Doctor of Philosophy (PhD)
Current global energy consumption relies heavily on the use of fossil fuels, which releases greenhouse gases into the atmosphere. This advances the rate of anthropogenic climate change. In efforts to slow the effects of climate change, energy dense materials are needed to offset current harmful energy uses. The conversion of solar energy into electricity through solar panels and the subsequent use of electricity toward energy storage, or the production of chemical fuels, are promising methods for these goals. Electrocatalysts are poised to be ideal materials which can do these transformations. Increasing catalytic efficiency is an attractive prospect to make these materials even more useful, especially when degradation and deactivation can occur rapidly. This is often observed in molecular electrocatalysts. There are three main categories of catalyst stabilization techniques: ligand tailoring, immobilization, and confinement. Of these, confinement is the most promising, as no modifications are generally needed of the parent molecular electrocatalyst. Confinement systems such as metal-organic frameworks are useful, but are not typically suited for electrocatalysts as they lack conductivity. Supramolecular coordination cages are ideal electrocatalyst stabilization systems which can encapsulate guest molecules and are conductive, rendering electrochemical measurements applicable to these systems. Unfortunately, prior research on this is sparse.
This dissertation covers the assessment of supramolecular coordination cages as suitable systems for use in electrochemical environments and measurements of the electrochemical activity of redox-active guests. A library of cages, built from literature precedents, is presented and the electrochemical performance of the cages is assessed and quantified. A series of redox-active guest molecules are tested for incorporation within a cage, and several novel host-guest complexes are formed. Electrochemical testing reveals that the effect of encapsulation upon redox activity varies, but in at least one case, the electrochemical behavior of the guest remains intact while encapsulated. While attempting to form variations on a redox-active cage, an unprecedented lower ordered football-like capsule is discovered, and its relationship to the cage is determined. Overall, this work demonstrates the use of supramolecular coordination cages as useful stabilization environments for future combinations with molecular electrocatalysts, especially those suffering from rapid deactivation, to increase catalytic efficiency.
Bujol, Ryan Joseph, "Anionic Supramolecular Coordination Cages Based on Catecholate Ligands: Synthesis, Electrochemical Properties, and Encapsulation of Redox-active Probes" (2023). LSU Doctoral Dissertations. 6039.
Available for download on Tuesday, January 15, 2030