ingest cdrApp 2017-07-05T20:20:40.362Z b743dd6f-fb31-445f-b2b9-a0aa4f8b7562 modifyDatastreamByValue RELS-EXT fedoraAdmin 2017-07-05T20:45:50.732Z Setting exclusive relation modifyDatastreamByValue RELS-EXT fedoraAdmin 2017-07-05T20:45:51.311Z Setting exclusive relation addDatastream MD_TECHNICAL fedoraAdmin 2017-07-05T20:45:59.258Z Adding technical metadata derived by FITS modifyDatastreamByValue RELS-EXT fedoraAdmin 2017-07-05T20:46:14.686Z Setting exclusive relation addDatastream MD_FULL_TEXT fedoraAdmin 2017-07-05T20:46:23.833Z Adding full text metadata extracted by Apache Tika modifyDatastreamByValue RELS-EXT fedoraAdmin 2017-07-05T20:46:44.821Z Setting exclusive relation modifyDatastreamByValue RELS-EXT cdrApp 2017-07-06T11:39:59.209Z Setting exclusive relation modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-01-25T07:26:35.897Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-01-27T07:57:06.046Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-03-14T04:19:39.451Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-05-17T15:57:29.330Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-07-11T02:47:21.959Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-07-17T23:07:08.101Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-08-15T19:16:33.128Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-09-21T19:37:23.567Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-09-26T22:52:29.862Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2018-10-11T23:29:26.270Z modifyDatastreamByValue MD_DESCRIPTIVE cdrApp 2019-03-20T17:12:29.099Z Catherine Pitman Author Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. Spring 2017 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. Spring 2017 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. Spring 2017 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017-05 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation Chemistry Alexander Miller Thesis advisor Michel Gagne Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 University of North Carolina at Chapel Hill Degree granting institution Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagné Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis; electrochemistry; hydricity; photochemistry; solar fuels eng Doctor of Philosophy Dissertation Chemistry Alexander Miller Thesis advisor Michel Gagne Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 University of North Carolina at Chapel Hill Degree granting institution Catherine Pitman Creator Department of Chemistry College of Arts and Sciences Molecular Photoelectrocatalyts for Solar Fuel Production: Discovery, Mechanism, and Exploration An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis, electrochemistry, hydricity, photochemistry, solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Chemistry Alexander Miller Thesis advisor Michel Gagne Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Catherine Pitman Creator Department of Chemistry College of Arts and Sciences An exploration of the chemistry of molecular photoelectrocatalysts, beginning with the Cp*Ir(bpy) framework, is presented. Chapter 1 covers approaches to hydrogen evolution with an eye towards solar fuel production. The importance of both metal-hydride species and methods to measure metal-hydride bond strength is discussed. In Chapter 2, the central complex of this dissertation, [Cp*Ir(bpy)(H)]+, is introduced when in situ electrochemical generation permits the construction of a photoelectrocatalytic cycle. Irradiation of neutral aqueous solutions containing [Cp*Ir(bpy)(H)]+ poised at cathodic potentials produces H2 in high Faradaic efficiency. Chapter 3 presents a general synthetic scheme whereby precipitation of Cp*Ir(bpy) and analogues from water and subsequent reaction with electrophiles enabled access to a wide range of water-soluble metal-hydride and metal-alkyl complexes. Chapter 4 explores the hydricity—the hydride donor ability—of Cp*Ir(bpy)- and (arene)Ru(bpy)-based hydrides. The hydricity of [Cp*Ir(bpy-COO)(H)]– is measured using a potential-pKa cycle, and the hydricities of the metal-hydrides accessed in Chapter 3 are measured relative to this reference complex. The thermodynamic measurements presented explain why [Cp*Ir(bpy)(H)]+ is stable in neutral, aqueous solutions in the dark. Chapters 5 and 6 present results of alterations to the [Cp*Ir(bpy)(H)]+ structure. In Chapter 5, Rh is exchanged for Ir, resulting in an entirely unexpected activation of Cp*. Formation of the transient [Cp*Rh(bpy)(H)][Cl] complex leads to in the more stable species (Cp*H)Rh(bpy)(Cl). The implications of this structure on the reduction of NAD+ are discussed. In Chapter 5, the hydride ligand is exchanged for a methyl ligand making [Cp*Ir(bpy)(CH3)]+. This metal-methyl complex is characterized and its photochemical reactions are explored. Kinetic order, radical traps and clocks, and isotope labelling suggest that excitation results in homolysis of the Ir–CH3 bond. 2017 Inorganic chemistry Chemistry aqueous catalysis; electrochemistry; hydricity; photochemistry; solar fuels eng Doctor of Philosophy Dissertation University of North Carolina at Chapel Hill Graduate School Degree granting institution Alexander Miller Thesis advisor Michel Gagne Thesis advisor Maurice Brookhart Thesis advisor Joseph Templeton Thesis advisor Marcey Waters Thesis advisor text 2017-05 Pitman_unc_0153D_16870.pdf uuid:6b4890c0-d209-4f3b-a44e-fcdc80f71cb4 proquest 2019-07-05T00:00:00 2017-04-10T20:38:30Z application/pdf 7672278 yes