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

A colorimetric chemosensor displays a quick response for fluoride ion based on dimeric azulene boronate ester and the color change is from light green to yellow, exhibiting the excellent selectivity and stability. The detecting limit of 0.6 mg·L−1 for fluoride anion is lower than the WHO limit of 1.5 mg·L−1.112