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Restriction of Molecular Rotors in Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets for Sensing Signal Amplification
摘要： Covalent organic frameworks (COFs) have emerged as promising crystalline porous materials with well-defined structures, high porosity, tunable topology and functionalities suitable for various applications. However, studies of few-layered ultrathin two-dimensional (2D) COF nanosheets, which may lead to unprecedented properties and applications, are still limited. Herein we report the targeted synthesis of three azine-linked and imine-linked 2D COFs named NUS 30-32 using monomers containing aggregation-induced emission (AIE) rotor-active tetraphenylethylene (TPE) moieties, affording micro- and meso- dual pores in NUS-30 and NUS-32, and triple pores in NUS-31. For the first time, we demonstrate that these isostructural bulk COF powders can be exfoliated into ultrathin 2D nanosheets (2 – 4 nm thickness) by temperature-swing gas exfoliation approach. Compared with TPE monomers and COF model compounds, the AIE characteristic of NUS 30-32 nanosheets is distinctly suppressed due to the covalent restriction of the AIE molecular rotors in the confined 2D frameworks. As a result, the enhancement of conjugated conformations of NUS 30-32 nanosheets with unusual structure relaxation show signal amplification effect in biomolecular recognition of amino acids and small pharmaceutical molecules (L-dopa), exhibiting much higher sensitivity than their stacked bulk powders, TPE monomer, and COF model compound. Moreover, the binding affinity of the COF nanosheets toward amino acids can be controlled by increasing the number of azine moieties in the structure. Density functional theory (DFT) calculations reveal that binding affinity control results from the crucial geometric roles and stronger host-guest binding between azine moieties and amino acids. In addition, we demonstrate that minimal loading of the NUS-30 nanosheets in composite membranes can afford excellent performance for biomolecule detection. Our findings pave a way for the development of functional ultrathin 2D COF nanosheets with precise control over the nature, density, and arrangement of the binding active sites involved in enhanced molecule recognition.
关键词： molecular rotors,Covalent organic frameworks,aggregation-induced emission,biomolecular recognition,signal amplification,two-dimensional nanosheets
更新于2025-09-04 15:30:14
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Visualizing the Initial Step of Self-Assembly and the Phase Transition by Stereogenic Amphiphiles with Aggregation-Induced Emission
摘要： Many highly ordered structures with smart functions are generated by self-assembly with stimuli responsiveness. Despite the electron microscopes enable us to directly observe the end products, they are hard to visualize the initial step and the kinetic stimuli-responsive behavior of self-assembly. Here, we report the design and synthesis of stereogenic amphiphiles, namely (Z)-TPE-OEG and (E)-TPE-OEG, with aggregation-induced emission (AIE) characteristics from the hydrophobic tetraphenylethene core and thermoresponsive behavior from the hydrophilic oligoethylene glycol monomethyl ether chain. The two isomers can be easily isolated by high-performance liquid chromatography and characterized by 2D NMR spectroscopy. While (Z)-TPE-OEG self-assembles into vesicles, its (E)-cousin forms micelles in water. The initial step of their self-assembly processes can be visualized based on AIE characteristics, with the sensitivity much higher than the method based on transmittance measurement. The entrapment and release capabilities of the (Z)-stereogenic amphiphile are demonstrated by employing pyrene as a guest. The thermoresponsive behavior of the (Z)-amphiphile results in its continuous phase transition from microscopic self-assembly to macroscopic aggregation, which is successfully visualized in-situ by confocal laser scanning microscopy accompanied with AIE technique. Such kinetic process shows different stages according to the microscopic visualization and these stages have never been monitored through roughly observing the appearance of precipitates. It is anticipated that this study can deepen the understanding of the self-assembly processes for better monitoring and controlling them in different systems.
关键词： phase transition,aggregation-induced emission,self-assembly,amphiphiles,microscopic visualization
更新于2025-09-04 15:30:14
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Synthesis of novel luminescent copper nanoclusters with substituent driven self-assembly and aggregation induced emission (AIE)
摘要： We demonstrate a novel strategy to synthesize highly stable luminescent mercaptoimidazole-capped copper nanoclusters (CuNCs). Herein we depict that a simple modification of substituents on the mercaptoimidazole ligand dictates the self-assembly and photophysical properties of the clusters. These CuNCs showed aggregation induced emission (AIE) with a large Stokes shift (Dk 4 200 nm), and the formation of clusters corresponding to Cu4L3 was confirmed by MALDI-TOF mass spectrometric analyses. Interestingly, these nanoclusters e?ectively internalize into mammalian cells while retaining their fluorescent properties and exhibit negligible toxicity.
关键词： mercaptoimidazole-capped,luminescent copper nanoclusters,AIE,aggregation induced emission,self-assembly
更新于2025-09-04 15:30:14
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Mechanoresponsive Material of AIE-Active 1,4-Dihydropyrrolo[3,2-b]pyrrole Luminophores Bearing Tetraphenylethylene Group with Rewritable Data Storage
摘要： A new tetraphenylethylene (TPE) functionalized 1,4-dihydropyrrolo[3,2-b]pyrrole derivative (APPTPECN) was synthesized with obvious aggregation-induced emission (AIE) active by simple synthetic method. APPTPECN exhibited reversible mechano?uorochromic (MFC) behavior. The powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) investigations exhibited that the MFC nature is originated through a conversion from the microcrystalline to amorphous phase under the stimulus of external force. The results obtained would be of major help in understanding the MFC mechanism and designing new MFC materials. Compound APPTPECN has the potential possibility to employ in rewritable data storage and is of assistance in the rational design of smart luminescent materials.
关键词： rewritable data storage,reversible mechanochromism behavior,aggregation-induced emission (AIE),1,4-dihydropyrrolo[3,2-b]pyrrole derivative
更新于2025-09-04 15:30:14
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Far‐Red/Near‐Infrared Emissive (1,3‐Dimethyl)barbituric Acid‐Based AIEgens for High‐Contrast Detection of Metastatic Tumors in Lung
摘要： Despite of the enthusiastic research in aggregation-induced emission luminogens (AIEgens) in recent years, the ones that can be smoothly used for sophisticated biomedical applications such as in vivo bioimaging of pulmonary metastatic tumors during surgery are still limited. Herein, we report the design and synthesis of a new series of fluorescent AIEgens that consist of methoxy-substituted tetraphenylethene (TPE) as the electron-donating moiety, (1,3-dimethyl)barbituric acid as the electron-withdrawing moiety, and different π-bridge units. As compared to benzene or 3,4-ethylenedioxythiophene, using thiophene as the π-conjugation unit between the donor and acceptor results in relatively higher absolute fluorescence quantum yield (14.5%) in water when formulating the corresponding AIEgens into nanoparticles (AIE dots) with amphiphilic co-polymer as the doping matrix. The highly FR/NIR emissive thiophene-based AIE dots are demonstrated to be potent for intraoperative detection of pulmonary metastatic tumors particularly the micro-sized ones with excellent signal-to-background ratio.
关键词： barbituric acid,AIE dot,fluorescence imaging,image-guided cancer surgery,aggregation-induced emission luminogen
更新于2025-09-04 15:30:14
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A solid-state emissive and solvatofluorochromic fluorophore and its application in high-contrast, fast, and repeatable thermochromic blends
摘要： Organic thermochromic luminescent materials are very promising in applications of thermo-history recording, sensing and anti-counterfeiting. However, the current reported organic thermochromic systems still have the drawbacks of slow responsive speed, low colour contrast and unsatisfactory repeatability. In this paper, we reported a twisted fluorophore based on 1,4-bis[2,2-bisphenyl-vinyl]benzene skeleton with A-D-A structure (OD-CN), which shows strong solvatochromism in solution with emission shifts up to 135 nm, highly efficient red emission in solid state (660 nm, 11.62%) and unprecedented thermochromic behaviour in linear low density polyethylene matrix with high emission contrast (red to greenish yellow), fast responsiveness (within 1 s) and good repeatability (over 10 times). OD-CN doped LLDPE films show potential applications in anti-counterfeiting and as an example, it was applied as multi-channel anti-counterfeiting printings on paper money. What's more, the strategy of blending fluorophores with solvent effects and solid-state emission into apolar polymer matrixes to realize thermochromisms is general.
关键词： Thermochromism,Intramolecular charge transfer (ICT),Aggregation induced emission enhancement (AIEE),1,4-bis[2,2-bisphenyl-vinyl]benzenes
更新于2025-09-04 15:30:14
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Efficient synthesis of high solid content emulsions of AIE polymeric nanoparticles with tunable brightness and surface functionalization through miniemulsion polymerization
摘要： Efficient production and flexible surface functionalization are important developing directions for the synthesis of polymeric nanomaterials. In this work, aggregation-induced emission (AIE) polymeric nanoparticles (PNPs) were efficiently synthesized by encapsulating a model AIE luminogen, tetraphenylethylene (TPE), within a polymeric matrix via miniemulsion polymerization. The AIE PNPs with similar emission and particle properties were synthesized in a wide solid content range of 8–40 wt%. The particle size and photoluminescence intensity of AIE PNPs could be flexibly tuned by synthetic parameters including the surfactant content and TPE content. Furthermore, the surface carboxyl- and amino-functionalization of AIE PNPs were conveniently achieved through copolymerization of styrene and functional monomers methacrylic acid and 2-aminoethyl methacrylate hydrochloride, respectively, in miniemulsions. The surface functionalization extent could be facilely tuned by the content of functional monomers. This miniemulsion polymerization based technique could be a feasible and efficient method to prepare AIE PNPs with versatile surface functionalization, tunable brightness, and controllable particle properties for the applications in biodetection, bioimaging, etc.
关键词： high solid content,miniemulsion polymerization,Aggregation-induced emission,AIE polymeric nanoparticles,surface functionalization
更新于2025-09-04 15:30:14