Latest ArticlesClick chemistry has become a useful tool for diverse molecular linkage and modification, and the development of new click strategy that enable reversibility and multifunctionality is of high demand for the multifunction and drug release. Herein, compositionally clicking combined regioselective iridium-catalyzed azide-alkynthio cycloaddition (Ir-AAC) and disulfuration has been developed for the sequential linkage from N-acetylenethio phthalimides, naturally occurring thiols and readily available azides. This method has been successfully applied to the construction of drug hybrids, peptide modification and glycosylation. Furthermore, by the design of diacetylenethio phthalimide as a platform molecule, trifunctional conjugants were sequentially linked through independent Ir-AAC, disulfuration and Cu-AAC reaction for hydrophobic tagging ternary PROTACs.
Aqueous zinc-ion batteries (AZIBs) have aroused significant research interest around the world in the past decade. The use of low-cost aqueous electrolytes and a metallic Zn anode with a suitable redox potential and high energy density make AZIBs a potential alternative to commercial Li-ion batteries in the development of next-generation batteries. However, owing to the narrow electrochemical stability window (ESW) of aqueous electrolytes, the choice of cathode materials is limited, because of which AZIBs exhibit a relatively low operating voltage and energy density. Hence, expanding the ESW of aqueous electrolytes is important for the development of practical AZIBs. This paper systematically reviews the electrolyte engineering strategies being explored to broaden the ESW of AZIBs. An in-depth analysis of high-voltage AZIBs is also presented. We suggest that the realization of high-voltage AZIBs depends on the synergistic development of suitable electrolytes and cathode materials. In addition, the cost associated with their fabrication as well as the use of standardized electrochemical tests should be considered during the design of high-voltage AZIBs.
A facile and environmentally friendly visible-light-induced three-component reaction of α-diazoesters, cyclic ethers and NaSCN to construct organic thiocyanates has been developed at room temperature. This reaction could occur under photocatalyst- and additive-free conditions to afford a number of organic thiocyanates with moderate to good yield and favorable functional group tolerance.
With the help of the redox mediator, decoupled water-splitting allows O2 and H2 to be produced at different times, at different rates, and even in different cells, which promotes both the operation safety and the utilization of renewable power sources. However, the current densities and stabilities of these redox mediators are commonly low, which require further improvements for practical applications. Here, we propose to use supercapacitors as solid state redox mediators for decoupled water splitting. For demonstration, Na0.5MnO2 (pseudocapacitor) and active carbon (double layer capacitor), are both used as the redox mediator. These supercapacitors show superior current density (1 A/cm2) and ultralong cycle-life (8000 cycles) compared with commonly investigated battery-based mediators (NiOOH/Ni(OH)2). Our research proves supercapacitors can be used as redox relay with high current density and stability, which may bring new insights in the design of decoupled water splitting systems.
A practical synthetic method for 4-thiocyanato-1H-pyrazoles through the electrochemical cascade reaction of hydrazines, 1, 3-diones and NH4SCN under metal-, chemical oxidant- and external electrolyte-free conditions was established. Importantly, both a gram-scale synthesis of 4-thiocyanato-1H-pyrazoles and five one-pot sequential transformations starting from hydrazine were successfully accomplished.
Thermally regenerative batteries (TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide (GO) modified anion exchange membrane (AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result, it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.
Carbocations such as tropylium and trityl cation, can be stable enough to be isolated and used without inert conditions. They can act as Lewis acids to lower the LUMO of electrophile, thus promoting reactions with nucleophiles. Additionally, the interaction between carbocations and alcohols can form Brønsted acids with enhanced acidity. Furthermore, electrophoto activation of TAC+ (trisaminocyclopropenium ion) delivers the excited radical dication TAC•2+*, which is a strong oxidant and capable of oxidizing a range of challenging substrates. Moreover, Pr-DMQA+ is disclosed as a versatile photoredox catalyst as its excited state can be quenched through both oxidation and reduction. This review summarizes recent advance in carbocation-catalyzed reactions. These developed methods provide an environmentally friendly pathway for the synthesis of valuable compounds and will inspire chemists to discover more interesting transformations promoted by carbocations.
Dynamic manipulation of enzymatic activity is a challenging task for applications in chemical and pharmaceutical industries due to the difficult modification and variable conformation of various enzymes. Here, we report a new strategy for reversible dynamic modulation of enzymatic activity by near-infrared light-induced photothermal conversion based on polyphenol-functionalized liquid metal nanodroplets (LM). The metal-phenolic nanocoating not only provides colloidal stability of LM nanodroplets but also generates nanointerfaces for the assembly of various enzymes on the LM nanodroplets. Upon near infrared (NIR) irradiation, the localized microenvironmental heating through photothermal effect of the LM nanodroplets allows tailoring the enzymatic activity without affecting the bulk temperature. A library of functional enzymes, including proteinase K, glucoamylase, glucose oxidase, and Bst DNA polymerase, is integrated to perform a reversible control and enhanced activities even after five times of cycles, demonstrating great potential in bacterial fermentation, bacteriostasis, and target gene amplification.
The issue about how outstanding scientists obtained innovative findings has drawn the interest of researchers in science, policy and scientometrics. Here, we attempt to address this question by using computational methods to measure the cognitive content and concepts of K. Barry Sharpless' research and estimate the knowledge flow of his click chemistry to other fields. First, we traced Sharpless' conceptual journey over time through topic modeling approach, mapping and clustering of the epistemic network from distant reading his publications. We find that connectivity and functions, the core features of click chemistry, are embodied in his constant search for simplicity. What makes simplicity possible is his continuous work with collaborators on reactivity and reaction mechanisms. Moreover, citation and link analysis show that click chemistry had a much richer impact on other research fields than what is generally acknowledged, and drew solutions to significant and practical questions back to chemistry from biology. Together with these findings, we propose that the click chemistry philosophy follows the way that values nature's principle. Chemistry has a clear-cut epistemic domain in modeling Nature. Thus, click chemistry as a concept on doing science beyond a connective technology goes across the boundaries between disciplines and impacts many other fields.
Development of adsorbent materials for highly efficient iodine capture is high demand from the perspective of ecological environment and human health. Herein, the two kinds of thiophene-based covalent organic frameworks (COFs) with different morphologies were synthesized by solvothermal reaction using thieno[3, 2-b]thiophene-2, 5-dicarbaldehyde (TT) as the aldehyde monomer and tri(4-aminophenyl)benzene (PB) or tris(4-aminophenyl)amine (PA) as the amino monomer (denoted as PB-TT COF and PA-TT COF) and the as-prepared two heteroatoms-rich COFs possessed many excellent properties, including high thermal stability and abundant binding sites. Among them, PB-TT COF exhibited ultra-high iodine uptake up to 5.97 g/g in vapor, surpassing most of adsorbents previously reported, which was ascribed to its high specific surface (1305.3 m2/g). Interestingly, PA-TT COF with low specific surface (48.6 m2/g) showed good adsorption ability for iodine in cyclohexane solution with uptake value of 750 mg/g, which was 2.38 times higher than that obtained with PB-TT COF due to its unique sheet-like morphology. Besides, the two COFs possessed good reusability, high selectivity and iodine retention ability. Based on experimental results, the adsorption mechanisms of both COFs were studied, revealing that iodine was captured by the physical-chemical adsorption. Furthermore, the both COFs showed excellent adsorption ability in real radioactive seawater treated safely, demonstrating their great potential in real environment.
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