电化学还原二氧化碳合成碳材料电催化还原氧气合成过氧化氢北大核心CSCD

研究了3种不同阳极(铜丝,镀锌铁丝和镍丝)材料对在熔盐中电化学还原CO_(2)制备的碳材料结构和形貌的影响,并探究了制备的3种碳材料,中空四面体碳(HQC,Cu作为阳极时的还原产物)、碳纳米片(CNS,Fe作为阳极时的还原产物)和海绵状多孔碳(SPC,Ni作为阳极时的还原产物),对2电子氧还原反应(2e;ORR)的电催化性能。研究表明,使用镀锌铁丝作为阳极材料制备的CNS由大量的碳纳米片构成,且该纳米片上具有丰富的孔洞结构以及较大的I_(D)/I_(C)(Raman光谱中D峰与G峰的强度之比,其比值反映材料的缺陷程度)值(0.996)。与HQC和SPC相比,CNS表现出最高的2e;ORR电催化活性和H_(2)O_(2)选择性(接近90%)。CNS的高活性和高选择性归因于其高的I_(D)/I_(C)值和高C—O/C=O比值,说明结构缺陷和C—O/C=O官能团对CNS催化性能至关重要。此外,CNS还具有非常优异的电催化稳定性,在长达14 h的恒电压电化学催化测试后,环电流几乎无衰减。这种以CO_(2)为碳源合成可用于电催化合成过氧化氢(H_(2)O_(2))的碳材料的方法,不仅可以作为缓解温室效应的潜在选项,也为CO_(2)衍生碳的实际应用提供了新的思路。     

Double dehydrogenation of carbocyclic β-dicarbonyl compounds:Koser's reagent can do what iodine(V) reagents can

Koser's reagent is found to be effective in the oxidative double dehydrogenation of various carbocyclic β-dicarbonyl compounds,which constitutes the first example on dehydrogenation reactivity of hypervalent iodine(Ⅲ) reagents for carbocyclic carbonyl compounds. DFT calculations reveal that the rate-determining step is the electrophilic addition of PhI+OH onto enolate of monodehydrogenated product.     

Molecular structure and properties of click hydrogels with controlled dangling end defect

In this study, controlled amount of dangling ends is introduced to the two series of poly(ethylene glycol)‐based hydrogel networks with three and four crosslinking functionality by using click chemistry. The structure of the gels with regulated defect percentage is confirmed by comparing the results of low‐field NMR characterization and Monte Carlo simulation. The mechanical properties of these gels were characterized by tensile stress–strain behaviors of the gels, and the results are analyzed by Gent model and Mooney–Rivlin model. The shear modulus of the swollen gels is found to be dependent on the functionality of the network, and decreases with the defect percentage. Furthermore, the value of shear modulus well obeys the Phantom model for all the gels with varied percentage of the defects. The maximum extension ratio, obtained from the fitting of Gent model, is also found to be dependent on the functionality of the network, and does not change with the defect percentage, except at very high defect percentage. The value of the maximum extension ratio is between that predicted from Phantom model and the Affine model. This indicates that at the large deformation, the fluctuation of the crosslinking points is suppressed for some extend but still exists. Polymer volume fractions at various defect percentages obtained from prediction of Flory–Rehner model are found to be in well agreement with the swelling experiment. All these results indicate that click chemistry is a powerful method to regulate the network structure and mechanical properties of the gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1227–1236     

Synthesis and characterization of a photoaffinity labelling probe based on the structure of the cystic fibrosis drug ivacaftor

Cystic Fibrosis (CF) is a genetic disorder caused by loss-of-function mutations to the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Ivacaftor (1) was the first therapeutic approved for the treatment of CF that is able to restore gating activity to certain CFTR variants although the mechanism of action is poorly understood. Herein we describe the synthesis of a photoaffinity labelling (PAL) probe (2) based on the structure of ivacaftor incorporating a photoreactive diazirine moiety for use in labelling studies designed to identify the binding site for ivacaftor on mutant CFTR. The PAL probe 2 retained potentiation activity, with a potency similar to 1, using a Fluorescent Imaging Plate Reader (FLIPR^®) assay measuring ion conductance potentiation of wild type (Wt)-CFTR. Photolabelling experiments with human serum albumin (HSA) as a model protein have shown that probe 2 can label HSA in a manner consistent with observed and predicted binding.     

Acid-promoted furan annulation and aromatization: An access to benzo[b]furan derivatives

An unprecedented PTSA-promoted furan annulation and aromatization in one pot has been developed. This process offers a simple and efficient synthetic route for the construction of various highly substituted benzo[b]furan derivatives, which are widely used not only in drug active molecules but also organic semiconductor and organic light-emitting devices. The preliminary mechanism study indicated this transformation proceeded sequentially via furan annulation and aromatization.     

Low-temperature fabrication and photocatalytic activity of clustered TiO2 particles formed on glass fibers

Clustered anatase phase TiO₂ particles were uniformly formed on the surface of glass fibers by a liquid phase deposition (LPD) method at 60 °C using TiF₄ and H₃BO₃ as the precursors. The clustered TiO₂ particles deposited on the glass fibers and as a photocatalyst these particles not only have a larger surface area than TiO₂ thin films, but also can avoid the disadvantages of using TiO₂ powders encountered in air purification or water treatment. The photocatalytic activity of the sample was evaluated by the photocatalytic oxidation of nitrogen monoxide (NO) in the gaseous phase. The deposition conditions and chemical composition of the clustered TiO₂ particles were discussed. It was found that the clustered TiO₂ particles that formed on the glass fibers obviously showed photocatalytic activity without high-temperature calcination. A formation mechanism was proposed to account for the formation of TiO₂ clustered morphology on the glass fibers.     

钯（II）-克林霉素-卤代荧光素体系的共振瑞丽散射光谱及其分析应用

在pH为5.0-5.4的乙酸-乙酸钠缓冲溶液中,克林霉素（Clin）与钯(Ⅱ)形成螯合阳离子,它能进一步与二碘荧光素（DIF）,赤藓红（Ery）,曙红Y（EY）等卤代荧光素类染料反应形成1：1：1的三元离子缔合物,此时将引起吸收光谱变化和荧光猝灭,同时还导致共振瑞利散射(RRS)的急剧增强并产生新的RRS光谱,钯(Ⅱ)-克林霉素与DIF,Ery和EY形成产物的最大散射波长分别位于285,287,32 1nm处,另外还有些较弱的散射峰存在。散射增强（ΔI）与克林霉素浓度在一定范围内成正比,可用于克林霉素的定量测定。对于DIF,Ery和EY体系的线性范围和检出限分别为0.025-2.1μg•mL-1和7.8 ng•mL-1,0.053-2.4μg•mL-1和16.0 ng•mL-1;以及0.038-2.4μg•mL-1和11.0 ng•mL-1。本文研究了适宜的反应条件,考察了共存物质的影响,表明方法有较好的选择性,基于三元离子缔合物的RRS光谱,发展了一种高灵敏、简便快速测定克林霉素的新方法。文中还对离子缔合物的组成,结构和反应机理,以及离子缔合物对吸收,荧光和RRS光谱的影响进行了讨论。     

Chiral Phosphoric Acid Catalyzed Asymmetric Ugi Reaction by Dynamic Kinetic Resolution of the Primary Multicomponent Adduct

Reaction of isonitriles with 3‐(arylamino)isobenzofuran‐1(3H)‐ones in the presence of a catalytic amount of an octahydro (R)‐binol‐derived chiral phosphoric acid afforded 3‐oxo‐2‐arylisoindoline‐1‐carboxamides in high yields with good to high enantioselectivities. An enantioselective Ugi four‐center three‐component reaction of 2‐formylbenzoic acids, anilines, and isonitriles was subsequently developed for the synthesis of the same heterocycle. Mechanistic studies indicate that the enantioselectivity results from the dynamic kinetic resolution of the primary Ugi adduct, rather than from the C?C bond‐forming process. The resulting heterocycle products are of significant medicinal importance.