Latest ArticlesMeso-Ni@HZSM-5 bi-functional catalysts were successfully post-encapsulated with about 3–7 nm Ni nanoparticles within HZSM-5 crystals, which exhibited significantly efficient conversion activity (67.4 g[palmitic acid] g[Ni]−1 h−1) of palmitic acid and 100% selectivity of hydrocarbons with the outstanding stability during recycling application, compared to the impregnated Ni/HZSM-5 catalyst (14.0 g[palmitic acid] g[Ni]−1 h−1).
Various enzymatic reactions or enzymatic cascade reactions occur efficiently in biological microsystems due to space constraints or orderly transfer of intermediate products. Inspired by this, the horseradish peroxidase (HRP)-like nanozyme (Fe-aminoclay) was in situ synthesized on the surface of alkali-activated halloysite nanotubes and the natural enzyme (glucose oxidase, GOx) was immobilized on it to construct a high-efficiency GOx-FeAC@AHNTs cascade nanoreactor. In which, FeAC@AHNTs can not only be used as a carrier for immobilized enzymes, but also help its catalytic activity to cooperate with glucose oxidase in a cascade reaction. The microcompartments and substrate channel effect of this enzyme-nanozyme microsystem exhibit a superior catalytic performance than that of natural enzyme system, and exhibits excellent long-term stability and recyclability. Subsequently, the GOx-FeAC@AHNTs cascade nanoreactor was employed as a glucose colorimetric platform, which displayed a low detection limit (0.47 µmol/L) in glucose detection. This enzyme-nanoenzyme nanoreactor provides a simple and effective example for constructing a multi-enzyme system with limited space, and lays the foundation for subsequent research in the fields of biological analysis and catalysis.
Light-driven conversion of CO2 into chemicals/fuels is a desirable approach for achieving carbon neutrality using clean and sustainable energy. However, its scale-up application is restricted due to insufficient efficiency. Herein, we present a photothermal catalytic hydrogenation of CO2 into CH4 over Ru/black TiO2 catalysts, aiming to achieve the synergistic use of light and heat in solar energy during CO2 conversion. Owing to the desirable spectral response ability and photothermal conversion performance of black TiO2, an efficient combination of photocatalysis and thermocatalysis has been established. The CO2 hydrogenation was significantly accelerated because of the increased catalyst surface temperature enabled by the photothermal effect of black TiO2. Simultaneously, through the in situ X-ray photoelectron spectroscopy (XPS) observation, electron-rich Ru nanoparticles was achieved based on the photo-induced excitation, thereby providing more negative hydride to improve nucleophilic attack to the CO2, obtaining the CH4 yield of 93.8%.
An iron-catalyzed coupling reaction of difluoroenol silyl ethers and cyclobutanone oxime esters is described. This protocol provides a convenient access to various previously unknown and potentially useful gem-difluoromethylenated ketonitriles inmoderate to good yields. The transformations of resulting products to other fluorinecontaining products is also documented.
Life on Earth uses a common set of l-amino acids (l-aa) to construct proteins and d-nucleosides (d-Nu) to form nucleic acids, which serve as the carrier of genetic information. Herein, we reveal the intrinsic mechanism of chiral selection of l-aa and d-Nu from the perspective of chemical origin of life. This work employed 15N-labeled l-aa and performed one-pot synthesis of nucleotide amidate of amino acid (N-aa-NMP) using equal amounts of l-15N-aa and d-14N-aa with d-/l-Nu in the aqueous solution of trimetaphosphate, generating l-15N-aa-NMP and d-14N-aa-NMP, respectively. The 31P-NMR data indicated that l-aa was preferentially selected during the formation of N-aa-NMP in the presence of d-Nu. Surprisingly, d-aa was preferred over l-aa in the presence of l-Nu. Further analysis revealed that l-15N-aa-d-NMP vs. d-14N-aa-l-NMP and d-14N-aa-d-NMP vs. l-15N-aa-l-NMP were mirror isomers of each other, respectively. These data suggest that there could be a set of chiral systems opposite to that on Earth, which infers there might be a world of life that is a mirror image of the Earth.
The synthesis of cyclic polymer is an important topic in polymer chemistry. Herein, we report a one-step method to prepare cyclic polypyrazoles. Monomers with two functional groups, diazo and alkyne, were synthesized and polymerized via 1,3-diploar cycloaddition in bulk under heating without any catalyst. Polypyrazoles with molecular weights in the range of 3800-4400 g/mol and yields in the range of 78.8-98.7% were successfully synthesized. No chain end group was detected by LC-QTOF-MS and FTIR, which proves the cyclic structure of polypyrazoles. What is noteworthy is that the cyclic polypyrazoles can self-assemble into vesicles during the reprecipitation process, which was proved by the results of SEM and TEM. The reason for that is the formation of intermolecular hydrogen bond between NH and ester groups.
This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes, providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield (up to 97%) and branched-regioselectivity (up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.
Film morphology of emissive layers is crucial to the performance and stability of solution-processable organic light-emitting diodes (OLEDs). Compared to the interpenetration of conjugated polymer chain, small molecular emitter with a flexible side chain always presents easily aggregation upon external treatment, and caused π-electronic coupling, which is undesirable for the efficiency and stability of deep-blue OLEDs. Herein, we proposed a side-chain coupling strategy to enhance the film morphological an emission stability of solution-processable small molecular deep-blue emitter. In contrary to "parent" MC8TPA, the crosslinkable styryl and vinyl units were introduced as ended unit at the side-chain of CmTPA and OEYTPA. Interestingly, CmTPA and OEYTPA films present a relatively stable morphology and uniform deep-blue emission after thermal annealing (160 ℃) in the atmosphere, different to the discontinuous MC8TPA annealed film. Besides, compared to the CmTPA and OEYTPA ones, serious polaron formation in the MC8TPA annealed film also negative to the deep-blue emission, according to transient absorption analysis. Therefore, both CmTPA and OEYTPA annealed film obtained at 140 ℃ present an excellent deep-blue ASE behavior with a 445 nm, but absence for MC8TPA ones, associated with the disruption of annealed films. Finally, enhancement of device performance based on CmTPA and OEYTPA film (~40%) after thermal annealing with a similar performance curves also confirmed the assumption above. Therefore, these results also supported the effectiveness of our side-chain coupling strategy for optoelectronic applications.
The CpXRh(Ⅲ)-catalyzed asymmetric cascade C-H coupling/intramolecular cyclization of azomethine imines with propargyl carbonates has been developed, affording a variety of chiral tetracyclic indenopyrazolopyrazolone frameworks with good substrate/functional group tolerance and enantioselectivity (up to 97:3 er). Combined experimental studies and DFT calculations revealed the Rh(Ⅲ)-catalyzed stepwise annulation process and clarified the synergy coordination mode of dual directing groups in tuning the selectivity.
Here, a rhodium(Ⅲ)-catalyzed benzo[c]azepine-1, 3(2H)-dione synthesis via tandem C–H alkylation and intramolecular amination of N-methoxylbenzamide with 3-bromo-3, 3-difluoropropene as the alkylation agent is reported. The substituted benzamides and protected indoles are all tolerated, yielding the corresponding products in moderate to good yields. Further study revealed those bioactive compounds such as piperic acid and a key precursor of Roflumilast all perform well, highlighting the synthetic utility of this method.
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