Latest ArticlesRoxarsone (ROX) is a commonly used antibacterial and growth-promoting additive to animal feed. The development of an effective method for detecting ROX and its conversion products is of importance because of their potential harm to human health and ecosystem. Herein, we report the designed synthesis of a novel one-dimensional covalent organic framework (1D COF), named EP-COF, and its application as a fluorescent probe for ROX sensing. EP-COF is constructed based on imine linkages, exhibiting high crystallinity, strong fluorescence emission, and good dispersibility in water. It displays a remarkable capability to efficiently detect ROX, with an impressive detection limit of 4.5 nmol/L. Moreover, EP-COF also offers advantages of excellent selectivity, and high structural stability. This work not only presents a promising approach for the detection of harmful substances like ROX, but also serves as a valuable reference for exploring application of 1D COFs in chemical sensing.
Antibiotic resistance poses a critical threat to human healthcare, largely driven by bacterial biofilms. These biofilms resist the immune system and antibiotics, rendering enclosed microbial cells 10–1000 times more antibiotic-resistant than planktonic cells, leading to severe infections. Therefore, there is an urgent need to develop innovative tools for investigating biofilm regulators and devising novel antibacterial strategies. In this study, we developed Cy-NEO-PA, a near-infrared (NIR) fluorescent probe responsive to penicillin G acylase (PGA), with bacteria-targeting ability. This probe was designed to visualize the influence of environmental factors on biofilm formation in Acinetobacter baumannii (A. baumannii). Our findings demonstrated that glucose suppressed PGA production, leading to enhanced biofilm formation, whereas phenylacetic acid (PAA) stimulated PGA production and inhibited biofilm formation in A. baumannii. These observations highlight the remarkable capability of Cy-NEO-PA to accurately measure PGA dynamics, shedding light on the critical role of PGA in biofilm development. Additionally, Cy-NEO-PA exhibited excellent biocompatibility, potent reactive oxygen species (ROS) generation, efficient photothermal conversion, and bacteria-targeting abilities, making it a promising agent for combating bacterial infections and promoting wound healing through photothermal (PTT)/photodynamic (PDT) therapy. These discoveries emphasize the significant role of PGA in antibacterial therapy and offer valuable insights for the design of effective strategies targeting PGA to combat biofilm-associated infections.
Reported here is the synthesis of a new macrocycle bearing anionic carboxylate groups with water-soluble aggregation-induced emission (AIE). The water-soluble macrocycle without typical AIE luminogens is constructed based on the building block of benzothiadiazole. It exhibits a remarkable AIE effect. This water-soluble macrocycle can selectively bind different types of biogenic amines in aqueous media with the tightest binding towards spermine. The fluorescence enhancement induced by supramolecular encapsulation is used to detect spermine.
A new 1,4-amidocyanation of 1,3-enynes with N-amidopyridin-1-ium salts and TMSCN using a copper and photoredox synergetic catalysis for producing α-amido allenyl nitriles is developed. Employing N-amidopyridin-1-ium salts as the amidyl radical precursors, the reaction enables the formation of two new bonds, one C(sp3)-N bond and one C(sp2)-C(sp) bond, in a single reaction step. This reaction represents a mild, general route to the construction of the α-amido allenyl nitrile architectures, which characterizes a broad scope, a good functional group compatibility and an excellent selectivity.
Nanographenes (NGs) with twisted backbones are emerging as new candidates for chiroptical materials. In this work, we describe a new strategy for synthesizing a [10]twistacene-embedded NG which exhibits a rare flag-hinge-like geometry. By neatly creating steric crowding on the [6]helicene breaches of the NG skeleton, the synthesis only provided homochiral isomers without generating the "meso‑" isomer. The formed NGs showed high luminescence with quantum yield up to 52%, and promising circularly polarized luminescence (CPL) performance with |glum| up to 5.0 × 10−3. Besides, these NGs also showed outstanding CPL brightness (BCPL) up to 305 L mol−1 cm−1 among chiral NGs.
The supramolecular Förster resonance energy transfer (FRET) is seen as a promising approach for organic photocatalysis using dyes as catalysts, because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions. Here we propose a supramolecular FRET photocatalysis strategy for α-oxyamination reaction based on supramolecular confinement effect. The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate (SDS). Benefitting from the supramolecular confinement space provided by SDS in aqueous environment, the FRET process between the monomer and Nile Red is effectively achieved (exciton migration rate: 3.99 × 1014 L mol‒1 s‒1). On this basis, the supramolecular FRET system is used as an efficient energy source to catalyze α-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light, showing a yield as high as 94% and a turnover frequency value of 3.92 h‒1. This photocatalytic result shows a great enhancement compared to that of Nile Red alone.
Highly active transition metal nitrides are desirable for electrocatalytic reactions, but their long-term stability is still unsatisfactory and thus limiting commercial applications. Herein, for the first time, we report a unique and universal room-temperature urea plasma method for controllable synthesis of N-doped carbon coated metal (Fe, Co, Ni, etc.) nitrides arrays electrocatalysts. The preformed metal oxides arrays can be successfully converted into metal nitrides arrays with preserved nanostructures and a thin layer of N-doped carbon (N-C) via one-step urea plasma. Typically, as a representative case, N-C@CoN nanowire arrays are illustrated and corresponding formation mechanism by plasma is proposed. Notably, the designed N-C@CoN catalysts deliver excellent electrocatalytic activity and long-term stability both in oxygen evolution reaction (OER) and urea oxidation reaction (UOR). For OER, a low overpotential (264 mV at 10 mA/cm2) and high stability (>50 h at 20 mA/cm2) are acquired. For UOR, a current density of 100 mA/cm2 is achieved at only 1.39 V and maintain over 100 h. Theoretical calculations reveal that the synergetic coupling effect of CoN and N-C can significantly facilitate the charge-transfer process, optimize adsorbed intermediates binding strength and further greatly decrease the energy barrier. This strategy provides a novel method for fabrication of N-C@ metal nitrides as highly active and stable catalysts.
Heterojunction engineering is recognized as a promising strategy to modulate the photocatalytic properties of semiconductors. Herein, lead-free Cs2CuBr4 perovskite quantum dots (PQDs) were confined in a mesoporous CuO framework and a p-n type S-scheme heterojunction of Cs2CuBr4/CuO (CCB/CuO) photocatalyst was fabricated. Experimental characterizations confirmed the effective confinement of the Cs2CuBr4 PQDs in the mesoporous CuO framework, which enabled intimate contact in the interface of CCB/CuO heterojunction, thus facilitating the interfacial charge migration and separation between p-type CuO and n-type Cs2CuBr4. Owing to the outstanding charge transport property and CO2 adsorption capacity, the developed CCB/CuO heterojunction exhibited remarkably enhanced photocatalytic CO2 conversion efficiency with an electron consumption rate (Relectron) of 281.1 µmol g−1 h−1, which was approximately 2.8 times higher than that of pristine Cs2CuBr4. These findings provide some insights into the rational engineering design of lead-free perovskite-based heterostructures for efficient photocatalytic CO2 conversion.
Shape-persistent arylene ethynylene molecular cages have been investigated as transmembrane channels for ions and small molecules. The molecular cages were obtained starting from tetrayne monomers through alkyne metathesis cyclooligomerization. We found these porphyrin-based rigid molecular cages can insert into the lipid bilayer and efficiently transport ions and small molecules (e.g., calcein). Our study reveals longer hydrophobic alkyl chains on the cage molecule promote the channeling efficiency, while shorter and/or more polar side chains impair such activity. Kinetic analysis shows linear correlation between the rate of proton transport and the concentration of the cage, suggesting the active species is likely a monomeric cage. We found that C70-encapsulated cages are nearly inactive for transmembrane ion transportation, indicating that ions are likely transported through the internal cavity of the cage. Discrete shape-persistent organic cages represent highly stable synthetic ion channels or pores, which could have interesting applications in biomimetic signaling and drug delivery.
Defects can strongly affect the lattice, strain, and electronic structures of nanomaterials photocatalysts, like a double-edged sword of both positive significance and negative influence on photocatalytic performances. To date, most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis. However, a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered. Here, a series of TiO2−X mesoporous spheres (MS) with different oxygen vacancy concentrations for photocatalytic applications were prepared by high-temperature chemical reduction. The link between oxygen vacancy concentration and photocatalytic performance was successfully established. The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration, which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis. As the reduction temperature rises to 300 ℃, carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs, thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants, as demonstrated by a hydrogen evolution rate of 523.7 µmol g-1 h-1 and a ninefold higher RhB photodegradation rate compared to TiO2 MS. The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.
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