A highly selective naked-eye and fluorescent probe for fluoride ion based on 1,8-naphalimide and benzothizazole

Abstract

Based on benzothizazole and 1,8-naphalimide, a novel colorimetric and fluorescent probe (probe 1) for fluoride ion was synthesized by Schiff base reaction. The striking yellow-to-blue color change of the probe 1 in the CH3CN was observed with the naked eyes only in presence of F− among the eight anions (F−, Cl−, Br−, I−, NO3−, HSO4−, H2PO4−, AcO−). Besides that, upon addition of F−, both of the absorption and emission peaks shifted to near-infrared region (NIR) (>600 nm) in UV–vis and fluorescent spectra, and the detection limit reached as low as 0.41 μM. Furthermore, the 1H NMR titration and theoretical calculation based on TD-DFT indicated that the fluoride ion induced deprotonation of the probe 1 through hydrogen bonding interaction between amino group of probe 1 and fluoride ion.