Selective recognition of fluoride by using a benzobisimidazolium derivative through aggregation-induced fluorescence

Abstract

A new benzobisimidazolium derivative (1) bearing four naphthalene moieties was synthesized and demonstrated as an F– ion-selective fluorescent chemosensor. The fluorescence of 1 in acetonitrile (CH3CN) is significantly stronger with F– and acetate (CH3CO2 –), but not with other anions (Cl–, Br–, I–, HSO4 –, and H2PO4 –). The fluorescence of 1 is enhanced selectively with F– in the presence of a small amount of water. Our DFT calculations indicate that the electrostatic interactions between the positively charged benzobisimidazolium moieties and F– play an important role in the formation of stable aggregates. The formation of stable aggregates of 1 with F– in CH3CN is a key step for the selective sensing of F–, and the fluorescence of the aggregates is further enhanced in a mixture of 95% CH3CN and 5% water, which can be attributed to the aggregation-induced emission. © 2017 The Authors.