Purdue University Graduate School
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Oily Molecule Hydration-shell: The Influence of Crowding, Electrolytes and Small Molecules

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posted on 2021-05-07, 19:01 authored by Aria J BredtAria J Bredt

Open questions remain on the influence of various conditions and ion behavior on the hydration-shell of oily molecules. My research uses Raman spectroscopy and Raman multivariate curve resolution to study the hydration-shell of oily molecules as tools to help answer some of these open questions.

More specifically, I present results on the effect of molecular crowding on the structure of water around various oily molecules, and report the effect of molecular crowding on hydrophobic crossover. These results are important, as crowding has the potential to influence several fields, such as biology and environmental sciences. This work shows that increasing molecular concentration results in oil-oil crowding, decreases the tetrahedrality of the water structure around the oily molecules, and subsequently, the crossover temperature.

In addition to studying the hydration-shell under crowded conditions, I also present work on ion affiliation for the hydration-shell of an oily molecule. Ion affiliation for oil/water interfaces has been an ongoing topic of research since the Hoffmeister experiments because of their effect on biological processes. This study focuses on hydroxide and its affiliation for tert-butyl alcohol in comparison to other electrolytes. These results show iodide is less repelled by the oil/water interface in comparison to hydroxide.

Finally, I present findings on the influence of hydrogen peroxide in comparison to other small molecules on the water structure of an oily molecule. Hydrogen peroxide has been shown to reach supercooled temperatures, which may be useful in future studies of liquid phase transitions or studies on solute behavior at supercooled conditions. It is found that hydrogen peroxide does not significantly influence the water structure around tert-butyl alcohol, while other small molecules display significant water structure changes.

All these projects aim to contribute results to heated debates, as well as share information for future experiments.


Degree Type

  • Doctor of Philosophy


  • Chemistry

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Dor Ben-Amotz

Additional Committee Member 2

Garth Simpson

Additional Committee Member 3

Christopher Uyeda

Additional Committee Member 4

Lynne Taylor