Public Release: 

Virginia Tech Chemists Build Supramolecules With Applications To Solar Energy Conversion

Virginia Tech

BLACKSBURG, VA -- Virginia Tech Chemistry Professor Karen Brewer and colleagues are building metal-based molecules aimed at producing systems that will bind to organic elements. This could result in a new class of highly-reactive catalysts for creating organic materials or even for creating high-energy fuels from the common elements that make up air and water. This work is supported by the National Science Foundation.

Brewer is building supramolecules, which are large molecules composed of subunits with each subunit designed to perform a specific task. A supramolecule is still a single molecule but it is engineered to act as a complex system. Brewer and her students have designed supramolecules, or "molecular devices," that perform their designed function as a result of interaction with light.

At the American Chemical Society meeting in San Francisco on April 13-17, she will present research on the design of molecular devices that collect electrons when photoinitiated. When subunits of the system absorb photons of light the system is triggered to collect electrons. This allows the conversion of light energy into electrical energy.

Brewer's research group first introduced electron-collecting supramolecules in 1994. Since then, the group has refined the molecules so that they are more efficient and so that the molecular devices can collect electrons at different locations within the supramolecule.

In one application, where a rhodium metal center is used, electron collection results in a chemical change in the device that opens up points of contact on the molecule's center. These points of contact could be used to bind to organic materials, Brewer reports. Thus the highly-reactive metal-based molecules would be catalysts for the creation of organic materials.

By being designed to bind to specific elements in water, supramolecules could extract hydrogen for use as a fuel; or supramolecules could be created to capture elements from carbon dioxide to be converted to flammable gases such as methanol. "The result could be a fuel that produces a large amount of heat from a low weight of material," Brewer explains.

Brewer presented a paper on "Spectroscopic and electrochemical properties of mixed-metal supramolecular complexes with applications as molecular devices for photoinitiated electron collection," on Sunday, April 13. Co-authors are Virginia Tech graduate students Sumner Jones, Elizabeth Bullock, and Jeff Clark.

Bullock presented a poster on a different approach to "Synthesis and characterization of a device for photoinitiated electron collection," on Sunday. Co-authors are Brewer and graduate student Sharon Molnar.

Contact for further information:

Karen J. Brewer, Associate Professor, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0212 (540)231-6579 or kbrewer@chemserver.chem.vt.edu
http://www.chem.vt.edu/chem-dept/brewer/brewer.html

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