Adaptive binding of a shape-shifting bullvalene within β-cyclodextrin.

Herein, we report adaptive host-guest binding between an amphiphilic dicationic bis-pyridinium bullvalene and cyclodextrins. Isothermal titration calorimetry identifies β-cyclodextrin as the strongest 1:1 host, while low-temperature NMR spectroscopy shows that complexation drives the guest ensemble toward the β,γ' isomer through inclusion of the hydrophobic bullvalene core. Computational modelling supports this shape-selective binding mode and predicts supramolecular dynamic deracemization in favour of the (Rα)-β,γ' enantiomer.