Highly Selective Fluorescence Turn-On Sensor for Fluoride Detection

Through click chemistry, triazole and triazolium groups have been explored to recognize anions through C-H center dot center dot center dot A(-) hydrogen-bonding complexion. Herein, we demonstrate evidence of fluoride-induced deprotonation of a C-H bond and its application in fluoride detection. The combination of fluorene and triazolium units produced a highly selective fluorescence turn-on prototype sensor for fluoride. The interactions between the C H bond and F- were studied by fluorescence spectroscopy and H-1 NMR titrations. Test papers were prepared to detect fluoride in aqueous media at concentrations down to 1.9 ppm, important for estimating whether the fluoride concentration in drinking water is at a safe level.