Highly Selective Turn-On Fluorescent and Colorimetric Sensing of Fluoride Ion Using 2-(2-Hydroxyphenyl)-2,3-dihydroquinolin-1H)-one based on Excited-State Proton Transfer

A simple, highly selective and sensitive colorimetric system for the detection of fluoride ion in an aqueous medium has been developed using 2-(2-hydroxyphenyl)-2,3-dihydroquinolin-4(1H)-one. This system allows selective turn-on fluorescence detection of fluoride ion, which is found to be dependent upon guest basicity. An excited-state proton transfer is proposed to be the signaling mechanism, which is rationalized by DFT and TD-DFT calculations. The present sensor can also be applied to detect fluoride levels in real water samples.