Bouncing to a Nobel prize

Sir Harold Kroto has scored a chemistry Nobel prize for Britain for his pivotal role in discovering ’buckyballs’, Richard Stevenson reports.

The discovery and isolation of buckminsterfullerene has been high on most chemists’ list of Nobel-worthy achievements for a long time; the question has always been which of several credible candidates would share the accolade with ’Harry’. For no-one had any doubt that Kroto was the driving force behind the most newsworthy molecule of the 1980s. In the event, the Royal Swedish Academy of Sciences chose to recognise the contributions of Richard Smalley, the cluster chemist at Rice University, Houston, in whose lab the key experiments were carried out, and Robert Curl, the spectroscopist (also at Rice) who brought Kroto and Smalley together.

In the early 1980s Kroto was using microwave spectroscopy to study stellar atmospheres, particularly the carbon-rich stars, and began to speculate about the origin of certain long-chain carbon compounds that could be predicted from the spectra. Through Curl, Kroto discovered that Smalley had built a laser-supersonic cluster beam apparatus that could be used to investigate these molecules.

The story of how Smalley, Kroto, Curl, and three graduate students, J. R. Heath, Yuan Liu and S. C. O’Brien, began making carbon clusters with this apparatus; how the magic C60 line kept appearing in the spectra; how they solved the elegantly simple truncated icosahedron cage structure; how they named it after Buckminster Fuller, the designer of geodesic structures; and how they submitted their paper to Nature just 12 days after starting work ? this has become one of the best-known scientific adventure tales of recent years (Chem. Br., September 1996, p 32)

Sir Harold Kroto was born in 1939 in Wisbech, Cambridgeshire. He gained a PhD in chemistry from the University of Sheffield and since 1967 he has been at Sussex University, latterly as a Royal Society research professor. He was knighted in this year’s New Year honours list.

Robert Curl was born in Alice, Texas, in 1933, gaining his chemistry PhD in 1957 at Berkeley, and has worked at Rice since 1958.

Richard Smalley was born in 1943 in Akron, Ohio, and gained a PhD in chemistry from Princeton in 1973. He has been professor of chemistry at Rice since 1981, latterly with a joint appointment as a professor of physics.

Their Nature paper, published on 14 November 1985, attracted a flurry of interest - of both the critical and the enthusiastically accepting kind, as the Swedish Academy acknowledged. Although the Sussex?Rice group spent the next five years obtaining further evidence that their structure for C₆₀ and other members of the fullerene family were correct (Chem. Br., January 1990, p 40), it was only in 1990 that two physicists, W. Kr?tschmer and D. R. Huffman, succeeded in isolating the material.

The Kr?tschmer and Huffman method for making fullerenes, which passes an arc between graphite rods in a helium atmosphere, proved so simple that it led to an explosion of research into these intriguing compounds. So far no commercial applications have emerged, but that is not for lack of ideas. C₆₀’s chemical stability puts it into consideration for physical and material applications, particularly those that make use of its unusual electronic and optical properties, but methods have now been devised to derivatise it chemically and have further fuelled the rapidly growing literature.

Proposed uses for spherical fullerenes range from lubricants and catalyst supports, light intensity limiting devices and superconductors, to encapsulants for metals and drugs. The related carbon nanotubes extend the range of possibilities still further.

Britain’s return to Nobel-prizewinning form - and the popular appeal of the carbon balls - meant that chemistry for once drove physics into second place in the newspaper reports. As journalists swamped the Sussex University switchboard, Kroto had a larger stage than usual for his well-rehearsed criticisms of funding policy. He has always complained that he had to go to the US to carry out the experiments that led to the buckminsterfullerene discovery. He has criticised the low level of funding available in the UK for fundamental research and the pressure for industrial relevance. Newspaper reporters were quick to point out that on the very day of the Nobel prize announcement he had been turned down yet again for a research grant from the Engineering and Physical Sciences Research Council.

Cold news
Three US scientists have shared the Nobel prize in physics for their discovery of superfluid helium-3. David Lee, Robert Richardson and Douglas Osheroff produced the new phase in the Low Temperature Laboratory at Cornell University, New York, in 1972. This was a discovery of something that ’should not happen’.

Normal helium (⁴He) contains an even number of subatomic particles (2 protons; 2 neutrons; 2 electrons), therefore has integral spin, and is termed a boson. The rarer isotope ³He contains an odd number of particles, has half-integral spin, and is thus a fermion. At temperatures approaching absolute zero these small differences can have major effects on the isotopes’ physical characteristics.

Bosons follow Bose?Einstein (classical) statistics, which means that they condense into a least-energy state. Fermions follow Fermi?Dirac (quantum) statistics and should not actually be condensable in the lowest possible energy state. However, a more complex form of condensation, proposed in the Bardeen?Cooper?Schrieffer (BCS) theory for superconductivity, allows single electrons (themselves fermions by definition) to form ’Cooper pairs’ and act like bosons.

Lee and Richardson, with their then graduate student Osheroff (now a professor at Stanford University in California) were the first to achieve Bose?Einstein condensation of ³He, succeeding where many other research groups had failed. In fact, they had been trying to achieve a different phenomenon: a phase transition to a kind of magnetic order in ³He ice. No matter: the observant Osheroff noticed extra small jumps in the pressure curve they were measuring, and although at first they interpreted these as phase transitions in solid ³He, the researchers followed up with a second publication showing that there were two phase transitions in liquid ³He. The frictionless superfluidity of the new phase was soon confirmed, and further superfluid phases of ³He have since been found.

Immune response
This year’s Nobel prize for physiology or medicine has been awarded for work done in the early 1970s to unravel the molecular recognition processes involved in the body’s immune system. Peter Doherty and Rolf Zinkernagel, then working at the John Curtin School of Medical Research in Canberra, Australia, demonstrated conclusively that for the cellular immune system to work it had to recognise simultaneously both ’foreign’ molecules and ’self’ molecules - the major histocompatibility antigens (HLA antigens). This work demonstrated the importance of the HLA antigens and allowed Doherty and Zinkernagel to devise theoretical models to explain many aspects of immunology.

Subsequent molecular work has confirmed Doherty and Zinkernagel’s models and clarified the structural basis of their discovery: that a small part of the foreign agent - a viral peptide, for example - is directly bound to a defined variable part of the body’s own histocompatibility antigens, and that it is this complex that is recognised by the specific recognition molecules of the T cells that then hunt down the intruders.

Swiss-born Zinkernagel was a visiting fellow at the Curtin School at the time of the work. He is now head of the Institute of Experimental Immunology in Zurich. Doherty, born in Australia, has been at the St Jude Children’s Research Hospital in Memphis, Tennessee, since 1988.

Source: Chemistry in Britain