Date of Award

2016

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

College of Arts and Sciences

First Advisor

Ken D. Shimizu

Abstract

Non-covalent aromatic interactions govern many of the unique structures and properties of biological and synthetic molecules. Despite the importance of these interactions, their weak nature makes it challenging to study the interactions. To accurately measure weak non-covalent aromatic interactions in solution, we have designed molecular torsion balances that provide a quantitative measure of non-covalent intramolecular interaction strengths. First, we investigated the importance of electrostatic interactions in aromatic interactions. Substituent effects were strongly correlated with electrostatic Hammett parameters. In addition, the substituent effects were additive and showed significant direct substituent-arene interactions that support the recent direct substituent effect model. Next, the studies of dispersion interactions were carried out by introducing various sized arenes, alkyl groups, and heteroatoms. First, dispersion contributions in organic solution were found to be minimal. Second, the interaction surface distances played a more important role than the size of the alkyl groups.3 Lastly, larger changes in the interaction strengths were observed in the sulfur-arene versus the oxygen-arene interactions, presumably due to greater dispersion and steric interaction from sulfur atoms.

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