Fluorescence spectra of pyrene

Figure 5. Fluorescence spectra of pyrene tagged novolac and free pyrene butyric acid (PBA) in diglyme. Spectra are labeled with percent of monomer units tagged. The pyrene concentration in solution is 1 x 10 bM, except in the inset where different pyrene concentrations are compared along with the spectra of a film containing the tagged polymer.

Fig. 7.8. Fluorescence spectra of pyrene in hexane, n-butanol, methanol and acetonitrile showing the polarity dependence of vibronic band intensities (excitation wavelength 310 nm) (reproduced with permission from Kalyanasun-daran and Thomas, 1977b).

Figure 8.3. Concentration effect on the fluorescence spectra of pyrene on silica gel (l) c = 0.5 mol g 1, (2) c = 3 /tmol g-1. Aft = monomer, M - aggregate fluorescence. = 340 nm (close to the absorption maximum of M ).

Fluorescence spectra of pyrene were employed in order to see the polarity of the environment given by the molecular assemblies mentioned so far. The III/I ratio of vibronic spectra of pyrene, a good measure of microenvironmental polarity(194.2Q). is plotted for the DODACl systems as a function of MEGA-n concentrations in Figure 11. 

FIGURE 10.8 UV absorption and fluorescence spectra of pyrene in cyclohexane (adapted from Karcher et al., 1985). 

Figure 13.10 Fluorescence spectra of pyrene in n-heptane at 20°C (a) 5 x 10 s mol/ liter (b) 1.8 x 10-4 mol/liter (c) 3.1 x 10-4 mol/liter (d) 7.0 x 10-3 mol/liter. From T. Forster, Angeui. Chem. Int. Ed., 8, 333 (1969). Reproduced by permission of Verlag Chemie, GmbH.

Pyrene is a frequently used probe in photophysical studies of solid state surfaces. A report on the time resolved fluorescence spectra of pyrene adsorbed on calcinated Vycor glass surfaces is one such study. Quenching of pyrene fluorescence by O2, CHjNOj, and nitropropionic acid has been used to distinguish... 

Figure 2.22 Left fluorescence spectra of pyrene in cyclohexane. Intensities are normalized to a common value of < f. A, 10-2m B, 7.75 x 10-3m C, 5.5 x 10-3m D, 3.25 x 10-3m E, 10-3m G, 10-4m. Reproduced by permission from ref. 109. Copyright 1970, John Wiley Sons, Ltd. Right potential energy surfaces for excimer formation />... P represents the distance between two pyrene molecules. The vibrational levels shown for the monomers at large separation refer to degrees of freedom other than rP... P...

Figure 2. Fluorescence spectra of pyrene-appended y-CD (6-deoxy-6-amino-[4-(pyrenyl)butanoyl]-y-CD) at different /-bomeol concentrations in 10% DMSO aqueous solution (Adapt from lef. 5).

Figure 5 Shpol skii fluorescence spectra of pyrene in crude bird extract, />octane at 28 K laser excitation 372.10 nm. Upper spectrum without time resolution. Lower spectrum with lime-resolved detection delay=50ns.

Rgure 2 Site-specific, laser-induced fluorescence spectra of pyrene, 4-melhylpyrene (4-MP), B[a]P, and B[fc]F present in a solvent-retained coal liquid (SRC-11) sample measured in a frozen n-octane solution at 15 K. The excitation wavelengths for the PAHs are given. (Reprinted with permission from Yang Y, O Silva AP, Fassel VA, and lies M (1980) Direct determination of poiy-nuclear aromatic hydrocarbons in coai iiquids and shaie oii by laser exited Shpol skii spectrometry, Analytical Chemistry 52 1350-1351 American Chemical Society.)... 

Pulmonary surfactant protein C (SP-C) is a small hydrophobic peptide. The effect of acylation of SP-C on its structure and function was reported by Haagsman et al. [146] using the Whilelmy plate method and CD spectra measurement. Also, SP-C-induced bilayer interaction was studied via the lipid mixing method by the use of fluorescence spectra of pyrene-PC labeled vesi-... 

From the above-mentioned aromatic hydrocarbons, pyrene is for sure the most widespread excimer forming fluorescent probe. The fluorescence spectra of pyrene are known to display the characteristic vibronically resolved pyrene band with a maximum at 375 nm, together with a stractureless long-wavelength band (ca. 480 nm). Typically, only at concentrations of pyrene above ca. 10 mol dm , intermolecular excimer formation is clearly observed. For intramolecular excimer formation (concentration independent kinetics) the long-wavelength emission band can be observed for concentrations as low as 10 mol dm . ... 

The fluorescence spectrum of pyrene has been very often nsed as a photophysical probe. The fluorescence spectmm shows the vibronic strnctnre, which is sensitive to the polarity of the environment (Nakajima, 1971 Kalyanasnndaram, 1977). Moreover, pyrene forms excimer due to one molecnle in the groimd state and one in the excited state for concentrated systems. Therefore, fluorescence spectra of pyrene can be expected to reveal the stmctnral changes of sol-gel silica and trapping mechanism of organic molecnles along the sol-gel-xerogel transitions... 

The intensity ratio of the third peak (384 nm) to the first peak (373 nm 0-0 band) ih/h) has been used (Matsui, 1990). Figure 20-1 shows examples of the fluorescence spectra of pyrene in the starting sol-gel solution of ethanol, water and tetraethoxysilane (TEOS) and the xerogels. It is clearly seen that the relative intensities of the vibronic... 

Figure 20-1. Fluorescence spectra, of pyrene in a TEOS-derived sol and xerogel The relative intensity of the vibronic bands (1, 3, and 5) is correlated with solvent polarity.

Fuii T., Murayama K., Negishi N., Anpo M., Winder E.J., Neu D.R., EiUis A.B. Fluorescence spectra of pyrene and humidity effects on them during the sol-to-gel-to-xCTogel transitions of mixed silicon-aluminum alkoxide systems. Bull Chem. Soc. Jpn. 1993 66 739-747 Fujii T. Fluorescence spectra of aromatic molecules during the sol-gel transition ofmetal alkoxides. 

A Nakajima. Fluorescence spectra of pyrene in chlorinated aromatic solvents. J Lumin 11 429, 1976. 

The shape of the fine structure in the absorption and fluorescence spectra of pyrene is very sensitive to local polarity (15a). The so-called Py--scale" of solvent polarities (15b) is a manifejstation of the Hamm effect (15c), whereby locally anisotropic electric fields relax the forbiddenness of the (0,0) band in Si -> So transitions of symmetrical aromatic chromophores. Thomas has used pyrene fluorescence to probe local polarity in aqucious micelles and in aqueous solutions of polyelec trolytes (15d). 

Figure 15.8 Fluorescence spectra of pyrene in (C FisCH2NH2)o.38GO, together with that in (CsHi NFI2)0.400. (unpublished data)...

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