A ratiometric fluorescent sensor for Zn2+ based on internal charge transfer (ICT)

A ratiometric fluorescent chemosensor 5 was designed and synthesized based on internal charge transfer (ICT). The indicator absorbs and emits light in the visible wavelength range. In acetonitrile, blue shifts in fluorescent emission upon zinc binding are due to the formation of a 1:2 metal/ligand complex, which induced a fluorescent emission at 616 nm at the expense of the fluorescent emission at 672 nm.