Chemists Keep an Eye on the `Buckyball'
Sphere-shaped carbon molecule has potential for diverse materials
IT's nothing unusual for chemists and physicists to tinker with elements like cooks, to find new combinations and form new compounds. But when the discovery is a recipe to make a new form of carbon - one of the most common elements and a basic building block of life and much of what we eat, make, and use - it's perhaps reason for a bit of excitement.
Add an aesthetic appeal - the new form is shaped like a soccer ball - and the whole world can identify with what might normally be the scientifically esoteric. Stir in a dash of intrigue - the recipe was lost, then found. Add a pinch of unconventionality - it was discovered outside the normal scientific grant process. And it all adds up to Carbon 60, also known as Buckminsterfullerine, because its geometry is like a geodesic sphere and no less novel.
``It took a while to sink in, but we finally realized that we are probably the first people on earth to ever see this stuff,'' says University of Arizona physicist Donald Huffman, recalling when he and his co-discoverers glimpsed at the crystals formed by the 60-atom molecule. ``It's like suddenly discovering a three-dimensional benzene ring.''
Dr. Huffman was referring to the versatile hexagonal molecule of six carbons and six hydrogens that is a fundamental industrial material, with uses in making nylon, epoxy resins, detergents, oil additives, drugs, dyes, wood preservatives, and aspirin. Others compare ``buckyball'' (as Carbon 60 is also known) to boron, another element whose caged forms have produced a rich chemistry with numerous applications.
Huffman and longtime colleague Wolfgang Kr"atschmer of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and their graduate students, Lowell D. Lamb and Konstantin Fostiropoulos, published their recipe and a confirmation of the structure of ``buckyball'' last year. Since then, chemists have hailed the development as a start of a new, diverse field of materials science, as promising as the uses of the other two forms of solid carbon: diamond and graphite.
``We have run into a new material with incredible prospects,'' says Francois Diederich, an organic chemist at the University of California, Los Angeles, one of the researchers who have shown that Carbon 60 holds potential for a new class of rechargeable batteries, among other things. ``It's really something new. It's not a development out of something that was before.''
The scientific world has known of the existence of a 60-carbon molecule since chemical physicist Richard Smalley and colleagues at Rice University in Houston detected its presence, predicted its soccer-ball geometry, and gave it its names in 1985. But it was known to exist only in minute quantities under special laboratory conditions - until the Arizona/Germany announcement in Nature magazine in September.
NOW, Dr. Smalley says, Carbon 60 may turn out to be the oldest molecular substance in the universe, because its resistance to breakdown by light may have allowed molecules of it to endure since their original formation. And already improved methods of producing it hold promise to make it a bulk commodity.
``It's really quite bizarre that this late into the history of mankind that we've found a third form of carbon that is available in such large amounts,'' Smalley says. ``And that virtually guarantees that it will have major technological applications.''
That was evident in late November, just two months after the Arizona/Germany announcement, when a Materials Research Society symposium in Boston drew some 500 scientists, who delivered 25 papers and stayed from 5 p.m. until 1 a.m. In the crowd were researchers from International Business Machines, Exxon, Bell Laboratories, and other corporations.
``When talk turned to applications, few people were forthcoming,'' says Andrew Kaldor, director of resource chemistry at Exxon Research and Engineering. ``There's a lot of patent activity going on in this area.''
Mr. Kaldor, who helped organize the Boston symposium, says part of the reticence may result from a lack of firm results as yet. But he said the excitement is warranted. ``The imagination can work much faster than your synthesis techniques,'' he says, explaining that developing methods to make Carbon 60-based compounds and then purifying them takes time.
Among potential applications sought, Kaldor says, are binding buckyballs to salts needed for making semiconductors, using it in dry and wet lubricants, caging catalysts inside the molecule for industrial applications, and making polymers from it for uses ranging from cars to luggage.
At the University of California at Berkeley, organic chemist Joel M. Hawkins and his colleagues added oxygen to buckyball, using osmium tetroxide. Such early developments are significant, because they show that buckyball can undergo chemical reaction without falling apart, he says.
Dr. Hawkins says the oxygenated form may help reveal subtleties of buckyball's chemical bonds that will help chemists better understand how it reacts.
Huffman says he and Dr. Kr"atschmer believe they actually first made Carbon 60 as early as 1983. They spent years understanding what they were seeing and convincing themselves that oil from a vacuum pump, among other things, wasn't contaminating their results. Huffman also lost his knack for making it. But graduate student Lamb took it upon himself to rediscover it, and did, finding that a faulty pressure gauge may have been to blame.
Their caution also was reinforced, Huffman says, by the experience of Stanley Pons and Martin Fleischmann, who violated scientific protocol in 1989 by announcing their so-called cold-fusion discovery through the news media and then suffered the wrath of the scientific world, which was unable to replicate their experiments.
IN contrast, making buckyball has proved little problem because it is a relatively simple process of vaporizing graphite to helium in a vacuum chamber, then separating Carbon 60 from the resulting soot using a solvent. Some well-equipped high-school chemistry labs could do the experiment, but Huffman discourages them from doing so for the time being. Carbon 60 has not yet been screened for carcinogenicity or other health threats.
Under a licensing agreement through Research Corporation Technologies, a technology-transfer firm, Materials and Electrochemical Research Corporation (MER) of Tucson, Ariz., is manufacturing and selling research quantities of Carbon 60. A gram goes for $1,250.
James C. Withers, MER's chief executive officer, says researchers making inquiries or purchases, who haven't insisted on confidentiality, include Exxon, Allied Signal, Argonne National Laboratory, and the Office of Naval Research.
Some researchers are producing their own Carbon 60, and MER actually encourages that, Mr. Withers says, because it will assist development of Carbon 60 for profitmaking purposes. By that stage, Withers said, the price will have dropped substantially as larger-scale production methods are developed from the Arizona/Germany laboratory apparatus.
Smalley, who says he and his colleagues have used a Sears arc welder to improve on the Arizona/Germany method, predicts that Carbon 60 will eventually cost only a few dollars a pound.
Meanwhile, Carbon 60 may only be the beginning. The Arizona/Germany recipe also produced Carbon 70 in small quantities. It has a slightly squashed sphere geometry - like a rugby ball. And researchers are already on the trail of ``fullerines'' with 72, 74, 76, 80, 82, and 84 carbons, Exxon's Kaldor says. Huffman also believes that Carbon 240 exists.
But the legacy of buckyball will be as much one of how big discoveries do not necessarily require big dollars, Huffman says. His Carbon 60 work resulted from institutional support, a year's leave sponsored by the Alexander von Humboldt Society that put him and Kr"atschmer in closer contact, and what he called the ``bootleg'' method of finding supplies.
``One thing I've been kind of proud of is it hasn't taken big government grants to do this,'' he says.