3-Urea-1,8-naphthalimides are good chemosensors: a highly selective dual colorimetric and fluorescent ICT based anion sensor for fluoride

The 1,8-naphthalimide sensor 1 was developed as a colorimetric and fluorescent sensor for anions. Being the first example of such anion sensors, where the 3-position of the naphthalimide ring is used to incorporate the anion recognition moiety, in this case a trifluromethyl derived aryl urea moiety, the sensors gave rise to significant changes in both the absorption and the emission spectra, which were both red shifted upon interacting with anions. The changes were most pronounced for fluoride, and to a lesser extent for acetate and hydrogen phosphate, in DMSO, making 1 a highly selective sensor for F⁻.