Latest ArticlesDetection and observation of reactive intermediates is an essential step in investigation of reaction pathways. However, most reactive intermediates are unstable and present at low concentrations; their short lifetimes make them difficult to detect and characterize. Supramolecular containers offer opportunities for the stabilization and characterization of those labile species, through isolation from the media and protection inside the cavity of the host. In this review, we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers. The container compounds include carcerands, deep cavitands and amide naphthotubes. We focus on unstable guest species – cyclobutadiene, benzocyclopropenone, o-benzyne, 1,2,4,6-cycloheptatetraene, anti-Bredt's olefin, fluorophenoxycarbene, O-acylisoamide, and hemiaminal – that act as intermediates in certain organic reactions
A variety of research reports on novel supramolecular topologies have been published over the last years. However, it is still a great challenge to tap into the inner functional properties of these complexes. Herein, two tetranuclear metallamacrocycles 1 and 2 and four octonuclear [2]catenanes 3–6 were constructed successfully via a coordination-driven self-assembly strategy, by conscious design and use of the tetramethyl bidentate pyridine ligand L1, and the appropriate selection of six binuclear half-sandwich rhodium building units with different longitudinal dimensions. The complexes have been fully characterized by single crystal X-ray diffraction analysis and NMR spectroscopy. Furthermore, near-infrared photothermal studies of the obtained [2]catenanes reveal different photothermal response in solid and solution states, which may be attributed to a strong fluorescence quenching effect of the half-sandwich organometallic fragment and different conjugated effect of Cp*Rh based building blocks in the interlocking structures. The photothermal conversion efficiencies of [2]catenanes 4–6 fall in the range 30.5%–16.5% respectively. This contribution aims to play a key role in the experimental development of Cp*-based photothermal materials.
The practical application of high-energy-density lithium-sulfur (Li-S) batteries have been highly praised for energy storage devices, while are largely hindered by the "shuttling effect". Herein, core-shell carbon spheres composed of interlinked porous core and lamellar shell were designed to restrain the polysulfide shuttling. The microporous structure with pore size of around 1 nm effectively trap lithium polysulfides. Furthermore, the interconnected porous core shortens the ion transfer distance and the lamellar carbon shell endows the carbon spheres with fast electron conduction, finally facilitating polysulfide conversion kinetics. Therefore, the Li-S batteries with the carbon spheres as the interlayer show high discharge specific capacity of 1002 mAh/g at 2 C with 574 mAh/g remaining after 600 cycles, and high areal capacity of 5.48 mAh/cm2 with sulfur loading of 4.67 mg/cm2 at 0.1 C. The corresponding pouch cells also exhibit stable cycling stability with an initial discharge specific capacity of 1082 mAh/g at 0.1 C.
With the deep integration of electrochemical research with energy, environment, catalysis, and other fields, more and more new electrochemical catalytic reactions have entered our research field. Alloy catalysts have recently emerged as a new type of nanomaterial due to the rapid development of kinetic controlled synthesis technology. These materials offer several advantages over monometallic catalysts, including larger element combinations, complex geometries, bifunctional sites, and reduced use of precious metals. This paper provides a review of alloy electrocatalysts that are designed and prepared specifically for electrocatalytic applications. The use of alloy materials in electrocatalyst design is also discussed, highlighting their widespread application in this field. First, various synthesis methods and synthesis mechanisms are systematically summarized. Following that, by correlating the properties of materials with the structure, relevant strategies toward advanced alloy electrocatalysts including composition regulation, size, morphology, surface engineering, defect engineering, interface engineering and strain engineering are classified. In addition, the important electrocatalytic applications and mechanisms of alloy electrocatalysts are described and summarized. Finally, the current challenges and prospects regarding the development of alloy nanomaterials are proposed. This review serves as a springboard from a fundamental understanding of alloy structural dynamics to design and various applications of electrocatalysts, particularly in energy and environmental sustainability.
Traditional photo-electcatalyst structures of small noble metal nanoparticles assembling into large-scale photoactive semiconductors still suffer from agglomeration of noble metal nanoparticles, insufficient charge transfer, undesirable photoresponse ability that restricted the photo-electrocatalytic performance. To this end, a novel design strategy is proposed in this work, namely integrating small-scale photoactive materials (doped graphene quantum dots, S,N-GQDs) with large-sized noble metal (PdP) nanoflowers to form novel photo-electrocatalysts for high-efficient alcohol oxidation reaction. As expected, superior electrocatalytic performance of PdP/S,N-GQDs for ethylene glycol oxidation is acquired, thanks to the nanoflower structure with larger specific surface area and abundant active sites. Furthermore, nonmetal P are demonstrated, especially optimizing the adsorption strength, enhancing the interfacial contact, reducing metal agglomeration, ensuring uniform and efficient doping of S,N-GQDs, and ultimately significantly boost the catalytic activity of photo-electrocatalysts.
Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by persistent inflammation of the colon and disrupted intestinal function. Ramulus mori (Sangzhi) alkaloids (SZ-A), derived from twigs of mulberry, were approved by the National Medical Products Administration in 2020 for treating type 2 diabetes mellitus. Accumulated evidence has confirmed that SZ-A also alleviates non-alcoholic fatty liver disease and ameliorates inflammation, indicating its potential to address inflammation in UC. However, the treatment of UC faces challenges due to low drug delivery efficiency and short retention time. To overcome these challenges, an injectable and adherent in-situ thermo-sensitive hydrogel containing SZ-A was developed for rectal drug delivery, utilizing the thermo-sensitive polymers Poloxamer 407 and 188. The thermo-sensitive hydrogel system was designed with a moderate gelation temperature of 32 ± 0.5 ℃, a short gelation time of 64 s, a pH range of 7–10, high moisturizing capability exceeding 90%, and moderate mechanical strength of 4–5 s. In a rat model with UC, the in situ thermo-sensitive hydrogel significantly extended the retention time at the colonic site and enabled sustained release after rectal administration. Symptoms of UC were markedly reduced following rectal administration of SZ-A thermo-sensitive hydrogel. Furthermore, the release of inflammatory factors, such as interleukin-1β (IL-1β), IL-6, IL-18, tumor necrosis factor-α (TNF-α), and transforming growth factor-β1 (TGF-β1), significantly decreased in the SZ-A thermo-sensitive hydrogel group. The integrity of the colonic mucosal barrier was significantly enhanced following the application of SZ-A thermo-sensitive hydrogel. In conclusion, rectal administration of SZ-A in situ thermo-sensitive hydrogel effectively alleviated UC symptoms, inhibited the secretion of inflammatory factors, and promoted the repair of the colonic mucosal barrier. This approach holds promise as a potential treatment for UC.
A photoinduced copper-catalyzed alkoxyl triggered C−C bond cleavage/aminocarbonylation cascade is presented. Through adjusting the structure of alkoxyl radical precursors, functionalized lactones and keto-amides were synthesized with good yields and excellent functional group tolerance under redox-neutral conditions. Notably, this protocol enables the integration of lactone fragments with many amine drugs and drug fragments.
Carbon dots (CDs) with precise targeting function show great potential in the field of drug delivery therapeutics. In this study, the functionalized nucleus-targeting orange-emissive CDs with nuclear localization sequence (NLS) were loaded with adriamycin (DOX) to obtain a nucleus-targeting orange-emissive CDs drug delivery system (CDs-NLS-DOX), which delivered DOX to tumor cell nuclei to enhance its anti-tumor activity. The drug carrier orange-emissive CDs showed excitation-independent behavior, stable and enhanced imaging capability and good biocompatibility in vitro and in vivo. Meanwhile, the CDs-NLS could target the nuclei efficiently, and the CDs-NLS-DOX complexes had a high drug loading rate (59.4%) after loading DOX, exhibiting pH-dependent DOX release behavior through breaking acylhydrazone bond in a weak acidic environment. In addition, the CDs-NLS-DOX complexes exhibited an enhanced killing activity against human hepatoma cells (HepG2). The in vivo therapeutic effects on HepG2 nude mice transplanted tumors indicated the CDs-NLS-DOX had a stronger ability to inhibit tumor growth compared to free DOX. In short, CDs-NLS-DOX is expected to be a precise and efficient nucleus-targeting nano-drug delivery system for tumor treatment.
Glycosyl radicals, produced under mild photoredox conditions, show unique utility in the preparation of C-linked glycoconjugates. We herein report the construction of C-glycosidic bonds on α,β-dehydroalanine (DHA) of peptides with easily available glycosyl bromides as glycosyl radical precursors under highly anomeric control, leading to C-glycosylation modifications of peptides. This method not only has outstanding functional group compatibility, but also is feasible in near-physiological conditions (pH ~ 7 and temperature T ≤ 37 ℃ in aqueous media).
Inkjet printing has emerged as a potential solution processing method for large-area patterned films. During inkjet printing, a single droplet without satellite droplet is required for high-quality film. Herein, we propose a strategy for obtaining a single droplet by adjusting the reduced concentration (c/c*, where c* is the critical overlap concentration) in the range of 1.0–1.5. Droplet formation can be categorized into three distinct regimes: (1) c/c* < 1.0, satellite droplet; (2) c/c* = 1.0–1.5, single droplet; (3) c/c* > 2.0, no droplet. Furthermore, an inertial-capillary balance led to the 2/3-power scaling of the minimum radius with time for the solutions of c/c* < 1.0. However, for the solutions of c/c* = 1.0–1.5, the ligament radius decreased exponentially with time. Moreover, the Weissenberg number was higher than the critical value of 0.5, indicating that the polymer chains underwent coil-stretch transition. The viscoelastic-capillary balance dominated instead of the inertial-capillary balance. The resulting viscoelastic resistance reduced the length of the ligament and increased the velocity difference between the satellite and main droplets. Consequently, a single droplet was formed. In addition, the law can be successfully generalized to various molecular weights, molecular structures and solvents.
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