Theses and Dissertations

Date of Award


Document Type


Degree Name



Chemical and Biomolecular Engineering

Committee Chair

Brooks Rabideau, Ph.D.


Several perarylphosphonium based mesothermal ionic liquids (ILs) have been shown to be stable at high temperatures for prolonged periods of time and with high heat capacities making them good candidates for use in many processes such as usage as a heat transfer fluid, as an absorbent for separation of aromatics from aliphatics, and as a solvent for high temperature reactions. Many, however, have melting points above 100o C, limiting their use. Recently, it was shown that the melting point of an IL can be lowered by simply increasing the dipole moment of the cation or by structurally rigidifying the cations movement with a carbon-to-carbon bond, preventing efficient crystal packing. The applicability of the dipole adjustment to additional anions of different sizes: BF4, PF6, NTf2, and BETI and the cause for the structural alteration melting point change needs to be investigated. To do this several ILs were synthesized, their melting points determined, and their crystal structures obtained. Using molecular dynamics, the melting process of these crystals were simulated, and several molecular dynamic tools were used to analyze the intermolecular energy changes. This allows for the key interaction changes to be determined and allows for a better understanding of how the melting point changes occur, to predict if these modifications are useful for similar compounds.