Novel fluorene-based chemodosimeters for mercury and methylmercury species in aqueous media

Four novel compounds 1a–4a consisting of fluorene as signaling unit and thiourea as responding unit were developed as fluorescent chemodosimeters for mercury and methylmercury species. Upon treatment with Hg2+ and CH3Hg+, the fluorescence of 3a is effectively quenched, whereas 1a, 2a and 4a show evident fluorescent color variations under illumination with 365 nm light: yellow to pale blue, yellow to bright blue, light red to orange yellow, respectively. They all exhibit specific sensitivity and selectivity for Hg2+ and CH3Hg+ over other examined metal ions in CH3CNH2O solution at room temperature.