Reactive Fluorescent and Colorimetric Probe for Highly Selective and Sensitive Detection of Hg²⁺ in Real Water Samples

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.