Hydrogen bond-like equatorial C–H⋯O interactions in aqueous 1,3-dioxane: A combined high-pressure infrared and Raman spectroscopy study

Our results demonstrate that the equatorial C–H groups of 1,3-dioxane form hydrogen-bond-like C–H⋯O interactions more readily than do the axial C–H groups. The peak frequency of the strong axial C–H stretch band of 1,3-dioxane in a dilute D2O solution possesses an unusual non-monotonic pressure dependence, which indicates enhanced C–H⋯O hydrogen bond formation at high pressure. We performed density functional theory calculations to predict the relative energies and total interaction energies of 1,3-dioxane/(water)n clusters and found that the equatorial C–H groups are more favorable sites for hydrogen bonding than are the axial C–H groups.