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Fluorescence quenching

Tìm thấy 13+ kết quả cho từ khóa "Fluorescence quenching"

Exploring inhibition of chemiluminescence mechanisms with fluorescence quenching studies and interaction energy calculations

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Exploring inhibition of chemiluminescence mechanisms with fluorescence quenching studies and interaction energy calculations. The capacity to inhibit the CL of three carbamates is in the order of carbaryl (CBL) >carbofuran (CBF). Mechanisms of carbamates inhibiting SCC-luminol-H 2 O 2 CL are investigated using fluorescence quenching and quantum chemistry simulations for the first time in this work.

A rapid and sensitive spectrofluorometric method for the determination of Au(III) based on fluorescence quenching of a 1,3,5-triphenyl-2-pyrazoline

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Au(III) caused a significant decrease in fluorescence response of the ligand at 464 nm.. Spectrofluorometric titrations were carried out between the ligand and Au(III) to examine the fluorescence quenching based on Au(III) ions (Figure 2).. Fluorescence Intensity. Inset: The fluorescence intensity changes of ligand during the addition of µg L − 1 Au (III).

Highly sensitive fluorometric method based on nitrogen-doped carbon dot clusters for tartrazine determination in cookies samples

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Figure 5 shows the changes in the fluorescence spectra of the CDs with the food dyes, all of which caused fluorescence quenching in the spectra. The quenching mechanism of the CDs with tartrazine was investigated using Stern–Volmer analysis (Figure S5). The results are given in the Supplemental information.. Effect of the food dyes on the fluorescence spectra of the CDs. Figure 6 shows the change in the fluorescence spectra of the CDs with increasing tartrazine concentration..

Investigation of the photophysical and photochemical behavior of substituted zinc phthalocyanines and their water-soluble quaternized derivatives

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Fluorescence emission spectral changes of M) during fluorescence quenching studies in DMSO.. (Inset: Stern–Volmer plots for BQ quenching of 7 in DMSO).. The K SV and biomolecular quenching constant (K q ) values of the ZnPcs (6–9) are listed in Table 3.. The K SV values of the tetrasubstituted ZnPc complexes (6–9) are lower than those of unsubstituted ZnPc..

Synthesis and spectral and thermal characterization of new metal-free and metallophthalocyanines: investigation of their photophysical, photochemical, and thin film properties

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For metal-free (2) and zinc (3) phthalocyanines, photochemical (photodegradation and singlet oxygen quantum yields) and photophysical (fluorescence quantum yields and fluorescence lifetimes) properties were analyzed in dimethylsulfoxide (DMSO). The metal-free (2) and zinc (3) phthalocyanines’ fluorescence quenching behaviors were also investigated. The new phthalocyanine compounds’ fluorescence emissions were effectively quenched by 1,4-benzoquinone in DMSO.

Microwave-assisted synthesis of novel nonperipherally substituted metallophthalocyanines bearing (7-(trifluoromethyl)quinolin-4-yl)oxy groups

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Furthermore, the fluorescence quenching of the zinc Pc (2) in DMF solution using benzoquinone (BQ) as a quencher is reported.. The synthetic route is shown in the Scheme..

Naked eye and smartphone applicable detection of toxic mercury ions using fluorescent carbon nanodots

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Studies with the real samples: a) fluorescence response of NC-DotsCHIT to the water samples contaminated with changing amounts of Hg(II) aq. and b) digital images showing the fluorescence quenching of test strips before and after the addition of water samples containing 43.5 µg/mL Hg(II) aq.

Highly luminescent water-dispersed silicon quantum dots for fluorometric determination of oxytetracycline in milk samples

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Besides, when a different excitation wavelength as 425 nm was chosen, where absorption of OTC was negligible, there was no quenching observed. As a result, the fluorescence quenching of OTC on SiQDs was caused by the inner filter effect. Therefore, the fluorescence emission intensity decreased with the increasing of the concentration of OTC (Figure 3), providing the detection of OTC was realized.. K SV is the Stern–Volmer quenching constant and [Q] is the concentration of the quencher.

Fluorescent sensing platform for low-cost detection of Cu2+ by coumarin derivative: DFT calculation and practical application in herbal and black tea samples

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The increase in the stability indicates that the route of the reaction tends to the formation of MCPC-Cu 2+ complex, and therefore the fluorescence quenching occurs.. Fluorometric sensing and ICP-OES analysis of the tea samples. To assess the potential usage of probe MCPC for practical applications, Cu 2+ levels were measured in various herbal tea samples, as well as black tea samples (Table 2).

Synthesis, characterization, and luminescence of zinc(II) and cadmium(II) coordination complexes: [Zn(phen)2(CH3COO)](ClO4), [Zn(bpy)2(ClO4)](ClO4), and [Cd(phen)2(NO3)2]

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to fluorescence quenching of the carboxyl group of CH 3 COO − (a strong electron-withdrawing group)..

Application of structural, functional, fluorescent, and cytometric indicators for assessing physiological state of marine diatoms under different light growth conditions

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According to (Konyukhov, 2009), the decrease in the quantum efficiency is due to a decrease in the number of PS II reaction centers, as well as an increase in the nonphotochemical fluorescence quenching.. Changes in the functioning of microorganisms’. intracellular esterases are widely applied as indicators of the physiological state of the studied object (Dorsey et al., 1989).

Introduction to Modern Liquid Chromatography, Third Edition part 22

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Figure 4.15 Fluorescence quenching of naphthalene by dissolved oxygen in the mobile phase.. Mobile phase sparged with helium (He) or air, as shown. As with other fluorescence techniques, fluorescence detection can be compromised by background fluorescence of the mobile phase or sample matrix, and by quenching effects. An example of fluorescence quenching is shown in Figure 4.15 [25].

Preconcentration of rifampicin prior to its efficient spectroscopic determination in the wastewater samples based on a nonionic surfactant

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Determination of rifampicin based on fluorescence quenching of GSH capped CdTe/ZnS QDs.. doi: 10.1016/j.jlumin . Journal of Pharmaceutical and Biomedical Analysis 1999. doi:10.1016/. HPLC determination of rifampicin and related compounds in pharmaceuticals using monolithic column. Determination of rifampicin in human plasma and blood spots by high performance liquid chromatography with UV detection: a potential method for therapeutic drug monitoring.

Fluorescence quenching study of moxifloxacin interaction with calf thymus DNA

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[Q ] represents the concentration of the quencher, K sv is the quenching constant of the reaction, τ 0 is the fluorescence lifetime without quencher, the average life of fluorescence molecule is 10 − 8 s, 15 and K q is the bimolecular quenching rate constant.. Figure 2 shows the characteristic changes in fluorescence emission spectra during the interaction of MOX with ct-DNA. The concentration of MOX (0.5 µ M) was fixed and the concentration of ct-DNA was varied in assay solutions.

Synthesis, characterization, and photophysical and photochemical properties of 3-(4-phenyloxy)coumarin containing metallo- and metal-free phthalocyanines

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Fluorescence quenching experiments on the substituted zinc, indium, and metal-free phthalocyanine complexes (2a/3a, 2c/3c, and 2d/3d) were carried out by the addition of different concentrations of BQ to a fixed concentration of the complexes (2a/3a, 2c/3c, and 2d/3d) as reported in the literature.

Principles of Fluorescence Spectroscopy

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Derivation of the Equations for Phase- Modulation Fluorescence. Relationship of the Lifetime to the Phase Angle and Modulation. Derivation of the Lippert Equation. Application of the Lippert Equation. Derivation of the Stern-Volmer Equation. Interpretation of the Bimolecular Quenching Constant. Derivation of the Quenching Sphere of Action. Quenching of the Multiple Decay Times of Proteins. Quenching-Resolved Emission Spectra of the E. Origin of the Definitions of Polarization and Anisotropy.

3-Hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-one and 3-hydroxy-6H-benzo[c] chromen-6-one act as on-off selective fluorescent sensors for Iron (III) under in vitro and ex vivo conditions

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Accordingly, it was observed that through the addition of various concentrations of iron (III), the intensity of fluorescence peak at 420nm for URO-B, and 460nm for THU-OH decreased in a proportional way. At 2.7mM of iron (III) concentration, the fluorescence was found almost totally quenched for THU-OH. On the other hand, 0.5mM concentration of Iron (III) made a total quenching of the fluorescence of URO- B.

Photochromic and fluorescence properties of coumarin fulgimides

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Photochromic reaction changes the energy of the singlet excited state of the fulgimide moiety so that it will control the quenching of the fluorescence of coumarin moiety (Figure 1).. To achieve it, the anhydride moiety of fulgides 1E–4E were converted to their fulgimides 5E–8E by the dehydrative condensation of highly florescent 6-aminocoumarin (Figure 2).

Fluorescent mono- and tetra-dansylated cavitands: synthesis and acid sensitivity

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Fluorescence emission spectra of cavitand 3 (A) and 5 (B), and reference compound 6 (C) with perchloric acid titration. L −1 , (perchloric acid. where I 0 and I are the fluorescence intensities of fluorophore in the absence and presence of quencher, respec- tively. Figures 6A and 6B show the quenching of cavitand 3 and cavitand 5 with perchloric acid in acetonitrile..

Synthesis of acetamide derivatives of 1,2,4-triazole bearing azinane and their binding interactions with bovine serum albumin using spectroscopic techniques

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Results of the fluorescence studies showed that the triazole derivatives were able to interact with BSA, causing a static quenching of the fluorescence intensity of BSA in a similar way to that of the well-known drugs warfarin and ibuprofen. The presence and position of different substituents on the triazole ring was found to affect the binding affinity of the synthesized compounds for BSA.