Retarded solid-state rotations of an oval-shaped guest in a deformed cylinder with CH-π arrays.

Abstract

Upon encapsulating an oval-shaped hydrocarbon guest, a cylindrical host deforms its shape to maximize intermolecular contacts. Structure-assembly relationships studies with a series of hydrocarbon guests disclosed the importance of molecular shapes and CH-π contacts. Multiple contacts with weak CH-π hydrogen bonds resulted in an optimal assembly; however, the shape deformation resulted in severe retardation of rotational motions in the crystal. Thus, unlike a circular guest, the oval-shaped guest did not change its orientation in the host. Unexpectedly, the planar guest did not affect the packing structure to form a double helix in intertwined host arrays.