Inhibition of C(2)-H Activity on Alkylated Imidazolium Monocations and Dications upon Inclusion by Cucurbit[7]uril

The inclusions of 1-methyl-3-alkylimidazolium cations (ICn+, n = 4, 6, and 8) and 3,3′-bis(3-(1-methylimidazolium))-1,n-alkane (DICn2+, n = 4, 6, and 8) in the macrocyclic cucurbit[7]uril result in a decrease (up to 25-fold) of the C(2)-H/D exchange rate constants and an increase in the C(2)-H pKa values (ΔpKa = 0.34 to 1.45). The alkyl chain lengths were found to play an important role in the extent of C(2)-H activity inhibition, upon complexation with cucurbit[7]uril.