Synergistic γ-In2 Se3 @rGO Nanocomposites with Beneficial Crystal Transformation Behavior for High-Performance Sodium-Ion Batteries.

Crystal transformation of metal compound cathodes during charge/discharge processes in alkali metal-ion batteries usually generates profound impact on structural stability and electrochemical performance, while the theme in anode materials, which always occurs and completes during the first redox cycle, is rarely explored probably due to the fast transformation dynamics. Herein, for the first time, a unique crystal transformation behavior with slow dynamics in anode of sodium-ion batteries (SIBs) is reported, which further promotes electrochemical performance. Specifically, irreversible γ → ß crystal transformation of In2 Se3 is observed, induced by the persistent size degradation of In2 Se3 particles during repeated sodiation/desodiation, supported by a series of ex situ characterizations, such as HRTEM, XRD, and XPS of γ-In2 Se3 /reduced graphene oxide (γ-In2 Se3 @rGO) nanocomposite. The hybrid electrode shows ultrahigh long-term cycling stability (378 mA h g-1 at 1.0 A g-1 after 1000 cycles) and excellent rate capability (272 mA h g-1 at 20.0 A g-1 ). Full battery with Na3 V2 (PO4 )3 cathode also manifests superior performance, promising ß-In2 Se3 dominated electrode materials in high-power and long-life SIBs. The first-principle calculations suggest the crystal transformation enhances electric conductivity of ß-In2 Se3 and facilitates its accessibility to sodium. In combination with the synergistic effect between rGO matrix, substantially enhanced electrochemical performance is realized.

Constructing a Low-Cost Si-NSs@C/NG Composite by a Ball Milling-Catalytic Pyrolysis Method for Lithium Storage.

Silicon-based composites are promising candidates as the next-generation anode materials for high-performance lithium-ion batteries (LIBs) due to their high theoretical specific capacity, abundant reserves, and reliable security. However, expensive raw materials and complicated preparation processes give silicon carbon anode a high price and poor batch stability, which become a stumbling block to its large-scale practical application. In this work, a novel ball milling-catalytic pyrolysis method is developed to fabricate a silicon nanosheet@amorphous carbon/N-doped graphene (Si-NSs@C/NG) composite with cheap high-purity micron-size silica powder and melamine as raw materials. Through systematic characterizations such as XRD, Raman, SEM, TEM and XPS, the formation process of NG and a Si-NSs@C/NG composite is graphically demonstrated. Si-NSs@C is uniformly intercalated between NG nanosheets, and these two kinds of two-dimensional (2D) materials are combined in a surface-to-surface manner, which immensely buffers the stress changes caused by volume expansion and contraction of Si-NSs. Attributed to the excellent electrical conductivity of graphene layer and the coating layer, the initial reversible specific capacity of Si-NSs@C/NG is 807.9 mAh g-1 at 200 mA g-1, with a capacity retention rate of 81% in 120 cycles, exhibiting great potential for application as an anode material for LIBs. More importantly, the simple and effective process and cheap precursors could greatly reduce the production cost and promote the commercialization of silicon/carbon composites.

Modulating the Graphitic Domains and Pore Structure of Corncob-Derived Hard Carbons by Pyrolysis to Improve Sodium Storage.

Biomass-derived hard carbon materials are considered as the most promising anode materials for sodium-ion batteries (SIBs) due to their abundant sources, environmental friendliness, and excellent electrochemical performance. Although much research exists on the effect of pyrolysis temperature on the microstructure of hard carbon materials, there are few reports that focus on the development of pore structure during the pyrolysis process. In this study, corncob is used as the raw material to synthesize hard carbon at a pyrolysis temperature of 1000~1600 °C, and their interrelationationship between pyrolysis temperature, microstructure and sodium storage properties are systematically studied. With the pyrolysis temperature increasing from 1000 °C to 1400 °C, the number of graphite microcrystal layers increases, the long-range order degree rises, and the pore structure shows a larger size and wide distribution. The specific capacity, the initial coulomb efficiency, and the rate performance of hard carbon materials improve simultaneously. However, as the pyrolysis temperature rises further to 1600 °C, the graphite-like layer begins to curl, and the number of graphite microcrystal layers reduces. In return, the electrochemical performance of the hard carbon material decreases. This model of pyrolysis temperatures-microstructure-sodium storage properties will provide a theoretical basis for the research and application of biomass hard carbon materials in SIBs.

Discovery of seneciobipyrrolidine derivatives for the amelioration of glucose homeostasis disorders through 4E-BP1/Akt/AMPK signaling activation.

Modulating the glucose transport in skeletal muscle is a promising strategy for ameliorating glucose homeostasis disorders. However, the complicated mechanisms of glucose transport make it difficult to find compounds therapeutically relevant molecular mechanisms of action, while phenotypic screening is thought to be an alternative approach to mimic the cell state of interest. Here, we report (±)-seneciobipyrrolidine (1a) is first found to enhance glucose uptake in L6 myotubes through phenotype-based screening. Further SAR investigation led to the identfication of compound A27 (EC50 = 2.7 µM). Proteomiic analysis discloses the unique function mechanism of A27 through upregulating the level of the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), subsequently enhancing the Akt and AMPK phosphorylation, thereby promoting the glucose uptake. Chronic oral administration of A27 significantly lowers blood glucose and improves glucose tolerance in db/db mice. This work is new research on seneciobipyrrolidine derivatives, providing a promising avenue for ameliorating glucose homeostasis.

A pre-synthetic strategy to construct single ion conductive covalent organic frameworks.

A pre-synthetic strategy was developed for the construction of single ion conductive covalent organic frameworks (COFs). A high Li+ conductivity of 1.6 × 10-3 S cm-1 at 273 K was achieved, and single Na+ and K+ COFs were also obtained by using Na+ and K+ salts as monomers according to this synthetic method.

A general asymmetric copper-catalysed Sonogashira C(sp3)-C(sp) coupling.

Continued development of the Sonogashira coupling has made it a well established and versatile reaction for the straightforward formation of C-C bonds, forging the carbon skeletons of broadly useful functionalized molecules. However, asymmetric Sonogashira coupling, particularly for C(sp3)-C(sp) bond formation, has remained largely unexplored. Here we demonstrate a general stereoconvergent Sonogashira C(sp3)-C(sp) cross-coupling of a broad range of terminal alkynes and racemic alkyl halides (>120 examples) that are enabled by copper-catalysed radical-involved alkynylation using a chiral cinchona alkaloid-based P,N-ligand. Industrially relevant acetylene and propyne are successfully incorporated, laying the foundation for scalable and economic synthetic applications. The potential utility of this method is demonstrated in the facile synthesis of stereoenriched bioactive or functional molecule derivatives, medicinal compounds and natural products that feature a range of chiral C(sp3)-C(sp/sp2/sp3) bonds. This work emphasizes the importance of radical species for developing enantioconvergent transformations.

The In-Situ Synthesis of a 3D SnS/N-Doped Graphene Composite with Enhanced Electrochemical Performance as a Low-Cost Anode Material in Sodium Ion Batteries.

SnS/N-doped graphene (SnS/NG) composites are promising anode materials for sodium ion batteries. Generally, SnS is synthesized from SnCl2·2H2O. However, SnCl2·2H2O is not suitable for large-scale production due to its high price. Compared with SnCl2·2H2O, SnCl4·5H2O has a lower price, more stable chemical properties and better water solubility. Until now, there have been no related reports on the synthesis of SnS from SnCl4·5H2O. In this work, the fabrication of SnS/NG in a facile, two-step process, which combines a hot water bath and thermal annealing and uses SnCl4·5H2O as a precursor, is described. The mechanism of phase transformation in the direct synthesis of SnS from Sn4+ is also discussed in detail. Applying our methodology, SnS nanoparticles were grown in-situ on graphene sheets and wrapped by N-doped graphene sheets to form a 3D SnS/NG composite. With 35.35% content of graphene in the SnS/NG composite, the reversible specific capacity remained at 417.8 mAh/g at 1000 mA/g after 100 cycles, exhibiting a high specific capacity and good cycling stability. In addition, the composite also had an excellent rate performance, with a specific capacity of 366.9 mAh/g obtained even at 5000 mA/g. Meanwhile, the fast sodium storage kinetics of SnS/NG were also analyzed, providing some theoretical support for further study.

A Copper-Catalyzed Tandem Cyclization Reaction of Aminoalkynes with Alkynes for the Construction of Tetrahydropyrrolo[1,2-a]quinolines Scaffold.

A synthetic method for diversely substituted tetrahydropyrrolo[1,2-a]quinolines was developed via CuCl-catalyzed cascade transformation of internal aminoalkynes with alkynes under microwave- irradiation.

Direct access to α-trifluoromethyl enones via efficient copper-catalyzed trifluoromethylation of Meyer-Schuster rearrangement.

A novel domino copper-catalyzed trifluoromethylated Meyer-Schuster rearrangement reaction with Togni's reagent was developed, leading to α-trifluormethyl (CF3) enone products with moderate to good yields. Furthermore, α-CF3 enones can be transformed toward important trifluoromethyl heterocyclic motifs in a one-pot version.

Efficient copper-catalyzed direct intramolecular aminotrifluoromethylation of unactivated alkenes with diverse nitrogen-based nucleophiles.

A mild, convenient, and step-economical intramolecular aminotrifluoromethylation of unactivated alkenes with a variety of electronically distinct, nitrogen-based nucleophiles in the presence of a simple copper salt catalyst, in the absence of extra ligands, is described. Many different nitrogen-based nucleophiles (e.g., basic primary aliphatic and aromatic amines, sulfonamides, carbamates, and ureas) can be employed in this new aminotrifluoromethylation reaction. The aminotrifluoromethylation process allows straightforward access to diversely substituted CF3-containing pyrrolidines or indolines, in good to excellent yields, through a direct difunctionalization strategy from the respective acyclic starting materials. Mechanistic studies were conducted and a plausible mechanism was proposed.