Arene-Perfluoroarene Interactions in Solution
Ga Young Lee, Elizabeth Hu, Arnold L. Rheingold, K. N. Houk, Ellen M. Sletten
Abstract
A systematic study of arene-perfluoroarene interactions in solution is presented. Using a combination of NMR titration experiments, X-ray crystallography, and computational analysis, we analyze the effects of fluorination, substituents, ring size, and solvation on the arene-perfluoroarene interaction. We find that fluorination, extension of the π systems, and enhancement of solvent polarity greatly stabilize the stacking energy up to 3 orders of magnitude (Ka = <1 to 6000 M–1), with the highest Ka achieved for the interaction of water-soluble variants of perfluoronaphthalene and anthracene in buffered D2O (pD = 12). Combining computational and experimental results, we conclude that this impressive binding energy is a result of enthalpically favorable electrostatic and dispersion interactions as well as the entropically driven hydrophobic effect. The enhanced understanding of arene-perfluoroarene interactions in aqueous solution sets the stage for the implementation of this abiotic intermolecular interaction in biology and medicine.