This research involves the development of tools for examining fast proton transfer in heterogeneous condensed phases, including polymers and proteins, and the formation of practical physical and theoretical models for their use. Thus, this effort includes design of new substrates, synthetic methodology, kinetic analysis, and theoretical modeling. Proton transfer encompasses a vast array of physiologically and chemically important processes. Most of these processes occur in heterogeneous media and relatively simple diffusion models have been used to account for the rates in such systems up to this point. Professor Tolbert's work will include the synthesis of new photoacids, studies of proton transfer dynamics, photocatalysis studies, studies of proton transfer at interfaces and in supercritical fluids and studies of Green Fluorescent Protein (GFP). The studies proposed represent an effort to advance our understanding of excited state acidity so that the tools available for studying excited-state proton transfer are as accessible as those for studying photoexcited electron transfer. The possibility of using "super" photoacids to catalyze chemically amplified reactions such as photo polymerizations and depolymerizations will be investigated. Matrix effects on the fluorescence properties of GFP are currently of great interest. The proposed studies in biological excited-state proton transfer in GFP will address some of these effects. Understanding these effects could greatly expand the usefulness of GFP as a biological tool.
With this award, the Organic and Macromolecular Chemistry Program supports the research of Professor Laren Tolbert of the School of Chemistry and Biochemistry at Georgia Institute of Technology. Proton transfer is a fundamental process in numerous chemical and biological systems. Achieving a better understanding of the factors controlling excited state acidity and the mechanisms of proton transfer in diverse environments are therefore highly desirable goals. The chemical industry is increasingly moving toward so-called "green" chemistry, which involves heterogeneous solventless or minimal solvent "complex fluid" environments. Thus experimental approaches that are amenable to studying proton transfer in these systems are required. Professor Tolbert's approach has been to elucidate the transition state by synthesizing unique substrates, then using these to test various models for proton transfer both in the strong acid and weak acid regime. Professor Tolbert has been unusually successful in involving students at all levels in research and these students have contributed significantly in all areas of chemistry. The strong international collaborations and proven track record of Professor Tolbert in developing minority Ph.D. students will make significant contributions to the human resources needs of the chemical enterprise in the United States.
