Latest ArticlesRhodium-catalyzed C4aryl−H activation and ring-retentive annulation of 2H-imidazoles with internal alkynes to build imidazo[5,1-a]isoquinolinium salts with high yields and broad scope has been disclosed. These novel salts serve as new full-color emissive fluorophores (433−633 nm), just by simply modifying the substituents on C3 and C4 positions of isoquinoline ring. Furthermore, these salts can undergo ring-opening C5aryl−H activation/annulation with a different alkyne to form non-symmetric and AIE-active 1,1′-biisoquinolines, where NH4OAc plays an indispensable role that accounts for Hofmann elimination and imine formation, leading to an unprecedented imine dance: cyclic imine → N-alkenyl imine → NH imine. The 15N labelling experiments indicate that the 2nd annulation includes two pathways: N-exchange (major) and N-retention (minor).
Chemotherapy has been recommended as the standard protocol for triple-negative breast cancer (TNBC) at the advanced stage. However, the current treatment is unsatisfactory due to inefficient drug accumulation and rapid chemo-resistance. Thus, rational design of advanced drug delivery systems that can induce multiple cell death pathways is a promising strategy to combat TNBC. Ferroptosis is a powerful non-apoptotic cell death modality, showing potential in tumor inhibition. Herein, we propose a binary prodrug nanoassemblies that combines chemotherapy with ferroptosis for TNBC treatment. In this system, paclitaxel is linked with paracetamol (ferroptosis activator) by a disulfide linkage to construct self-assembly prodrug. Meanwhile, 2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-methyl(polyethylene glycol)-2000-tyrosine (DSPE-PEG2k-tyrosine) is applied for large neutral amino acid transporter 1 (LAT1) targeting, which is highly expressed in TNBC. The prodrug nanoassemblies exhibit good stability and a glutathione (GSH)-responsive release profile. Furthermore, the LAT1-targeted nanoassemblies show stronger cytotoxicity, higher cellular uptake, and more obvious ferroptosis activation than non-decorated ones. In a TNBC mice model, the prodrug nanoassemblies demonstrate strong anti-tumor efficacy. The application of ferroptosis-assisting chemotherapy may provide a promising strategy for TNBC therapy.
Using hydrogen-bonded organic frameworks (HOFs) as photosensitizers to perform photocatalytic oxidation reactions under green and mild conditions is still a challenge for the application of HOFs materials. This study presents a novel approach that exploits HOFs to enhance the efficiency of photocatalytic oxidation for achieving visible light catalytic oxidation of styrene and its derivatives in the aqueous environment. By using 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) as the monomer, a pyrene-based hydrogen-bonded organic framework (PFC-1) with a microporous structure was successfully prepared. Compared with monomer H4TBAPy, due to the exciton effect and the interlayer confinement of HOFs, the singlet oxygen (1O2) production efficiency is significantly improved, which has great potential in photocatalytic oxidation reactions. Subsequently, the practicality of PFC-1 as a photocatalyst was studied, and the photocatalytic oxidation of styrene and its derivatives in aqueous solution was achieved under visible light with high catalytic efficiency, indicating that PFC-1 has significant potential to promote photocatalytic oxidation reactions under mild conditions. The utilization of HOFs as photosensitizers in this straightforward approach enables the attainment of green photocatalytic oxidation, hence expanding the potential applications of HOFs materials within the realm of photocatalysis.
Oligo[n]rotaxanes are one of the most extensively studied categories of mechanically bonded macromolecules. In this study, a supramolecular oligo[2]rotaxane is successfully constructed driven by platinum(Ⅱ) metallacycle and pillar[5]arene-based host–guest interactions in an orthogonal way. The supramolecular oligo[2]rotaxane is further applied in fabricating a light harvesting system.
Antibiotics, as widely used antibacterial drug, exist in various environmental media. Antibiotic residues can affect biological metabolism and lead to bacterial resistance and the formation of antibiotic-resistance genes, posing a threat to human health and ecological safety. Establishing efficient detection methods for antibiotics and antibiotic-resistance genes has great environmental significance. Fluorescence detection methods, due to their fast response, high sensitivity and specificity, and low-cost, are widely used in chemical and biological sensing. This review first summarizes the pre-treatment methods for different types of environmental samples, and then focuses on the recent advances of fluorescence methods for the detection of antibiotics and antibiotic-resistance genes. Finally, main challenges and future research directions of fluorescence methods for antibiotic and antibiotic-resistance genes detection are discussed. This review highlights the promising prospect of fluorescence methods in-situ detection and monitoring of antibiotics and antibiotic-resistance genes, and provides guidance for the construction of overall risk assessment system of environmental media.
A rhodium-catalyzed desymmetrization reaction for enantioselective methyl C−H arylation is achieved by utilizing an in situ arylating reagent via nucleophilic cyclization of o-aminoaryl alkyne. The reaction results in chiral indoles containing all-carbon quaternary stereocenters under atmospheric conditions, with a wide range of substrates exhibiting good enantioselectivity (44 examples). Mechnism and DFT studies show that the stereocontrol is reasonably achieved through the collaborative control of a large silicon substituted chiral ligand and C−H···π, LP···π interactions between aryl rings of the carboxylate group and the substrate. Control experiments demonstrate that Rh-aryl bond formation via in situ nucleophilic cyclization is more critical for reaction efficiency than via C−H activation of the nucleophilic cyclization byproduct.
Molecular-based ferroelastics with dielectric switching properties are highly desirable for their applications on microelectronic dielectric switches, sensors, data storage, and so on. However, the current reports mostly focus on organic-inorganic hybrids containing toxic heavy metal atoms, and the relatively low phase transition temperature limits their application. In this paper, low-toxic organic salt ferroelastic enantiomers (R/S)-4-fluoro-1-azabicyclo[3.2.1]octonium chloride [(R/S)-F-321] were designed and synthesized under the introducing chirality strategy. They undergo a 432F422-type ferroelastic phase transition with a high Curie temperature (Tc) of 470 K, simultaneously exhibiting excellent dielectric switching characteristics. In addition to the ordered-disordered movement of cations, the significant displacement of anions is also responsible for such high Tc and large dielectric switching ratios, which is very rare in molecular-based switching materials. This work enriches the development of molecular ferroelastic switching materials and gives inspiration for the exploration of environmentally friendly high Tc organic salt ferroelastics with prominent switching performances.
Triphenylamine (TPA)-containing 2-(2′-hydroxyphenyl)benzoxazoles (2a-2c) have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction. Compound 2a is a novel mechanofluorochromic material with blue-shifted mechanochromic properties. Compounds 2b and 2c presented opposite mechanochromic trends. For 2b, the enol-form emission enhanced, and the keto-form emission blue-shift after grinding. In contrast, 2c exhibited the weak enol-form emission disappeared and the keto-form emission slightly red-shift after grinding treatments. The estrone-containing 2b-based water-dispersed nanoparticles (NPs) exhibit apparent dual-emission and were applied for fluorescence images. In addition, bis(TPA)-containing 2c-based devices exhibit dual-emission with good performance and a singlet exciton yield of 92%, which breaks through the theoretical upper limit of 25% in conventional fluorescent OLEDs. This is one of the highest exciton utilization values recorded for the ESIPT molecules with a dual emission system.
DNA-based hydrogels are exceptional materials for biological applications because of their numerous advantages such as biodegradability, biocompatibility, hydrophilicity, super absorbency, porosity, and swelling. Among these advantages, the ability of DNA-based hydrogels to respond to specific physical and chemical triggers and undergo reversible phase transitions has garnered significant attention in the fields of disease diagnosis (biosensors) and treatment (drug delivery). This article focuses on the recent advancements in the research of DNA-based hydrogels and discusses the different types of these hydrogels, the synthetic methods, their unique properties, and their applications in biosensors and drug delivery. The types of DNA hydrogels are categorized based on their building blocks, and the process of synthesis as well as the unique characteristics of DNA-based hydrogels are described. Then, DNA-based responsive hydrogels utilized as intelligent materials for the development of biosensors are reviewed. Furthermore, this article also presents the current status of DNA-based responsive hydrogels in drug delivery for cancer treatment, wound healing, and other therapeutic applications. Ultimately, this paper discusses the current challenges in expanding the practical application of DNA-based hydrogels.
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