Super Bowl

Chemist Scott's 'buckybowls' may hold more promise than their spherical cousins

By Michael Seele
Chronicle Editor

Buckyballs, the soccer ball-shaped molecules touted as revolutionary when they were discovered over a decade ago, may not have lived up to their promise yet, but Prof. Larry Scott (Chemistry) is adding to their list of potential applications by creating pieces of them in his laboratory.

Scott was the first scientist to synthesize large fragments of buckyballs, dubbed "buckybowls" by the science press, and has found they exhibit properties that hold vast potential.

Buckyballs, the nickname for a family of molecules called buckminsterfullerenes (after the architect who popularized the geodesic dome which the molecules resemble), are made entirely of carbon atoms linked with unusual chemical bonds. The first buckyballs were composed of 60 carbon atoms, called C-60, though larger variants of these "fullerenes" have since been discovered. The only practical application thus far is the computer industry's use of another fullerene relative, the buckytube, as an atomic-scale probe.

Scott's bowls are fragments of buckyballs, some as large as 60 percent of a C-60 fullerene. But they are not carved from buckyballs; they are synthesized from scratch. Scott made his first buckybowls in 1990 and has since created many more, while exploring their unique properties.

"What we've been doing is learning how to build networks of carbon atoms that have the same pattern of five- and six-sided rings as C-60," Scott said. "They also have the same curvature as the ball. We believe they have as much or more potential in the long run as buckyballs or buckytubes."
Prof. Larry Scott (Chemistry) holds a model of his buckybowl molecule next to a model of a buckyball. (Photo by Gary Gilbert)

Perhaps the buckybowl's most intriguing property is its electron-holding capability, Scott said. "The buckybowl has the ability to take up electrons and give them back up later, under the right conditions, in higher concentrations than buckyballs."

Scott believes that may facilitate the invention of plastic batteries. They would be lighter, smaller and more environmentally friendly than the rechargeable batteries now used to power cellular telephones and laptop computers, and thus would allow for further miniaturization of portable electronic devices.

The molecule's shape may also allow it to bond with other molecules and since it fits over the buckyball much like a contact lens, it may be able to serve as a medium that links other substances to the balls.

Under natural conditions, such as in graphite, carbon atoms are bonded together in flat sheets resembling honeycombs, Scott explained. But in 1985, scientists discovered that after heating the carbon to more than 2,000 degrees Fahrenheit in a helium atmosphere, buckyballs could be culled from the residue.

Scientists knew they put carbon into the process and pulled buckyballs out the other end, but no one understood the step-by-step chemical transformation that took place until Scott developed his method for making buckybowls. He is the first scientist to use a rational process, rather than a scattershot approach, to create such molecules.

"We built special features into the molecules that will form the bonds we want," he said. Scott fits the carbon atoms around the edge of the sheet with atoms or groups of atoms that break off when heated. The carbon atoms are left in a highly reactive state and bond with distant carbon atoms at predetermined places around the edge of the sheet - something they wouldn't ordinarily do - thus lifting the rim of the bowl.

Scott is working to create larger bowls with this method and hopes to be able to synthesize an entire buckyball within a few years.

"Nobody had thought to use temperature in this way," Scott said. "It's the sort of thing any organic chemist could have thought of.

"One of the highest compliments scientists can pay to each other is saying, 'Gee, I wish I'd thought of that.'"

Scott said he has been hearing many of those compliments lately.

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