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Stepwise Solvation of Organic Radical Cations by Ionic Hydrogen and Halogen Bonding in the Gas Phase

The ability to characterize the interactions between ions and solvent molecules plays a critical role in understanding fundamental aspects of thermodynamics in solution chemistry. These interactions are often difficult if not impossible to observe in solution due to the number of solvent molecules far exceeding that of the ions. However, this challenge can be circumvented in the gas phase which enables the isolation and study of reactions between a single ion and single solvent molecule.
Within the field of ion-molecule chemistry are two sub-categories of interactions known as ionic hydrogen bonds (IHBs) and ionic halogen bonds (IXBs). In these interactions, the incorporation of a charged species permits ion-dipole interactions which are innately stronger than those found in dipole-dipole interactions among neutral molecules.
This dissertation describes and explains the interactions which take place between halogenated benzenes (F-, Cl-, Br-, and Iodobenzene) and neutral polar molecules (water, acetonitrile, acetone, and methanol). Additional studies on ionic hydrogen bonding involve the exploration of protonated benzonitrile monomer and dimer solvated by methanol. All systems were examined using the mass-selected ion mobility technique using the VCU mass selected ion mobility mass spectrometer. Thermochemical equilibrium measurements, in conjunction with density functional theory (DFT) calculations, were performed, enabling comparison between experimentally and theoretically determined binding energies. Additionally, the DFT calculations were able to validate hypothetical predictions for the lowest energy structures of each interaction. Furthermore, the averaged collision cross sections of the benzonitrile dimer radical cation, protonated benzonitrile dimer, and benzonitrile solvated hydronium ion were elucidated using the technique of ion mobility where experimentally determined cross sections were compared with theoretical collision cross section calculations on predetermined geometries that were optimized using DFT calculations.

Identiferoai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-7094
Date01 January 2019
CreatorsMason, Kyle
PublisherVCU Scholars Compass
Source SetsVirginia Commonwealth University
Detected LanguageEnglish
Typetext
Formatapplication/pdf
SourceTheses and Dissertations
Rights© The Author

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