Competition between In-Plane vs Above-Plane Configurations of Water with Aromatic Molecules: Non-Covalent...

Area of Science:

• Physical Chemistry
• Chemical Physics
• Spectroscopy

Background:

• Non-covalent interactions between aromatic molecules and water are crucial for chemical and biological processes.
• Accurate modeling of these interactions is essential for understanding molecular configurations.

Purpose of the Study:

• To investigate the water complexes of polycyclic aromatic hydrocarbon 1,4-naphthoquinone (1,4-NQ) using rotational spectroscopy.
• To analyze the binding sites and configurations of water molecules interacting with 1,4-NQ.
• To benchmark theoretical methods for predicting energy orderings in aromatic-water complexes.

Main Methods:

• Rotational spectroscopy was employed to study 1,4-NQ-(H2O)1,2 and 1,4-NQ-(H2O)3 complexes.
• Analysis of spectral data to determine molecular structures and non-covalent interactions.

Main Results:

• Water molecules in 1,4-NQ-(H2O)1,2 complexes bind via O-H···O and C-H···O hydrogen bonds, lying on the 1,4-NQ plane.
• 1,4-NQ-(H2O)3 complexes exhibit both in-plane and above-plane water configurations.
• Observed interactions include O-H···O, C-H···O, and lone pair···π-hole interactions.
• Theoretical methods struggle to predict energy orderings due to competing C-H···O, π, and π-hole interactions.

Conclusions:

• The study provides detailed insights into water arrangements around 1,4-naphthoquinone.
• Highlights significant challenges in accurately modeling non-covalent interactions in aromatic-water systems.
• Emphasizes the need for improved theoretical approaches for complex molecular interactions.