An anionic sensor based on Reichardt's betaine is described here. The dye is blue-green in chloroform but becomes colorless under protonation. Increasing amounts of different anions were added into the solution of the protonated dye. The addition of F− and H2PO4-caused the reappearance of the original blue-green color, while the addition of I− made the solution of the protonated dye yellow. The observations are discussed based on the fact that F− ...
