Science China Chemistry最新文献

The universal synthesis of highly stable covalent organic frameworks (COFs) for ultra-sensitive and multi-component electrochemical detection in different scenarios remains a great challenge. Herein, a series of metallophthalocyanine-based two-dimensional (2D) dioxin (DXI)-linked metalophthalocyanine (MPc)-nDXI-COFs (M = Ni, Zn; n = 1, 2) are afforded in high yield (80%–96%) by a facile trace-quinoline assisted one-pot condensation of tetracarbonitrile precursors. Powder X-ray diffraction and electron microscopy investigations disclose their lamellar texture 2D network with AA stacking mode. Experiments and calculation results elucidate that the 2DXI-linked MPc-2DXI-COFs provide the stronger built-in electronic field and more electrostatic/hydrogen bonding adsorption sites than DXI-linked MPc-DXI-COFs, and the lower electrode reaction Gibbs free energy and stronger adsorption of analytes at NiPc than ZnPc unit, which grants NiPc-2DXI-COF excellent sensing properties for various analytes including neurotransmitters, organic pollutants, and heavy metal ions, with high sensitivity and low detection limit of 0.53 to 25.66 nM. Especially in binary and ternary systems and even in real-world conditions, simultaneous multi-component detection could be achieved.

Magnetic resonance imaging (MRI) plays an important role in precision medicine that is hampered by the lack of contrast agents with high efficiency and the ability to translate diagnostic accuracy into therapeutic intervention. Herein, we demonstrate a DNA-based MRI probe that overcomes previous single-mode enhancement and provides a mechanism of action for aggregation-induced dual-modal MRI signal enhancement. A facile method is developed to produce aggregated T₁/T₂ dual-modal NaGdF₄: Dy@PDA-DNA (PDA = polydopamine) MRI probes. When aggregated, this probe can further amplify MRI signal intensity and exhibit improved geometrical and positional stability in vivo. The performance of the NaGdF₄:Dy@PDA-DNA MRI probe toward MRI-guided preoperative planning and visualization-guided surgery is verified using an orthotopic tumor-bearing mouse model. The result shows that the rapid metabolism of the degraded probe leads to the mitigation of long-term toxic effects. Therefore, the developed high-performance MRI probe is of great significance for enhancing MRI diagnostic accuracy into precision medical therapeutic interventions.

2,2,7,7-Tetrakis-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (Spiro-OMeTAD) has been identified as the most widely used and effective hole transporting material (HTM) in perovskite solar cells (PSCs). However, the complicated multistep synthesis and low intrinsic hole mobility of Spiro-OMeTAD limit its commercialized application. Therefore, developing highly efficient HTMs with less synthetic steps becomes increasingly important. Moreover, understanding hot carriers transfer dynamics at the interface of perovskite layer and hole transport layer is crucial for further enhancing PSCs performance towards Shockley–Queisser limit, which still lacks full investigation to date. Herein, a new HTM based on tetraphenylethene (WP1) was successfully synthesized by a simple one-step reaction process. It was found that WP1-based HTM exhibits more matched energy level, higher hole mobility and conductivity than those of the control Spiro-OMeTAD. The femtosecond transient absorption results reveal that the transfer rate of hot holes in perovskite/WP1 sample is four times higher than that of perovskite/Spiro-OMeTAD, thereby helping enhance the device performance. Consequently, the efficiency of PSCs is enhanced to 24.04% (WP1) from 22.85% (Spiro-OMeTAD). Moreover, the un-encapsulated device prepared with WP1 exhibits better long-term stability, retaining 87% of its initial PCE value after storing for 72 days under air environment, while the reference device shows 76% of its initial value. This work indicates that simple tetraphenylethene-based organic small molecule could be a very promising HTM candidate for highly efficient PSCs, and gives some significant insights for understanding intrinsic hot carriers transfer dynamics in device.

Enantioenriched pyrrolidines and derivatives are ubiquitous substructures in compounds of importance to medicinal and biological chemistry. Herein, we report an efficient cobalt-catalyzed intramolecular asymmetric hydroamination reaction that produces chiral pyrrolidines with good to excellent yield and enantiocontrol. Compared with previously reported radical-involved methodologies for enantioenriched pyrrolidines, these conditions feature two elegant versatilities, enabling (1) the use of cobalt-catalyzed hydrogen atom transfer (HAT) to generate organocobalt intermediates that bring radical reaction to organometallic chemistry, and (2) enantioselective intramolecular C–N bond forging through an S_N2-like displacement involving dynamic kinetic resolution (DKR). This approach provides a new alternative and efficient methodology for enantioselective radical-involved C–N bond construction that can be used in the synthesis of both chiral pyrrolidines and homologous nitrogen heterocycles.

Nanomedicine delivery technology plays an important role in modern medicine and has shown good therapeutic effects in scientific research. Polysaccharides have the characteristics of wide sources, excellent biocompatibility, and non-toxicity. In addition, there are multifunctional groups on the main chain of polysaccharides, which can be surface-modified or functionalized to have targeting ability through specific sugar parts. Amphiphilic polysaccharide micelles with good biocompatibility, degradability, high safety, easy structural modification, and special core-shell structure are regarded as ideal carriers for nanomedicines. Therefore, this review is focused on the hydrophobic modification designs of polysaccharides, the preparation methods and characteristics of micelles, and the applications of amphiphilic polysaccharide micelles in the field of biomedicine. It is expected to provide some ideas and inspiration for the design of polysaccharide drug carriers.

Sulfide-based all-solid-state lithium metal batteries (ASSLMBs) have received extensive attention due to their high energy density and high safety, while the poor interface stability between sulfide electrolyte and lithium metal anode limits their development. Hence, a hybrid SEI (LICl/LiF/LiZn) was constructed at the interface between Li_5.5PS_4.5Cl_1.5 sulfide electrolyte and lithium metal. The LiCl and LiF interface phases with high interface energy effectively induce the uniform deposition of Li⁺ and reduce the overpotential of Li⁺ deposition, while the LiZn alloy interface phase accelerates the diffusion of lithium ions. The synergistic effect of the above functional interface phases inhibits the growth of lithium dendrites and stabilizes the interface between the sulfide electrolyte and lithium metal. The hybrid SEI strategy exhibits excellent electrochemical performance on symmetric batteries and all-solid-state batteries. The symmetrical cell exhibits stable cycling performance over long duration over 500 h at 1.0 mA cm⁻². Moreover, the LiNbO₃@NCM712/Li_5.5PS_4.5Cl_1.5/Li-10%ZnF₂ battery exhibits excellent cycle stability at a high rate of 0.5 C, with a capacity retention rate of 76.4% after 350 cycles.

Herein we report the facile synthesis of a series of novel N-O reagents and identify N′-di-Boc-N″-[(mesitylsulfonyl)oxy]-guanidine as an efficient imidating reagent. This reagent is synthetically scalable and bench-stable, yet it shows unprecedented reactivity and chemoselectivity towards S(II) in buffer/hexafluoroisopropanol (HFIP) system, to generate a new class of N-guanyl sulfilimines. Further transformation of N-guanyl sulfilimines to N-guanyl sulfoximines provides us a chance to investigate these rarely reached compounds, which are shown to be versatile precursors to a variety of N-heterocyclic and NH-sulfoximines. Our work provides an addition to the tool box of both sulfur imidation and guanidine synthesis, especially for the need of rapid and selective modifications of sulfur(II) center under biocompatible conditions.

Chiral pollutants often pose significant differential environmental health risks. In this study, the biotransformation of chiral dinotefuran (DIN) and its enantioselective metabolic toxicity mechanisms have been systemically investigated. Firstly, reversed-phase chromatography-high resolution mass spectrometry was developed to quantify the content of DIN R/S chiral enantiomer with pg level sensitivity, revealing a lower elimination rate constant (K_e) of S-DIN (0.730 h⁻¹) than R-DIN (0.746 h⁻¹). Secondly, the interaction mechanism between DIN metabolism and important endogenous bioactive molecules, such as aldehyde oxidase (AOX) and neurotransmitters, was revealed. The DIN nitro-group was converted into a guanidine group by the reducing site of nearby flavin adenine dinucleotide (FAD) in AOX with the preferred higher affinity of S-configuration. Meanwhile, the endogenous tryptophan (Trp) aldehyde metabolic intermediate, 5-hydroxyindoleacetaldehyde (5-HIAL), provides a persistent electron donor for DIN reduction via the oxidation-catalyzed site in AOX, resulting in remarkable up-regulation of monoamine neurotransmitters such as serotonin and dopamine. Thirdly, the higher level of neurotransmitters further mediated dysregulation of oxylipin homeostasis via the serotonergic pathway, where S-DIN exhibited more pronounced liver lipid damage and environmental health risk with the accumulated lipid biomarkers, oxidized triglyceride (OxTG) and oxidized sphingomyelin (OxSM). This study elucidates the AOX-mediated enantioselectivity metabolic pathway of DIN, providing a new analytical method for chiral pollutants and paves the way for their health risk assessments.