waugh结构(NH_4)_6[MnMo_9O_(32)]·8H_2O催化合成乙酸异戊酯

以Waugh结构钼锰杂多酸盐作为催化剂对乙酸异戊酯的合成进行了催化研究.确定了最佳反应条件:醇酸摩尔比为1.646∶1,酸化催化剂用量为0.2 g,带水剂为3 mL甲苯,反应时间63 min左右,选择性100%,转化率达82.70%.     

XANES speciation of mercury in three mining districts – Almadén,Asturias (Spain), Idria (Slovenia)

The mobility, bioavailability and toxicity of mercury in the environment strongly depend on the chemical species in which it is present in soil, sediments, water or air. In mining districts, differences in mobility and bioavailability of mercury mainly arise from the different type of mineralization and ore processing. In this work, synchrotron‐based X‐ray absorption near‐edge spectroscopy (XANES) has been taken advantage of to study the speciation of mercury in geological samples from three of the largest European mercury mining districts: Almadén (Spain), Idria (Slovenia) and Asturias (Spain). XANES has been complemented with a single extraction protocol for the determination of Hg mobility. Ore, calcines, dump material, soil, sediment and suspended particles from the three sites have been considered in the study. In the three sites, rather insoluble sulfide compounds (cinnabar and metacinnabar) were found to predominate. Minor amounts of more soluble mercury compounds (chlorides and sulfates) were also identified in some samples. Single extraction procedures have put forward a strong dependence of the mobility with the concentration of chlorides and sulfates. Differences in efficiency of roasting furnaces from the three sites have been found.     

Theoretical Studies on S-Phenyl-thiabenzene,S-Phenyl-thianaphthalene,and S-Phenyl-thiaanthracene

The molecular structures of S-phenyl-thiabenzene 1, S-phenyl-1-thianaphthalene 2, S-phenyl-2-thianaphthalene 3, and S-phenyl-9-thiaanthracene 4 are studied by ab initio calculations using HF as well as DFT methods at the 6–311+G? level of theory. The non-planar boat conformers of 1–4 with 6π electrons in the heterocyclic ring appear to be more stable than the corresponding planar conformers with 8π electrons in the ring. The activation energy for the inversion at the sulfur atom is compared for 1–4. Conformational flexibility of 1–4 is studied.     

Beryllium(II) Complexes with Bis(dimethylamino)phosphorylfluoride: A Multinuclear NMR (31P, 19F,and 9Be) Characterization in Solution

Complexes of beryllium chloride and nitrate with (Me₂N)₂P(O)F were characterized in solution by multinuclear NMR spectroscopy and in some cases by IR spectroscopy and conductimetry. ³¹P and ¹⁹F NMR spectra were informative of changes associated with complex formation revealing resonances consistent with different species in solution and suggest an equilibrium between these species in both beryllium derivatives. These compounds show narrow lines in the solution ⁹Be NMR spectra, indicative of a highly symmetric environment for beryllium. The presence of the different species was more pronounced in beryllium chloride complexes. The results are compared to those reported in the literature for hexamethylphosphoramide (HMPA).     

COMMUNICATION. B-THIOACYLTHIO-9-BBN AS A THIOACYLATING REAGENT

Abstract

Convenient syntheses of S-aryldithioesters and thioamides are described: thus, thiols and amines are readily thioacylated with the S-borondithioester formed in situ, by the mild reaction of a dithioacid with 9-BBN.     

A novel covalent functionalisation of poly (styrene-alt-maleic anhydride) with 4-amino benzo-9-crown-3 ether

The grafting of 4-amino benzo-9-crown-3 ether to poly (styrene-alt-maleic anhydride) has been described. The covalent grafting of crown ether has led to a considerable increase in the solubility of polymer in organic solvents such as dimethyl sulphoxide, dimethylformamide and tetrahydrofuran. The highest solubility was attained in DMF and DMSO. The covalently bonded 4-benzo-9-crown-3 ether allowed the hosting of Li⁺. The covalently grafted crown ether to polymer was identified by infrared spectroscopy and thermogravimetric analysis methods.     

Toward a light-harvesting Hyperbranched Polyesteramine Host–guest Complex

A novel hyperbranched polyesteramine (PEA) architecture 1 was found to display light-harvesting properties by hosting anthracene-9-carboxylic acid guest 3. The light-harvesting ability has been studied by means of fluorescence spectroscopy. The binding behaviour has also been described by FT-IR and ¹H NMR spectroscopic methods. Hyperbranched host 1 also acts as the photon-harvesting chemosensor of the anthracenyl guest over the benzoic acid guest. Furthermore, the host loaded with the anthracenyl guest also exhibited ‘ON–OFF’ switching on protonation of amine sub-units with HCl, thereby making it of potential use as a pH-assisted photon-harvesting material.     

Bi2Fe4O9/g-C3N4/UiO-66三元复合材料的协同光催化作用

通过水热法合成具有协同机制的三元复合材料Bi₂Fe₄O₉/g-C₃N₄/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi₂Fe₄O₉更易于和g-C₃N₄结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。     

Multicomponent Domino [4+1+1] Carbocyclization Providing an Efficient and Regioselective Strategy to Fluoren-9-ones

Concise and efficient three‐component domino [4+1+1] carbocyclization to highly substituted fluoren‐9‐one derivatives promoted by K₂CO₃ has been developed under microwave irradiation conditions. The direct bis‐cyanation and aryl amination residing in fluoren‐9‐one framework were achieved in a one‐pot operation. The reaction proceeds at fast rates and can be finished within 30 min, which makes workup convenient to give good to excellent chemical yields.     

基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法,对Cs₃Bi₂X₉(X=Cl、Br、I)的光电特性进行理论计算,并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明,3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中,材料的吸收峰会随卤素原子序数的增加呈现红移,其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感;二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响;零维结构的Cs₃Bi₂I₉非常稳定,且几乎不受表面特性和晶体厚度的影响。