Colorimetric and ratiometric fluorescent sensor for F− based on benzimidazole-naphthalene conjugate: Reversible and reusable study & design of logic gate function

Abstract

A novel benzimidazole-naphthalene conjugate molecule has been successfully designed and applied as a colorimetric and ratiometric fluorescent sensor for direct visual detection of F− with high selectivity over other anions. Addition of F− to the sensor resulted in an obvious color change from colorless to pale green under ambient light and blue to green under 365 nm UV light, respectively. 1H NMR and DFT calculations studies confirm that the recognition towards F− is due to the formation of an NH⋯F hydrogen bond and subsequent deprotonation. In addition, the sensor can be reversible and reusable for sensing fluoride ion in the presence of H+, thus it can be developed as an INHIBIT type logic gate at molecular level. Moreover, the sensor with high sensitivity and fast response has also been successfully applied to the detection of F− from inorganic origins and in the solid state.