Ratiometric and selective fluorescent sensor for F(-) based on intramolecular charge transfer (ICT)

A simple colorimetric and ratiometric fluorescent anion sensor 1, was rationally designed and synthesized by facile one-step condensation on basis of the mechanism of intramolecular charge transfer (ICT). The sensor 1 shows more highly and selectively ability to F(-) that induced the color changes from little yellow to purple, absorption-transferred to long wavelength and emission-transferred to short wavelength. Accordingly, (1)H NMR analysis reveals that the F(-)-induced colorimetric and fluorometric responses of 1 are simply driven by hydrogen bonding interaction between the NH protons and F(-) ions.