Competition Between Water-Water Hydrogen bonds and Water-pi Bonds in Pyrene-Water Cluster Anions

17 January 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


We present infrared spectra and density functional theory calculations of hydrated pyrene anion clusters with up to four water molecules. The experimental spectra were acquired using infrared Ar messenger photodissociation spectroscopy. Water molecules form clusters on the surface of the pyrene, forming hydrogen bonds with the -system. The structures of the water clusters and their interaction with the system are encoded in the OH stretching vibrational modes. We find that the interactions between water molecules are stronger than between water molecules and the -system. While all clusters show multiple conformers, three- and four-membered rings are the lowest energy structures in the larger hydrates.


polyaromatic hydrocarbons
water clusters
vibrational spectroscopy
hydrogen bonding

Supplementary materials

Supporting Information
Mass spectrum of anionic pyrene and its hydrated clusters; experimental and calculated spectra of Py- dihydrate; top and side view of Py-·(H2O)2 conformers; experimental and calculated spectra of Py- trihydrate.; top and side view of Py-·(H2O)3 conformers; experimental and calculated spectra of Py- tetrahydrate; top and side view of Py-·(H2O)4 conformers; patterns of motion of the symmetric OH stretching modes in conformer 4A; coordinates of selected conformers


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