A highly selective colorimetric and "off-on-off" fluorescent probe for fluoride ions.

In this paper, a highly selective and sensitive probe for fluoride ions (F(-)), containing a phenylpyridylvinylene derivative reporter and a Si-O bond receptor, was designed and characterized. The reaction mechanism is based on the intramolecular charge transfer (ICT) mechanism. Upon addition of F(-), probe 1 showed a remarkable red-shift (183 nm) in the absorption spectra accompanying with the color changes from colorless to purple, so probe 1 could serve as a "naked-eye" probe for F(-). The absorbance of probe 1 at 545 nm increased linearly with the concentration of F(-) from 20 to 150 µM. The detection limit was calculated to be 0.1 µM. Besides, "off-on-off" fluorescence intensity changes were also observed in the fluorescence spectra. The present results may provide a useful approach for the development of highly selective dual-channel probes for F(-).