A naked-eye visible colorimetric and fluorescent chemosensor for rapid detection of fluoride anions: Implication for toxic fluorine-containing pesticides detection

A dual-modal colorimetric and fluorescent probe based on 1,8-naphthalimide, 4-(2,2-dichloroacetamide)-N-n-butyl-naphthalimide (CNA), has been designed and synthesized for the detection of fluoride anion (F−) in CH3CN. CNA exhibited highly sensitivity and selectivity for F− over the other anions, such as Cl−, Br−, I−, NO3−, ClO4−, HSO4−, NO2− and SCN−. The evident colorless to yellow color change of the solution of CNA was observed with the naked eyes only in the presence of F− among the other anions, together with drastically fluorescence quenched. The Job's plot analysis revealed that the binding between the CNA with F− was in 1:1 stoichiometry. The detection limits of the CNA for F− from fluorescence and ratiometric absorption spectra were 0.52, 1.41 μM, respectively. The 1H NMR titration indicated that F− induced the deprotonation of the CNA through hydrogen bonding interaction between amino group of the CNA and F−. Based on this detection system, an IMPLICATION logic gate could be constructed. Furthermore, it could be successfully employed as a selective fluoride anion probe to the fluorescence detection of fluorine containing pesticides (oxyfluorfen).