Latest ArticlesOsteoarthritis (OA) is the most prevalent joint disease and icariin is a promising drug for its treatment. However, the clinical use of icariin is hindered by poor water solubility, low bioavailability, and non-specific release and biological distribution. Herein, sulfonated azocalix[4]arene (SAC4A) with enhanced water solubility, recognition capacity, and designed responsiveness was used to improve the efficiency of icariin for OA therapy. SAC4A, a macrocycle with well-defined molecular weight and structure, could encapsulate and enhance water solubility of various drugs. In addition, SAC4A enables hypoxia-responsive release of loaded drug. Compared with icariin treatment, supramolecular complex icariin@SAC4A significantly relieved OA symptoms of rats, including more regular bone morphology and structure, and lower degree of cartilage damage. Moreover, the supramolecular formulation demonstrated various advantages, including easy preparation, hypoxia-triggered release, and small size that conducive to drug penetration.
Ag2CO3-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine source. The reaction involves β-fragmentation of primary alkoxy radicals, followed by the fluorination of the resulting C-centered radical intermediates. The transformation proceeds under mild reaction conditions and exhibits a broad substrate scope, thus opening up a new entrance to the synthesis of fluorinated constructs including α-fluoroimides and 1-fluoroalkyl benzoates as well as secondary and tertiary alkyl fluorides like versatile 2-fluoro-2-alkyl 1,3-propandiol derivatives. The divergent functionalization of the obtained α-fluoroimides enables an efficient access to amine derivatives through C–F bond activation under the action of BF3·OEt2.
The rational design of high-performance bifunctional electrocatalysts for overall water splitting (OWS) is the key to popularize hydrogen production technology. The active metal oxyhydroxide (MOOH) formed after surface self-reconfiguration of transition metal sulfide (TMS) electrocatalyst is often regarded as the "actual catalyst" in oxygen evolution reaction (OER). Herein, an Fe doped CoS2/MoS2 hollow TMS polyhedron (Fe-CoS2/MoS2) with rich Mott-Schottky heterojunction is reported and directly utilized as an OWS electrocatalyst. The spontaneous built-in electric field (BEF) at the heterogeneous interface regulates the electronic structure and D-band center of the catalyst. More importantly, the “TMS-MOOH” core-shell structure obtained in the KOH electrolyte shows enhanced OER properties. And the introduction of Fe ions activates the inert basal plane of MoS2, which greatly steps up the performance of HER. Hence, the preferable Fe-CoS2/MoS2–400 presents superior OER activity (η10 = 178 mV, η100 = 375 mV), HER activity (η10 = 92 mV) and ultra-high stability for 50 h. This work has deeply explored the catalytic mechanism of TMS and provided a new idea for the construction of efficient bifunctional catalysts.
Higher initial (de)hydrogenation temperature and sluggish kinetics are the main bottlenecks to develop Mg-based hydrogen storage alloys with high hydrogen capacity. One of the effective methods of solving these problems is introducing additives to enhance (de)hydrogenation kinetics and decrease particle sizes to lower (de)hydrogenation temperatures. In this work, Mg85-Ni10-La4.5-Y0.5 alloy doped with Cu@C nanoparticles is prepared, which could enhance (de)hydrogenation kinetics via introducing Cu nanoparticles as a catalyst and reduce the alloy particle sizes via acting as a grinding agent to lower (de)hydrogenation temperature. The results indicate the dehydrogenation temperature of the modified Mg85-Ni10-La4.5-Y0.5 composite could be decreased to 308.5 ℃, absorb 4.73 wt% H2 at 220 ℃ within 1 min and release 5.01 wt% H2 within 4 min at 300 ℃. Moreover, the capacity retention could be maintained around 98.8% after 10 cycles at 300 ℃, superior than those of Mg85-Ni10-La4.5-Y0.5 and milled-Mg85-Ni10-La4.5-Y0.5. DFT results and characterizations suggest that in-situ formed Mg2Cu could accelerate the dissociation of Mg-H bonds and the presence of amorphous carbon in Mg-Ni-La-Y-Cu system will further synergistically improve the (de)hydrogenation kinetics of Mg85-Ni10-La4.5-Y0.5. Reduced particle sizes under the aid of carbon frameworks also help introduce boundaries of the particles and shorten hydrogen diffusion pathways.
Since the discovery of the Nernst effect in 19th century, it has been an important transverse thermoelectric charge transport phenomenon in solid states. Conjugated polymers have recently attracted great attention as promising optoelectronic materials. However, the Nernst effect is yet to be explored for conducting polymers. Here, we report the first theoretical investigations of the Nernst effect in doped conducting polymers by first-principles calculations under the frame work of Fermi-liquid theory. Specifically, the Nernst coefficients of PBTTT are found to be ranging from 0.0029 to 0.039 µV K−1 T−1. They are monotonically decreased with the doping level due to both much enhanced Fermi energy and the decreased charge mobility at high doping level. Our theoretical findings not only enhance our fundamental understanding of the doping mechanism that controls the charge transport properties of conducting polymers, but more importantly, they also offer initial predictions of the transverse thermoelectric conversion capability of conducting polymers. These predictions are crucial for the development of future flexible thermoelectric applications based on the Nernst effect.
Temperature plays a crucial role in regulating polymorphism in supramolecular polymers. Understanding the mechanism behind temperature-dependent supramolecular polymorphism is crucial as it provides an opportunity to tailor polymorphs for specific properties and applications. In this study, we present our findings on a naphthalimide-substituted benzene-1,3,5-tricarboxamide derivative, R-Nap-1, which exhibits two distinct polymerization pathways at varying temperatures. At 313 K, polymerization results in the formation of an M-chiral polymorph, whereas at 253 K, a P-chiral polymorph is formed. Both polymorphs are notably stable, remaining unchanged for over six months under ambient conditions. Theoretical calculations and experimental investigations allowed us to elucidate the mechanisms underlying these polymorphic transformations. The formation of the M-chiral polymorph at 313 K is attributed to the nucleation and growth of R-Nap-1 monomers once their concentration surpasses a critical threshold. Conversely, at lower temperatures (e.g., 253 K), the monomers undergo facile transformation into dimers due to a lower energy barrier and reduced Gibbs energy compared to the monomeric state. Subsequently, these dimers undergo nucleation-elongation to form the P-chiral polymorph when their concentration exceeds the critical polymerization concentration. The stability and lack of interconversion between the two polymorphs can be attributed to their close thermodynamic stabilities, as evidenced by variable-temperature CD spectra and DFT calculations. These findings highlight the importance of accurate temperature control in supramolecular polymerization processes, making a significant contribution to the understanding of supramolecular polymorphism, thus advancing the field of supramolecular chemistry.
The carboxylation of readily available organo halides with CO2 represents a practical strategy to afford valuable carboxylic acids. However, efficient carboxylation of inexpensive unactivated alkyl chlorides is still underdeveloped. Herein, we report the electro-reductive carboxylation of CCl bonds in unactivated chlorides and polyvinyl chloride with CO2. A variety of alkyl carboxylic acids are obtained in moderate to good yields under mild conditions with high chemoselectivity. Importantly, the utility of this electro-reductive carboxylation is demonstrated with great potential in polyvinyl chloride (PVC) upgrading, which could convert discarded PVC from hydrophobic to hydrophilic functional products. Mechanistic experiments support the successive single electron reduction of unactivated chlorides to generate alkyl anion species and following nucleophilic attack on CO2 to give desired products.
The battery energy density can be improved by raising the operating voltage, however, which may lead to rapid capacity decay due to the continuous electrolyte decomposition and the thickening of electrode electrolyte interphases. To address these challenges, we proposed tripropyl phosphate (TPP) as an additive−regulating Li+ solvation structure to construct a stable LiF–rich electrode carbonate−based electrolyte interphases for sustaining 4.6 V Li||LiCoO2 batteries. This optimized interphases could help reduce the resistance and achieve better rate performance and cycling stability. As expected, the Li||LiCoO2 battery retained 79.4% capacity after 100 cycles at 0.5 C, while the Li||Li symmetric cell also kept a stable plating/stripping process over 450 h at the current density of 1.0 mA/cm2 with a deposited amount of 0.5 mAh/cm2.
Dendrite growth of zinc (Zn) anode at high current density severely affects the fast-charging performance of aqueous zinc metal batteries (AZMBs). While interfacial modification strategies can optimize Zn performance, challenges such as complicated preparation processes, excessive layer thicknesses, and high voltage hysteresis should be addressed. Herein, we utilize a cost-effective liquid fluorosiloxane, (3,3,3-trifluoropropyl)trimethoxysilane, for scalable modification of Zn foil via drop-casting at room temperature, resulting in an ultra-thin interphase layer of only 20 nm. The Si-O-Zn bonds formed between fluorosiloxane and Zn ensure interfacial stability, and the Si-O-Si bonds between fluorosiloxane molecules help to homogenize the electric field distribution. Additionally, the abundant highly electronegative fluorine atoms on the anode surface act as zincophilic sites, promoting the uniform deposition of Zn2+. Thus, the modified Zn foil (SiFO-Zn) exhibits excellent dendrite suppression, reduced voltage hysteresis, and prolonged cycle life at ultra-high current density (40 mA/cm2), achieving a cumulative areal capacity of 12.9 Ah/cm2. Further, the full cell assembled with 10 µm-thick SiFO-Zn anode and MnO2 cathode achieves 2600 cycles at 5 A/g with minimal capacity degradation, and a large-size (22.5 cm−2) pouch cell powers the light-emitting diode even after reverse bending, demonstrating the potential of AZMBs for fast-charging flexible devices.
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