Harry Kroto (1939–2016) Discoverer of New Forms of Carbon

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COMMENT OBITUARY Harry Kroto (1939–2016) Discoverer of new forms of carbon.

arry Kroto was part of the team that arose from a combination of mass-spectra discovered buckminsterfullerene, data and circumstantial evidence. This was the football-shaped carbon-60 hardly the gold standard of single-crystal Hmolecule that came to be known as a bucky- X-ray analysis for absolute molecular struc- ball. The realization that such a large mol- ture determination. However, the football ecule could self-assemble from hot carbon structure followed Occam’s razor: it tied vapour forced a reassessment of the science together many observations in a simple and of carbon. By prompting searches for other elegant way, and yielded many predictions structures — carbon nanotubes and nano that were later proved to be correct, includ- SOCIETY ANNE PURKISS/THE ROYAL wires were among the materials later found ing the structure of a second fullerene, C70. — the discovery ultimately provided a foun- Absolute confirmation of these structures dation for nanoscience and nanotechnology. came five years later, when physicists Don Kroto, who died on 30 April, was born Huffman and Wolfgang Krätschmer and their Harold Krotoschiner in 1939 in Wisbech, groups worked out how to make C60 in bulk. UK, the son of German refugees. During Today, the buckyball is a crucial component the Second World War, his father Heinz of solar cells. was interned on the Isle of Man as an enemy In 1996, Kroto shared the Nobel Prize alien, and Kroto and his mother Edith went in Chemistry with Smalley and one of us to live in the town of Bolton. After the war, (R.F.C.), and was knighted. From 2002 to the family stayed in Bolton, where his father 2004, he served as president of the Royal opened a balloon factory and shortened the expansion: a high-pressure gas was passed Society of Chemistry, and in 2004 he left family name to Kroto. After finishing school, through a small orifice into a large vacuum Sussex to take up a chair at Florida State Kroto studied chemistry at the University of chamber to cool the molecules and stop all University in Tallahassee. Sheffield, completing his undergraduate chemical reactions. Harry was strongly opinionated. He did degree in 1961 and his PhD in 1964. The technique offered the perfect way to not profess modesty, and as an atheist, he After two postdoc positions, Kroto and his test whether vaporized carbon would con- would often engage his religious acquaint- wife Margaret moved to Brighton in 1967, dense to form carbon chains similar to those ances in fierce debate. But with children (he where he took up a teaching post at the Uni- found in certain interstellar environments. had two sons), he was always terrific. After versity of Sussex. During the 1970s, Kroto So in 1985, Kroto travelled to Houston to receiving the Nobel, he devoted much of his began work that led to a lifelong fascination work in Smalley’s lab. It was during this visit time to elevating the importance of science with the chemistry of interstellar space. that he, along with Smalley and his group teaching. Seeing that the football-like struc- Kroto studied a class of linear molecules (including the two of us), discovered C60 ture of C60 would resonate with almost called cyanoacetylenes with the atomic and the other fullerenes. And Kroto was any child, he would set up games in which composition H–(C)n–C;N. These were able to prove his hypothesis that long carbon buckyballs would pop out of unexpected hypothesized to exist in the molecular clouds chains were reaction products of condens- places, or have children assemble buckyballs that surround stars with carbon-rich atmos- ing carbon. themselves. pheres. He combined molecular spectroscopy Before that, three different crystal- Harry had an impish sense of humour of these carbon chains — which he created line forms, or allotropes, of carbon were similar to that of the British comedy group fleetingly in the lab — with measurements known: graphite, diamond and lonsdaleite, Monty Python, which he greatly admired. made by radioastronomers who were aiming a rare modification of diamond. The first He also had the distinction of being the only to detect the same molecules in the material two provided text-book examples of how Nobel laureate to have appeared on stage with surrounding carbon stars. By the early 1980s, physical properties reflect atomic struc- the actor Ian McKellen — in a school produc- radioastronomers had detected cyanoacety- ture: the electron arrangement in graphite tion when they were both teenagers. lenes in space that contained up to 11 carbon (sp2-hybridized) makes the allotrope an elec- Harry (who remained friends with atoms. The relatively high abundance of trical conductor and a dry lubricant; whereas McKellen) had a deep appreciation of the these molecules challenged existing models that of diamond (sp3-hybridized) makes it arts, and was himself a skilled graphic artist. of interstellar chemistry, which predicted the an insulator and the hardest known mineral. He published several designs, one of which presence of much smaller molecules. Equally fundamental, the molecular chem- was chosen for the 2001 UK postage stamp Around this time Kroto learned about istry of carbon provides the foundation of celebrating the Nobel centenary. Of course, Richard Smalley’s cluster-beam experi- organic chemistry and biochemistry. it included a drawing of a buckyball. ■ ments. Smalley, then a physical chemist at It is thus not surprising that our proposed Rice University in Houston, Texas, was using structure for C60 — a truncated icosahedron James R. Heath is professor of chemistry a laser to vaporize a material with a high in which the 60 carbon atoms form a cage of at the California Institute of Technology, melting point (called a refractory target). interlocking pentagons and hexagons — was Pasadena, California, USA. Robert F. Curl As the hot atoms cooled, they would con- initially viewed with scepticism (H. W. Kroto is emeritus professor of chemistry at Rice dense. Smalley halted this chemistry after et al. Nature 318, 162–163; 1985). Our University, Houston, Texas, USA. only a few microseconds using supersonic experimental support for the C60 structure e-mails: [email protected]; [email protected]