A Reaction‐Based Colorimetric Fluoride Probe: Rapid “Naked‐Eye” Detection and Large Absorption Shift

Taking advantage of both the well‐known azobenzene structure and the special fluoride‐promoted cleavage reaction of the SiO bond, a new ratiometric colorimetric probe (F‐1) toward the fluoride anion was designed and synthesized by using intramolecular charge transfer (ICT) as a signal mechanism. Upon the addition of F− ions, the probe displayed apparent color changes from colorless to deep blue, with a dramatic shift of the maximum absorption wavelength (≈230 nm). With the aid of UV/Vis measurements, the detection limit could be as low as 15 μM. The probe possessed much higher selectivity for fluoride over other common anions. Excitingly, by virtue of a “dipstick” approach, F‐1 could serve as colorimetric probe for convenient measurements, without the requirement of any additional equipment.