Catalytic asymmetric brominative dearomatization reaction of benzofurans

A catalytic asymmetric brominative dearomatization reaction of benzofuran derivatives was achieved by using hydroquinidine 1,4-phthalazinediyl diether [(DHQ)₂PHAL] as the catalyst and N-bromoacetamide (NBAc) as the brominating reagent. A series of brominated spiro[benzofuran-2,5'-oxazoles] bearing two contiguous stereogenic centers were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 97% ee).     

Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl3/TFA Catalytic System

By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl₃/TFA catalytic system was developed to replace the [Cp*RhCl₂]₂/AgSbF₆ system generally used in oxidative C?H/C?H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl₃/TFA system avoids the use of the expensive Cp* ligand and AgSbF₆. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield.     

Peripheral Amplification of Multi‐Resonance Induced Thermally Activated Delayed Fluorescence for Highly Efficient OLEDs

Multi‐resonance induced by boron and nitrogen atoms in opposite resonance positions endows a thermally activated delayed fluorescence (MR‐TADF) emitter with a strikingly small full width at half maximum of only 26 nm and excellent photoluminescence quantum yield of up to 97.48 %. The introduction of a carbazole unit in the para position of the B‐substituted phenyl‐ring can significantly boost up the resonance effect without compromising the color fidelity, subsequently enhancing the performances of the corresponding pure blue TADF‐OLED, with an outstanding external quantum efficiency (EQE) up to 32.1 % and low efficiency roll‐off, making it one of the best TADF‐OLEDs in the blue region to date. Furthermore, utilizing this material as host for a yellow phosphorescent emitter, the device also shows a significantly reduced turn‐on voltage of 3.2 V and an EQE_max of 22.2 %.     

Scalable Wet Deposition of Zeolite AEI with a High Degree of Preferred Crystal Orientation

Producing zeolite films with controlled preferred orientation on an industrial scale is a long‐standing challenge. Herein we report on a scalable approach to the direct wet deposition of zeolite thin films and membranes while maintaining a high degree of control over the preferred crystal orientation. As a proof of concept, thin films comprising aluminophosphate zeolite AEI were cast on silicon wafer or porous alumina substrates. Electrical properties and separation performance of the zeolite thin films/membranes were engineered through controlling degree of preferred crystal orientation.     

NiFe2O4/g-C3N4 heterojunction composite with enhanced visible-light photocatalytic activity

Spinel structure nickel ferrite (NiFe₂O₄) doped graphitic carbon nitride (g-C₃N₄) photocatalyst NiFe₂O₄/g-C₃N₄ was synthesized by the coprecipitation route to enhance the photocatalytic activity for the visible-light driven degradation of methyl orange. The NiFe₂O₄ doping content is responsible for the microstructure and photocatalytic activity of NiFe₂O₄/g-C₃N₄ samples. Compared with pure NiFe₂O₄ and g-C₃N₄, the 2-NiFe₂O₄/g-C₃N₄ composite with NiFe₂O₄ doping of 2.0 wt% exhibited excellent photocatalytic activity and superior stability after five runs for degrading methyl orange under visible light irradiation. The catalytic activity of 2-NiFe₂O₄/g-C₃N₄ sample produced using the coprecipitation route was higher than those of conventional 2-NiFe₂O₄/g-C₃N₄ bulks prepared by the impregnation approach. The prepared samples for the photocatalytic degradation of methyl orange followed pseudo-first-order reaction kinetics. It’s ascribed to the synergistic effect between NiFe₂O₄ and g-C₃N₄, which can inhibit the recombination of photoexcited electron-hole pairs, accelerate photoproduced charges separation, and enhance the visible light absorption.     

Brønsted Acid Enabled Nickel‐Catalyzed Hydroalkenylation of Aldehydes with Styrene and its Derivatives

A Brønsted acid enabled nickel‐catalyzed hydroalkenylation of aldehydes and styrene derivatives has been developed. The Brønsted acid acts as a proton shuttle to transfer a proton from the alkene to the aldehyde, thereby leading to an economical and byproduct‐free coupling. A series of synthetically useful allylic alcohols were obtained through one‐step reactions from readily available styrene derivatives and aliphatic aldehydes in up to 88 % yield and with high linear selectivity.     

液相色谱-串联质谱联用技术检测人尿中去氨加压素及其在人尿中的消除研究

建立了液相色谱-串联质谱(LC-MS/MS)检测人尿中去氨加压素的方法。样品经Waters C_(18)固相萃取净化,Phenomenex Onyx Monolothic C_(18)色谱柱分离,以10 mmol/L甲酸铵水溶液(用甲酸调至p H 3.5)-乙腈作为流动相进行梯度洗脱,流速为0.4 m L/min,串联质谱正离子模式电离(ESI~+),多反应监测模式(MRM)检测。收集8名志愿者在服用单次单剂量去氨加压素后留取3 d内全部尿液样本,使用建立的方法进行检测并绘制代谢曲线。结果表明:尿中去氨加压素的检出限为0.2μg/L;线性范围为0.5~20μg/L,相关系数(r~2)大于0.997;在低、中、高3个加标浓度下,回收率均高于59%,日内及日间精密度均小于10%,基质效应在20%以内。8名志愿者的阳性尿中去氨加压素浓度峰值在服药后70~150 min之间,最高浓度为0.2~2.4μg/L,检测窗口期最长可至服药后13 h左右。该法对于尿中去氨加压素具有特异性,能显著降低实验时间和成本,完全满足世界反兴奋剂组织对该药物的检测要求。该实验考察了服药后阳性尿中去氨加压素的浓度变化,研究了去氨加压素在人体内的消除情况。     

Influence of Ring Structures on Optical Properties of Trivalent Bismuth in Bi-Doped Silica Optical Fiber

We report silica fiber with trivalent bismuth (Bi³⁺) in first-principles calculations. The influences of members of “Si–O–Si” rings are considered to study atomic structures, frontier molecular orbital and optical properties of Bi-doped optical fiber. Our results reveal that the luminescence of Bi³⁺-doped optical fiber is the result of a combination of Bi³⁺ ions and silica matrix. Different ring structures affect the luminescence properties, which explained why Bi³⁺-doped silica fiber usually cover a broad spectral range from the UV to visible light.     

Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd‐Catalyzed Asymmetric Dearomative Formal [3+2] Cycloaddition

A stereodivergent synthesis of tetrahydrofuroindoles through palladium‐catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70–99 %), diastereoselectivity (87/13‐>95/5 d.r.), and enantioselectivity (85/15–94/6 e.r.) were obtained, regardless of the properties of the substituents on nitroindoles. In acetonitrile, tetrahydrofuroindoles of a different diastereoisomer were produced with good to excellent yields (75–98 %) and stereoselectivity (78/22–93/7 d.r., 93/7–99/1 e.r.). Mechanistic studies were conducted to illustrate the origin of the diastereodivergency. The kinetic experiments indicate that the rate‐determining step of this reaction is different in different solvents. ESI‐MS experiments also support the existence of key palladium complex intermediates and the catalytic cycle of the reaction.     

Fuel‐Free Bio‐photoelectrochemical Cells Based on a Water/Oxygen Circulation System with a Ni:FeOOH/BiVO4 Photoanode

A bio‐photoelectrochemical cell (BPEC) based on a fuel‐free self‐circulation water–oxygen–water system was fabricated. It consists of Ni:FeOOH modified n‐type bismuth vanadate (BiVO₄) photoanode and laccase catalyzed biocathode. In this BPEC, irradiation of the photoanode generates photocurrent for photo‐oxidation of water to oxygen, which is reduced to water again at the laccase biocathode. Of note, the by‐products of two electrode reactions could continue to be reacted, which means the H₂O and O₂ molecules are retained in an infinite loop of water–oxygen–water without any sacrificial chemical components. As a result, the assembled fuel‐free BPEC exhibits good performance with an open‐circuit potential of 0.97 V and a maximum power density of 205 μW cm^?2 at 0.44 V. This BPEC based on a self‐circulation system offers a fuel‐free model to enhance multiple energy conversion and application in reality.