Optical Sensing of Fluoride Through a Self-Organized Fluorescent Ensemble of Quinizarin-Al(III) Complex

A one-pot, cost-effective system for sensing fluoride ions using quinizarin as a novel chromophore is reported. Quinizarin complexes with Al(III) to form a self-organized turn-on fluorescence system in methanol. In the presence of fluoride ions, this system undergoes a subsequent ligand swap reaction with the fluoride ion and consequently the fluorescence turns off, delivering a sensitive route for the estimation of fluoride. This domino effect presents a sensitive and selective reaction system for the detection of fluoride ions in the concentration range 0.5-15 ppm. The study was performed using spectrophotometric and spectrofluorimetric techniques. Various analytical parameters such as pH, equilibration time, ambient temperature, and applicability of the method have been reported along with the study of the associated interfering ions.