Wet Sunscreens in the Gas Phase: Structures of Isolated and Microsolvated Oxybenzone.

New insights into the structural intricacies of solvated sunscreen compounds are presented. Using high-resolution rotational spectroscopy with supersonic jets and quantum-chemistry calculations, we navigate the conformational space of oxybenzone and oxybenzone-water clusters. We unambiguously assign the global minimum structure, resolving any prevailing ambiguities, and locate the primary hydration sites of the ground-state enol conformer. Two microsolvated molecular models of oxybenzone are validated by rotational spectroscopy of isotopically enriched species. Theoretical predictions based on these models suggest that water influences the ground-state enol-keto energetic constraints and that its effect is biased depending on which water docking-site is at play.