4,4' Functionalized 2,2'-Bipyridines : Synthesis and Applications as Catalytically Active Nanoparticle Stabilizers and Ligands for Ruthenium Dye Molecules

This thesis presents two applications of 2,2'-bipyridine (bipy) derivatives, the first involves their use as stabilizers for nanoparticle (NP) catalysts and the second is concerned with the use of bipy ligands for ruthenium dye molecules applied in dye sensitized solar cells (DSCs). Chapters 2 and 3 describe the work concerning the ability of bipy derivatives to stabilize catalytically active Rh NPs for ionic liquid based, biphasic arene hydrogenation, with cationic bipy derivatives being first evaluated with a series of monocyclic aromatic hydrocarbons. The recyclability of the cationic bipy stabilized Rh NP systems were evaluated in catalysis and analyzed further by X-ray spectroscopy. The stereoelectronics were examined with respect to catalytic activity using various neutral bipy ligands. The differences in catalytic activity were rationalized with steric and electronic arguments throughout. Chapter 4 concerns the application of a cationic bipy derivative as a modifier/stabilizer in the Pd NP catalyzed partial hydrogenation of hexyne to 1-hexene. Factors for the high selectivity have been studied, including the presence of a ligand and/or an IL. The Pd NPs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Leaching was investigated by atomic absorption spectroscopy and the kinetcis of the reaction analyzed using a Langmuir-Hinshelwood model. Chapter 5 describes three heteroleptic ruthenium complexes incorporating new ancillary bipy based ligands synthesized by sequential connection of different alkyl functionalities using a triazole linker, prepared via click chemistry. These complexes were effective dyes when applied in DSCs with both a volatile and non-volatile IL electrolyte. The complexes were characterized and compared using their photovoltaic conversion efficiencies as well as their photophysical and electrochemical properties. A stability study was conducted at 60 °C for 1000 h to determine the most stable substituent.