Role of Host–Guest Charge Transfer in Cyclodextrin Complexation: A Computational Study

Abstract

Charge transfer (CT) was proposed to play a role in the cyclodextrin (CD) complexation with guest molecules. To elucidate the importance of CT interactions, here we used computational methods of quantum mechanics, docking, and molecular dynamics (MD) to investigate α-CD complexes with aromatic guest molecules of nitrobenzene, carboxybenzene, benzoate, 4-nitrophenol, and 4-nitrophenolate. Considering host–guest CT in the docking has more of a chance to search reasonable guest orientations relative to α-CD matching the experiment, compared to that without CT. The CT interaction enlarges the difference in binding affinities of varied guests, as evidenced from potential of mean force (PMF) MD calculations. Energy decomposition of the total enthalpy and entropy shows the CT influence on the binding reactions in detail and indicates that there are considerable compensating effects of individual contributions from the binding partners and surrounding water. Charge transfer reduces the total dipole of α-CD by 9% ...