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A fluorescence method of detecting sulfur dioxide derivatives
摘要： A fluorescence spectrometry method is proposed to detect SO3 2? and α, β-unsaturated compounds, exhibiting remarkable blue-shift the maximum emission wavelength (from 650 nm to 555 nm). Preliminary experiments are conducted and results show that the method exhibits high selectivity and sensitivity toward sulfite over other common anions. The fluorescence intensity ratio at 555 nm and 650 nm (I555/I650) has a good linearly with sulfite concentration ranging from 0.5 to 15 μM with a detection limit of 0.28 μM. These results provide theoretical fundamentals for sulfite detection in practical water samples.
关键词： sulfur dioxide derivatives,sulfite detection,fluorescence method,nucleophilic addition reaction
更新于2025-09-23 15:21:01
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Synergistic effect of fluorescence recovery and enhancement on ultrasensitive visual assay of cyanide anions based on N-Acetyl-L-Cysteine-Capped CdTe quantum dots and carbon dots
摘要： Developing a reliable fluorescent nanosensor for cyanide anions (CN?), with the potential to enable visual discrimination by naked eye, is highly sought after yet is limited by low sensitivity and selectivity. Herein based on the synergistic effect of fluorescence recovery and enhancement, a specific dual-emission nano-system was designed for ultrasensitive detection of CN?, by employing carbon dots (peaking at 443 nm) as a reference and N-acetyl-L-cysteine (NALC)-capped CdTe quantum dots (QDs, peaking at 611 nm) as a reporter. The red fluorescence of CdTe QDs is first quenched by Cu2+ primarily with electron transfer. Upon addition of CN?, coordinates with Cu2+ to form [Cu(CN)n](n?1)? complex, causing the Cu2+ to detach from the QDs, and consequently fluorescence recovery. More importantly, the CN? can undergo a nucleophilic addition reaction with the carbonyl group of NALC ligands, inducing 1.3-fold fluorescence enhancement towards the original QDs while the blue fluorescence of carbon dots remains constant. This results the fluorescence intensity ratios (I611/I443) are proportional to the concentrations of CN? in the ranges of 0.02―10 and 15―80 μM, and an ultra-low detection limit down to 10.35 nM is achieved. By using both Cu2+-promoted complexation and addition reaction as recognition units, the present method also showed excellent selectivity for CN? over other coexisting anions. Especially, we have already demonstrated, by spiked tests, the practicability of monitoring the concentration changes of CN? in both environmental water and cassava samples, and further realized visual monitoring of CN? changes in aqueous solution and test paper.
关键词： Ratiometric detection,Visual identification,Nucleophilic addition,Quantum dots,Turn-on,Cyanide anions
更新于2025-09-16 10:30:52
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Reversible chemical reactivity of non-fullerene acceptors for organic solar cells under acidic and basic environment
摘要： Chemical stability of non-fullerene acceptors under acidic and basic environment is important because the printable electrodes and interfacial layers are typically acidic (such as PEDOT:PSS) or basic (such as PEI, or amine-stabilized ZnO nanoparticles). In this work, we report reversible chemical reaction of non-fullerene acceptors (ITIC-family) under acidic and basic environment. OH- anions react as a nucleophile with C=C linkage of the donor and acceptor moieties of ITIC, resulting in a product of ITIC-OH. The reaction breaks the intramolecular charge transfer and destroys the photovoltaic performance. Furthermore, the ITIC-OH can be converted back to ITIC after adding H+. Thus, the non-fullerene acceptors are stable in acidic environment, but not in basic environment. This finding provides guide for the design of interfaces for efficient and stable non-fullerene organic solar cells.
关键词： nucleophilic addition reaction,stability,acidic and basic environments,non-fullerene acceptors,organic solar cells
更新于2025-09-11 14:15:04
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Novel asymmetrical phenothiazine for fluorescent detection of cyanide anions
摘要： Novel asymmetrical phenothiazine (PTZ) bearing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)-malononitrile (OIM) moiety as the cyanide receptor was synthesized. The sensor fluorophore displayed an intramolecular charge transfer (ICT) electronic absorption peak at 500 nm and fluorescence peak at 576 nm in CH3CN:H2O (90:10) solution. When running a titration of the prepared phenothiazine fluorophore with a range of concentrations of cyanide, the electronic absorption and fluorescence peaks diminish in a ratio-metric mode. This can be attributed to the nucleophilic Michael-attack of cyanide anion at the α-position of the oxoindenylidenemalononitrile vinyl moiety of the fluorophore. This results in switching such electron acceptor to anionic electron donor and thus breaking the conjugated molecular system, which eventually influence the ICT and the emission peak position of the fluorophore. It was found that the fluorescent sensor displayed high sensitivity with a rapid responding time as low as than 50 second. A high selectivity was also detected toward cyanide ion at a recognition limit as low as 3.2 × 10?9 mol L-1.
关键词： Cyanide,Fluorescence,Phenothiazine,Nucleophilic addition,Knoevenagel condensation
更新于2025-09-10 09:29:36