Highly selective and sensitive detection of Hg2+ by a novel fluorescent probe with dual recognition sites

A novel thionocarbonate-coumarin-thiourea triad-based probe with dual recognition sites for sensing mercury (Hg2+) ion was developed. The synthesized probe possessed both fluorogenic ("off-on") and chromogenic (from colorless to blackish brown) sensing performance towards Hg2+ ions. The fluorescence intensity was increased by 70 fold after the addition of Hg2+. As expected, the probe exhibited excellent selectivity and sensitivity for Hg2+ compared to other common competitive metal ions. The fluorescence intensity of the probe improved linearly with the increase of the concentration of Hg2+ (0-40 μM). Also, the minimum limit of detection (LOD) of the synthesized probe was 0.12 μM. Considering the importance of test feasibility in the harsh environment, the developed probe was applicable for detecting Hg2+ ions over a broad working pH range of 3-11. It is reliable and qualifies for the quantitative determination of Hg2+ concentrations in actual water samples. Finally, the probe achieved the bioimaging performance of Hg2+ in living cells and plants with good biocompatibility.