A selective and colorimetric chemosensor for fluoride based on dimeric azulene boronate ester

The dimeric azulene boronate ester 1 was designed and synthesized as a potential chemosensor for fluoride ion. UV-Vis titration analysis shows that with the enhancement of fluoride equivalents, the absorption peaks have been decreasing at 408 and 434 nm, while the peak at 370 nm has been increasing remarkably. Job's plot proves that the formation of a 1:2 [1.2F]2(-) species is responsible for the observed absorbance enhancement in THE solution. Furthermore, this probe displays a quick response for fluoride ion and the color is from light green to yellow in solution, exhibiting a high selectivity and excellent stability. It is noted that a test paper for effective detection of fluoride has been prepared by using dimeric azulene boronate ester as a colorimetric chemosensor without any spectroscopic instrumentation. In addition, TD-DFT calculation has also been carried out in aqueous media for comparison.