Switchable Supramolecular Jalousie Constructed from a Fluorenone Macrocycle

Abstract

Organic crystal engineering is a promising strategy to construct functional materials. Herein, we demonstrate that the marriage of organic crystal engineering and macrocyclic chemistry yields a supramolecular jalousie that can be reversibly opened and closed in crystals. The synchronous rotation of fluorenone units in macrocycles triggered by toluene/phenylmethanol vapor contributes to such motions. This supramolecular jalousie is assembled from a trimeric fluorenone macrocycle, which is synthesized in 46% yield by the condensation of a 2,7-bis(2,4-dimethoxyphenyl)fluorenone monomer with paraformaldehyde. Mechanistic studies indicate that the large size (∼1.6 nm) and the rigid skeleton of the trimeric fluorenone macrocycle provide enough space for the rotation of fluorenone units as well as the encapsulation of guests in the solid state. Moreover, the bistable conformations and induced-fit structural adjustment guarantee such switchable single-crystal-to-single-crystal transformations.