SDSC and UCSD Chemists Help Put New Face on Benzene

Published 04/12/1996

For more information, contact:
Ann Redelfs
SDSC
619-534-5032
619-534-5113 (FAX)
redelfs@sdsc.edu

SAN DIEGO, CA - The cover of the April 1, 1996, Chemical & Engineering News features an image of a cyclohexatriene molecule that resulted from the computational and experimental collaboration of Kim K. Baldridge, a computational chemist at the San Diego Supercomputer Center (SDSC), and Jay S. Siegel, associate professor of chemistry at the University of California, San Diego (UCSD).

The molecule, trisbicyclo[2.1.1]hexabenzene, centers on a six-carbon benzene ring that has been forced to become a cyclohexatriene. In its normal state, benzene's six carbon-carbon bonds have the same length and are equivalent, while six delocalized electrons float above and below the ring, giving benzene its aromatic character. When these six floating electrons are localized -- associated with a particular bond -- the benzene becomes a cyclohexatriene.

The C&EN cover story, titled "Scientists Localize Benzene's Electrons, Trap Elusive Cyclohexatriene Motif," discusses the work of Baldridge, Siegel, and Siegel's lab at UCSD, and the related research of K. Peter C. Vollhardt, professor of chemistry at UC Berkeley.

By creating molecules that force benzene to become cyclohexatriene, the research has provided new insights into aromaticity and, in practical terms, may open up new ways to control chemical reactivity and to synthesize molecules, according to Siegel.

C&EN also features the computational work that made it possible to synthesize Siegel and Baldridge's cyclohexatriene. While synthesizing a molecule in the lab may take six months, computational results can often be available in a week. Using SDSC's CRAY C90 and Intel Paragon, Baldridge's computational efforts helped focus Siegel's attention on the most likely candidates for successful synthesis.

Baldridge has also received a Visiting Professorships for Women grant from NSF's Education and Human Resources Directorate, as part of which she is teaching courses in computational chemistry and modeling at UCSD.

SDSC, a national laboratory for computational science and engineering, is sponsored by NSF, other federal agencies, the State and University of California, and private organizations; is affiliated with the University of California, San Diego; and is administered by General Atomics. For more information, see http://www.sdsc.edu or contact Ann Redelfs, SDSC, redelfs@sdsc.edu, 619-534-5032.