Professor Kenneth Leopold

CSENG Chemistry
College of Science & Engineering
Twin Cities
Project Title: 
Structure and Dynamics of Molecular Complexes

This group uses supercomputing resources to carry out quantum chemical calculations on the structures and internal dynamics of weakly bound molecular complexes. Broadly speaking, an important aim is to elucidate the effect of microsolvation on reactivity. The work involves fundamental science but, at the same time, informs our understanding of atmospheric chemical processes, particularly aerosol nucleation. Overall, the combination of theory and experiment provide a more complete picture of the systems studied than can be obtained from either one alone. MSI support also provides the flexibility to address new questions as they arise.

Currently, the researchers are interested in the incipient hydrolysis of acid anhydrides and the effect of microsolvation on proton transfer. The anhydride work stems from the group's recent publications on carboxylic sulfuric anhydrides derived from formic, acetic, trifluoroacetic, and acrylic acids. A Feature Article for the Journal of Physical Chemistry describes similar experiments on the propiolic acid derivative, reviews the group's prior work on these anhydride systems, and reports new statistical thermodynamic calculations. An experimental and theoretical study of the water complex of acetic sulfuric anhydride has also been published and experiments on the monohydrate of trifluoroacetic anhydride has been completed.

In the arena of proton transfer work, the researchers have completed studies of the superacid CF3SO2OH (triflic acid), its mono-, di-, and trihydrates, and its complex with trimethylamine. They have also conducted studies of methanesulfonic acid (CH3SO2OH) and are currently recording spectra of its monohydrate.

Future work will include experimental and computational studies of benzenesulfonic acid (C6H5SO2OH) and its hydrates, higher hydrates of methanesulfonic acid, and the hydrates of pyvalic anhydride, (CH3)3C(=O)OC(=O)C(CH3)3. The researchers also plan to study the trifluoroacetic acid – trimethylamine complex, in this case as a likely collaboration with St. Cloud State University. For all these systems, ab initio and DFT calculations help the researchers narrow spectral searches, aid in the assignment of spectra, and supplement the interpretation of experimental results.

Research by this group was featured on the MSI website in October 2015: A New Atmospheric Sulfur Compound.

Project Investigators

Kaitlyn Belmont
Anna Huff
Jeffy Jeffy
Professor Kenneth Leopold
Nathan Love
CJ Smith
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