Novel Discrete and Imprinted Fluoride‐Selective Sensors: Bridging the Gap from DMSO to Aqueous Samples

Abstract

AbstractFluoride in drinking water has beneficial or harmful health effects depending on its concentration. This highlights the need for new low‐cost and portable sensors capable of in situ monitoring of F− ions. Unfortunately, achieving high levels of water compatibility and fluoride specificity remains a challenge. Here, four new urea‐based discrete sensors are prepared and characterized. The sensors containing anthracenyl‐ (5) and 9H‐fluorenyl‐ (7) signaling units exhibit intense luminescent emissions in dimethyl sulfoxide, the former being particularly sensitive and selective to fluoride. In water, 5 displays a superior sensitivity (871 M−1) and a detection limit (8 µm) below international guidelines, albeit with cross‐sensitivity to H2PO4‾. To enhance the performance, 5 and 7 are embedded into a fluoride‐imprinted polymeric matrix to give solid‐state sensors (5P and 7P, respectively). 5P shows good sensitivity (360 M−1) and specificity in water. Besides, it has a low detection limit (35 µm) and a response linear range (118–6300 µm) encompassing the limit established by the Environmental Protection Agency (211 µm). Furthermore, 5P also displays good reusability and adequate recovery values in real‐sample testing (102 ± 2%), constituting the first example of a low‐cost anion‐imprinted polymeric probe tailored for the selective sensing of fluoride in aqueous samples.