Published in JACS, researchers in the Papanikolas and Waters groups, in collaboration with members of the Meyer group at Carolina Chemistry and the Papoian Group at the University of Maryland, describe how solid-phase peptide synthesis has been applied to the preparation of phosphonate-derivatized oligoproline assemblies containing two different RuII polypyridyl chromophores coupled via "click" chemistry.
In water or methanol the assembly adopts the polyproline II (PPII) helical structure, which brings the chromophores into close contact. Excitation of the assembly is followed by rapid, efficient intra-assembly energy transfer to the inner RuII. The oligoproline/click chemistry approach holds great promise for the preparation of interfacial assemblies for energy conversion based on a family of assemblies having controlled compositions and distances between key functional groups.
The sun provides about 10,000 times our current daily energy needs and is the ultimate solution to the world's need for renewable, environmentally friendly energy. However, to be practical, utilization of solar energy requires energy storage on massive scales, far greater than any existing technology. Photosynthesis provides a role model in this regard, with the only practical approach consisting of an "Artifical Photosynthesis" strategy with "solar fuels" as the product. Solar fuels are high-energy molecules like carbohydrates or hydrogen with the energy of the sun stored in chemical bonds. Target reactions are water splitting into hydrogen and oxygen and light-driven reduction of CO2 to CO or other reduced forms of carbon.
At the U.S. DOE-funded Energy Frontier Research Center here at the Department of Chemistry, the goal is to generate solar fuels using dye-sensitized photoelectrosynthesis cells, DSPEC. Molecules do most of the work in this approach, absorbing light, transferring electrons, and catalyzing reactions. The DSPEC design also benefits from a modular approach, allowing the separate parts to be synthesized, evaluated, and improved in an iterative manner. Using an integrated team-based structure, we are making real progress in translating our concept of the DSPEC into a viable prototype. Many challenges lie ahead but there is light shining at the end of a very long tunnel.