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A novel colorimetric and ratiometric fluorescent probe CHa based on Ag + -induced hydrolysis of hydrazone was designed and synthesized. To the best of our knowledge, this is the first time the ratiometric sensing of Ag + based on a chemical reaction has been accomplished. When Ag + was added to a solution of CHa , a visible color change from yellow to colorless and a fluorescence color change from yellow to blue were observed. Probe CHa displayed a 203-fold enhancement of the fluorescence intensity ratio (I 450nm /I 520nm ) toward Ag + with outstanding sensitivity, high selectivity and a low detection limit (LOD 61 nM). Moreover, CHa was successfully applied to the ratiometric imaging of Ag + in HepG2 and HeLa cells. [ABSTRACT FROM AUTHOR]

The selective detection of Cu 2+ and S 2− in pure water systems is very challenging. To address this problem, we here present a novel fluorescent probe CF536 for the reversible detection of Cu 2+ and S 2− in a 100% aqueous solution via a displacement approach based on fluorescence quenching and the ESIPT mechanism, and characterized by IR, NMR, HRMS and X-ray analysis. The introduction of Cu 2+ (1.0 equiv.) to the aqueous solution of CF536 led to quenching of the intense green fluorescence within 2 min. On the addition of S 2− (3.0 equiv.), the emission of the ESIPT probe soon recovered from the CF536 -Cu 2+ system due to the abolishment of paramagnetic Cu 2+ . The fluorescence “ON-OFF-ON” cycle can be repeated a minimum of 5 times by the alternate addition of Cu 2+ and S 2− , implying that CF536 is a renewable dual-functional probe. The probe displayed high selectivity, a rapid response time, excellent water solubility due to introduction of the extremely hydrophilic trihydroxyl group and outstanding anti-interference ability for its large Stokes shift of 101 nm (λ abs = 435 nm, λ em = 536 nm), thus making the method highly suitable for bioimaging. The probe CF536 was successfully used for fluorescent imaging of copper and hydrogen sulfide in living cells. [ABSTRACT FROM AUTHOR]