An inclusion complex (1) has been preparted by cyclodextrin with22.7( )]-aminopyridine. The result of X-[(ray crystallo)(graphic analyses showed that th)]eα-aminopyridine molecules in thecyclodextrin cavities possess two opposite orientations, i.e. the amine group ofα-aminopyridine pointing to the primary side (1a, occupancy:41.2%) of the secondary side (1b, occupancy:58 ofβ-[(cyclodextrin, forming two scaleli)(ke )]supramolecular aggregations. The studies of 2D NMR and circular dichroism spectra indicated that theaminopyridine molecule is deeply embedded in thecyclodextrin 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.
The self-assembly behavior of mono(6-phenolic-6-deoxy)-β-cyclodextrin (1) both in solu- tion and the solid state is comparatively studied by X-ray crystallography and 1H NMR spectroscopy. The results obtained show that the phenolic groups in the crystal 1 can successively penetrate into the adjacent β-cyclodextrin cavities from the secondary side to form head-to-tail linear polymeric su- pramolecule with a 2-fold screw axis. The self-assembly behavior also can be determined in D2O so- lution, giving a self-association constant of 240 mol?1?L. Using the present and previous structures reported for the relevant β-cyclodextrin derivatives, i.e., mono(6-anilino-6-deoxy)-β-cyclodextrin (2), mono(6-phenylselenyl-6-deoxy)-β-cyclodextrin (3), and mono(6-phenylthio-6-deoxy)-β-cyclodextrin (4), we further reveal the factors governing the formations of supramolecular assemblies.
