Latest ArticlesIn this contribution, we describe the preparation and recognition characteristics of a novel tetrapodal benzene cage (1). The cage can express a wide recognition range without losing selectivity for the object of appropriate size and functional groups. The key to obtaining the desired structural isomer of 1 is the synthesis and isolation of the o-bis(bromomethyl)benzene precursor (5). Three distinct guests, F− (extremely small size), D-lactate (appropriate size) and L-Asp (branched shape), were selected as examples to demonstrate the recognition characteristics of 1. By NMR titration studies, they all expressed good binding affinity (K > 105 L/mol) in competitive medium (10% DMSO/THF), indicating that 1 has a wide recognition scope. The highest binding constant was observed for D-lactate, revealing that 1 has good selectivity for D-lactate versus F− and L-Asp. Moreover, the NMR titration study of F− in DMSO indicates 1 can achieve different binding modes (1:1 and 2:1 guest-host) for small-sized guests, which allows for the further development of binary binding properties and thereafter applications in the field of catalysis.
Hydrogen (H2) is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy. However, current H2 production via steam methane reforming of natural gas or gasification of coal are laden with high CO2 footprints. Recently, methane (CH4) pyrolysis has emerged as a potential technology to generate low-carbon H2 and solid carbon. In this review, the current state-of-art and recent progress of H2 production from CH4 pyrolysis are reviewed in detail. Aspects such as fundamental mechanism and chemistry involved, effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically discussed. Temperature, among other factors, plays the most critical influence on the methane pyrolysis reaction. Molten metal/salt could lower the operating temperature of methane pyrolysis to < 1000 ℃, whereas plasma technology usually operates in the regime of > 1000 ℃. Based on the reaction kinetics, metal-based catalysts were more efficient in lowering the activation energy of the reaction to 29.5–88 kJ/mol from that of uncatalyzed reaction (147–420.7 kJ/mol). Besides, the current techno-economic performance of the process reveals that the levelized cost of H2 is directly influenced by the sales price of carbon (by-product) generated, which could offset the overall cost. Lastly, the main challenges of reactor design for efficient product separation and retrieval, as well as catalyst deactivation/poisoning need to be debottlenecked.
This work describes intermolecular acylfluorination of gem-difluoroenynes using acyl fluorides as both acyl source and fluorine source. Trifluoromethyl-substituted allenones or furans could be selectively achieved via phosphine and silver catalysis. These approaches exhibit high regioselectivity, atom economy and broad functionality tolerance.
Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ production of hydrogen peroxide, which relies on sustainable solar energy. However, the commonly used photocatalyst, i.e., carbon nitride (CN), still suffers from the drawbacks of narrow light absorption range and fast charge recombination. Here, we report a facile method to introduce nitrogen defects into carbon nitride together with sodium ion. By adjusting the ratio of sodium dicyandiamide, the band gap of carbon nitride can be controlled, while the carrier separation and transfer ability of carbon nitride is improved. The modified CN with sodium doping and nitrogen defect (SD-CN) demonstrates outstanding H2O2 production performance (H2O2 yield rate of 297.2 µmol L−1 h−1) under visible light irradiation, which is approximately 9.8 times higher than that of pristine CN. This work deepens the understanding of the coordinated effect of structural defect and element doping of carbon nitride on the photocatalytic H2O2 production performance, and provides new insight into the design of photocatalytic system for efficient production of H2O2.
Heterogeneous porous carbon (PC) materials have gained unique importance in the catalysis community due to their captivating properties, including high specific surface area, tunable porosity, and functionality. PC can play a prominent role in the sustainable synthesis of functional heterocycles, as they are a low-cost alternative while being an efficient and user-friendly material. This review examines the preparation and applicability of these carbonaceous materials used as catalysts or support for biologically active heterocycles synthesis, including hydrogenation, oxidation, oxidative dehydrogenation, cross-coupling, and other organic reactions. Moreover, the challenges, potential future development directions, and opportunities in the synthesis of potent bioactive heterocycles over PC materials have been addressed. This review will inspire further research to explore novel PC materials and their implications in heterocyclization.
Sulphur (S)-template method based on conventional slurry-casting method has been developed to produce porous silicon (Si) electrodes. The facile fabrication technology is suitable for current production line and expected to be widely applied to various electrode materials under large volume change during operation. Specifically, S particles as template agent are mixed with active material Si, carbon conductor and binder forming uniform slurry. After casting and drying, the electrodes are immersed in carbon disulfide solution to remove S particles rapidly, generating pores in-situ at the original position of S particles. Electrochemical analysis shows that the pores inside electrodes are able to shorten lithium ion diffusion paths, reduce normal expansion rate and decrease formation of cracks in the Si electrode (2 mgSi/cm2), demonstrating a reversible capacity of 951 mAh/g at 0.5 A/g after 100 cycles (with a capacity retention of 99.5%) and a capacity of ~826 mAh/g at 2 A/g.
The self-assembled structures of H3BDA molecule with multiple meta-dicarboxylic groups and their stimulus responses to the guest molecules (COR and T4PT) are thoroughly investigated by scanning tunneling microscopy (STM). STM observations display that two kinds of nanostructures are fabricated by H3BDA molecules through intermolecular hydrogen bonds, in which a linear structure is formed at a higher concentration and a flower-like structure is obtained at a lower concentration. After the addition of COR and T4PT, H3BDA appears different responsiveness resulting in different co-assembled structures, respectively. The linear structure is regulated into a flower-like structure by COR and COR molecules are trapped in the cavities. When the pyridine derivative (T4PT) is introduced, a new bicomponent porous structure emerges via the hydrogen bond formed between the carboxyl group and the pyridine. Furthermore, the deposition of additional COR to the H3BDA/T4PT system results in the breakdown of the porous structure and the generation of H3BDA/COR host–guest system. Combined with density functional theory (DFT) calculations and molecular dynamics (MD) simulations, the transformation phenomenon of bi-component nanostructure induced by guest molecules is formulated. The results are expected to understand the modification effect of guest molecules on the host network, which is of great significance for the design and construction of multi-component nanostructures and crystal engineering.
The monkeypox virus (MPXV) outbreak, declared a Public Health Emergency of International Concern (PHEIC) by the World Health Organization (WHO) in 2022, continues to pose a significant threat due to the absence of vaccines or drugs for MPXV infection. In this study, we developed an mRNA vaccine that expressing the A29L antigen, a specific protein of the intracellular mature virus. Our vaccine utilizes a thermostable ionizable lipid nanoparticle (iLNP) platform and has been administered to mice. Our findings demonstrate that the MPXV A29L mRNA vaccine candidate induces robust cross-neutralizing immune responses against both vaccinia virus (VACV) and MPXV live virus. Furthermore, immunization with the vaccine candidate provided protection against the VACV challenge in mice. These findings underscore the potential of mRNA-LNP vaccines as safe and effective candidates against monkeypox epidemics. Given the current absence of specific interventions for MPXV infection, our study represents a significant step forward in developing a viable solution to combat this ongoing public health threat.
Herein, a modified metal-free acetylene black (MMF-AB) catalyst was synthesized by a simple solvothermal-calcination method and designed successfully to activate peroxodisulfate (PDS) for the degradation of sulfisoxazole (SIZ). Due to the doping of N, S and O metal-free elements, the modified catalyst showed excellent catalytic performance with 100% SIZ removal within 30 min. Pseudo first-order reaction rate constants (evaluating catalytic efficiencies and activity) of MMF-AB (kobs = 0.105 min−1) was 3 times higher than pure-AB (kobs = 0.029 min−1). Interestingly, it was demonstrated that the reaction system is based on the transfer of electrons from SIZ to PDS to realize an electron-transfer-based mechanism by the evidence of premixing, electron paramagnetic resonance (EPR) spectroscopy, salt-bridge experiments and electrochemical analyses. The introduction of recyclable filtration device solved the secondary pollution caused by the dispersion of the powdered catalyst in the treated water, which further proved the practicality and superiority of the MMF-AB catalyst.
Transition-metal-catalyzed remote sp2C—H functionalization of aryl sulfonic acids was hardly ever realized owing to competitive ortho-C—H functionalization of aryl sulfonates and electron-deficient nature of phenyl ring. Herein, with the assistance of a practical biaryl indolyl directing template, palladium-catalyzed remote sp2C—H alkylation of aryl sulfonic acids have been achieved in moderate to good yields with exclusive meta selectivity. Moreover, remote meta-selective C—H alkynylation of aryl sulfonic acids was also accomplished with a rhodium catalyst. These meta-C—H functionalized products proved to be the superior synthetic precursors, which are difficult to access using the conventional strategy.
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