Interior Editing via Dynamic Molecular Recognition

The ability to engineer the interior space of molecular
containers
is crucial for realizing precise control over their selectivities
in molecular recognition, transport, and catalysis. Despite decades
of research in synthetic chemistry and materials sciences, the selective
editing of chemical bonds inside molecular containers remains a formidable
challenge, limiting our capacity to mimic the nanoconfined environments
of bioreceptors. Here, we describe a new catalytic paradigm for activating
interior chemical bonds in nanoconfined space via dynamic molecular
recognition. Quinuclidine, a catalyst that can reversibly bind the
cavity of α-cyclodextrin, was found to abstract hydrogen atoms
selectively from one of its endo C–H bonds
upon single-electron oxidation, causing the geminal hydroxyl group
to flip to the interior face of the macrocycle. The endo-hydroxylated α-cyclodextrin was able to separate chiral compounds
that could not be resolved by its natural counterpart in gas chromatography
owing to its desymmetrized cavity and polar recognition site.