Colorimetric and fluorescence sensing of Cu2+ in water using 1,8-dihydroxyanthraquinone-β-cyclodextrin complex with the assistance of ammonia.

1,8-Dihydroxyanthraquinone (DHAQ) can form an inclusion complex with β-cyclodextrin(β-CD) in aqueous media, which can be employed to solubilize and stabilize the DHAQ in water. With the assistance of ammonia, the supramolecular DHAQ-β-CD complex showed a selective chromogenic behavior toward Cu(2+) ions by changing the color of the solution from citrus red to purple red, which could be easily observed with the naked eye. Moreover, fluorescence emission of the system was selectively quenched by Cu(2+) ions. The fluorescence response was concentration-dependent and can be well described by the typical Stern-Volmer model. An easily applied method for Cu(2+) determination in an aqueous medium was thus established. Under the optimum conditions, the method exhibits a dynamic response range for Cu(2+) from 8.0×10(-7) to 2.0×10(-5) M, with a detection limit of 2.7×10(-7) mol L(-1).