Gas-Phase Infrared Spectroscopy of Anionic Fluoranthene-Water Clusters

Graphene exhibits properties that make it a promising candidate for water desalination and purification applications. The underlying interactions of water with graphene’s π system are encoded in the vibrational spectrum of the combined system. However, the infrared spectroscopic response of bulk water tends to obscure the signatures of water-graphene interactions in solution phase spectroscopy. Clusters of water with anionic polycyclic aromatic hydrocarbons (PAHs) offer a set of convenient model systems to study the molecular-level details of water interacting with graphene-like molecular structures. With an anionic PAH, the negative charge is delocalized in its π system and forces the water molecules to interact with it through hydrogen bonds. In this work, we present infrared (IR) photodissociation spectra of hydrated fluoranthene anion clusters, [Fl⁻(H₂O)ₙ] (n = 1–4). By comparing experimental spectra with density functional theory calculations, we elucidate the structure and arrangement of water networks on the fluoranthene anion surface.