New Colorimetric and Fluorometric Fluoride Ion Probe Based on Anthra[1,9-cd]pyrazol-6(2H)-one

New colorimetric and fluorometric fluoride ion probe, anthra[1,9-cd]pyrazol- 6(2H)-one (1), was synthesized by one-step condensation. The probe 1 shows F−-selective color change from colorless to pink and appearance of red fluorescence. The fluorescence quantum yield of free probe 1 in DMSO was calculated to be 0.03. After addition of 15 equiv. of F−, its fluorescence quantum yield can be increased to 0.37. The analytical detection limit for F− was 2.8 × 10− 7 M. 1H NMR analysis and DFT calculation show that the F−-induced colorimetric and fluorometric responses of 1 are driven by deprotonation process.