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Novel rhodamine-based colorimetric and fluorescent sensor for the dual-channel detection of Cu2+ and Co2+/trivalent metal ions and its AIRE activities
摘要： A rhodamine hydrazone 1 bearing coumarin moiety was designed and prepared. Compound 1 exhibited high selectivity toward Co2+ and trivalent metal ions with fluorescence enhancement in CH3OH solution. However, 1 selectively responded to Al3+ in nearly pure H2O media and was further applied to monitor Al3+ in live cells. Moreover, 1 could also act as a colorimetric probe toward Cu2+ in either CH3OH or H2O solution. In addition, sensor 1 displayed aggregation-induced ratiometric emission (AIRE) activities in mixed H2O/CH3OH solution.
关键词： cell imaging,coumarin,fluorescent probe,Aggregation-induced ratiometric emission,metal ions,rhodamine
更新于2025-09-23 15:23:52
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Polarized THz Emission from In-Plane Dipoles in Monolayer Tungsten Disulfide by Linear and Circular Optical Rectification
摘要： Recent advances in the development of polarized terahertz (THz) emission from nanomaterials have not only opened up a new “TeraNano” interdiscipline but also provided a new tool for nonlinear optical process research. Herein, THz radiation mechanism of monolayer tungsten disulfide (WS2) is first investigated by both linear and circular polarization laser excitations at room temperature. The results reveal that polarized THz emission is dominated by the optical rectification based on in-plane nonlinear dipoles, which is totally different from that of bulk WS2. The mechanism is verified by the azimuthal angle and pump polarization angle dependence of THz emission in both experiment and theory. Furthermore, controllably elliptically polarized THz emission is observed with the maximum ellipticity of ≈0.52 based on nonresonant nonlinear process under the circularly polarized excitation. A clear understanding of THz radiation mechanism of 2D materials will facilitate further design, optimization, and polarization control of integrable 2D THz optoelectronics.
关键词： THz radiation,monolayer WS2,in-plane nonlinear dipoles,optical rectification,elliptically polarized THz emission
更新于2025-09-23 15:23:52
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Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection
摘要： Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W?1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W?1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.
关键词： single-crystal core/shell,AlN,ZnO nanowires,ultraviolet emission,dual-color ultraviolet photodetection
更新于2025-09-23 15:23:52
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Nuclear Spin Singlet States in Photoactive Molecules: From Fluorescence/NMR Bimodality to a Bimolecular Spin Singlet State Switch
摘要： Nuclear spin singlet states are silent states in nuclear magnetic resonance (NMR). However, they can be probed indirectly and offer great potential for the development of contrast agents for magnetic resonance imaging (MRI). Here, we are introducing two novel concepts: Firstly, we investigate the bimodal NMR/fluorescence properties of 13C2-tetraphenylethylene. It possesses a long-lived singlet state in organic solvents, which shortens upon the addition of water. This simultaneously increases the fluorescence emission in a substantial enhancement of fluorescence. Secondly, we introduce a bimolecular singlet state switch based on 3-2H-coumarin containing an isolated proton. Upon UV-light exposure, a dimer forms leading to a coupling between two previously isolated protons. A nuclear spin singlet state can now be populated. Excitation with a wavelength of 254 nm results in partly cleavage of the molecule back into its monomer.
关键词： Photoswitches,NMR spectroscopy,Aggregation induced emission,Fluorescence,Nuclear spin singlet state
更新于2025-09-23 15:23:52
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Enhanced green photoluminescence of erbium doped Zn2SiO4 glass-ceramics as phosphor in optoelectronic devices
摘要： This paper reported the fabrication of Er3+-doped zinc silicate (Zn2SiO4:xEr3+) glass-ceramics using recycle waste glass bottles. The glass-ceramics samples were synthesized with different percentage doping of Er2O3 using conventional melting and quenching method. The structural of α-Zn2SiO4:Er3+ crystal phase and microstructure growth were analysed via X-ray diffraction and field emission scanning electron microscopy, respectively. Fourier transform infrared spectroscopy has confirmed the network structure of α-Zn2SiO4:Er3+ crystal phase. The three excited transition states from UV-visible absorption spectra were enhanced significantly at the states 4F7/2, 2H11/2, 4F9/2. The wide-ranging green emission at around 553-559 nm under excitation 385 nm from α-Zn2SiO4:Er3+ crystal exhibit the energy transition of Er3+ ions from 4S3/2 → 4I15/2. Such luminescence of α-Zn2SiO4:Er3+ based glass-ceramics are probably to have a huge prospective application for glass phosphor devices.
关键词： emission,phosphor,zinc silicate,waste glass,glass-ceramic
更新于2025-09-23 15:23:52
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The red persistent luminescence of (Sr,Ca)AlSiN3:Eu2+ and mechanism different to SrAl2O4:Eu2+,Dy3+
摘要： (Sr,Ca)AlSiN3:Eu2+ phosphors have been widely used in phosphor-converted white light emitting diodes. Herein, we reported the strong red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ under UV light excitation. The Sr0.8Ca0.2AlSiN3:0.15% Eu2+ shows the strongest red persistent luminescence with a peak emission wavelength at ~628 nm and a persistent time of ~9600 s at the 0.32 mcd/m2 threshold value. A new persistent luminescence mechanism, which is different to that of SrAl2O4:Eu2+,Dy3+, was proposed by comparing the thermoluminescence excitation spectrum (TLES) and the photoluminescence excitation spectrum (PLES) of Sr0.8Ca0.2AlSiN3:0.15% Eu2+. The electrons are directly excited from 4f ground states to the conduction band or from valence band to conduction band in (Sr,Ca)AlSiN3:Eu2+; while, in SrAl2O4:Eu2+,Dy3+, they are first excited to 5d level and then stimulated thermal process to the conduction band. The effect of Eu2+ concentration on red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ were discussed. The proposed mechanism of persistent luminescence can help us to design and find new persistent luminescence materials.
关键词： Persistent luminescence,SrAl2O4:Eu,Dy,Red emission,(Sr,Ca)AlSiN3:Eu,Persistent luminescence mechanism
更新于2025-09-23 15:23:52
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Direct patterned growth of intrinsic/doped vertical graphene nanosheets on stainless steel via heating solid precursor films for field emission application
摘要： Vertical graphene nanosheets (VGNs), normally consisting of one to several graphene layers vertically aligned on substrates, are promising in a variety of applications including field electron emitters, gas sensors and energy storage devices. Herein, we report a simple, green, easily scalable and cost-effective strategy of growing both intrinsic and nitrogen (N)-doped VGNs on stainless steel (SS) just by heating the solid thin layers of glucose and/or urea in a resistance-heating furnace. It is interesting that VGNs mainly grow on the roughened regions, which can be attributed to the more nucleation and catalyzing sites on such regions than smooth SS. Meanwhile, the N doping concentration can be adjusted by varying the urea addition. Field electron emission measurement indicates that the obtained N-doped VGNs exhibit excellent field emission with a relatively low turn-on electric field strength (~2.6 V μm?1 at the current density of 10 μA cm?2), large field enhancement factor (~9428) and high stability.
关键词： Green synthesis,Nitrogen doping,Vertical graphene nanosheets,Field electron emission,Direct patterned growth
更新于2025-09-23 15:23:52
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Light emitting self-healable hydrogel with bio-degradability prepared form pectin and Tetraphenylethylene bearing polymer
摘要： Self-healable hydrogel have wide applications in bioscience. In this research, self-healable hydrogel were prepared from TPE-[P(DMA-stat-DAA)]2 and acylhydrazide functionalized pectin. The TPE containing polymer endowed the hydrogel with light emission property while the pectin make the hydrogel biodegradable. Results showed that the pectin acylhydrazide can be prepared conveniently from pectin through hydrazinolysis. Light emissive hydrogels formed and self-healed without additional stimulus. More importantly, the hydrogel become light emitting with PL intensity higher than the polymer solution. The reason for this result is because the TPE units aggregated in the hydrophobic pectin ring and triggered AIE property. With biodegradable pectin, the hydrogel could be degraded naturally without worrying about the toxicity of the hydrogel in future bio-applications.
关键词： Self-healing,Hydrogel,TPE,Pectin,Light emission
更新于2025-09-23 15:23:52
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Catalytic Growth of 1D ZnO Nanoneedles on Glass Substrates Through Vapor Transport
摘要： In this study, one-dimensional (1D) zinc oxide (ZnO) nanoneedles are successfully fabricated on a Ag catalyst-coated glass substrate through simple physical vapor deposition via thermal evaporation of zinc (Zn) powder in the presence of oxygen (O2) gas at a low growth temperature of 450°C. The growth rate and diameter of ZnO nanoneedles increase as a function of varying silver (Ag) film thicknesses and argon (Ar) flow rates. Detailed structural investigations confirm that the synthesized nanoneedles have high crystallinity with a hexagonal wurtzite structure, and they preferentially grow along the c-axis orientation. This approach provides a simple and cost-effective method for the synthesis and controlled growth of 1D nanostructures, which can be useful in solid-state devices and various optoelectronic applications.
关键词： 1D ZnO,x-ray diffraction,UV emission enhancement,structural properties
更新于2025-09-23 15:23:52
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Facile fabrication of cross-linked fluorescent organic nanoparticles with aggregation-induced emission characteristic via the thiol-ene click reaction and their potential for biological imaging
摘要： Over the past several years, the biomedical applications of fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) feature have been extensively explored because the AIE-active FONs could effectively overcome the aggregation caused quenching (ACQ) effect of FONs based on conventional organic dyes. The development of novel methods for synthesis of AIE-active FONs plays a centre role for their biomedical applications. In this work, we reported a facile one-step thiol-ene click reaction for fabrication of AIE-active FONs through conjugation of acrylated PEG and AIE-active tetraphenylethylene (TPE) with two ene bonds using pentaerythritol tetra(3-mercaptopropionate) as the linkage. The successful synthesis of TPE containing AIE-active copolymers was evidenced by various characterization techniques. The particle size and fluorescence properties of the resultant TPE-S-PEG copolymers were evaluated by transmission electronic microscopy and fluorescence spectroscopy. Moreover, the cell viability and cell uptake behavior was also examined to evaluate their potential for biological imaging. We demonstrated that the cross-linked TPE-S-PEG show small size, high water dispersibility, low cytotoxicity and strong fluorescence for tracing. All of these advantages endow the TPE-S-PEG FONs great potential for biological imaging applications. Furthermore, this novel click reaction can take place under mild experimental conditions with high efficiency. It could be also further expanded for preparation of multifunctional AIE-active materials due to the universality of the thiol-ene click reaction and good precursor applicapability. Taken together, we have developed a novel and effective thiol-ene click reaction to fabricate the cross-linked AIE-active FONs, which display excellent physicochemical and biological properties and are promising for biomedical applications.
关键词： thiol-ene click reaction,Aggregation-induced emission,biomedical applications,fluorescent organic nanoparticles,cross-linked FONs
更新于2025-09-23 15:23:52