Latest ArticlesHerein, we report an efficient photochemical method for the synthesis of poly-substituted pyrazoles through a multicomponent reaction of acceptor-only diazoalkanes, alkynes, and solvents (cyclic ethers or nitriles). The key to this success was driven by the photolysis of acceptor-only diazoalkanes to form free carbene species and the fast in situ [3 + 2]-cycloaddition formation of nucleophilic NH pyrazole derivatives. This work also serves as an entry to allow future reaction design on the combination of carbene reactivity of diazoalkanes with their other reaction modes.
Transition metal sulfides are demonstrated to play an increasingly important role in boosting the deployment of ecofriendly electrocatalytic energy conversion technologies. It is also widely recognized that the introduction of vacancies is now becoming an important and valid approach to promote the electrocatalytic performance. In this review, the significance of sulfur vacancies on the enhancement of catalytic performance via four main functionalities, including tuning the electronic structure, tailoring the active sites, improving the electrical conductivity, and regulating surface reconstruction, is comprehensively summarized. Many effective strategies for the sulfur vacancy engineering, such as plasma treatment, heteroatom doping, and chemical reduction are also comprehensively provided. Subsequently, recent achievements in sulfur vacancy fabrication on various hotspot electrocatalytic reactions are also systematically discussed. Finally, a summary of the recent progress and challenges of this interesting field are organized, which hopes to guide the future development of more efficient metal sulfide electrocatalysts.
Macromolecular drugs have attracted great interest as biotherapy to cure previously untreatable diseases. For clinical translation, biomacromolecules encounter several common druggability difficulties, such as in vivo instability and poor penetration to cross physiologic barriers, thus requiring sophisticated systems for drug delivery. Inspired by the natural biomineralization via interaction between inorganic ions and biomacromolecules, herein we rationally screened biocompatible transition metals to biomineralize with carbonate for macromolecules loading. Among the metal ions, Cu2+ was found to be the best candidate, and its superiority over the widely studied Ca2+ minerals was also demonstrated. Capitalized on this finding, copper carbonate nanoparticles were prepared via a simple mixing process to co-load glucose oxidase (GOx) and a HIF-α DNAzyme (DZ), achieving ultra-high loading capacity of 61%. Upon encapsulation into nanoparticles, enzymatic activity of both drugs was passivated to avoid potential side-effects during circulation, while the drugs could be rapidly released within 1 h in response to acidic pH to fully recover their activities. The nanoparticles could accumulate into tumor via intravenous injection, facilitate the cell membrane penetration, and release the payloads of GOx, DZ and Cu2+ inside cells to exert a series of anti-tumor effects. GOx caused tumor starvation by catalytic glucose consumption, and the concomitantly generated H2O2 byproduct boosted the Cu2+-mediated chemodynamic therapy (CDT). Meanwhile, the DZ silenced HIF-α expression to sensitize both starvation therapy and CDT. As a result, a synergistic tumor growth inhibition was achieved. This work provides a simple method to prepare biomineralized nanoparticles, and offers a general approach for macromolecular drugs delivery via Cu2+-based biomineralization.
Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative, 5-aryl-1, 3-dioxan-5-ol, as versatile 1, 3-biselectrophile. In the reactions, 5-aryl-1, 3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes, and can react with 2-naphthols and β-keto amides, allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones. High yields, good functional group tolerance, broad substrate scope and simple reaction operation make this protocol attractive.
Organics present significant prospects as environmentally friendly and sustainable electrode materials for potassium ion batteries (PIBs) because of their abundant, recyclable and highly customizable characteristics. However, small molecular organics are easily solubilized in organic electrolytes, resulting in a low capacity and poor stability. Herein, the folic acid-based supermolecules (SM-FAs) are successfully prepared by a hydrothermal assisted self-assembly strategy. Due to multi-locus hydrogen bonds (HBs) and the cyclized π-conjugated interactions, the structural stability of SM-FAs has been significantly improved, and the solubility in carbonate electrolytes has been effectively inhibited. As an anode for PIB, the SM-FA-6 sample exhibits a large capacity (206 mAh/g at 50 mA/g) and an outstanding cycle stability (capacity retention of 91% after 1000 cycles at 50 mA/g). More impressively, an integrative storage mechanism which combines both the general enolization reaction between C=O groups and K+, and the atypical π–K+ interaction within the assembled conjugation framework, is unraveled for potassium ion accumulation. It is envisioned that this facile self-assemble strategy opens up a promising avenue to modulate the stability of small molecular organic electrodes with enhanced storage capacity.
An algorithm capable of predicting and optimizing the gradient separation of LC × LC system was developed in this paper. Two groups of structural analogues, five ginsenosides as well as eight bisphenols, which were difficult to discriminate in routine analysis, were used to verify the effectiveness of the proposed algorithm in fast separation optimization. Average errors of retention times below 1% were found in the retention prediction for all types of gradient programs, implying that the theory could lead to high quality in prediction of the retention times under gradients elution. Meanwhile, 84% of relative average deviations (RADs) between the predicted peak width and the measured ones were less than 20%. The larger deviation occurred at the time when the peak appeared while the gradient of the mobile phase changed, which led the deviations increased to 20%–42%. In all, method development and optimization for LC × LC tandem system was realized by the homemade user-friendly software. The present protocol may turn on great opportunities for the convenient method development in analysis of trace structural analogues in environmental, food and biological samples.
Stroke is a common disease and is the major cause of death and disability. It occurs and generates devastating neurological deficits when cerebral blood vessel is blocked (ischemic stroke, IS) or ruptured (hemorrhagic stroke, HS). Hydrogel, being biodegradable and biocompatible, have shown attractive advantages in stroke therapy as a new biomaterial with desirable mechanical properties and tunability of structure, owing to special ability to load different cargoes for multiple treatment strategies, such as pharmacotherapy based on drug-delivery systems and cell therapy including mesenchymal stem cells (MSCs) and neural progenitor cells (NPCs) for improving functional outcomes. However, a comprehensive review of the functional hydrogel for treatment of stroke is still lacking. Therefore, in this work, the main pathological mechanisms of stroke including IS and HS are comprehensively described. The benefits of hydrogel for stroke treatment are also summarized regarding the natural advantages and the delivery advantages. Simultaneously, the application development of hydrogel for treatment of stroke is highlighted. Finally, the unique considerations and challenges in the design and application of hydrogel is discussed for treatment of stroke and clinical application in the future.
The visible light induced multicomponent reaction of styrene, carbon disulfide, amine and ethyl difluorobromoacetate for the synthesis of thiodifluoroesters is disclosed. This developed protocol offers a facile and general route to access various valuable thiodifluoroesters in moderate to good yields. Preliminary mechanistic studies revealed that a radical process might be involved in this transformation.
Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor, substrate and solvent, which leads to energy loss and obvious heat transfer limits. In this study, induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts. It was found that, at the same apparent reaction temperatures, the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield, as compared to the reactions using conventional joule heating. The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites, which dissipates the electromagnetic energy through Néel relaxation mechanism. Moreover, it has be found that the reactions have been largely accelerated, resulting in much shorter reaction time required to approach a given value of reactant conversion. These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process, and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.
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