Inhibition of C(2)-H/D exchange of a bis(imidazolium) dication upon complexation with cucubit[7]uril

Abstract

Inclusion of the alpha,alpha'-bis(3-(1-methylimidazolium))-p-xylene dication in cucurbit[7]uril (CB[7], K(CB[7]) = (4.3 x 10(9) M(-1)), with C-H...O=C hydrogen bonding between the guest C(2)-protons and the carbonyl oxygens of the host portals, inhibits the H/D exchange for the C(2)-proton with k(OD) (25 degrees C, D2O) decreasing from 1.2 x 10(3) M(-1) s(-1) (pKa = 22.3) in the absence of CB[7] to 0.9 M(-1) s(-1) (pKa = 25.4) in the presence of 1.1 equiv. CB[7].