Journal of Fluorescence最新文献

In this paper, 1-phenyl-3-ferrocenylenone aminourea Schiff bases were synthesized by a novel method. A multifunctional molecular probe (Probe A) of 1-phenyl-3-ferrocenylenone, carbon-based solid acid, aminourea, and anhydrous ethanol was synthesized by adding them to a vessel at elevated temperatures and refluxing for the synthesis of a multifunctional molecular probe (Probe A) of 1-phenyl-3-ferrocenylenone aminourea Schiff base, and it was found that it recognizes tryptophan (Trp) in solution, and that the catalyst can be reused more than five times after recycling. This method is characterised by low cost, high efficiency, green environment and no waste acid. Fluorescence and UV spectra show that probe A specifically recognizes tryptophan (Trp) without interference by other amino acids or pH and time does not affect it within 45 min. The lowest limit of detection for Trp was 1.307 × 10^- 4 mol/L for probe A. The binding ratios of probe A to Trp were measured to be 1:1 by Job's plotting method, respectively. The complexation constant of probe A with Trp was found to be 2.733 × 10⁷ L/mol according to the Benesi-Hildebrand equation. The bonding mechanism was explored through IR spectroscopy and ¹H NMR titration.

Solubilization of the styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and its homodimers Dbt-5 and Dbt-10 in aqueous solution of sodium dodecyl sulfate and Triton X-100 has been studied by steady state and picosecond time-resolved fluorescence spectroscopy. At low concentration of sodium dodecyl sulfate in solution, between Sbt, Dbt-5 dyes molecules and surfactant ion pairs are formed followed by the formation non-luminescent H-aggregates. The nature of the interaction between molecules of dyes and surfactants has been revealed. The binding constants K_s of the dyes to the surfactants, free energy changes (ΔG₀), the number of dye molecules (n) included in a single micelle and photophysical parameters have been determined. The degree of solubilization of dyes in micellar solution of Triton X-100 is higher as compared to sodium dodecyl sulfate and depends on the molecular weight and size of both dye molecules and micelles.

The rotational dynamics of 3-(benzo[d]thiazol-2-yl)-7-(diethylamino)-2 H-chromen-2-one (3BT7D2H-one) in two non-polar solvents acetone and ethyl acetate have been studied with varying temperatures. The rotational dynamics follow follows the Stoke's-Einstein-Debye (SED) model in ethyl acetate solvent but shows deviation in acetone solvent when temperature is increased. Quasi-hydrodynamic models Gierer and Wirtz (GW) model and Dote-Kivelson Schwartz (DKS) is studied in a qualitatively way.

Rhodamine-imidazole hydrazones (RIH-1 & RIH-2) based chemosensors have been synthesized. These are characterised and evaluated by FT-IR spectroscopy, ¹H-NMR, ¹³C-NMR, LCMS, absorption and fluorescence spectroscopy. These chemosensors exhibit enhanced sensitivity and selectivity in detecting the biologically significant Fe³⁺ metal ion through both colorimetric and fluorescence changes. The optical properties have been investigated using binary acetonitrile-water (7:3 v/v) semi-aqueous solution. The probe RIH-1 can be deployed as a fluorescent and colorimetric probe for the detection of Fe³⁺ ion. It shows an absorption band at 559 nm and an intensity band at 579 nm increasing up to 50-fold with the increase in the concentration of Fe³⁺ with the detection limit as low as 11nM. In the visible light, RIH-1 helps in the detection of Fe³⁺ ion through the naked eye, while the addition of Fe³⁺ to the probe RIH-1 results in a colour change from colourless to pink. This is primarily due to the opening of the lactone ring in RIH-1. Notably, RIH-1 probe displays a high quantum yield of 0.51, after binding with Fe³⁺ ions. Indeed, it has been found that sensor RIH-1 is very effective in sensing Fe³⁺ ions through both fluorescence based and visual detection methods. Additionally, DFT studies of these chemosensors have been evaluated, TGA and DSC analysis showed good thermal stability.

Oxide matrix red-emitting phosphors are deemed as excellent color converters for white light emitting diodes (WLEDs) and laser diodes (LDs). Manganese-doped MgAl₂O₄ powder was synthesized by a solid-state reaction method at different sintering temperatures. Microstructure shows that grain size is mainly in the range of 0.2-5 μm, and grain agglomeration occurs with increased sintering temperature. XPS analysis indicates that the doped Mn ion exhibits a valence state of + 4 within the MgAl₂O₄ matrix. The diffraction peak of the phosphors is shifted by the sintering temperature, which affects lattice constant. Upon excitation by 300 nm ultraviolet light, the samples emit asymmetric broadband red light within the range of 620-720 nm, attributed to Mn⁴⁺ ion's transition from ²E_g to ⁴A_2g states. With the increasing temperature, the main emission peak shifts from 677 nm to 650 nm, ascribed to the change in energy level (²E_g) resulting from the reduction of Al₂O₃ phase. Crystal field theory confirmed that Mn⁴⁺ ions are within a strong crystal field environment created by MgAl₂O₄ matrix. By affecting particle size and crystallinity, the sintering temperature influences the fluorescence lifetime of the Mn⁴⁺ ion. Notably, these red-emitting phosphors exhibits remarkable thermal stability as their emission intensity remains approximately at 58% of initial intensity even at elevated temperature (435 K). Consequently, Mn⁴⁺: MgAl₂O₄ red-emitting phosphors with high thermal stability render them promising candidates for WLED applications.

The 5',5''-bis(4-carboxyphenyl)-[1,1':3',1'':3'',1'''-quaterphenyl]-4,4'''-dicarboxylic (H₄L1) ligand has a large conjugated rigid planar structure and good absorption of ultraviolet radiation, which can provide effective "antenna effect". However, rare earth complexes using H₄L1 as the sole ligand have not been reported. In this paper, rare earth Eu was combined with H₄L1 ligand to produce organic rare earth composite L1-Eu by solvothermal synthesis method. It was found through fluorescence spectroscopy that the emission of L1-Eu complex has a linear response to nitrobenzene compounds. The L1-Eu composite material has a low detection limit for nitrobenzene compounds, with detection limits of 0.910, 8.401, 24.510, and 8.171 µM for nitrobenzene, o-nitrophenol, m-nitrophenol, and p-nitrophenol, respectively. Further more the L1-Eu complex can sensitively respond to nitrobenzene compounds while resisting interference from common metal ions and organic solvents. In particular, L1-Eu composite material has good stability and recyclability. Therefore, L1-Eu composite material can serve as a fluorescent probe for specific detection of nitrobenzene compounds. We believe that the L1-Eu complex provides a new method for fluorescence detection of nitrobenzene compounds.

Accurate quantification of antibiotics in environmental samples is typically challenging due to the low antibiotic concentrations and the complexity of environmental matrices. This paper presents a fluorescence spectrometry method for determining oxytetracycline under alkaline conditions. The ionic distribution of the oxytetracycline solution was analyzed based on its dissociation constant. The dimethylamino group plays a crucial role in this method, as it promotes intramolecular charge transfer in the electronic excited state through its electron-donating capability with a lone electron pair. The presented method is straightforward, cost-effective, and holds potential for analyzing oxytetracycline in water sample after further investigation.

Using o-phenylenediamine as carbon source and phytic acid as phosphorus source, two P-rich carbon quantum dots RCDs and BCDs were synthesized successfully by changing the reaction temperature and time of hydrothermal method. It was found that RCDs with red emission could realize sensitive detection of 2-methylimidazole, and 2-methylimidazole had no obvious quenching effect on BCDs with blue emission, which made RCDs a sensitive, quick and selective fluorescence sensor for 2-methylimidazole detection. Under the optimal experimental conditions, the fluorescence intensity of RCDs decreased with the increasing of 2-methylimidazole concentration. The detection of 2-methylimidazole concentration by the carbon quantum dots sensor showed a good linear relationship in the range of 5 ~ 110 µM, and the low detection limit was 0.61 µM (S/N = 3). The sensor is able to detect 2-methylimidazole in lake water, enabling the application of real samples. The results show that this work provides a simple fluorescence method to detect 2-methylimidazole in water.

In recent years, perovskite quantum dots (PQDs) have successfully attracted widespread attention due to their excellent optical properties. However, the instability and toxicity problems of perovskite quantum dots are the main obstacles limiting their applications. In this work, bismuth-based perovskite quantum dots were synthesized by a ligand-assisted reprecipitation method, based on which a novel boric acid-functionalized bismuth-based non-toxic perovskite quantum dots fluorescent sensor (Cs₃Bi₂Br₉-APBA) that can be stabilized in the ethanol phase was prepared by a boron affinity technique. Based on the covalent binding interaction of Cs₃Bi₂Br₉-APBA with oxytetracycline (OTC), a highly selective and sensitive method for the detection of OTC was developed, which effectively solved the problems of poor stability and toxicity in the application of perovskite quantum dots. Under the optimal conditions, the fluorescence intensity of the synthesized Cs₃Bi₂Br₉-APBA was linear with the concentration range of 0.1 ∼ 18 µM OTC, and the detection limit could reach 0.0802 µM. The fluorescence detection mechanism was explored and analyzed by spectral overlap analysis, suppression efficiency study of observed and corrected fluorescence, and fluorescence lifetime decay curve fitting, the mechanism of OTC detection by Cs₃Bi₂Br₉-APBA was identified as the inner filter effect (IFE). In addition, the sensor successfully realized the quantitative detection of trace OTC in the environment, and our study provides a new idea for the preparation of green perovskite materials with high stability and selectivity.

In various fields, including analytical, environmental, and biochemistry, the detection of ions is significant. A simple probe, 3-(1-((4-aminophenyl)imino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (DPD), was designed for this study and used for the detection of Cu²⁺ ions in methanol, based on dehydroacetic acid and phenylenediamine moieties. Binding interactions studies were performed using UV-Vis measurements, which showed selective binding behaviour towards Cu²⁺ ions. The HRMS spectral data and Job's plot were used to check the stoichiometry ratio of 2:1 of a probe to Cu²⁺ ions. A detection limit of 1.38×10^-7 M for Cu²⁺ ions was observed. Theoretical DFT calculations were used to determine the quantum parameters and the energy gap between frontier molecular orbitals. Interestingly, the DPD-Cu²⁺ complex acted as a probe for the detection of SCN^- ions at a low LOD value, i.e., 1.97×10^-7 M. A novel incidence of reversibility with SCN^- ions was reported using the HRMS technique. Next, real water and blood samples were used, and the concentration of Cu²⁺ ions was calculated to further analyse the practical applicability of the probe. The DPD probe showed better selectivity and sensitivity than previously reported sensors, especially in complex matrices, where other sensors frequently experience interference and detection limit issues, indicating its potential as an advanced tool for ion detection in various applications.