Interactive force between cyclodextrin inclusion complexes studied by atomic force microscopy

Change in the intermolecular interaction between cyclodextrins (CyDs) with guest materials was observed by measuring the adhesion force using atomic f orce microscopy (AFM) in air. The observed adhesion force with water as the guest material is weaker for alpha -CyD (composed of 6 glucose) than beta -CyD (7 glucose), contrary to the fact that alpha -CyD is more hydrophilic than beta -CyD, indicating that the intrinsic interaction of molecules coul d be obtained separately from the meniscus force even in air. In addition, the adhesion force depends on the type of guest molecules (H2O, para-nitrop henol, and triethylendiamine) for alpha -CyDs, but not for beta -CyDs. The observed change was explained well by the change in the dipole moment induc ed by the structural deformation due to the guest materials.