A curved host and second guest cooperatively inhibit the dynamic motion of corannulene

Biomolecular systems show how host-guest binding can induce changes in molecular behavior, which in turn impact the functions of the system. Here we report an artificial host-guest system where dynamic adaptation during guest binding alters both host conformation and guest dynamics. The self-assembled cage host employed here possesses concave walls and a chirotopic cavity. Complementarity between the curved surfaces of fullerenes and the inner surface of the host cavity leads the host to reconfigure stereochemically in order to bind these guests optimally. The curved molecule corannulene undergoes rapid bowl-to-bowl inversion at room temperature. Its inversion barrier is increased upon binding, however, and increased further upon formation of a ternary complex, where corannulene and a cycloalkane are both bound together. The chiral nature of the host also leads to clear differences in the NMR spectra of ternary complexes involving corannulene and one or the other enantiomer of a chiral guest, which enables the determination of enantiomeric excess by NMR. The preparation of artificial host-guest systems that display dynamic adaptation during guest binding is challenging. Here the authors report a chiral self-assembled tetrahedral cage featuring curved walls that reconfigures stereochemically to fit fullerene guests, regulates corannulene inversion, and enables the determination of co-guest enantiomeric excess by NMR spectroscopy.

Automated summary

The study presents an artificial host-guest system where dynamic adaptation during guest binding alters both host conformation and guest dynamics. The self-assembled cage host reconfigures stereochemically to fit fullerene guests, thereby regulating guest dynamics and enabling determination of co-guest enantiomeric excess by NMR spectroscopy.