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.

Nickel-catalyzed cross-coupling and cross-electrophile coupling reactions

Abstract: In this talk, three projects will be discussed that utilize nickel catalysis for C–C bond formation. While the most common coupling reactions employ palladium catalysts, the unique properties and benefits of nickel catalysts enable greater development of this field.

Trace Gas Emissions from California Landfills and Dairies: The Impact on Disadvantaged Communities and the Environment

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Understanding NO3 oxidation of monoterpenes at different scales: Insights from molecular modeling, chamber experiments, and field observations

Abstract: It has been shown though numerous field studies, laboratory measurements, and the occasional modeling study that NO₃ radical oxidation of monoterpenes is a significant, though often overlooked, source of secondary organic aerosol (SOA). However, this generalization is complicated by the fact that while most abundantly emitted monoterpenes (e.g. β-pinene, ∆-carene, and limonene) have moderate-to-high SOA yields with NO₃ radical, the most abundantly emitted monoterpene (α-pinene) has a negligible SOA yield with NO₃.

Aqueous sequestration and solid-phase separation of actinyl ions with PAMAM dendrimers

Abstract: Nuclear energy is a sustainable baseload power source with low life cycle carbon emissions, and no emissions during power plant operations. Research into new separatory schemes and technology to reprocess used nuclear fuel (UNF) can further improve carbon emissions and the efficiency of the nuclear fuel cycle. Improved aqueous separatory and extraction agents have the additional benefit of making the use of radionuclides safer with their ability to carefully segregate selected materials from environments such as natural bodies of water or waste streams.

Macrocyclic β-Hairpin Peptides Derived from Amyloid β, Medin, and the IQGAP1 WW Domain And Conversion of In-Person Chemistry Courses to Online Versions in Response to the COVID-19 Pandemic

Bioorthogonal cyclopropenones for biomolecule ligation and reaction development

Abstract: Bioorthogonal chemistry enables researchers to study biomolecules in their native environments without perturbing endogenous cellular processes. Over the past two decades, significant strides have been made in developing new, and refining existing, bioorthogonal reactions. The continuously expanding toolbox has opened avenues for tackling increasingly complex biological questions. Despite these advances, limitations remain.

UCI Department of Chemistry

PhD defense