Gating and Entropy in Guest Exchange by Rebek's Sportsballs. Theoretical Studies of One-Door, Side-Door, and Back-Door Gating

摘要

"Tennis ball" and "softball" are spherical dimeric molecules held together by hydrogen bonds yet able to exchange guest molecules. Mechanisms of guest exchange were explored with AMBER~* force field calculations. The "one-door" S_N1 and the "side-door" S_N2 gating mechanisms are predicted for guest exchanges in the "softball", while a dissociation mechanism is predicted for the "tennis ball". Entropy changes have an important influence on the guest exchange mechanisms.