Ruthenium and Iridium Complexes for Applications in Solar Energy and Green Chemistry

Growing awareness of the negative impact of some chemical processes on the environment has driven interest in developing new, "greener" alternatives. This dissertation focuses on the development of three of these green systems. Chapters 2 and 3 will describe efforts at modeling important processes within dye-sensitized solar cells (DSSC) using a newly developed ruthenium(II) polypyridyl framework. Chapter 2 investigates electron transfer between the dye and the titanium dioxide semiconductor as a function of the anchoring moiety binding the surface. Hydroxamate anchors are found to facilitate the highest overall sunlight-to-electricity conversion efficiency. Chapter 3 will demonstrate a thiocyanate linkage isomerism process likely occurring under operating conditions in DSSCs. Chapter 4 will investigate singly oxidized cyclopentadienyl (Cp) and pentamethylcyclopentadienyl (Cp*) complexes of iridium(III). These singly oxidized species are related to proposed intermediates in the catalytic cycle of water oxidation catalyzed by these, and other Cp*Ir III precatalysts. Finally, Chapter 5 will investigate ligand effects in transfer hydrogenation catalysis. Our newly synthesized series of closely related Cp*IrIII demonstrate that even subtle differences in the ligand framework can have a marked effect on the catalytic efficiency. Additionally, evidence for the previously proposed monohydride transfer mechanism is provided by isolation of the proposed intermediate for our best catalyst.