1. Biomimetic Systems for Solar to Fuel Conversion Christopher J. Chang UCB Chemistry LBNL Solar Energy Workshop 28-29 March 2005

2. Global Energy Deficit 2000 World Energy Assessment, 2000 2050 Solar Energy 1.2 × 10 5 TW 600 TW available ? fossil fuels (10.2) biomass (1.2) wind/hydro (max 2.7 TW) nuclear (0.8) renewable (0.3) fossil fuels (10.2 TW) biomass (max 7 TW) 10,000 new nuclear plants (10 TW) wind/hydro (0.3) 10.1 TW short 12.8 TW (U.S. 3.3 TW) 35 TW

3. Photosynthesis in a Beaker Solar energy stored in energy-rich molecules Hydrogen affords a clean, CO 2 -neutral fuel

4. Reframing the Hydrogen Economy Solar energy stored in heteroatom molecules, not H 2 Light must be used to drive reactions of M-X or M-O bonds

5. Photosystem II: Nature’s Paradigm of Solar to Fuel Light Harvesting Proton-Coupled Electron Transfer Catalysis/Energy Storage

6. Challenges for Biomimetic Solar to Fuel Conversion Multielectron Photochemistry (n 1h /1e – events or 1h /ne – ) Bond-Forming Catalysis with Light Metals (O 2, H 2, X 2 production using Mn, Fe, Co, Ni, Cu, Zn) Controlling Proton and Electron Transfer (facilitates charge separation and catalysis) Supramolecular Self-Assembly (spatial organization of components)

7. O—O Bond Making and Breaking in Nature Photosystem II O—O formation Cytochrome c oxidase O—O cleavage  G in  G out G.T. Babcock Biochim. Biophys. Acta 1998, 1365, 170

8. Biomimetic Approach to O—O Bond Formation Attack of nucleophilic substrate on electrophilic metal–oxo O–Atom Transfer O—O Formation