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Title: Proton-Coupled Electron Transfer in Organic Synthesis and Materials Science: Photochemical Strategies for Olefin Hydroamidation, Biomass Valorization, Plastic Recycling, and Diamond Surface Functionalization
Authors: Nguyen, Suong
Advisors: Knowles, Robert
Contributors: Chemistry Department
Keywords: C–C bond cleavage
Diamond surface functionalization
Photoredox Catalysis
Proton-Coupled Electron Transfer
Subjects: Chemistry
Organic chemistry
Materials Science
Issue Date: 2022
Publisher: Princeton, NJ : Princeton University
Abstract: Proton-coupled electron transfer (PCET) is a redox process in which electrons and protons move together in a single elementary step. It is used ubiquitously in biological processes to generate reactive radical intermediates through homolytic activation of strong chemical bonds. Recently, organic chemists have made great strides towards harnessing this powerful mechanism to develop a wide range of new chemical transformations.This dissertation describes unique applications of PCET that range from synthetic methodology to materials functionalization. Chapter 2 presents the development of olefin hydroamidation reactions for the construction of aliphatic C–N bonds. These reactions proceed through transient amidyl radicals that are formed via PCET activation of the N–H bonds in N-alkyl amides. Chapter 3 describes the use of PCET in a new catalytic method to valorize lignin biomass into arene feedstocks under ambient conditions. PCET activation of the hydroxyl groups along the polymer backbone produces alkoxy radicals that promote chain fragmentation through C–C bond β-scission. Building on this initial study, chapters 4 and 5 detail the development of a catalytic technology that can chemically recycle commercial phenoxy resin, novel degradable-by-design hydroxylated polyolefins, and epoxy thermosets. These depolymerization processes produce well-defined and isolable small molecule product mixtures that can be derivatized to yield monomers amenable to subsequent condensation polymerization. This recycling technology has the potential to establish new links within a circular polymer economy and influence the development of next-generation polymers that are degradable by design, thereby helping to address global concerns about plastic pollution and sustainability. Finally, chapter 6 describes a versatile strategy for the controlled surface functionalization of single crystalline diamond. This approach employs hydrogen atom transfer, a variant of PCET, to enable the activation of C–H bonds on the diamond surface. The resulting carbon-centered radicals react with various radical acceptors to form a range of carbon-heteroatom bonds with high surface coverages. As an important application, these novel functionalization methods provide a reliable platform to covalently attach molecules of interest to the surface for nanoscale quantum sensing experiments. Altogether, this dissertation illustrates the vast potential of PCET to address diverse challenges across many areas of research.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Chemistry

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