Control of the ketone to gem-diol equilibrium by host-guest interactions.
In water, N-methyl-4-(p-substituted benzoyl)pyridinium cations, BP-X, exist in equilibrium with their hydrated forms (gem-diols), whose concentrations depend on the para substituent (-X). In the presence of cucurbit[7]uril (CB[7]), the benzoyl group shows a preference for the CB[7] cavity, and the ketone to gem-diol equilibrium is shifted toward the keto form, meaning that the stabilization realized through hydrophobic interactions of the benzoyl group in the CB[7] cavity exceeds the hydrogen-bonding stabilization of the gem-diols in the aqueous environment.
Rawashdeh
Abdel Monem M
AM
Department of Chemistry, Yarmouk University, Irbid, 211-63, Jordan.
Thangavel
Arumugam
A
Sotiriou-Leventis
Chariklia
C
Leventis
Nicholas
N