Cucurbit[8]uril•guest complexes: blinded dataset for the SAMPL6 challenge

We investigated the formation of host guest complexes between cucurbit[8]uril (CB[8]) and 14 cationic guest compounds (2 - 15) by(1)H NMR spectroscopy and isothermal titration calorimetry (ITC). Although these two component systems generally form 1:1 host:guest complexes, other stoichiometries are also observed (e.g. 1:2 host:guest and 3:1 host:guest) in situations where one guest fills roughly half of the cavity of CB[8] or where the guest contains multiple binding epitopes. We used the changes in chemical shift observed upon binding to glean information about the geometry of the host-guest complexes and in cases of slow exchange to confirm the host:guest stoichiometry. The complexes form with binding constants that range from 5.34 x 10(4) to 8.26 x 10(9) M-1. The complexes are driven by negative Delta H degrees values (-2.00 to -14.4 kcal mol(-1)). The data from these experiments were used as a blinded dataset for the SAMPL6 computational chemistry challenge. [GRAPHICS] .