Dimethyl Sulfoxide Complexes Detected at Ambient Conditions

Area of Science:

• Atmospheric Chemistry
• Chemical Physics
• Environmental Science

Background:

• Dimethyl sulfide (DMS) is a primary natural sulfur source emitted from oceans.
• Atmospheric oxidation of DMS produces dimethyl sulfoxide (DMSO), a key intermediate.
• Sulfate aerosols formed from DMS oxidation significantly influence climate and air quality.

Purpose of the Study:

• To investigate the role of hydrogen bonding in the atmospheric chemistry of DMSO.
• To quantify the formation of binary hydrogen-bound complexes involving DMSO.
• To understand how water and other molecules interact with DMSO and affect its atmospheric behavior.

Main Methods:

• Experimental identification of water·DMSO and methanol·DMSO complexes in an Argon (Ar) matrix.
• Determination of the Gibbs free energy for methanol·DMSO complex formation at room temperature.
• Comparative analysis of complex formation between DMSO and acetone to assess electronic effects.

Main Results:

• Binary hydrogen-bound complexes of water·DMSO and methanol·DMSO were successfully identified.
• A Gibbs free energy of 0.7 kJ/mol was determined for methanol·DMSO complex formation.
• Complex formation significantly decreased when sulfur in DMSO was replaced by carbon (acetone).

Conclusions:

• Hydrogen bonding, particularly with water, is likely significant for DMSO in the atmosphere.
• DMSO hydrates may be relatively abundant compared to monomeric DMSO.
• The electronic nature of the atom bound to the oxygen acceptor influences hydrogen bond strength and complex stability.