X-ray absorption spectroscopy as a tool for characterizing sulfur based reactive intermediates

• Main Author: Martin-Diaconescu, Vlad
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/24162

Sulfur K-edge X-ray absorption spectroscopy (XAS) has proven to be a great tool for the investigation of sulfur oxidation states and sulfur-metal ligand bonding. In this thesis, XAS has been applied in the detection and characterization of sulfur-based reactive intermediates and products of photo-reacted sulfur species, with applications in both bioinorganic and inorganic chemistry. Low molecular weight thiols and their derivatives have important protein modulation, signal transduction and antioxidant activities. This includes glutathione (GSH), nitrosoglutathione (GSNO), and lipoic acid (LA), which are involved in complex redox pathways resulting in a variety of intermediates and products that can be difficult to characterize. These compounds have been used as models for thiol nitrosation and oxidation reactions, and their reactivity was probed with sulfur K-edge XAS, which has been developed into a valuable tool for the investigation of sulfur-containing radical species and related non-radical intermediates. XAS was also applied to investigate the reactivity of p-toluene sulfonyl chloride, an initiator in metal catalyzed living radical polymerization, to explore the effect of hyperconjugation on the reactivity of the S-Cl bond. A series of model compounds of the form RSO₂G(G = -Cl, -OH, -alkyl) were used to evaluate the effect of aryl versus alkyl R groups on the photo-reactivity and orbital mixing of the S-G bond.