The molecular conformation of cyclodextrins (β CD,γ CD) bearing benzoyl moiety was studied by circular dichroism and 1H NMR.The circular dichroism intensity of mono[6 (benzoyl ethylendiamino)] β CD (1) was reduced by adding of guests.In contrast,the circular dichroism intensity of mono(6 o benzoyl) γ CD (2) was increased by adding of guests.The benzoyl moiety of 1 was extruded outside from the cavity of β CD by guests,while the benzoyl moiety of 2 was included together with guests in the cavity of γ CD.