We show that Cucurbit[7]uril (CB[7]) can slip over motifs as large as 21-crown-7, and that unexpectedly, CB[7] dethreading is promoted by metallic cations, which stabilize intermediate(s) and transition state(s) along the slippage pathway by interacting with both the crown ether unit and the carbonylated portal of CB[7]. Rate enhancements of up to 500-fold have been measured. To the best of our knowledge, this �lubricating� effect of metallic cations on the motion of CB[n]s along an axle is unprecedented.

Cucurbituril slippage: Metallic cations as supramolecular lubricants

243rd National Meeting (2012)

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