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Tuning the Functional Groups on Carbon Nanodots and Antioxidant Studies
摘要： Carbon nanodots (CNDs) have shown good antioxidant capabilities by scavenging oxidant free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH?) and reactive oxygen species. While some studies suggest that the antioxidation activities associate to the proton donor role of surface active groups like carboxyl groups (–COOH), it is unclear how exactly the extent of oxidant scavenging potential and its related mechanisms are influenced by functional groups on CNDs’ surfaces. In this work, carboxyl and the amino functional groups on CNDs’ surfaces are modified to investigate the individual influence of intermolecular interactions with DPPH? free radical by UV-Vis spectroscopy and electrochemistry. The results suggest that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH?.
关键词： carbon nanodots,radical scavenging,electro-chemistry,functional groups,antioxidation,charge transfer
更新于2025-11-19 16:56:35
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Visible-light-triggered generation of persistent radical anions from perylenediimides: A substituent effect and potential application in photocatalytic reduction of Ag+
摘要： Three perylenediimide derivatives were reduced to their persistent radical anions in N-methyl-2-pyrrolidone (NMP) under ambient conditions by a visible light photoinduced electron transfer (PET). UV?vis and electron paramagnetic resonance (EPR) measurements were carried out to confirm the formation of radicals. The relationships between molecular structure, electrochemical property, phototransformation kinetics, and air stability of radical anions were investigated by the introduction of pyrimidine rings at the core position and fluoroalkylation substituents at the imide position. This study reveals that the electron-deficient pyrimidine rings and electron-withdrawing fluoroalkylation substituents can effectively enhance the phototransformation rate and the radical stability at ambient conditions. The effects of solvents and illuminance levels on the photoinduced reduction of perylenediimides were also studied. A photocatalytic reduction of Ag+ was successfully carried out using the perylenediimide with pyrimidine and fluoroalkylation substituents as catalyst upon irradiation with visible light.
关键词： Photocatalytic reduction,Perylene diimide derivative,Silver ion,Persistent radical anion,Visible light irradiation
更新于2025-11-14 17:03:37
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Photocatalytic Degradation of Methylene Blue over TiO2 Pretreated with Varying Concentrations of NaOH
摘要： In this paper, different NaOH concentrations (2, 5, 10, and 15 M) were used to treat {001}TiO2. The effect of NaOH on the crystal structure, morphology, optical properties, light raw electronic-hole recombination, and degradation performance of {001}TiO2 on methylene blue were studied. The results demonstrate that rutile TiO2 appeared when the NaOH concentration was as high as 10 M, showing much better photolytic performance than others. As the concentration of sodium hydroxide increases, the morphology changes accordingly. The specific surface area increases and the optical electronic-hole recombination rate decreases. Radical scavenging tests showed that hydroxyl radical and hole are very important in photocatalysis.
关键词： NaOH concentration,radical scavenging,{001}TiO2,methylene blue,photocatalysis
更新于2025-11-14 17:03:37
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Degradation of tetracycline by medium pressure UV-activated peroxymonosulfate process: Influencing factors, degradation pathways, and toxicity evaluation
摘要： This study employed the medium pressure UV/peroxymonosulfate (MPUV/PMS), a new sulfate radical-based advanced oxidation process, to eliminate tetracycline (TTC) in water. At pH = 3.7, initial TTC concentration of 11.25 μM, PMS dosage of 0.2 mM and UV dose of 250 mJ cm-2, 82 % of TTC was degraded by MPUV/PMS. The second-order reaction rate constants of TTC with SO4?- and ?OH were found to be 1.4 × 1010 M-1 s-1 and 6.0 × 109 M-1 s-1, respectively. Radical quenching experiments indicated that ?OH played the major role in the degradation of TTC. Higher PMS dosage (0.1 mM~1.0 mM) and higher pH (3~11) could accelerate the TTC removal. Besides, the presence of Cl- (0.1 mM~5.0 mM) and CO32- (0.05 mM~0.5 mM) could also promote the reaction. Eight transformation products (TPs) were identified, and the potential degradation pathways mainly involved hydroxylation, demethylation and decarbonylation processes. The variation in the genotoxicity was investigated using the umu-test, and the results indicate that the genotoxicity of TTC after the MPUV/PMS treatment significantly increased during the initial stage. In addition, the ecotoxicity and mutagenicity of TTC and its TPs were predicted using quantitative structure-activity relationship (QSAR) analysis, and the results revealed that some TPs could have equivalent and even higher toxicity than TTC. MPUV/PMS showed better performance in TTC degradation in real waters than in Milli-Q water. MPUV/PMS is concluded to be an efficient method for removing TTC, but more attention should be paid to the changes of toxicity during this process.
关键词： Tetracycline,Toxicity,Hydroxyl radical,Sulfate radical,Transformation products
更新于2025-09-23 15:23:52
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Anthracene-Attached Persistent Tricyclic Aromatic Hydrocarbon Radicals
摘要： Anthracene-attached tricyclic aromatic hydrocarbon radicals having different central polygons, Ant-5, Ant-6, and Ant-7, were synthesized to evaluate the role of an anthracene substituent group in the stability and reactivity of tricyclic aromatic hydrocarbon radicals. The bulky anthryl group effectively protects a carbon atom with high spin density, resulting in high persistence of the radicals. On the other hand, the combination of the anthryl group and the tricyclic aromatic scaffold makes the molecular structure drastically change from a twisted form to a folded form and an unpaired electron moves into the anthryl moiety, eventually affording a tail-to-tail σ-dimer.
关键词： anthracene,mechanochlomism,persistent radical,dimerization,hydrocarbon radical
更新于2025-09-23 15:23:52
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Mass Spectrometric Imaging Reveals Photocatalytic Degradation Intermediates of Aromatic Organochlorines Resulting from Interfacial Photoelectron Transfer and Hydroxyl Radical Abstraction on Semiconductor Nanoparticles
摘要： Organochlorines are highly persistent and toxic contaminants that are widely distributed and accumulated in various aquatic or soil environments as well as food chains. Heterogeneous photocatalytic degradation of such pollutants by using semiconductor nanoparticles has been recognized as one of the effective purification ways. Understanding of degradation mechanisms and designing of highly efficient semiconductor nanoparticles require structural identification of various degradation intermediates that are difficult to achieve with current spectroscopic techniques. Herein a mass spectrometric approach was developed to tackle interfacial photoelectron transfer and hydroxyl radical abstraction on different semiconductor nanoparticles. Chlorobenzenes (including hexachlorobenzene and chlorothalonil) adsorbed on the surfaces of nanoparticles were found to instantly undergo dechlorination and ring dissociation through photoelectron capture dissociation and abstraction of a chlorine atom from aromatic C-Cl bond by hydroxyl radicals. Different intermediates have been unambiguously identified with experimental evidences provided by a Q-TOF mass spectrometer. It has been demonstrated that both electron density around atoms and steric effects of side chains contribute to the site selectivity for photoelectron capture and hydroxyl radical abstraction. But the energies needed for chemical bond cleavages and the stabilization of acquired charges play important roles in degradation efficiency. By using mass spectrometric imaging, photocatalytic differences of different semiconductor nanoparticles have been revealed.
关键词： Photoelectron Capture Dissociation,Interfacial Photoelectron Transfer,Chlorobenzenes,Mass Spectrometry,Hydroxyl Radical
更新于2025-09-23 15:23:52
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The efficiency and mechanism in a novel electro-Fenton process assisted by anodic photocatalysis on advanced treatment of coal gasification wastewater
摘要： A novel dual-chamber photo-electrochemical oxidation system with Fe@Fe2O3/CF cathode was constructed by combining cathodic electro-Fenton and anodic photocatalysis for advanced treatment of biologically pretreated coal gasification wastewater (CGW). In the electro-Fenton cathode chamber, maximal chemical oxygen demand (COD) removal efficiency of 84.2% was arrived within 120 min at current density 10 mA/cm2, initial pH 3 and air flow rate 0.4 L/min for its initial concentration of 200 mg/L. Correspondingly, the effluent concentration of COD, BOD5, TOC and total phenols were 31.5, 3.9, 8.4 and 13.8 mg/L respectively, satisfying the stringent wastewater discharge standard. Moreover, the H2O2 concentration change and wastewater acute toxicity were analyzed. Furthermore, a reasonable degradation mechanism was proposed based on the contribution of hydroxyl radicals (%OH), and thus degradation pathway of phenol as typical pollutant was also speculated. The integrated system is confirmed to be high-effective and stable, and thus it is a potentially promising alternative for treatment toxic refractory industrial wastewater.
关键词： COD removal,Hydroxyl radical,Electro-Fenton,Fe@Fe2O3/CF,Coal gasification wastewater
更新于2025-09-23 15:23:52
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[Zn(OOCH)2(4,4′-bipyridine)] : A metal-organic-framework (MOF) with x-ray-induced photochromic behaviour at room temperature
摘要： Materials that may show photochromism under X-rays have higher spatial resolution for visual low-energy X-rays detection over the commercial instruments and greater X-ray sensitivity than silver salt-based radiographic films. In this work, we discovered that the known MOF, [Zn(OOCH)2(Bpy)]n (Bpy = 4,4′-bipyridine), showed rare photochromic behaviour upon irradiation of hard and soft X-rays at room temperature.
关键词： Metalloviologen,MOF,Photochromic,Radical,X-ray detection,Electron transfer
更新于2025-09-23 15:23:52
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Multi-arm polymers prepared by atom transfer radical polymerization (ATRP) and their electrospun films as oxygen sensors and pressure sensitive paints
摘要： New oxygen and pressure sensitive paints (PSPs) with four-arm polymeric structures were prepared by using a kind of controlled living polymerizations - atom transfer radical polymerization (ATRP). The polymers composing of poly(isobutyl methacrylate)-co-poly(trifluoroethyl methacrylate)s (PolyIBMA-co-PolyTFEM)s act as the matrices for the platinum porphyrin-based phosphorescence probes, which were copolymerized in the matrices. The polymers were characterized by using 1H-NMR, 19F-NMR, and GPC to demonstrate their successful preparation. The influence of polymer structures on sensing activity including the sensitivity and response time to oxygen and/or pressure was investigated. Results showed that copolymers with suitable compositions (herein P3) can have highest sensitivity. Polymer structure's influence on response time to oxygen was also investigated. For increasing the polymer's surface area for further improving sensing sensitivity, electrospinning method was used for preparing films with micro-spherical or fibrous structures. The morphologies of electrospinning coated films were observed by SEM. Results showed that electrospinning coated films can respond much better to oxygen and pressure than their corresponding sprayed plates. This is the first time to apply the controlled living polymerization approach to prepare PSPs with multi-arm structures, which will broaden the PSP functional materials' design strategy.
关键词： oxygen sensing,pressure sensitive paints,electrospinning,multi-arm polymers,atom transfer radical polymerization
更新于2025-09-23 15:23:52
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UV light irradiated trifluoromethylation of diheteroaryl disulfides with CF3SO2Na
摘要： A simple protocol for the UV light irradiated preparation of heteroaryl trifluoromethyl thioethers from disulfides and inexpensive, environmentally sodium triflinate (CF3SO2Na) is been developed. The features of simple and clean reaction conditions, in moderate to good yields, and broad substrate scope render this new approach synthetically attractive for the preparation of potentially pharmaceutically active compounds.
关键词： trifluoromethylation,heterocycle,disulfides,ketones,radical reactions
更新于2025-09-23 15:23:52