Molecular Dynamics of Methyl Viologen-Cucurbit[n]uril Complexes in Aqueous Solution

作者：El Barghouthi Musa I^*; Assaf Khaleel I; Rawashdeh Abdel Monem M

来源：Journal of Chemical Theory and Computation, 2010, 6(4): 984-992.

DOI：10.1021/ct900622h

In this work, molecular dynamics (MD) simulations have been used to study the dynamics of the inclusion complexes of methyl viologen (MV) with cucurbit[n]uril, CBn (where n = 6, 7, and 8) in aqueous solution. The obtained MD trajectories were analyzed and post-processed using the Molecular Mechanics-Poisson-Boltzmann Surface Area (MM-PBSA) method to shed some light on the host-guest intermolecular forces that play a significant role in the formation of the CB inclusion complexes. MV exhibits partial inclusion into CB6 cavity, while deep inclusion was observed for the larger macrocyclic hosts with the two cationic groups interacting with the carbonyl portals. The extracted snapshots reveal an increase in the macrocycle distortion of CB6 and CB7 upon inclusion of the guest molecule. MM-PBSA calculations indicate that CB7 forms the most stable complex with MV. The host-guest electrostatic interactions are the dominant contribution to the complex stability. Furthermore, van der Waals interactions add significantly to the complex binding free energy. The Potential of Mean Force (PMF) for the host-guest distance was obtained by umbrella sampling. No energy barriers were obtained for the guest movement inside the host cavity except in the case of CB6.

• 出版日期2010-4