Fluorescence yields of aromatic compounds

Abstract

Values of fluorescence yields for 18 compounds in solution at 23°are reported and they are compared with previous literature values. Modifications of the technique of Weber and Teale for measurement of fluorescence yields are described. Fluorescein in 0.1 N NaOH and anthracene in ethanol are the best fluorescence standards on the basis of agreement of fluorescence yields with other work. The use of quinine as a fluorescence standard is complicated by variation of its fluorescence yield with H2SO4 concentration and the excitation wavelength. Several other compounds, including chrysene, show no variation of fluorescence yield with a change of excitation wavelength. Radiative lifetimes estimated from integrated absorption spectra are found to be consistently shorter than the radiative lifetimes estimated from fluorescence yields and lifetimes. The fluorescence yields of pyrene-dw and anthracene-dm in ethanol are significantly lower than those of corresponding solutions of pyrene-and anthracene-, respectively. No significant effect of compound deuteration upon the fluorescence yields of seven other compounds is found.

Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation

“…The yield of quininesulfate in 0.1 N H2SO4 was also measured, to check the sensitivity and exactness of the evaluation method. The obtained value of 0.52 is in good accordance with the value discussed in literature [4,17], Each value of rjF in Table 2 was repeatedly reproduced within an accuracy of 1 to 3% according to the excitation wavelength. New dye solutions were prepared for each set of experiments.…”

Fluorescence characteristic and molecular interaction in the excited state of 1,2,3,4-tetrahydroquinoline

“…The fluorescence and excitation spectra were recorded with a Perkin-Elmer model MPF 44A fluorescence spectrophotometer provided with corrected spectra unit and the absorption spectra with a Shimadzu UV-VIS spectrophotometer model 2 10A. The fluorescence quantum yield of THQ in CH was measured from the corrected area under fluorescence curve relative to that of phenanthrene (26) in identical condition and the fluorescence life time T was determined therefrom (27).…”

Metal compounds with rigid polyaromatic ligands. Catalytic consequences

“…( [1][2][3] Although the preparation of a supramolecular catalyst must incorporate a large degree of design, noncovalent forces are difficult to predict, and therefore the 'a priori' chances to prepare a catalyst with assembling properties are still very low, thus most of the supramolecular effects in catalysis are recognized 'post-factum'. Once the 'supramolecular catalyst' has been prepared, the challenge is to determine whether the catalytic activity of the catalyst is influenced by non-covalent assembling properties, for which well-chosen control experiments are required to determine both, the nature of the non-covalent interaction and their direct involvement in the rate and selectivity-determining steps of the catalytic reaction.…”

“…1 Free NHC ligands are often more sensitive to air and moisture than their corresponding metal complexes, which have proved to be remarkably resistant to oxidation. The first NHC complexes were described by Öfele and Wanzlick in 1968; 2,3 and Herrmann described the first catalytic application of NHC complexes in 1995.…”

“…The first NHC complexes were described by Öfele and Wanzlick in 1968; 2,3 and Herrmann described the first catalytic application of NHC complexes in 1995. 4 Ever since, NHCs have been widely studied from any possible point of view, including their preparation, [5][6][7][8] stability, 9 stereoelectronic properties, [10][11][12] coordination strategies, 8,13,14 and use in homogeneous 15 and asymmetric catalysis, 16,17 and some books 1,[18][19][20] have been entirely devoted to the chemistry of this type of ligands.…”