Dynamics of a Supramolecular Capsule Assembly with Pyrene

Water-soluble octaacid cavitands (OAs) form dimeric capsules suitable for guest incorporation. Our studies reveal that the mechanism of pyrene (Py) binding involves the rapid (<1 ms) formation of the Py center dot OA complex followed by slower binding with the second OA. The dissociation of the capsular OA center dot Py center dot OA complex occurs with a lifetime of 2.7 s, which is 5 orders of magnitude slower than the microsecond opening/closing (breathing) previously observed to provide access of small molecules to the encapsulated guest. These different dynamics of the capsules have a potential impact on how the chemistry of included guests could be altered.