Latest ArticlesThe asymmetric conjugate additions of aryl Grignard reagents to trisubstituted enones by chiral P, N ligand L6 with low catalyst loading (0.25–1.0 mol%) are disclosed. Chiral 2-ester chromanone and its analogs bearing a quaternary stereogenic centers at C2 position were produced in high to excellent yields, enantioselectivities and high turnover number. The notable features of this reaction include its broad substrate scope, complete 1, 4-addition regioselectivities, applicability to both batch and flow for large scale synthesis. This report develops an efficient strategy to apply aryl Grignard reagents in asymmetric 1, 4-conjugation reactions and provides a direct method to incorporate quaternary chiral centers toward the synthesis of biologically relevant chromanone derivatives.
Fluorescence imaging-guided photodynamic therapy holds great promise for application in precise cancer diagnosis and treatment, which has motivated high requirements for phototheranostic agents. However, current photosensitizers (PSs) generally face limitations such as short emission wavelength and inadequate reactive oxygen species (ROS) production. Aggregation-caused quenching issue also hinders the phototheranostic efficiency of PSs. Herein, the π-bridge modulation strategy is proposed to construct ionic PSs with enhanced bioimaging and therapeutic outcomes. Two donor-π-acceptor (D-π-A) molecules TPCPY and TFCPY were obtained by incorporating phenyl and furan units as π-bridge, respectively. Both PSs feature aggregation-induced near-infrared emission. Under light irradiation, TPCPY and TFCPY can produce both type Ⅰ and Ⅱ ROS. Introducing furan ring in TFCPY enhances the ROS generation capacity by type Ⅰ photosensitization process, which is consistent with the reduced energy gap between singlet and triplet states from theoretical calculation. Furthermore, TFCPY can achieve quick cellular uptake, accumulate in mitochondria, and then efficiently kill cancer cells, which is superior to TPCPY. Consequently, TFCPY exhibited good antitumor outcomes and excellent in vivo fluorescence imaging ability. This work provides an efficient molecular engineering of introducing heterocycles into the D-π-A skeleton to develop high-performance PSs with both type Ⅰ and Ⅱ ROS generation.
A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented. This strategy provides an efficient and convenient method to access enantioenriched oxazolines such as valuable chiral S, N-oxazoline ligand as well as Ferrox ligand in high yields with excellent enantio– and diastereroselectivity. Furthermore, the optically active oxazoline products can be converted to valuable 1, 2-amino alcohols. More importantly, the synthetic utility of this transformation is demonstrated in the expeditious assembly of chiral Phox-type ligand, which shows excellent catalytic activities.
Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is an attractive technology for the visualization of metabolite distributions in tissues. However, detection and identification of low-abundance or poorly ionized metabolites remains challenging. Although on-tissue chemical derivatization (OTCD) holds great promise for improving MALDI MS detection sensitivity and selectivity by modification of specific chemical groups, the available methods for subsequent metabolite annotation are limited. Herein, a laser-assisted chemical transfer (LACT)-based parallel OTCD strategy was established for visualizing and annotating carbonyl metabolites in murine brain tissues. Girard's T and Girard's P reagents were applied for parallel OTCD to generate the characteristic m/z pairs with a 19.969 Da mass shift (±0.020 Da tolerance) for rapid recognition of derivatized metabolites. The similarity of spatial distribution patterns of each m/z pair was further statistically evaluated to remove the ambiguous annotations due to the occurrence of interference compounds. As a result, 90 ion pairs were annotated as candidate carbonyl metabolites, 66 were previously known and 24 were potential unreported carbonyls. Furthermore, the spatial alterations of carbonyl metabolites in the ischemic rat brain were successfully visualized and characterized, including small molecule aldehydes and ketones, long-chain fatty aldehydes, and monosaccharides. This further emphasizes great potential of parallel OTCD strategy for efficient and confident molecular annotation of spatial submetabolomics data associated with brain diseases.
Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport. The construction of these unique structures always requires new self-assembly behaviors with different building blocks, intriguing phenomena of colloidal chemistry. In this work, by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations, we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide (MoS2) hydrogel membranes with abundant fluidic channels. Given the interpenetrating ionic transport network, the MoS2 hydrogel membranes exhibit a high-level capacitive performance 1.34 F/cm2 at an ultrahigh mass loading of 11.2 mg/cm2. Furthermore, the interlayer spacing of MoS2 in the hydrogel membranes can be controlled with ångström-scale precision using different cations, which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.
Sodium metal has been widely studied in the field of batteries due to its high theoretical specific capacity (~1,166 mAh/g), low redox potential (-2.71 V compared to standard hydrogen electrode), and low-cost advantages. However, problems such as unstable solid electrolyte interface (SEI), uncontrolled dendrite growth, and side reactions between solid-liquid interfaces have hindered the practical application of sodium metal anodes (SMAs). Currently, lots of strategies have been developed to achieve stabilized sodium metal anodes. Among these strategies, modified metal current collectors (MCCs) stand out due to their unique role in accommodating volumetric fluctuations with superior structure, lowering the energy barrier for sodium nucleation, and providing guided uniform sodium deposition. In this review, we first introduced three common metal-based current collectors applied to SMAs. Then, we summarized strategies to improve sodium deposition behavior by optimally engineering the surface of MCCs, including surface loading, surface structural design, and surface engineering for functional modification. We have followed the latest research progress and summarized surface optimization cases on different MCCs and their applications in battery systems.
With the development of science and technology, there is an increasing demand for energy storage batteries. Aqueous zinc-ion batteries (AZIBs) are expected to become the next generation of commercialized energy storage devices due to their advantages. The aqueous zinc ion battery is generally composed of zinc metal as the anode, active material as the cathode, and aqueous electrolyte. However, there are still many problems with the cathode/anode material and voltage window of the battery, which limit its use. This review introduces the recent research progress of zinc-ion batteries, including the advantages and disadvantages, energy storage mechanisms, and common cathode/anode materials, electrolytes, etc. It also gives a summary of the current research status of each material and provides solutions to the problems they face. Finally, it looks at the future direction and methods to optimize the performance of zinc-ion full batteries.
Sodium metal batteries (SMBs) have drawn much attention as complement to lithium metal batteries for next generation high-energy batteries. However, it is still a big challenge to enhance their cycling stability without sufficient sodium reserve in anode, due to the non-uniform Na plating/stripping and uncontrolled Na dendrite growth. Herein, a dual layer host consists of sodiophilic graphene@antimony nanoparticles bottom layer and 3D polyacrylonitrile nanofiber top layer (PAN-G@Sb) is employed to enable highly reversible Na plating/stripping. Thanks to the uniform Na deposition, PAN-G@Sb delivers an outstanding average Coulombic efficiency of 99.8%, highly reversible Na plating/stripping for 1000 cycles at 2.0 mA/cm2, as well as over 1000 h of stable operation in symmetric cells. When paired with a high mass loading Na3V2(PO4)3 (NVP) cathode (16.2 mg/cm2), the full cell (N/P ratio = 1.4) also displays prominent capacity retention of 98.7% after 250 cycles with a high energy density of 284.6 Wh/kg. Moreover, PAN-G@SbNVP anode-free full cell also shows an excellent capacity retention of 91.0% after 50 cycles at 0.5 C, exhibiting the stable operation of high energy SMBs.
High-capacity Ni-rich layered cathodes LiNixCoyMn1−x−yO2 (NCM) have been widely recognized as highly promising candidates for lithium-ion batteries (LIBs). However, NCM cathodes are suffered from sluggish Li-ion kinetics and fast capacity decay. Herein, the Nb/Ti co-doping strategy has been proposed by formation energy analysis to enhance the mechanical and chemical integrities of NCM cathode. Nb/Ti co-doping facilitates Li-ion transport of NCM cathode for boosting the rate ability. Furthermore, the structure stability is prominently improved for the stronger Nb–O and Ti–O bonds, resulting from the suppressed sharp contraction of c axis, inhibited microcracks formation, and alleviated electrolyte corrosion. Inspired by the synergistic effect of Nb/Ti co-doping, the modified NCM exhibits superior comprehensive electrochemical performances. The Nb/Ti co-doping NCM exhibits an increased discharge capacity of 144.3 mAh/g at 10 C and an outstanding capacity retention remained 92.7% after 300 cycles at 1 C. This work offers a promising approach to developing high-performance cathode materials.
The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries. However, the poor structural stability and serious surface/interfacial side reactions during long cycles severely hinder the material's practical application. In this paper, Cs+ doping and polymethyl methacrylate (PMMA) coating are used to synergistically modify the NCM955 material. The results show that the corresponding discharge specific capacity of NCMCs-2@P-2 material reaches 152.02 mAh/g at 1 C (1 C = 200 mA/g) and 125.66 mAh/g at 5 C after 300 cycles, and the capacity retention is 78.11% and 72.21%, respectively. In addition, it still maintains 156.36 mAh/g discharge specific capacity at 10 C, and these rate and cycle properties exceed those reported on ultra-high nickel cathode material. Moreover, NCMCs-2@P-2 material has higher migration energy barrier of Ni2+ and lower migration energy barrier of Li+ than that of NCM955 material. Therefore, NCMCs-2@P-2 material has excellent electrochemical properties, which has been proved by a series of structural characterization, theoretical calculation and performance test. The synergistic enhancement of Cs+ doping and PMMA coating accelerates lithium ion diffusion kinetics, stabilizes crystal structure, and inhabits surface/interface side reaction.
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