PhD defenses.

New tools and technologies based on nature’s light-emitting chemistry

Abstract: Bioluminescent enzymes (luciferases) are among the most popular reporters for illuminating biological processes in vivo. Luciferases emit light by catalyzing the oxidation of small molecule luciferins. Since no excitation light is needed, there is virtually no background signal. Thus, bioluminescence imaging (BLI) is extremely sensitive and well-suited for applications in tissues and whole organisms.

Fundamental Investigations of Metal-Metal Oxide Model Catalysts and the Liquid/Vapor Interface of Aqueous Solutions

Abstract: Fundamental surface science investigations are primarily concerned with understanding the chemistry that occurs at the interface of phases, such as the solid/gas, solid/liquid, and liquid/vapor interface. Surface science investigations have led to breakthroughs in understanding chemisorption and physisorption on heterogeneous catalysts, reactions that occur at the interface of electrodes, and hydrogen bonding in aqueous solutions.

Developing new imaging tools inspired by nature's flashlight

Abstract: Bioluminescence imaging with luciferase-luciferin pairs is routinely used to monitor cellular events in real time. This technology relies on enzymes (luciferases) that catalyze the adenylation and oxidation of small molecules (luciferins), resulting in light. While powerful, this imaging modality has rarely been applied to multicomponent imaging due to a lack of distinguishable probes. Recent efforts have expanded the bioluminescence toolkit by engineering luciferases that selectively react with synthetic substrates (i.e., “orthogonal pairs”).

Secondary Coordination Sphere Effects on Properties and Reactivities of Metal complexes

Abstract: In nature, metalloproteins can perform difficult transformations with high selectivity and efficiency through precise control of the primary and secondary coordination sphere. Synthetic chemists have developed biomimetic ligand scaffolds to better understand the coordination environments in the active sites of metalloproteins. However, besides the ligands covalently bound to the metal center, control of the secondary coordination sphere that is comprised of non-covalent interactions also has significant influence in complex properties.

Understanding the Mechanisms of Salt Formation in New Particle Formation and Growth Using Nanoparticle Composition Measurements and Computational Modeling

Abstract: Atmospheric nanoparticle formation and growth processes are major sources of uncertainty in our understanding of global climate. However, nanoparticle composition is notoriously difficult to measure below 30~nm due to their incredibly low mass, and so a full understanding of the compounds that contribute to nanoparticle growth still remains elusive. In addition, nanoparticle physical and chemical properties are continuously changing at different sizes.

Hydrogen-Atom-Transfer Initiated Radical Bicyclizations: Concise Syntheses of Highly Oxidized Abietane Diterpenoids

Abstract: This dissertation describes the development and applications of a radical bicyclization reaction that is initiated via hydrogen-atom-transfer (HAT) to 1,1-disubstituted alkenes. In the first chapter, biomimetic radical polyene cyclizations and HAT-mediated C-C bond forming reactions are reviewed. Mechanistic and strategic aspects pertaining to radical-polar crossover are emphasized throughout, highlighting unique possibilities offered by oxidative or reductive termination.

Investigation of phosphate-based reactions in an evolving RNA world

Abstract: In light of the unique ability of ribonucleic acid (RNA) to both retain genetic information and catalyze chemical reactions, it has been proposed that life on Earth progressed through an RNA world. It has been demonstrated that phosphate was present on an early Earth and due to the prevalence of modern-day energy metabolisms that rely on phosphorylation, it is likely that phosphate played a key role in prebiotic chemistry. We characterize a number of phosphate-based reactions ranging from formation of triphosphates to RNA repair.

Investigations into the Reactivity of Transition Metal Complexes with Redox-Active Ligands for Proton Coupled Electron Transfer and Nitrene Transfer

Abstract: The work presented in this dissertation centers around understanding the propensity of transition metal complexes with redox and proton non-innocent ligands to serve as proton and electron transfer agents either in proton-coupled electron transfer or group transfer reactivity.

Quantum Effects in Small Clusters Using the Diffusion Monte Carlo Method

In this dissertation, the diffusion Monte Carlo (DMC) method is applied to study the ground state of anionic hydrogen, neutral para-hydrogen, and Lennard Jones clusters. The nuclear quantum effects in anionic hydrogen and neutral para-hydrogen clusters are investigated based on previous claims related to the existence of “magic numbers”. In anionic hydrogen clusters H−(H2)n, the binding energies are found to be a smooth function of increasing cluster size, and their ground state wavefunctions are highly delocalized and do not resemble the structures of the potential energy surface minima.


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