An inclusion complex (1) has been prepared by β-cyclodextrin with α-aminopyridine. The result of X-ray crystallographic analyses showed that the α-aminopyridine molecules in the β-cyclodextrin cavities possess two opposite orientations, i.e. the amine group of α-aminopyridine pointing to the primary side (1a, occupancy: 41.2%) or the secondary side (1b, occupancy: 58.8%) of β-cyclodextrin, forming two scalelike supramolecular aggregations. The studies of 2D NMR and circular dichroism spectra indicated that the α-aminopyridine molecule is deeply embedded in the β-cyclodextrin cavity to form host-guest inclusion complex, showing a circular dichroism spectrum induced by the chiral cavity of cyclodextrin. The results obtained are helpful for understanding the molecular recognition and aggregation mechanism between the host and guest.
