Fluoride-selective chemosensor based on an anion imprinted fluorescent polymer

The sensing of fluoride ion through convenient and inexpensive methods has become significant analytical goals. The state-of-the-art involves the supporting of urea/thiourea optical discrete anion sensors into a polymeric scaffold. Nevertheless, high levels of selectivity are difficult to achieve, since the colorimetric/fluorometric response is also quenched by other anions such as dihydrogenphosphate. In this work we present, for the first time, the design of a polymeric optical fluoride chemosensor by using the anion-imprinting technique. First, four polymerizable anion receptors containing a urea-type binding site and different fluorophores as signaling units were prepared. One of them (1-(4-vinylphenyl)-3-(1-naphtyl)-urea) shows the most intense fluorescence emission in solution, exhibiting high optical sensitivity only for F- and H2PO4-. The electronic and structural features behind the optical response and anion affinity were elucidated through experimental and computational tools. To enhance the optical sensitivity and selectivity, a fluoride-imprinted polymeric optical sensor was prepared starting from this soluble sensor. The fluorescent emission is 13 times higher for the polymer and it is switched off only in the presence of fluoride, while for the rest of the anions, including H2PO4-, there was almost no optical response. To the best of our knowledge, this is the first fluoride-imprinted polymeric optical sensor reported so far.

Automated summary

In this study, a polymeric optical fluoride chemosensor was designed for the first time using anion-imprinting technique. By preparing different polymerizable anion receptors and utilizing experimental and computational tools, the optical sensitivity and selectivity were successfully enhanced.