Structural Basis of Cucurbituril-Containing Self-Assembled Supramolecular Chiral Materials.

ABSTRACT

Macrocycle-based host-guest complexation offers an intriguing protocol in producing chiroptical materials, while the bulky size and dynamic exchange between hosts and guests hinders the ordered aggregation to afford the long-range chiral arrangement. It remains great challenges in assembling cucurbit[n]urils (CB[n]s) included complexes to induce supramolecular chirality ascribed to the excellent water solubility and flexible packing. Herein, we unveiled the structural basis on the formation of chiroptical coassemblies from CB[n] (n=6, 7) complexes. Perylene diimides (PDIs) with cationic chiral pendants formed complexes in the aqueous media, which selectively showed chiroptical properties. Chlorination at the bay position, increasing alkyl length of cationic chiral pendants or reducing the number of polyaromatic rings would hinder the chiral aggregation. In a comprehensive manner, CB[6] favors ordered aggregation into one-dimensional fibrous nanoarchitectures that greatly facilitates the supramolecular chirality. In contrast, CB[7] with larger cavity and water solubility shrinks the ordered arrangement of complexes, reducing the formation possibility of supramolecular chiral nanoarchitectures. This work suggests the great potential of CB[6] in the preparation and manipulation of supramolecular chiral assemblies, shedding light on the macrocycle-based functional chiroptical materials.