Probing Hydrogen-Bonding Preferences and Methyl Internal Rotation in Sotolon and Sotolon-(H₂O)_1,2.

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Supramolecular Chemistry

Background:

• Sotolon, a chiral furanone, possesses multiple oxygen atoms capable of hydrogen bonding.
• Understanding water's interaction with functional groups is crucial in various chemical and biological systems.
• Investigating early-stage hydration provides insights into solvation processes.

Purpose of the Study:

• To investigate the hydration of sotolon using microwave spectroscopy.
• To understand how water molecules interact with sotolon's functional groups.
• To probe the effect of hydration on sotolon's conformation and methyl group rotation.

Main Methods:

• Chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy was employed to study sotolon and its hydrated complexes.
• High-level theoretical calculations were performed to support experimental observations.
• Analysis of rotational spectra, including A/E splittings, provided detailed structural and dynamic information.

Main Results:

• A single dominant conformer of sotolon, stabilized by an intramolecular hydrogen bond, was identified.
• Hydration disrupts the intramolecular hydrogen bond, forming cyclic hydrogen-bonded structures with water.
• Water molecules significantly influence sotolon's conformation and the barrier to methyl group internal rotation.

Conclusions:

• Sotolon serves as an excellent model for studying water's preferential interactions with competing functional groups.
• Microwave spectroscopy reveals the intricate details of early-stage hydration and its impact on molecular structure and dynamics.
• Electrostatic interactions play a key role in stabilizing the hydrated complexes of sotolon.