Latest ArticlesNew fabrication method of nanostructures is of great importance for the applications of nanoscience and nanotechnology. This review summarizes cucurbit[n]uril (CB[n])-based nanostructure fabrication and modification approaches. These strategies include the use of CB[n]s as building blocks and supramolecular crosslinkers to fabricate nanostructures, to surface modify nanostructures, and as gatekeepers to control the release of encapsulated cargo. These nanostructures are used for drug delivery, bioimaging, chemical sensing, catalysis and other applications. CB[n]s often play a vital role in the fabrication of these nanostructures, and the realization of the applications.
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.
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.
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.
In 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.
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.
Highly branched poly(β-amino ester)s (HPAEs) have emerged as a safe and efficient type of non-viral gene delivery vectors. However, the presence of inactive terminal secondary amine groups compromises their gene transfection capability. In this study, HPAEs with similar topological structures and chemical compositions but varying numbers of terminal secondary 4-amino-1-butanol (S4) and secondary/tertiary 3-morpholinopropylamine (MPA) groups were synthesized. The results demonstrate that an increased number of secondary/tertiary MPA groups in-situ significantly enhances the DNA binding capability of HPAEs, leading to the formation of smaller HPAE/DNA polyplexes with higher zeta potential, ultimately resulting in superior gene transfection efficiency in bladder epithelial cells. This study establishes a simple yet effective strategy to maximize the gene transfection potency of HPAEs by converting the inactive terminal groups in-situ without the need for complex modifications to their topological structure and chemical composition.
Diradical polycyclic hydrocarbons (PHs) have unique open-shell structures and interesting physical properties. However, owing to high reactivity of unpaired electrons, such open-shell organic diradicaloids are usually less stable than closed-shell systems, limiting their practical applications. In this study, we report P=O-attaching of diradical PHs as a new strategy to enhance their stability while maintaining diradical properties. Three P=O-attached PHs containing the indeno[1,2-b]fluorene, fluoreno[3,2-b]fluorene and indeno[2,1-b]fluorene π-skeletons, respectively, were designed and synthesized. As theoretically and experimentally proved, two of them have the relatively large diradical characters and open-shell singlet diradical nature. In comparison to their all-carbon analogues, the attached electron-withdrawing P=O groups endow them with much lower LUMO/HOMO energy levels but preserved magnetic activities and physical properties, such as thermally accessible triplet species and multi-redox ability. Moreover, the P=O groups effectively decrease their oxidation activities and thereby lead to their remarkably excellent ambient stabilities. Thus, this P=O-attaching strategy will be applicable to other diradical PH systems and may promote the generation of stable organic diradicaloids for radical chemistry and materials.
Electrochemical-nitrate-reduction-reaction (eNitRR) synthesis of ammonia is an effective way to treat nitrate wastewater and alleviate the pressure of the Haber-Bosch ammonia production industry. How to develop effective catalysts to electrochemically reduce nitrate to ammonia and purify sewage under complex environmental conditions is the focus of current research. Herein, the dopamine polymerization process and the [(C12H8N2)2Cu]2+ complex embedding process were run simultaneously in time and space, and ultrafine Cu nanoparticles (Cu/CN) were effectively loaded on nitrogen-doped carbon after heat treatment. Using Cu/CN as the catalyst, the ammonia yield rate and Faradaic efficiency of the electrochemical conversion of to NH3 are highly 8984.0 µg h−1 mgcat.−1 and 95.6%, respectively. Even in the face of complex water environments, such as neutral media, acidic media, coexisting ions, and actual nitrate wastewater, nitrate wastewater can be effectively purified to form high value-added ammonia. The strategy of simultaneous embedding increases the exposure rate of Cu sites, and the support of CN is also beneficial to reduce the energy barrier of *NO3 activation. This study rationally designed catalysts that are beneficial to eNitRR, and considered the situation faced by practical applications during the research stage, reducing the performance gap between laboratory exploration and industrial applications.
Organic lasers with broad emission bands in near-infrared (NIR) region are crucial for their applications in laser communication, night-vision as well as bioimaging owing to the abundance of selectable lasing wavelengths. However, for most organic gain materials, gain regions are limited in a small wavelength range because of the fixed energy level systems. Herein, we design a strategy to realize NIR organic lasers with broad emission bands based on tunable energy level systems induced by cascaded excited-state intramolecular proton transfer (ESIPT). A novel gain material named DHNN was developed, which can undergo a cascaded double-ESIPT process supporting four-level and six-level systems simultaneously. By doping DHNN into polystyrene microspheres, NIR lasers with tunable emission bands can be achieved based on the careful modulation of microcavities. Finally, organic lasers with an ultra-broad emission band ranging from 700 nm to 900 nm was successfully achieved by harnessing four-level and six-level systems simultaneously.
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