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A new FRET-based ratiometric fluorescence probe for hypochlorous acid and its imaging in living cells
摘要： A novel ratiometric fluorescence probe for hypochlorous acid was constructed by coumarin and pyridinium fluorophore based on the Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) platform. In this ICT/FRET system, the energy transfer efficiency is high to 94.3%. Moreover, the probe could respond to hypochlorous acid with high selectivity and sensitivity, and exhibited a large Stokes shift. It was interesting to find that the probe could recognize hypochlorous acid via a new mechanism, in which the a -position of carbonyl group was oxidized to form a diketone derivative. More importantly, the probe was successfully applied to the ratiometric imaging of both exogenous and endogenous hypochlorous acid in living RAW 264.7 cells, with low toxicity and high photo-stability.
关键词： New reaction mechanism,FRET,Hypochlorous acid,Fluorescence probe,Cell image,Ratiometric
更新于2025-11-21 11:08:12
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Dehydrogenation-driven to synthesize high-performance Lu2Si4N6C:Ce3+- a broad green-emitting phosphor for full-spectrum?lighting
摘要： Green phosphor Lu2Si4N6C:Ce3+ (LSNC:Ce3+) shows an ideal feasibility to the near ultraviolet LED (n-UV LED) for “Full-Spectrum Lighting” (FSL). However, it is complex to synthesize pure Lu2Si4N6C phase. Herein, we prepared LSNC:Ce3+ via a novel dehydrogenation-driven high temperature solid-state reaction method, which distinctly optimized the morphology, and then significantly enhanced the photoluminescent performance of LSNC:Ce3+. The improving mechanism ascribed to the stepwise dehydrogenation of LuH3 which was beneficial to further shear LuH3 particles. The LSNC:Ce3+ phosphor obtained by the optimized process exhibits excellent thermal stability, and its external quantum efficiency is 57.3 %. Interestingly, the intensities of excitation peaks decrease at 375 nm while it increases at 425 nm gradually with the Ce3+ concentration. It is reasonably ascribed to the different ability of photo-ionization in different 5d levels. Finally, the constructed w-LED with the titled phosphor exhibits a well-distributed warm white light with high color rendering index (Ra = 96.6, R9 = 96, R12 = 82). It indicates that the LSNC:Ce3+ gives assistance to compensation for the “spectrum chasm” in blue-green region, as well as contributes to the improvement of Ra and R9, that is beneficial for full-spectrum lighting.
关键词： Carbonitride,n-UV LED,Reaction mechanism,Full-Spectrum,Green phosphor Lu2Si4N6C:Ce3+
更新于2025-09-23 15:23:52
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Atomic layer deposition of cobalt(II) oxide thin films from Co(BTSA) <sub/>2</sub> (THF) and H <sub/>2</sub> O
摘要： In this work, we have studied the applicability of Co(BTSA)2(THF) [BTSA = bis(trimethylsilyl)amido] (THF = tetrahydrofuran) in atomic layer deposition (ALD) of cobalt oxide thin films. When adducted with THF, the resulting Co(BTSA)2(THF) showed good volatility and could be evaporated at 55 °C, which enabled film deposition in the temperature range of 75–250 °C. Water was used as the coreactant, which led to the formation of Co(II) oxide films. The saturative growth mode characteristic to ALD was confirmed with respect to both precursors at deposition temperatures of 100 and 200 °C. According to grazing incidence x-ray diffraction measurements, the films contain both cubic rock salt and hexagonal wurtzite phases of CoO. X-ray photoelectron spectroscopy measurements confirmed that the primary oxidation state of cobalt in the films is +2. The film composition was analyzed using time-of-flight elastic recoil detection analysis, which revealed the main impurities in the films to be H and Si. The Si impurities originate from the BTSA ligand and increased with increasing deposition temperature, which indicates that Co(BTSA)2(THF) is best suited for low-temperature deposition. To gain insight into the surface chemistry of the deposition process, an in situ reaction mechanism study was conducted using quadrupole mass spectroscopy and quartz crystal microbalance techniques. Based on the in situ experiments, it can be concluded that film growth occurs via a ligand exchange mechanism.
关键词： atomic layer deposition,reaction mechanism,thin films,Co(BTSA)2(THF),cobalt oxide,water
更新于2025-09-23 15:23:52
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Thermal atomic layer etching: Mechanism, materials and prospects
摘要： In the semiconductors and related industries, the fabrication of nanostructures and nanopatterns has become progressive demand for achieving near-atomic accuracy and selectivity in etching different materials, particularly in ultra-thin gate dielectrics and ultra-thin channels used in field-effect transistors and other nanodevices below 10 nm scale. Atomic layer etching (ALE) is a novel technique for removing thin layers of material using sequential and self-limiting reactions. Different from most ALE processes using plasma-enhanced or other energetic particles-enhanced surface reactions, thermal ALE realizes isotropic atomic-level etch control based on sequential thermal-drive reaction steps that are self-terminating and self-saturating. Thermal ALE can be viewed as the reverse of atomic layer deposition (ALD), both of which define the atomic layer removal and growth steps required for advanced semiconductor fabrication. In this review, we focus on the concept and basic characteristics of the thermal ALE in comparison with ALD. Several typical thermal ALE mechanisms including fluorination and ligand-exchange, conversion-etch, oxidation and fluorination reactions are intensively introduced. The pros and cons of thermal ALE, plasma ALE, and traditional plasma etching are compared. Some representative materials and their typical thermal ALE processes are summarized. Finally, the outlook and challenges of thermal ALE are addressed.
关键词： Thermal atomic layer etching,Reaction mechanism,Atomic-scale precision,Atomic layer deposition,Self-limiting
更新于2025-09-23 15:22:29
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Kinetic and Mechanistic Investigation of the Photocatalyzed Surface Reduction of 4-Nitrothiophenol Observed on a Silver Plasmonic Film via Surface-Enhanced Raman Scattering
摘要： Hot electrons generated by photo-induced plasmon decay from plasmonic metal surface can reduce 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP). Comparing to the reduction with a reducing agent such as sodium borohydride, Surface-Enhanced Raman scattering (SERS) measurements were performed here to elucidate the complex molecular mechanism of the reduction in presence of halide ions and hydrogen ions. The SERS measurements were performed using a simply prepared silver plasmonic film (AgPF), which enables monitoring of the reaction in different conditions at a solid-liquid surface, and eliminates the need for use of a reducing agent. As the concentration of H+ and Cl- could controlled, the observation of the reaction under a systematic set of condition was possible. Based on the kinetic traces of the intermediates, a reaction mechanism for the 4-NTP to 4-ATP reduction is suggested. Rate constants for the individual reactions are presented that fit the measured kinetic traces, and the role of hydrogen in each reaction step is characterized. This work provides clarification on the molecular transformation directly using protons as hydrogen source and demonstrates an effective method of applying a simple and low-cost silver surface catalyst for SERS studies. Moreover, the monitoring of Cl--concentration-dependent spectra gained insight into the hot-electron conversion process during the photoreduction and strongly support the formation of AgCl for activation of H+.
关键词： in-situ SERS spectra,kinetic rate constants,reaction mechanism,time-resolved measurements,selective surface photocatalytic reaction
更新于2025-09-23 15:19:57
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Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes
摘要： Infrared spectra of the matrix isolated Sn(η2-O2S), Sn(η2-OSO), Sn(η2-O2S)(η1-OSO), Sn(η2-O2S)2, OSn2(η2-SO) and Sn(μ2-O2)SnS molecules were observed following laser-ablated Sn atoms reactions with SO2 during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S18O2 and 34SO2 isotopic shifts, and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η2-O2S) and Sn(η2-O2S)(η1-OSO) to Sn(η2-OSO) and Sn(η2-O2S)2, respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn2(η2-SO) and Sn(μ2-O2)SnS. Bonding in these products is discussed, and the electronic structures change associated with different bonding types are revealed which is crucial for the observed photochemical reactions.
关键词： Quantum chemical calculation,Matrix-isolation,Reactive intermediate,Infrared spectra,Reaction mechanism
更新于2025-09-19 17:15:36
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Chloro- and Dichloro-methylsulfonyl Nitrenes: Spectroscopic Characterization, Photoisomerization, and Thermal Decomposition
摘要： Chloro- and dichloro-methylsulfonyl nitrenes, CH2ClS(O)2N and CHCl2S(O)2N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH2ClS(O)2N3 and CHCl2S(O)2N3, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N2 (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH2ClS(O)2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0.0026 cm?1) and CHCl2S(O)2N (|D/hc| = 1.56 cm?1 and |E/hc| = 0.0042 cm?1) has been confirmed. In addition, dichloromethylnitrene CHCl2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0 cm?1), formed from SO2-elimination in CHCl2S(O)2N, has also been identified for the first time. Upon UV light irradiation (365 nm), the two sulfonyl nitrenes R–S(O)2N (R = CH2Cl and CHCl2) undergo concomitant 1,2-R shift to N-sulfonlyamines R–NSO2 and 1,2-oxygen shift to S-nitroso compounds R–S(O)NO, respectively. The identification of these new species with IR spectroscopy is supported by 15N labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level. In contrast, the thermally-generated sulfonyl nitrenes CH2ClS(O)2N (600 K) and CHCl2S(O)2N (700 K) dissociate completely in the gas phase, and in both cases, HCN, SO2, HCl, HNSO, and CO form. Additionally, ClCN, OCCl2, HNSO2, ?NSO2, and the atmospherically relevant radical ?CHCl2 are also identified among the fragmentation products of CHCl2S(O)2N. The underlying mechanisms for the rearrangement and decomposition of CH2ClS(O)2N and CHCl2S(O)2N are discussed based on the experimentally-observed products and the calculated potential energy profile.
关键词： decomposition,nitrenes,azides,reaction mechanism,photoisomerization,matrix isolation
更新于2025-09-19 17:15:36
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Solar Light Induced Photon-Assisted Synthesis of TiO2 Supported Highly Dispersed Ru Nanoparticle Catalysts
摘要： Ru/TiO2 are promising heterogeneous catalysts in different key-reactions taking place in the catalytic conversion of biomass towards fuel additives, biofuels, or biochemicals. TiO2 supported highly dispersed nanometric-size metallic Ru catalysts were prepared at room temperature via a solar light induced photon-assisted one-step synthesis in liquid phase, far smaller Ru nanoparticles with sharper size distribution being synthesized when compared to the catalysts that were prepared by impregnation with thermal reduction in hydrogen. The underlying strategy is based on the redox photoactivity of the TiO2 semi-conductor support under solar light for allowing the reduction of metal ions pre-adsorbed at the host surface by photogenerated electrons from the conduction band of the semi-conductor in order to get a ?ne control in terms of size distribution and dispersion, with no need of chemical reductant, ?nal thermal treatment, or external hydrogen. Whether acetylacetonate or chloride was used as precursor, 0.6 nm sub-nanometric metallic Ru particles were synthesized on TiO2 with a sharp size distribution at a low loading of 0.5 wt.%. Using the chloride precursor was necessary for preparing Ru/TiO2 catalysts with a 0.8 nm sub-nanometric mean particle size at 5 wt.% loading, achieved in basic conditions for bene?tting from the enhanced adsorption between the positively-charged chloro-complexes and the negatively-charged TiO2 surface. Remarkably, within the 0.5–5 wt.% range, the Ru content had only a slight in?uence on the sub-nanometric particle size distribution, thanks to the implementation of suitable photo-assisted synthesis conditions. We demonstrated further that a ?ne control of the metal Ru nanoparticle size on the TiO2 support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.
关键词： highly dispersed Ru nanoparticle,sub-nanometric particle size distribution,catalyst preparation,reaction mechanism,Ru/TiO2 catalyst,photodeposition,photon-assisted synthesis
更新于2025-09-10 09:29:36
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Insight into photocatalytic activity, universality and mechanism of copper/chlorine surface dual-doped graphitic carbon nitride for degrading various organic pollutants in water
摘要： It is still a challenging work to realize the universality of photocatalytic materials for unselective removing various organic pollutants in water. Here a surface dual-doped Cu/Cl-g-C3N4 photocatalyst is firstly prepared, which exhibits much more superior photocatalytic performance for degrading multifarious persistent organic pollutants including tetracycline hydrochloride (TC-HCl), o-chlorophenol, bisphenol A and 2-mercaptobenzothiazole in water than pure g-C3N4. The high-efficiency and unselective photocatalytic degradation performance derives from the surface dual-doped effect of Cu/Cl elements on g-C3N4, which results in the extended visible light harvest range, elevated CB potential and improved the separation efficiency of charge carriers. The intermediate products, degradation pathway, degree of mineralization and reaction mechanism of representative TC-HCl pollutant over the surface dual-doped Cu/Cl-g-C3N4 photocatalyst are revealed in depth. This work makes an important development for treating the persistent organic pollutants in the water environments by exploiting new, low-cost and high-efficiency photocatalytic materials.
关键词： reaction mechanism,photocatalytic degradation,dual-doped Cu/Cl-g-C3N4,various organic pollutants,universality
更新于2025-09-10 09:29:36
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Insights on the photocatalytic degradation processes supported by TiO2/WO3 systems. The case of ethanol and tetracycline
摘要： TiO2/WO3 composites are widely in the literature as engineered systems for photocatalytic and (photo)electrochemical applications, since the presence of WO3 can promote both visible light absorption and electron transfer phenomena of TiO2. The preparation of these system, depending on the preparation method, can also affect the surface feature with respect to TiO2, modifying adsorption and performance, as well as the reaction mechanisms. Here, TiO2/WO3 composites were prepared by precipitation of WO3 onto the TiO2 surface and characterized in terms of their structural, morphological, optical and surface properties. Raman and IR spectroscopy as well as a marked shift in the isoelectric point support the preferential surface location of WO3. Samples were photocatalytically tested towards the degradation of ethanol and of tetracycline and the adsorption and degradation behaviour were studied, suggesting, in both cases, significant variations of the reaction paths by the addition of WO3.
关键词： Surface properties,Photocatalytic oxidation,Tungsten oxide,Intermediates,Reaction mechanism
更新于2025-09-10 09:29:36