A ratiometric fluorescent probe for fluoride ions with a tridentate receptor of boronic acid and imidazolium

A new ratiometric fluorescent probe for fluoride ions was developed which complexed fluoride by a tridentate receptor of boronic acid and imidazolium. In the current study, a tridentate receptor 1 with one ortho boronic acid and two imidazolium groups was designed. The boron center can co-operate with imidazolium to bind F−. The formation of B–F complex stabilizes the interaction between fluoride and imidazolium which induces a ratiometric fluorescence response. With the addition of F−, a strongly increased fluorescent emission centered at 370 nm appears at the expense of the fluorescent emission centered at 445 nm.