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Development of fluorescent sensors with large Stokes shift for selective detection of heavy metals is of great importance. A novel fluorescent probe with extremely large Stokes shift (212 nm) was synthesized for selective and simultaneous detection of Hg2+ and Ag+ ions. The deep yellow probe turned colorless or pale yellow after addition of Hg2+ or Ag+. The new probe could be utilized for absorption spectral detection of Hg2+ and Ag+ both in ethanol and aqueous solution. Addition of Hg2+ and Ag+ ions caused significant decrease in the fluorescence intensity of the new probe and the selective recognition of Hg2+ and Ag+ was not interfered by common competitive metal ions including Li+, Na+, K+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+, Mn2+, Sr2+, Ca2+, Mg2+, Al3+, Cr3+ and Fe3+. The detection limit for Hg2+ and Ag+ was calculated to be 4.68 μM and 4.29 μM, respectively. Application of the new probe for quantitative determination of Hg2+ and Ag+ concentrations in real water samples was accomplished. [ABSTRACT FROM AUTHOR]

A new spiropyran derivative acts as colorimetric and fluorescent sensor for metal ions. Addition of Cu2+, Al3+, Cr3+ and Ce3+ to the sensor solution brings about marked increase in the absorption intensities while addition of other metal ions (Na+, K+, Li+, Sr2+, Hg2+, Zn2+, Co2+, Ni2+ and Ag+) fails to cause substantial change in the UV–Vis spectra. The sensor can be used for detection of Hg2+, Cu2+, Ce3+, Cr3+ and Al3+ ions by the naked eye and by fluorescence enhancement. The detection limit of Cu2+ and Hg2+ ions by the sensor is estimated to be 10 and 14 μM, respectively. Job's plot analysis on the sensor–Cu2+ complexation reveals the formation of a 2:1 stoichiometric complex between the sensor and Cu2+ ion. [ABSTRACT FROM AUTHOR]

Construction of efficient chemosensors for highly specific and sensitive detection of mercury ions remains a great challenge. In this work a highly selective and sensitive probe CY was designed and synthesized by using coumarin fluorophore as the matrix and thioacetal moiety as the reactive recognition site for Hg2+. By virtue of the thiophilicity of Hg2+, probe CL could be hydrolyzed to deprotect and the thioacetal was transformed to the acyl group after the addition of Hg2+, the blue-green fluorescence was quenched and meanwhile the solution changed from light green to yellow. The detection limit of probe CY for Hg2+ was as low as 6.8 nM, and it could completely react with Hg2+ within 3 min. Moreover, probe CY exhibited good resistance against interference from competitive metal ions and biothiols, high stability in pH 1–11 and applicability for fluorogenic and chromogenic dual-modal detection of Hg2+ in real water samples over a broad range of pH 5–10. [ABSTRACT FROM AUTHOR]