Host-Guest Complexation-Induced Chirality Switching of Pillararenes by Perylene Diimide-Based Hexagonal Metallacages

Abstract

Abstract Chirality in confined nanospaces has brought some new insights on chirality transfer, amplification and chiroptical properties. However, chirality switching, which is a common phenomenon in biological systems, has never been realized in confined environments. Herein, we report a type of hexagonal metallacages which shows good host-guest interactions with ethoxy pillar[5]arene, pillar[6]arene, as confirmed by single-crystal X-ray analysis. Importantly, when a chiral pillar[5]arene-based molecular universal joint (MUJ) is used as the guest, the host-guest complexation would drive the alkyl ring of the MUJ flip from outside to inside the cavity of its pillar[5]arene unit, which enables the configuration change along with the chirality inversion of the MUJ. Moreover, the host-guest complexation facilitates the chirality transfer from guests to hosts, giving circularly polarized luminescence for the system. This study provides a unique metallacage-pillararene recognition motif for the chirality switching of planar chiral pillararenes, which will promote the construction of host-guest systems with tunable chirality for advanced applications.