Abstract: The fluorescence quenching of dimethylamino chalcone modified β-cyclodextrin by different transition metal ions in various solvents has been studied. It was found that the modified β-cyclodextrin has a specific recognition ability to Cu2＋ in aqueous solution, and the quenching constant is about one order of magnitude larger than that of other metals which were studied in this work. But in non-aqueous solvents, such as in DMF, the specific recognition ability of Cu2＋ disappeared. And the Ni2＋, which has a planar configuration, presented the strongest ability of complex formation. It was resulted from the four ethylene groups connected each other by hetero-atom in linking chain of the modified β-cyclodextrin to make the formation of planar square configuration easily. The results demonstrated that the possibility of the special structure match of the host and the guest plays a very important role in the complex formation.

Key words: Modified β-cyclodextrin, Transition metal ion, Molecular recognition, Fluorescence quenching