- Photophysics of a series of efficient fluorescent pH probes for dual-emission-wavelength measurements in aqueous solutions
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This paper evaluates the 5-aryl-2-pyridyloxazole backbone to engineer donor-acceptor fluorescent pH probes after one- or two-photon absorption. Parent fluorophores, as well as derivatives that can be used to label biomolecules, can be easily obtained in good yields. These molecules exhibit a large one-photon absorption in the near-UV range, and a strong fluorescence emission that covers the whole visible domain. The 5-aryl-2-pyridyloxazole derivatives also possess significant cross sections for two-photon absorption. Upon pyridine protonation, large shifts were observed in the absorption spectra after one- and two-photon excitation, as well as in the emission spectra. This feature was used to measure the pKa of the investigated compounds that range between 2 and 8. In most of the investigated derivatives, the pKa increased upon light excitation and protonation exchanges took place during the lifetime of the excited state, as shown by phase-modulation fluorometry analysis. Several 5-aryl-2-pyridyloxazole derivatives are suggested as efficient probes to reliably measure the pH of aqueous solutions by means of ratiometric methods that are dependent on fluorescence emission.
- Charier, Sandrine,Ruel, Odile,Baudin, Jean-Bernard,Alcor, Damien,Allemand, Jean-Francois,Meglio, Adrien,Jullien, Ludovic,Valeur, Bernard
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p. 1097 - 1113
(2007/10/03)
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- Combinatorial discovery of novel fluorescent dyes based on Dapoxyl
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We have developed a combinatorial method for the fast and effective synthesis of a library based on a known fluorescent dye, Dapoxyl using parallel solution-phase chemistry. By screening the 140 new compounds using fluorescence-based assays, we identified three new fluorescent dyes with novel properties.
- Zhu, Qing,Yoon, Hai-Shin,Parikh, Puja B.,Chang, Young-Tae,Yao, Shao Q.
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p. 5083 - 5086
(2007/10/03)
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- Syntheses and Photophysical Properties of Some 5(2)-Aryl-2(5)-(4-pyridyl)oxazoles and Related Oxadiazoles and Furans
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A number of 5-aryl-2-(4-pyridyl)oxazoles, a 2-aryl-5-(4-pyridyl)oxazole, the related oxadiazole and furan, several 2-(4-pyridyl)cycloalkanooxazoles, and many of their quaternary salts were prepared.No single standard synthesis was effective for preparation of more than a few of the 25 free bases described; methods often unique to a base were employed.Minor variations in structure sometimes produced large differences in absorption and emission wavelengths, as well as in the magnitude of the extinction coefficient.The salts are of interest as laser dyes, scintillation fluors, biological stains, and shifters for luminescent solar concentrators.
- Hall, J. Herbert,Chien, Joseph Yuming,Kauffman, Joel M.,Litak, Peter T.,Adams, Jeffrey K.,et al.
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p. 1245 - 1273
(2007/10/02)
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- SPECTRAL-LUMINISCENCE PROPERTIES AND BASICITIES OF 2-(4-PYRIDYL)-5-(4-R-PHENYL)OXAZOLES
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The spectral-luminiscence and acid-base properties of 2-(4-pyridyl)-5-(4-R-phenyl)oxazoles were studied.Significant ?-electron conjugation between the individual fragments exists in the molecules of these compounds in solutions at room temperature.Bathochromic and bathofluoric effects, which are particularly appreciable for electron-donor substituents, are observed when substituents R are introducted into the 5-phenyl ring.Ethanol solutions of the investigated compounds have high fluorescence quantum yields which, for some of them, are close to unity.Electron-donor substituents R increase the basicity of the pyridine nitrogen atom.
- Afanasiadi, L. Sh.,Tur, I. N.,Kurapov, P. B.
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p. 397 - 400
(2007/10/02)
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