Novel azo dye-based color chemosensors for fluoride ions

Two novel fluoride (F(-)) sensors based on an azo dye (solvent yellow 4) were designed and synthesized. The chemosensors exhibited selectivity and high sensitivity towards F(-) over other anions such as Cl(-), Br(-), I(-), CH3COO(-), C6H5COO(-), and H2PO4(-), as noted by the naked eye and UV-vis spectral changes in DMSO/CH3CN (1:9, v/v). An obvious change in the color of the sensor solution from pale yellow to pink occurred after the addition of F(-), while the addition of other anions did not cause any change in color. These results imply that the two sensors are viable, portable chemosensors for the detection of F(-) ions in various biological and environmental fields.