Guest-adaptive chiral coassembly of a conformationally locked host into supramolecular boxes and ladders through arene-perfluoroarene force

Abstract

Unveiling the role of weak non-covalent forces in chiral self-assembly is pivotal in the design and fabrication of functional chiroptical materials. The nature of arene-perfluoroarene (AP) force is the electrostatic attraction between π-hole and π planes of perfluoroarenes and polyaromatic hydrocarbons (PAHs), which is emerging in constructing supramolecular motifs and coassembled optical devices. In this work, we reveal the potential of AP forces in building diversified levels of chiral coassemblies adaptive to the geometries of PAHs. The naphthalene-F₈ was covalently conjugated with a chiral amine, which folded into a semi-rectangular geometry via two intramolecular F⋯H bonds. PAHs of naphthalene, anthracene, pyrene, carbazole, perylene and benzoperylene were introduced to afford coassemblies in the crystalline state. X-ray structures suggest the formation of supramolecular boxes that encapsulate the PAHs with a 2:1 stoichiometric ratio, as well as the formation of consecutive layered ladders with a 1:1 stoichiometric ratio. The preference is adaptive to the geometries of PAHs, and experimental and computational results evidenced the ladder structures possess strong binding affinity. On this top, the selective chiral recognition in the mixtures of PAHs was realized, which shows promising applications in the separation of PAHs and rational design of crystalline chiroptical materials.