Date of Award

5-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Committee Chair

Dor Ben-Amotz

Committee Member 1

Adam Wasserman

Committee Member 2

Chittaranjan Das

Committee Member 3

Suzanne Bart

Abstract

My research aims to address long-standing questions in physical chemistry about water-mediated hydrophobic and ionic interactions of biological relevance. For example, my research has provided some of the first experimental evidence of water driving hydrophobic groups apart rather than pushing them together in solution, thus damping rather than enhancing the contact free energy of oily molecules in water. I have also obtained some of the first experimental evidence concerning the structure of water structure around nonpolar groups in solution, thus demonstrating that hydrophobic hydration-shells have a clathrate hydrate-like structure. In addition, I am currently studying ionic interactions in water, which are important due to the ubiquity of solvated ions in living systems, along with three additional projects investigating solute polarity, charge, and substituent placement effects on solute aggregation and water structure. Finally, I have contributed to one project that probes aggregation of hydrophobic solutes in binary alcohol/water mixtures and to another, highly collaborative project that addresses the continued debate regarding the structure of hydrated protons in liquid water. Here, the combined application of Raman spectroscopy and multivariate curve resolution (Raman-MCR) to aqueous solutions has been used to reveal solute-correlated (SC) spectra, which contain vibrational spectral features arising from the hydration shell around a dissolved solute, as well as the solute itself. Such spectra are used to obtain information about changes in water structure, as a function of solute identity, size, shape, polarity, and charge. Moreover, Raman-MCR is used to probe water-mediated interactions between solute molecules, by detecting interaction-induced changes in the SC spectra of variable solution concentrations.

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