Latest Articles1-Substituted 1, 2, 3-triazoles represents 'privileged' structural scaffolds of many clinical pharmaceuticals. However, the traditional methods for their preparation mainly rely on thermal [3 + 2] cycloaddition of potentially dangerous acetylene and azides. Here we report a base-mediated [4 + 1] annulation of azoalkenes generated in situ from readily available difluoroacetaldehyde N-tosylhydrazones (DFHZ-Ts) with amines under relatively mild conditions. This azide- and acetylene-free strategy provides facile access to diverse 1-substituted 1, 2, 3-triazole derivatives in high yield in a regiospecific manner. This transformation has great functional group tolerance and can suit a broad substrate scope. Furthermore, the application of this novel methodology in the gram-scale synthesis of an antibiotic drug PH-027 and in the late-stage derivatization of several bioactive small molecules and clinical drugs demonstrated its generality, practicability and applicability.
Herein, an electrocatalytic protocol for the synthesis of 2, 3-dihydroquinazolin-4(1H)-one has been disclosed. Methanol is activated and utilized as the C1 source to cyclize with 2-aminobenzamides. This cyclization reaction proceeds conveniently (room temperature and air atmosphere) without any homogeneous metal catalysts, external oxidants, or bases. A wide variety of N, N-disubstituted 2, 3-dihydroquinazolin-4(1H)-ones are obtained via this approach. Moreover, when methanol-d4 is used, a deuterated methylene motif is incorporated into the N-heterocycles, providing an efficient approach to the deuterated N-heterocycles.
Biopolymers, including DNA and peptides have been used as excellent self-assembling building blocks for programmable single-component or hybrid materials, due to their controlled molecular interactions. However, combining two assembling principles of DNA-based programmability and peptide-based specific molecular interactions for hybrid structures to microscale has not yet been achieved. In this study, we describe a hybrid microsystem that emerges from the co-assembly of DNA origami structure and short elastin-like polypeptide conjugated oligonucleotides, and initiates liquid-liquid phase separation to generate microdroplets upon heating above the transition temperature. Moreover, the hybrid microdroplets are capable for guest molecule trapping and perform bi-/tri-enzymatic cascades with rate enhancements as open "microreactors". Our programmed assembled DNA-peptide microsystem represents a new combination of DNA nanotechnology and peptide science and opens potential application routes toward life-inspired biomaterials.
The process of selectively introducing a CF3 group into an organic molecule using inexpensive, stable, and solid sodium trifluoromethanesulfinate has rapidly advanced in recent years to become an eco-friendly method used by organic chemists to synthesize various natural and bioactive molecules. This review focuses on advances made within the last five years regarding C–H functionalisation, namely thermochemical C(sp2)–H (thio)trifluoromethylations, photochemical C(sp2)–H trifluoromethylations, and electrochemical C(sp2)–H trifluoromethylations, using Langlois' reagent (NaSO2CF3).
N6-methyl adenosine (m6A) is an eminent epigenetic mark in mRNAs that affects a broad range of biological functions in diverse species. However, the chemically inert methyl group prevents a direct labeling of this modification for subsequent detection and sequencing. Therefore, most current approaches for the labeling of m6A still have limitations of relying on the utilization of corresponding methyltransferases, which resulted in the lacking of efficiency. Here we present an approach which selectively alkylated the N6-formyl adenosine (f6A), the key intermediate during chemical oxidation of m6A, with an alkyne functionality that can be further labeled with click reactions. This covalent labeling approach will be able to facilitate in the affinity purification, detection and genome-wide profiling studies.
Homocysteine (Hcy), cysteine (Cys) and glutathione (GSH) play crucial roles in redox homeostasis during mitochondria functions. Simultaneous differentiation and visualization of mitochondrial biothiols dynamics are significant for understanding cell metabolism and their related diseases. Herein, a multisite-binding fluorescent probe (MCP) was developed for simultaneous sensing of mitochondrial Cys, GSH and Hcy from three fluorescence channels for the first time. This novel probe exhibited rapid fluorescence turn-on, good water-solubility, high selectivity and large spectral separation for discriminating Cys, GSH and Hcy with 131-, 96-, 748-fold fluorescence increasement at 471, 520, 567 nm through different excitation wavelengths, respectively. Importantly, this probe was successfully applied to simultaneous monitoring of mitochondrial Cys, GSH, and Hcy in live cells and zebrafish from three fluorescence channels, promoting the understanding of the functions of Hcy, Cys and GSH.
A phosphorescent supramolecular foldamer is conveniently constructed by the 1:1 host–guest complexation with cucurbit[8]uril and 1, 2-diaminocyclohexane-bridged 4-(4-bromophenyl)-pyridinium salt. The tightly compact host–guest complexation in molecular foldamer can greatly suppress the fluorescence emissive channel and promote the intersystem crossing from singlet to triplet states, thus leading to the green phosphorescence at ambient temperature in aqueous solution. More intriguingly, the phosphorescence emission shows very rapid and sensitive responsiveness to different antibiotics in both inanimate milieu and living cells. Remarkably, the limit of detection of such binary inclusion complex toward sulfamethazine can reach as low as 1.86 × 10−7 mol/L. Thus, it is envisaged that this supramolecular nanoplatform featuring unique complexation-enhanced phosphorescence emission may hold great promise in sensing and detecting many other biological targets under physiological environment.
Lithium metal is deemed as an ideal anode material in lithium-ion batteries because of its ultrahigh theoretical specific capacity and the lowest redox potential. However, the rapid capacity attenuation and inferior security resulting from the dendritic lithium growth severely limit its commercialization. Herein a novel hybrid gel polymer electrolyte (GPE) based on electrospun lithium sulfonated polyoxadiazole (Li-SPOD) nanofibrous membrane swelled by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) ether liquid electrolyte is proposed to address the issue of lithium dendrites. The Li-SPOD membrane synthesized by a simple one-pot method exhibits excellent mechanical strength and thermal resistance due to its high molecular weight and rigid backbone. The electron-withdrawing oxadiazole ring and oxadiazole ring-Li+ complex, and N, O heteroatoms with lone pairs of electrons in Li-SPOD macromolecular chains facilitate the dissociation of -SO3Li group and Li+ transference. The hybrid Li-SPOD GPE exhibits both a high lithium-ion transference number (0.64) and high ionic conductivity (2.03 mS/cm) as well as superior interfacial compacity with lithium anodes. The LiFePO4-Li cell using this novel GPE can operate steadily at 2 C for 300 cycles, remaining a high discharge capacity of 125 mAh/g and dendrite-free anode. Remarkable performance improvements for the Li-Li and Cu-Li cells are also presented.
Developing non-noble-metal oxygen evolution reaction (OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated CoFe-layered double hydroxide (LDH) nanowire arrays on graphite felt (CoFe-LDH/GF) via a hydrothermal method. The CoFe-LDH/GF, as a robust integrated 3D OER anode, exhibits excellent catalytic activity with the need of low overpotential of 252 and 285 mV to drive current densities of 10 and 100 mA/cm2 in 1.0 mol/L KOH, respectively. In addition, it also maintains electrochemical durability for at least 24 h. This work would open up avenues for the development of GF like attractive catalyst supports for oxygen evolution applications.
Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation. Among them, core-shell structural nanomaterials have been widely fabricated for microwave absorption. However, the "structure-performance" relationship between shell thickness and microwave absorption performance is rarely reported. In this paper, we first explored the "structure-performance" relationship between shell thickness and microwave absorption performance, based on the core-shell α-Fe2O3@SiO2 nanoparticles with a constant α-Fe2O3-core size and changeable SiO2-shell thickness. With increasing the SiO2-shell thickness, the microwave absorption ability first increased, then decreased. Under a proper SiO2-shell thickness of 35 nm, α-Fe2O3@SiO2 sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of –4.3 dB, better than that of pure α-Fe2O3 (–3.8 dB). This enhanced microwave absorption performance was mainly derived from the dielectric loss. Although the absolute value of the reflection loss was relatively low (–4.3 dB), this study shed an important reference on designing next-generation advanced iron oxide-based materials for microwave absorption.
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