Unprecedented Bonding Dynamics during THF and DMSO Molecular Hydration

Hydration of organic molecules determines the fascinating properties of aqueous solutions with challenges for understanding the bonding and electronic dynamics. We found three types of unusual interactions in terms of the O/C−H:O coupling hydrogen bonds, the charge-inverted H:O-C and H:O=S, and the HH repulsion bridged CHHO interactions at the THF and DMSO hydration interfaces. Perturbative differential phonon spectroscopy and the first-principles computations further unveiled that the polarization effects of solute dipoles and the inter- and intramolecular coupling interactions cooperatively and disparately relax these bonds. These findings shall enrich the connotation of hydration interfacial bonding profoundly by incorporating the inter- and intramolecular coupling, charge inversion, and the coupling-enabled cooperativity and polarizability upon perturbation, which should offer impacts on dealing with systems involving molecular interactions, such as cryoprotectants, electrolytes, etc.