Competition between Water-Water Hydrogen Bonds and Water-π Bonds in Pyrene-Water Cluster Anions

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Pyrene anion clusters are relevant in atmospheric and astrochemistry.
• Understanding hydration of aromatic systems is crucial for chemical processes.

Purpose of the Study:

• To investigate the structure and bonding of hydrated pyrene anion clusters.
• To elucidate the interaction between water molecules and the pyrene π-system.

Main Methods:

• Infrared Ar messenger photodissociation spectroscopy to obtain experimental spectra.
• Density functional theory (DFT) calculations to model cluster structures and interactions.

Main Results:

• Experimental spectra reveal OH stretching vibrational modes indicative of cluster structure.
• Water molecules form hydrogen bonds on the pyrene surface.
• Water-water interactions are stronger than water-π-system interactions.
• Three- and four-membered rings are the lowest energy conformers in larger hydrates.

Conclusions:

• The study provides insights into the hydration of aromatic anions.
• DFT calculations and spectroscopy successfully characterize these complex systems.
• Hydration structure is dictated by a balance of water-water and water-π-system interactions.