A novel 2,5-diphenyl-1,3,4-oxadiazole-based fluorescent sensor for multi-analyte, ratiometric and relay recognition of a through modulating ESIPT has been developed.

A new 2,5-diphenyl-1,3,4-oxadiazole-based derivative (L) was synthesized and applied as a highly selective and sensitive fluorescent sensor for relay recognition of Cu and S in water (Tris-HCl 10 mM, pH = 7.0) solution. L exhibits an excellent selectivity to Cu over other examined metal ions with a prominent fluorescence 'turn-off' at 392 nm. L interacts with Cu through a 1:2 binding stoichiometry with a detection limit of 4.8 × 10 M. The on-site formed L-2Cu complex exhibits excellent selectivity to S with a fluorescence 'off-on' response via a Cu displacement approach. Copyright © 2016 John Wiley & Sons, Ltd.

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Selective fluorescence turn on Zn(2+) sensor with long-wavelength emission and a large Stokes shift is highly desirable in Zn(2+) sensing area. We reported herein the synthesis and Zn(2+) recognition properties of a new thiosemicarbazone-based fluorescent sensor L. L displays high selectivity and sensitivity toward Zn(2+) over other metal ions in DMSO-H2O (1:1, v/v, HEPES 10 mM, pH = 7.4) solution with a long-wavelength emission at 572 nm and a large Stokes shift of 222 nm. Confocal fluorescence microscopy experiments demonstrate that L is cell-permeable and capable of monitoring intracellular Zn(2+). Graphical Abstract We report a new thiosemicarbazone-based fluorescent sensor (L) for selective recognition of Zn(2+) with a long wavelength emission and a large Stokes shift.