Polymorphism or pseudopolymorphism of a macrocyclic compound: helical structure, layered structure and pseudorotaxane constructed by weak intermolecular interactions

Abstract

Molecules of macrocyclic aromatic hydrocarbon 1 assembled to form various three-dimensional (3D) structures via weak intermolecular interactions, including aromatic–aromatic interactions (1a–d). In the crystal obtained from a chloroform and acetonitrile mixture (1a), the molecules arranged in a columnar stack with a progressive helical twist between adjacent molecules due to intermolecular aromatic–aromatic interactions. The chirality of the helices was spontaneously resolved within individual single crystals. In the crystal obtained from a chloroform and nonane mixture (1b), the molecules formed a columnar stack through tilted T-shaped aromatic–aromatic interactions. Furthermore, in the crystal obtained by vapour diffusion of n-hexane or ethyl acetate into a chloroform solution, inclusion compounds (1c and 1d) were formed via van der Waals interactions between the guest molecule and the benzene ring of the biphenyl unit. The n-hexane penetrated 1 to construct [3]pseudorotaxane and an ethyl acetate molecule was trapped by 1.