Colorimetric and fluorogenic signalling of fluoride ions by diketopyrrolopyrrole-based chemosensor

Abstract

A new colorimetric and on–off fluorescence sensor based on diketopyrrolopyrrole (DPP) was synthesized for detection of fluoride anion. The sensor displayed a rapid responsivity and high selectivity and sensitivity towards F⁻ over other anions, and it also exhibited a very low detection limit of 4.07 × 10⁻⁸ M. The signaling process was confirmed by UV-vis, fluorescence measurements as well as ¹H and ¹⁹F NMR spectroscopy. The experimental results revealed that the formation of anionic species from deprotonation of the hydrazone N–H moiety by fluoride ion was responsible for the spectral changes. Density function theory calculations were conducted to rationalize the optical response of the sensor.