Single crystal X-ray diffraction data measured at 100 K for Dianin's compound (DC) and eighteen of its clathrates formed with a wide range of guest molecules provide considerable insight into the way the host adjusts to accommodate guest molecules. Detailed information is also obtained regarding the location, orientation and dynamics of the guests in the host cavity. Although all unit cells are closely similar in size, the host undergoes significant change in response to the imprisonment of its various guests. Enclathration typically results in a larger cell and cavity volume, but for the small molecules methanol, ethanol and nitromethane the host actually shrinks significantly around the guests in the cavity. In most clathrates there is evidence of close contacts between atoms in the guest and the phenol-OH group and/or ring of the DC host. The series of clathrates formed by benzene, toluene and the halobenzenes shows the orientation of the benzene ring to be progressively modifed by the increasing size of the substituent atom or group on the ring in a systematic manner that reflects functional group contributions to van der Waals volumes. € R3 and a hexagonal cell with a ~ 27 Å, c ~ 11 Å, 12,13 which requires most guest molecules to be disordered about the threefold axis and the inversion centre at the waist of the cavity. ASS OCIA TED C ONTENT Supporting Information. Experimental procedures and details of crystallography. This material is available free of charge via the Internet at http://pubs.acs.org.

The title compound undergoes two order-disorder transitions between 15 and 299 K, dictated by ordering of the guest molecules in the host cages, and resulting in three related crystal structures. We anticipate behaviour of this kind to be widespread, and speculate that the concept of "the crystal structure" for individual Dianin's clathrates may be elusive.