Time‐resolved fluorescence kinetics and 1B1(1Δg) vibronic structure in tunable ultraviolet laser excited SO2 vapor

1974 ◽  
Vol 61 (1) ◽  
pp. 97-105 ◽  
Author(s):  
L. E. Brus ◽  
J. R. McDonald
Keyword(s):  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Kinetics ◽  
Vibronic Structure ◽  
Ultraviolet Laser

Excited state acid catalysis of the 2 + 2 photocycloaddition of methyl 2-naphthoate and acetylacetone; the interaction of a nonfluorescent exciplex with H2SO4

1994 ◽  
Vol 72 (9) ◽  
pp. 2011-2020 ◽  
Author(s):  
Yuan L. Chow ◽  
Carl I. Johansson
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Fluorescence Quenching ◽  
Analytical Method ◽  
Acid Catalysis ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Kinetics ◽  
Quenching Analysis ◽  
Potential Acid

In this paper, the striking acid catalysis of the photocycloaddition of methyl 2-naphthoate (2MN) to acetylacetone (AA) to give 1 and 2 was traced to the enhanced conversion of the nonemissive *(2MN–AA) exciplex to 1 and 2 by H2SO4. The partial reversibility of the exciplex in CH3CN and CH3OH was established by extended fluorescence-quenching analysis using oxygen to perturb the system, whereas time-resolved fluorescence kinetics failed to reveal the presence of this exciplex. A similar analytical method demonstrated the interaction of the nonfluorescent *(2MN–AA) exciplex and H2SO4 with the rate constants of kap = (2 ± 1) × 109 M−1 s−1 in CH3CN and (4 ± 1) × 109 M−1 s−1 in CH3OH. The quantum yield of photocycloadducts was significantly enhanced at high 2MN conversions owing to the retardation of the competing excimer *(2MN)2 formation. In the range of low conversion (< 15%) and [H2SO4] ≤ 1 mM, the quantum yield was shown to be proportional to H2SO4 concentration; the slope from such plots was analyzed to give kap values similar to those obtained from the extended fluorescence-quenching analysis. This agreement, along with the elimination of other potential acid catalytic routes, unambiguously proves that the acid catalysis originates from the interaction of the *(2MN–AA) exciplex with H2SO4.

Time-resolved fluorescence and proton NMR studies of tyrosine and tyrosine analogs: correlation of NMR-determined rotamer populations and fluorescence kinetics

Biochemistry ◽  
1986 ◽  
Vol 25 (3) ◽  
pp. 599-607 ◽  
Author(s):  
William R. Laws ◽  
J. B. Alexander Ross ◽  
Herman R. Wyssbrod ◽  
Joseph M. Beechem ◽  
Ludwig Brand ◽  
...  
Keyword(s):  
Proton Nmr ◽  
Time Resolved Fluorescence ◽  
Nmr Studies ◽  
Time Resolved ◽  
Fluorescence Kinetics

scholarly journals Picosecond Absorption Spectroscopy of Polymethine Cis-Trans Isomerization

1988 ◽  
Vol 8 (1) ◽  
pp. 39-47 ◽  
Author(s):  
K.-H. Feller ◽  
R. Gadonas ◽  
V. Krasauskas
Keyword(s):  
Quantum Yield ◽  
Absorption Spectra ◽  
Time Resolved Fluorescence ◽  
Absorption Region ◽  
Time Resolved ◽  
Fluorescence Kinetics ◽  
Double Exponential ◽  
A Minor ◽  
Cis Isomer ◽  
Polymethine Dye

Results are presented of time resolved fluorescence and absorption investigations of DDEOCI (3,3'-diethyl-6,6'-diphenyl-9-ethyl-oxacarbocyanine iodide) in solvents which differ in polarity and viscosity. The measured picosecond absorption and fluorescence kinetics probed at various wavelengths of the polymethine dye studied can be fitted to a double exponential decay with a minor fast component of lifetime τ1 and a major slower component of lifetime τ2. Furthermore, probing in the S1←S0 absorption region and in the fluorescence region results in a residual with a lifetime of some ns and belonging to the detected red-shifted photoisomer with a low quantum yield (φ < 10%). The lifetime and the preexponential factors of the two components are in methanolic solution uneffected by changes of the anion.The detected two picosecond lifetime components are supposed to belong to two isomeric species (all-trans and mono-cis isomer) with strongly overlapping absorption spectra.

scholarly journals The influence of sugar–protein complexes on the thermostability of C-reactive protein (CRP)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreea Lorena Mateescu ◽  
Nicolae-Bogdan Mincu ◽  
Silvana Vasilca ◽  
Roxana Apetrei ◽  
Diana Stan ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Protein Complexes ◽  
C Reactive Protein ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Reactive Protein ◽  
In Vitro Diagnostic ◽  
The Stability ◽  
Positive Controls

AbstractThe purpose of the present study was to evaluate de influence of protein–sugar complexation on the stability and functionality of C-reactive protein, after exposure to constant high temperatures, in order to develop highly stable positive controls for in-vitro diagnostic tests. C-reactive protein is a plasmatic protein used as a biomarker for the diagnosis of a series of health problems such as ulcerative colitis, cardiovascular diseases, metabolic syndrome, due to its essential role in the evolution of chronic inflammation. The sugar–protein interaction was investigated using steady state and time resolved fluorescence. The results revealed that there are more than two classes of tryptophan, with different degree of accessibility for the quencher molecule. Our study also revealed that sugar–protein complexes have superior thermostability, especially after gamma irradiation at 2 kGy, the protein being stable and functional even after 22 days exposure to 40 °C.

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