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.