Structure of the inclusion complex of β-cyclodextrin with lipoic acid from laboratory powder diffraction data.

The crystal structure of the inclusion complex of β-cyclodextrin with lipoic acid was determined from laboratory powder diffraction data. Thermogravimetric data was used to estimate the number of water molecules in the crystal structure. Lipoic acid is included in β-cyclodextrin through its primary face with the five-membered ring reaching the center plane of the cyclodextrin cavity and its fatty acid chain adopting a bent conformation. Lipoic acid and β-cyclodextrin form a channel-like packing which is stabilized by guest-host hydrogen bonding and close contacts, host-host intermolecular interactions and hydrogen bonding involving the water molecules.