- Nickel-catalyzed carboxylation of aryl and heteroaryl fluorosulfates using carbon dioxide
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The development of efficient and practical methods to construct carboxylic acids using CO2 as a C1 synthon is of great importance. Nickel-catalyzed carboxylation of aryl fluorosulfates and heteroaryl fluorosulfates with CO2 is described, affording arene carboxylic acids with good to excellent yields under mild conditions. In addition, a one-pot phenol fluorosulfation/carboxylation is developed.
- Ma, Cong,Zhao, Chuan-Qi,Xu, Xue-Tao,Li, Zhao-Ming,Wang, Xiang-Yang,Zhang, Kun,Mei, Tian-Sheng
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p. 2464 - 2467
(2019/04/10)
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- 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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- Novel rare earth metal cryptates which are not very sensitive to the fluorescence quenching
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The invention relates to a process for reducing the fluorescence quenching caused by the measuring medium in a fluorescence assay, by introducing into said medium of rare earth metal cryptates which are not very sensitive to this fluorescence quenching, said rare earth metal cryptates comprising at least one pyridine radical which is substituted one or more times or unsubstituted. The invention also relates to novel rare earth metal cryptates which are not very sensitive to the fluorescence quenching caused by the measuring medium.
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- Not sensitive fluorescence quenching cryptate much new rare earth metal
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The invention relates to a process for reducing the fluorescence quenching caused by the measuring medium in a fluorescence assay, by introducing into said medium of rare earth metal cryptates which are not very sensitive to this fluorescence quenching, said rare earth metal cryptates comprising at least one pyridine radical which is substituted one or more times or unsubstituted. The invention also relates to novel rare earth metal cryptates which are not very sensitive to the fluorescence quenching caused by the measuring medium.
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