Date of Award
Summer 2007
Document Type
Dissertation - Restricted
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Kincaid, James R.
Second Advisor
Strommen, Dennis
Third Advisor
Reid, Scott
Abstract
The properties of Ruthenium (Ru) polypyridine complexes make them promising choice as photosensitizers for artificial solar energy conversion devices. My work focuses on the study of the properties of the excited states of these complexes in solution and in zeolites by using transient Resonance Raman (TR 2 ) or Time-resolved Resonance Raman (TR 3 ) spectroscopy. To investigate the effects of spectator ligands on excited state properties of 3 MLCT states, Resonance Raman (RR) and Transient Resonance Raman (TR 2 ) spectra are acquired for a series of heteroleptic complexes of ruthenium; i.e., RuL 2 (bpz) 2+ , where bpz is 2,2'-bipyrazine and L is 2,2'-bipyridine (bpy) or an alkylated 2,2'-bipyridine (i.e., diazafluorene, daf or 4,4'-dimethyl-5,5'-diethyl-2,2'-bipyridine, dmdeb). Resonance Raman spectra acquired at different excitation lines for the ground state complexes reveal selective enhancement of modes associated with the coordinated bpz or the spectator ligands, as expected. The TR 2 spectra, acquired with excitation at 355 nm, confirm selective population of a bpz-localized 3 MLCT excited state for each complex. Both the ground state RR spectra and the excited state TR 2 data indicate that only slight shifts are observed in a few modes as the donor strength of the spectator ligands are varied. Such data for a systematically manipulated set of complexes, acquired here for the first time, imply that both the RR and TR 2 spectral parameters are reliably characteristic for a given ligand, varying only slightly as the nature of other ligands in the complex are changed..