Abstract: The complexation reactions of myricetin(Myr) and β-cyclodextrin with its derivatives were studied by spectrophotofluorimetry.The results indicated that β-cyclodextrin(β-CD) and its derivatives could notably enhance the fluorescence intensity of myricetin.As the concentration of β-CDs increases,the fluorescence intensity increases and maximum emission peak shifts towards long wave.Hildebrand-Benesi equation showed that the inclusion complexe was formed at the ratio of Myr:CD=1:1.The complexation ability of β-CDs is as following order:HP-β-CD >HE-β-CD > DM-β-CD >β-CD.The complexation reactions are also studied by thermodynamics.The parameters of ΔG and ΔH are negative value,and ΔS is a negative or small positive value.This indicates that the complexation reactions release heat and happen spontaneously.Driving force of complexation reaction results from the change of heat content change of recognition within molecules.

Key words: myricetin, cyclodextrin, fluorescence spectrum, thermodynamics