[CCoE Notice] Colloquium Announcement * October 22, 2010 * Randolph Thummel * University of Houston, Houston, TX

[Lewis, Lindsay R]

***** Colloquium *****
Center for Integrated Bio and Nano Systems
Houston Chapter of IEEE Nanotechnology Council and Houston Chapter of IEEE Magnetics Society
Friday, October 22, 2010
12:30 p.m. (Refreshments served at noon)
Room: W122 Building D3

Designing Ligands to Capture the Sun

Randolph Thummel

John and Rebecca Moores Professor of Chemistry
University of Houston, Houston, TX

The project involves the rational design, preparation and study of model systems for the photoredox catalyzed decomposition of water into hydrogen and oxygen.  Particular attention will be paid to the bond breaking (O-H) and bond making (H-H, O=O) steps required in such a process. The ideal catalyst will be readily available, soluble in water, and absorb strongly in the useful region of the solar spectrum.  It will be stable with a high turnover number and have a high quantum yield for the conversion of light into useful redox equivalents. The initially examined systems are metal complexes involving Ru(II) where one coordination site on the metal is occupied by a water molecule and the other sites involve polypyridine ligands.

Two design approaches are under careful study.  The first approach involves an investigation of photooxidation of a Ru(II) aqua complex to the corresponding Ru(II) oxo  system.  We hope to take advantage of the increased basicity of an appropriately designed ligand in the photoexcited state of the complex to facilitate deprotonation of the bound water thereby assisting the oxidation step.  The second approach involves the synthesis of a dinuclear metal complex in which a supramolecular bridging ligand holds two Ru(II) centers in close proximity such that their bound waters are located close to one another.  A series of bridging ligands has been prepared and converted to their Ru(II)-Ru(II) complexes.  In the presence of a sacrificial oxidant at pH = 1, these complexes have been found to oxidize water to form dioxygen with high turnover numbers. Somewhat surprisingly the corresponding mononuclear Ru(II) complexes are also efficient water oxidation catalysts.

Bio of Prof. Thummel:

Randy Thummel is the John and Rebecca Moores Professor of Chemistry in the UH College of Natural Sciences and Math.  He earned his B.S. degree from Brown University in 1967 and his Ph.D. in Chemistry from UC Santa Barbara in 1971.  After a two year postdoctoral fellowship at the Ohio State University, he joined the UH faculty in 1973.  In 1990-91 he was a Senior Fulbright Fellow at the Université de Strasbourg and in 2005 he won the UH Award for Excellence in Research.  He is the author of more than 170 refereed research papers. His research is sponsored by the NSF and the DOE and relates to the synthesis of novel ligand systems and their application to the design of photosensitizers with application in the utilization of solar energy.

Contact Prof. Jiming Bao (jbao at uh.edu) if you would like to arrange for a time to meet with Prof. Thummel.







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