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BUCKYBALLS NAB NOBEL Chemistry prize goes to discoverers offullerenes
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he 1996 Nobel Prize in Chemistry This led to a series of experiments has been awarded to three chemists carried out in early September 1985 by for their discovery of fullerenes, a Smalley, Kroto, Curl, and a number of family of highly symmetrical carbon-cage molecules whose prototypical member is Q^. The discovery of this new form of carbon has opened up an entirely new branch of chemistry. Richard E. Smalley, Gene & Norman Hackerman Professor of Chemistry and physics professor at Rice University, Houston; Robert F. Curl Jr., a chemistry professor at Rice; and Harold Kroto, a chemistry professor at the University of Sussex, Brighton, England, will share this year's prize, which is worth about $1.1 million. "It's a terrific feeling," Smalley says. "Obviously, I'm delighted and elated," Kroto says. "Most scientists, when Courtesy of Richard E. Smalley they start, they are just happy to do science, and they don't dream of this. It's really unbelievable. I think it is very good for U.K. science." "This is the dream of every kid who's ever owned a chemistry set," Curl says. Like so many seminal discoveries in science, the discovery of the fullerenes was serendipitous. Kroto, Curl, and Smalley came together to study carbon clusters because Kroto, a microwave spectroscopist, was interested in carbon-rich red giant stars. Curl, a microwave and infrared spectroscopist, was a friend of Kroto's who often collaborated with Smalley. And Smalley had designed and built a device for creating and characterizing clusters of almost any element. Through the early 1980s, Kroto had been studying long-chain polyacetylenes, the spectral signatures of which he had discovered in interstellar gas clouds and the atmospheres of red giant stars. Kroto's idea was to use Smalley's laser vaporization supersonic beam apparatus to study the formation of Clockwise from top: Curl, Smalley, and Kroto opened up these species. an entirely new branch of chemistry.
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Rice collaborators. The chemists generated carbon clusters by laser vaporization of graphite into a pulsed stream of helium, and they analyzed them by time-offlight mass spectrometry. The time-of-flight mass spectra generated by the experiments had peaks corresponding to the expected polyacetylenes. But the spectra also had a series of mass peaks corresponding to molecules containing an even number of carbon atoms ranging from about 40 to well over 100 atoms. Even more striking, under certain laser vaporization conditions, the mass peak corresponding to CCl0 totally dominated the spectrum. "The data are really quite compelling," Smalley told C&EN at the time (C&EN, Dec. 23, 1985, page 20). "If one looks at the peaks corresponding to the C56, C58, C62, and C64 clusters, they are all roughly the same intensity. There is no indication that they are building toward a structure that is very stable. You need an explanation for it." The then-controversial explanation developed by the team was that C^ was a spherical molecule with the geometry of a truncated icosahedron—a polygon with 60 vertices and 32 faces, 12 of which are pentagons and 20 of which are hexagons. It's the same geometry as that of a soccer ball. In the paper on their work that the chemists rushed to Nature [318, 162 (1985)], they adopted the admittedly fanciful name "buckminsterfullerene'' for the Qo cluster, in honor of architect R. Buckminster Fuller's pioneering studies of polygonal structures. The name stuck. Around the lab, the chemists called C6() "buckyball." For the next five years, Smalley, Curl, and coworkers at Rice, and Kroto and coworkers at Sussex, independently probed the photophysics and photochemistry of the carbon clusters, continually adding to the body of evidence supporting the fullerene hypothesis. One of the most convincing experiments, carried out at Rice, became known as the "shrink wrapping" experiment. C^ is hollow, with enough space inside it to contain one or more atoms. Almost immediately after the first series of experiments, the team showed that laser vaporization of graphite impregnated with lanthanum chloride produced a complex of C6() and a tightly bound lanthanum atom. The chemists used the same approach to produce complexes of C^ and cesium and potassium. Intense irradiation of such complexes with laser light did not dissociate the metOCTOBER 14, 1996 C&EN 7
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istry and physics of these new materials was on. Physics Nobel honors work Working independently, Smalley and on helium-3 superfluidity Kroto again were at the forefront. But now they led a growing horde of chemists The 1971 discovery that helium-3 becomes a superfluid at a temperature of worldwide. As the Royal Swedish Acade0.0027 K has garnered David M. Lee, my of Sciences put it in announcing the Douglas D. Osheroff, and Robert C. Nobel Prize: "A whole new chemistry has Richardson the 1996 Nobel Prize in developed to manipulate the fullerene Physics. Lee and Richardson are physstructure. . . . It is possible to produce suics professors at Cornell University. Osperconducting salts of C^, new threeheroff, a Cornell graduate student at the dimensional polymers, new catalysts, and time of the discovery, is now a physics new materials. ... From a theoretical viewprofessor at Stanford University. point, the discovery of the fullerenes has When the trio made its discovery, influenced our conception of such widely scientists had known for more than separated scientific problems as the galacthree decades that helium-4, when cooled to around 2 K, becomes a sutic carbon cycle and classical aromaticity, a perfluid. In this exotic state where keystone of theoretical chemistry." quantum effects dominate macroNo one has yet developed a practical use scopic properties, the atoms move cofor fullerenes, though it's not for lack of tryherently, leading to an absence of vising. But the real significance of the cosity. As a result, a superfluid can befullerenes may be that they forced chemists have bizarrely, such asflowingup and and physicists to view carbon differently. In over a container wall or slipping efa talk earlier this year, Smalley called Ca) "a fortlessly through tiny pores that sort of Rosetta Stone of what we now realwould impede a normal fluid. Opinion on the likelihood of findize is an infinity of new structures made of ing superfluidity in the rare isotope carbon one way or another." helium-3 changed from pessimism to Carbon nanotubes, for example, are optimism through the years, and not fullerenes, but the fullerene structural many groups tried unsuccessfully to motif provides a ready explanation for the observe it The Cornell team's breakstructure of nanotubes. Much of Smalley's through and subsequent work at a research now focuses on nanotubes, and number of labs have shown that superhis lab recently reported a method for profluid helium-3 is stranger and more ducing crystalline bundles of metallic, sincomplex than superfluid helium-4. The gle-wall carbon nanotubes (C&EN, July 29, discovery 'transformed the direction of theoretical and experimental research page 5). These nanotubes "appear to be in low-temperature physics," says one molecularly perfect," Smalley tells C&EN. physicist, and has implications for a "I am convinced they are truly metallic, range of phenomena, from superconcomparable to copper." He says he exductors to cosmic strings. pects nanotubes "to find practical applicaRon Dagam tions much more quickly than fullerenes." Smalley was born in 1943 in Akron, Ohio. He received a B.S. degree in chemisal from the complex. Rather, the fullerene tryfromthe University of Michigan, Ann Arshrank by a successive loss of twcxarbon bor, in 1965 and a Ph.D. degree in chemisatom fragments—the shrink wrapping— try from Princeton University in 1973, after until a critical size was reached that varied a stint as a research chemist at Shell Chemical Co. from 1965 to 1969. Smalley joined with the size of the encapsulated metal. But efforts at Rice and Sussex to pro- the Rice faculty in 1976. duce macroscopic amounts of fullerenes Curl was born in 1933 in Alice, Texas. were unsuccessful. Then, in 1990, came a He received a B.A. degree in chemistry bombshell: Two physicists, Wolfgang from Rice University in 1954 and a Ph.D. Kratschmer of Max Planck Institute for degree in chemistry from the University Nuclear Physics, Heidelberg, Germany, of California, Berkeley, in 1957. He and Donald R. Huffman of the University joined the Rice faculty in 1958. of Arizona, Tucson, reported a simple way Kroto was born in 1939 in Wisbech, to vaporize graphite to produce CCiL) and Cambridgeshire, England. He received a other fullerenes. All of the powerful struc- Ph.D. degree in chemistry from the Uniture determination tools of chemistry versity of Sheffield in 1964. He joined the were brought to bear on C^, C70, and oth- faculty of the University of Sussex in er fullerenes—immediately confirming the 1967. In 1991, he was named Royal Socifullerene hypothesis. ety Research Professor. And the race to understand the chemRudy Baum 8 OCTOBER 14, 1996 C&EN
Immunologists win Nobel in medicine The 1996 Nobel Prize in Physiology or Medicine has been awarded to immunologists Peter C. Doherty of St. Jude Children's Research Hospital, Memphis, and Rolf M. Zinkernagel of the University of Zurich for their discovery that a two-part signal is needed for an immune-system cell to recognize that another host cell is infected with a virus and to kill the virus.
Doherty (above), and Zinkernagel laid basis for unraveling cellularQ immunity.
Their discovery "laid a foundation for an understanding of general mechanisms used by the cellular immune system to recognize both foreign microorganisms and self-molecules," says the Nobel Assembly at the Karolinska Institute in Stockholm, which awards the prize. "It relates both to efforts to strengthen the immune response against invading microorganisms and certain forms of cancer, and to efforts to diminish the effects of autoimmune reactions in inflammatory diseases . . . multiple sclerosis, and diabetes." The killer cells are T-lymphocytes, so called because they reach immunological maturity in the thymus gland. In humans, a virus-infected cell manages to digest some of the virus protein, bind the fragments to its own native proteins—called human leukocyte group A (HLA) antigens—and send the molecular packages to its cell surface for display. HLA antigens identify a cell as "self." In mice, which were the subjects of Doherty's
