Efficient Colorimetric Fluoride Anion Chemosensors With Varied Colors Based on Simple Aminobenzodifuranone Organic Π-Conjugated Dyes.

High selectivity and sensitivity detection of fluoride anions (F-) in an organic solution by the naked eye has always been a challenge. In this investigation, a simple compound based on aminobenzodifuranone (ABDF) was designed and synthesized. Deprotonation of the amino moiety caused by F- is responsible for a color change from dark blue to various colors (colorless, yellow, orange, and red) in different common organic solvents due to a blue shift over 200 nm in the UV/Vis spectrum. The color change is quite visible to the naked eye under ambient light. The detection limit for F- can reach a concentration of as low as 5.0 × 10-7 M with high selectivity, even in a solution containing multiple anions.