Abstract: The spectrophotometric and spectrofluorometric titrations have been performed to give the stability constants for the supramolecular systems formed by β-cyclodextrin(1), mono [6-(ethylenediamine)-6-dexoy]-β-cyclodextrin(2), mono[6-(diethylenetriamino)-6-dexoy]-β-cyclodextrin(3), mono [6-(triethylenetetraamino)-6-dexoy]-β-cyclodextrin(4) and their copper(Ⅱ) complexes(5, 6, 7) with some dyes in phosphate buffer solution(pH 7.2, 0.1 mol/L) and hydrochloric acid-potassium chloride buffer solution(pH 2.0, 0.1 mol/L) at 25 ℃. The results obtained indicated that the fluorescence intensity of RhB decreased with increasing concentration of native β-CD(1) and its derivatives(2-7), while the fluorescence intensity of other guest molecules simply increased with increasing concentration of host compounds. As compared with parent β-cyclodextrin, the stability constants of the formed inclusion complexes by copper(Ⅱ) complexes of polyamine modified β-cyclodextrins and protonated polyamine modified β-cyclodextrins were found to be increased by electrostatic interaction. The molecular recognition mechanism is discussed from the viewpoint of the size/shape matching between guest molecular structures and host cavity

Key words: Modified cyclodextrin, Dyes molecule, Molecular recognition, Supramolecular complex