Interactions of limonene with the water dimer

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Terpenes like limonene are prevalent in the atmosphere.
• Understanding interactions between volatile organic compounds and water is crucial for atmospheric chemistry.
• Water clusters can influence the properties and reactivity of organic molecules.

Purpose of the Study:

• To characterize the interactions between two water molecules and limonene.
• To identify different structural arrangements (isomers) of the limonene-(H2O)2 complex.
• To elucidate the binding mechanisms and preferred conformations.

Main Methods:

• Chirped-pulse Fourier transform microwave spectroscopy was employed to probe the molecular complexes.
• Experimental spectroscopic parameters were compared with theoretical predictions from computational methods.
• Analysis focused on identifying hydrogen bonding patterns and conformational preferences.

Main Results:

• Seven distinct isomers of the limonene-(H2O)2 complex were observed and identified.
• Water dimers bind to limonene through a combination of O-H⋯π and C-H⋯O interactions.
• A preference for binding to equatorial conformations of limonene was noted, with hydrogen bonds involving both endocyclic and exocyclic double bonds.

Conclusions:

• The study provides detailed insights into the non-covalent interactions governing water-limonene complexes.
• Specific binding modes and isomer preferences were established for the water dimer interacting with limonene.
• Findings contribute to a better understanding of water's role in atmospheric chemistry involving terpenes.