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This figure shows a self-powered ammonia sensor powered by a gelatin-polyimide based triboelectric nanogenerator (GP-TENG).

This paper reports MXene-based composite double-network multifunctional hydrogels as highly sensitive strain sensors.

The application of low-powered, sustainable sensors to detect the leak of toxic gases in factories has gradually become a future trend. In our work, we proposed a NO2 gas sensor based on an In2O3/SnS2 composite powered by a high-stability triboelectric nanogenerator (TENG), where weighing paper and a polytetrafluoroethylene (PTFE) film were used as friction materials. The peak-to-peak voltage of the TENG can reach stable 600 V and the output power can up to 13 mW, which exhibits superior performance. The TENG can power small portable electronic devices such as 50 LEDs and calculators. The TENG is directly connected in series with a chemoresistive gas sensor to form a TENG-driven nitrogen dioxide sensor (TENS) for the spontaneous detection of the concentration of NO2. The sensor exhibits a high response (∼15) and rapid response/recovery time (45 s/147 s) towards 50 ppm NO2 at 43% RH and room temperature of 25 °C. Finally, a self-powered alarm system based on the TENS has been developed to monitor the concentration of NO2 in the surrounding environment. This work not only broadens the application field of the TENG as a self-powered gas sensor, but also meets the requirements of industrial IoT technology for miniaturized, low-powered, and maintainable sensors.

Recent advances in thermally localized solar evaporation hold significant promise for vapor generation, seawater desalination, wastewater treatment, and medical sterilization. However, salt accumulation is one of the key bottlenecks for reliable adoption. Here, we demonstrate highly efficient (>80% solar-to-vapor conversion efficiency) and salt rejecting (20 weight % salinity) solar evaporation by engineering the fluidic flow in a wick-free confined water layer. With mechanistic modeling and experimental characterization of salt transport, we show that natural convection can be triggered in the confined water. More notably, there exists a regime enabling simultaneous thermal localization and salt rejection, i.e., natural convection significantly accelerates salt rejection while inducing negligible additional heat loss. Furthermore, we show the broad applicability by integrating this confined water layer with a recently developed contactless solar evaporator and report an improved efficiency. This work elucidates the fundamentals of salt transport and offers a low-cost strategy for high-performance solar evaporation.

Background The side reactions of dehalogenation or C–N coupling tend to occur when halogenated aromatic amines are prepared by catalytic hydrogenation reduction of halogenated aromatic nitro compounds. In this paper, we prepared the sub-microspherical Fe3O4@PDA-Pd NPs catalyst apply it efficiently in the hydrogenation reduction of halogenated aromatic nitro compounds to prepare the halogenated aromatic amines under atmospheric pressure. The catalyst shows a high selectivity of greater than 96% and can effectively inhibit the occurrence of the side reactions of dehalogenation and C–N coupling. Results The optimum condition of the hydroreduction reaction is when tetrahydrofuran is used as solvent and the reaction happens at 50 °C for 5 h. The selectivity of the chlorinated aromatic amine and the fluorinated aromatic amine products exceed 99% and the yield exceeds 90%. Only a small amount of dehalogenated products and C–N coupling by-products were produced in the brominated aromatic compound and the iodinated aromatic compound. Conclusion We developed a promising method for preparing the superparamagnetic and strongly magnetic Fe3O4@PDA core–shell sub-microsphere-supported nano-palladium catalyst for catalyzing the hydrogenation reduction of halogenated aromatic nitro compounds. The halogenated aromatic amines were efficiently and highly selectively prepared under atmospheric pressure, with the side reactions of dehalogenation and C–N coupling effectively inhabited simultaneously.

A novel method is developed for the enantioselective synthesis of highly functionalized 3,4-disubstituted dihydro-2(1H)-quinolinones bearing two trans contiguous stereogenic centers with excellent diastereoselectivities (up to >99 : 1 dr) and high to excellent enantioselectivities (up to >99% ee). The process combines an enantioselective organocatalytic Michael–hemiaminalization reaction and a highly efficient oxidation reaction sequence with good yields and stereoselectivity.

An organocatalytic Michael reaction of cycloheptanone and cyclooctanone with nitrodienes and nitroolefins catalyzed by a hydroquinine-based primary amine catalyst has been accomplished. The corresponding Michael adducts were obtained in good yields (up to 88%) with good to excellent diastereoselectivities (up to >100 : 1) and enantioselectivities (up to >99% ee). The absolute configuration of the Michael product was assigned by TDDFT simulation of the ECD spectrum. And the Michael products can be readily converted into analogues of cycloalkano[b] fused pyrrolidines.

The reaction allows the formation of xanthenones and chromans with three contiguous stereocenters with high to excellent enantioselectivity and moderate to mostly excellent diastereoselectivity.

The first highly enantioselective organocatalytic Michael addition of 4-hydroxycoumarins is reported.

Tiefsee-Diels-Alder-Reaktion: Die asymmetrische organokatalytische Diels-Alder-Reaktion zwischen Cyclohexenonen und aromatischen Nitroolefinen gelingt in Meerwasser und gesattigter Kochsalzlosung. Die Reaktion verlauft als saurekatalysierte Enaminaktivierung uber eine einstufige konzertierte Addition (siehe Schema).

An enantioselective oxa-Michael-Henry reaction of substituted salicylaldehydes with nitroolefins that proceeds though an aromatic iminium activation (AIA) has been developed by using a chiral secondary amine organocatalyst and salicylic acid as a co-catalyst. The corresponding 3-nitro-2H-chromenes were obtained in moderate-to-good yields with up to 91% ee under mild conditions. Based on the experimental results and ESI-mass spectrometric detection of the intermediates, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.

A series of trisubstituted alkenes containing (Z)-allylthio moieties as key structural units, that is, sodium (Z)-allyl thiosulfates, symmetrical di(Z-allyl) sulfides, and di(Z-allyl) disulfides, unsymmetrical diallyl sulfides were prepared in moderate to good yields via chemical transformations from the acetates of Baylis--Hillman adducts. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:188–198, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20394

A novel and facile C-H bond fluorination proceeds under remarkably mild conditions (close to room temperature in most cases). Both aromatic and olefinic C(sp(2))-H bonds with a wide range of electronic properties are selectively fluorinated in the presence of a catalytic amount of simple, cheap, and nontoxic nitrate as the promoter. A Pd(II)/Pd(IV) catalytic cycle that is initiated by an in situ generated cationic [Pd(NO3)](+) species was proposed based on preliminary mechanistic studies.

The first example of palladium-catalyzed direct ortho-nitration of aryl C—H bonds is presented.

The acetalisation of aldehydes with diols to corresponding 1,3-dioxolanes has been accomplished using ionic liquids as catalyst and reaction media. In the reaction process the removal of water produced and other catalysts were not necessary. High conversion and good selectivity were obtained when using HMImBF4, which could be easily recycled and reused.

A new approach to the preparation of 4-chloro-2-fluoronitrobenzene in high purity is developed using 3-chloroaniline as a starting material, comprising acetylation, nitration, deprotection and a Schiemann reaction.

A novel Pd(OAc)2-NFSI-TFA system was developed for the highly selective ortho-monofluorination directed by diverse aryl-N-heterocyclic directing groups e.g., quinoxaline, pyrazole, benzo[d]oxazole, and pyrazine derivatives. A Pd(II/IV) catalytic cycle was proposed based on the ESI-MS/MS studies.

An iron-catalyzed benzylic vinylation was developed to transfer the carbon atom in the N,N-dimethyl moiety of N,N-dimethylacetamide (or N,N-dimethylformamide) to 2-methyl azaarenes to generate 2-vinyl azaarenes.