Complex Formation of Cyclodextrins with a Dumbbell Molecule Bearing Two Ferrocene Moieties at the Ends

The complexation behavior of cyclodextrins (CDs) with a dumbbell molecule possessing ferrocene (Fc) moieties at both the ends (FcC10Fc) was investigated by 1H NMR, two-dimensional rotating frame Overhauser spectroscopy, circular dichroism spectroscopy, and cyclic voltammetry. α-CD includes the cyclopentadienyl rings of the Fc moiety shallowly from the wider side but not the decamethylene (C10) moiety, whereas β-CD and γ-CD include not only the Fc moiety but also the C10 moiety. These observations indicate that the Fc moiety can pass through β-CD and γ-CD cavities but not the α-CD cavity.