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Unexpected highly selective fluorescence 'turn-on' and ratiometric detection of Hg(2+) based on fluorescein platform

Y. B. Ruan and J. Xie Tetrahedron, 2011, 67, 45, 8717-8723

Methylated fluorescein 1 was explored for fluorescence 'turn-on' and ratiometric detection of Hg(2+) in THF and CH(2)Cl(2)/MeOH (v/v=9:1), respectively, with unexpected high selectivity. In the presence of Hg2+, characteristic structured absorption band of 1 diminished and a new sharp band appeared at 445 nm. Meanwhile a blue shifted and enhanced emission was observed. The ratio of the fluorescence intensity at 559 and 478 nm increased linearly with [Hg(2+)], and solution color changing from yellow to cyan under irradiation at 365 nm in CH(2)Cl(2)/MeOH. Job plot indicated a 1:1 stoichiometry or 1-Hg(2+) complex in solution. (1)H NMR titration and IR spectra suggested the coordination of carbonyl group in xanthene moiety to Hg(2+), affording its spectral behavior. Compound 2 bearing two triazolyl amino esters in place of methyl group showed quite similar behavior to Hg2+, which indicated that substituents did not interfere with the specific binding behavior of fluorescein platform. Our work presents a new way to explore xanthene dyes as new chemosensors by modulating electron density on the xanthene ring through non-covalent interactions with carbonyl group. (C) 2011 Elsevier Ltd. All rights reserved.

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Publication

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Paru le 14 septembre 2011

Informations complémentaires :

doi 10.1016/j.tet.2011.09.028