Where there's smoke there's fullerene

The Most Beautiful Molecule - Perfect Symmetry
February 10, 1995

Carbon is the king of mediocrity. Standing as it does at the midpoint of the periodic table, seeking neither other atoms' electrons nor willing particularly to surrender its own, it is content to bond to itself and to form chains and rings of intricate form and of seemingly infinite variety. To this intricate structure can be attached atoms of other elements, particularly those of hydrogen, nitrogen, and oxygen. These atoms bring to the basic carbon skeleton an awesome variety of reactions of such subtlety that they are the basis of organic life, producing com£ that constitute the rich field of organic chemistry, and of its ally biochemistry, a field so ploughed and turned during the past century and a half that although continuing elaboration of structure and reaction was expected, the basic building blocks - the chains and rings - were widely considered to be now in place.

But mediocrity, or perhaps it is humility, can be a fountain of surprises. A decade ago, an entirely new form of carbon was discovered that in effect adds to the basic building blocks a third dimension. In 1985, the first indications were discerned in a collaboration of Harry Kroto of the University of Sussex and Richard Smalley of Rice University in Texas of an almost spherical molecule composed of 60 carbon atoms in an arrangement of hexagons and pentagons that resembles a modern soccer ball. In an unhappy moment of ponderous wit, the new molecule was termed buckminsterfullerene in recognition of the analogy of its structure to Buckminster Fuller's geodesic domes. Five years later, another international collaboration of Donald Huffmann of the department of physics of the University of Arizona and Walter Kratschmer of the Max Planck Institute for Nuclear Physics in Heidelberg had made solid samples in which the buckminsterfullerene spheres are stacked together like oranges in a greengrocer's display. This new material, which is called fullerite, is now available in such abundance that it comes in bulk and has joined diamond and graphite as the third principal form of carbon.

The story of the discovery of this new form of carbon is the subject of the two books under review by Jim Baggott and Hugh Aldersley-Williams. There are as many layers to the story as there are in graphite itself, with personal relations, scientific endeavour, competition and conflict all playing a role. There is a multiple dose of irony too, for the discovery was motivated by a desire to explain certain astrophysical observations, yet it brought chemists down to earth when they realised that they had overlooked a form, possibly a highly abundant form, of one of the most important and well-understood elements. Another irony is that the bulk form of the new material was first prepared by physicists, much to the chagrin of chemists who pride themselves on their ability to prepare new substances.

Yet there is a deeper lesson touched on in both these accounts. The preparation of buckminsterfullerene, and of its cousins containing 70 and more atoms of carbon, collectively called the fullerenes, came at about the same time as the world's eyes were watching the unfolding of a scientific fiasco. Reports of cold fusion by a couple of chemists who relished tweaking the noses of particle physicists had swept the world, but had been shown to be a sign of experimental incompetence and over-hasty, financially inspired circumvention of the normal processes of scientific self-regulation. There was an understandable reluctance to claim the overthrow of another cherished paradigm and to come out of the closet waving a new form of carbon in the face of an annoyed community. Both accounts make clear, though, just how different the approach to the confirmation of the existence of buckminsterfullerene was from the sloppy over-exuberance of the claim to have achieved cold fusion. Here the reader will see the great care, the caution and the attention to detail that real scientists employ in establishing a major discovery.

Another irony, which is brought out more clearly in Baggott's seemingly more authoritative book, is that the first buckminsterfullerene molecules were not made at Rice. Indeed, there is increasing evidence that wherever there is smoke there is fullerene. In the cataclysmic impact with earth of the comet that hit Chicxulub in the Yucatan that probably led to the extermination of the dinosaurs, and that left its imprint in the soot of the Cretaceous/Tertiary layer, there is some buckminsterfullerene. There is even a mineral (shungite) found in a coal-like rock not far from St Petersburg that contains fullerenes (both C60 and C70).

Meteorites bring it from space (or form it on impact with earth). Indeed, space may be full of the stuff (or as full as almost empty space is ever full of anything), for the hot outer regions of red giants may be a super-sooting region and a fecund source of fullerenes. Indeed, the question that really confronts us is why the fullerenes had not been identified before: the answer appears to lie in the ease with which they can be destroyed under the conditions that in nature leads to their formation.

The importance of the fullerenes for chemistry and physics, and hence humanity, may lie not so much in the fact that the icosahedral symmetry of buckminsterfullerene is so compellingly eye-catching (as reflected in the titles of both books), but that they constitute an extraordinary family. There are the near-spherical fullerenes themselves with 60, 70, even as many as several hundred, carbon atoms. The feature that caught the eye of chemists was not so much the carbon but the void encased by the carbon. Here was a tantalising interior, and almost before the structure of buckminsterfullerene had been confirmed, chemists were considering enclosing atoms inside the spheres, so as to give shrink-wrapped elements. That has now been achieved. Just as spectacularly, it has been found that fullerene can shrink-wrap fullerene, and onion-like structures of nested spheres have been formed. Another branch of the family has been discovered by recognising that fullerenes also come in the form of tiny tubes, in some cases coaxial cables of wall upon wall of carbon atoms, and that metal atoms can be induced to flood into the interior of these tubes, so giving the ultimate microscopic versions of insulated wires.

Aldersey-Williams quotes at length from Hansard's report of a debate in the House of Lords when their lordships struggled to come to terms with the idea of a house well removed from their own mansions. Quite correctly, one peer asked: "My Lords, what does it do?'' A hundred and fifty years ago, Michael Faraday would probably have cut a poor figure had he been invited to speculate on what his molecule, benzene, might "do". As Faraday was then, so we now may be in a new age of involvement of carbon in our everyday lives. For those who seek applications worthy of headlines, the fullerenes have already raised their heads above the parapet, by showing superconductivity and by being found to be effective in the treatment of Aids. There is no knowing where these little spherical molecules and their relations will lead.

A final point that even the most casual reader and, it is hoped, governments, will learn from these books, is the importance of encouraging an inquisitive attitude and the freedom to explore observations that seem utterly remote from immediate applications. Who would have thought (other than scientists, who think in this way every day) that gazing into the stars in search of an explanation for a particular spectroscopic bump would have delivered such an important gift to science?

Both these books will be essential reading for those who determine where Nobel prizes should be scattered. Just as the discovery of a new fundamental particle requires the participation of dozens, even hundreds, of participants, so dozens have contributed to this equivalent event in chemistry. However, whereas the leader of a national facility can be given the prize in a symbolic gesture, for the fullerenes the task is rather different. For the battle has been fought by numerous generals. A clever solution would be to give the prizes in both physics and chemistry, since there can be little doubt that the molecules and the solids they form will make a substantial contribution to both disciplines. However, if and when the prize or prizes are awarded, they will not recognise the prescient individuals who came uncannily close to the discovery. Of these perhaps the most remarkable is David Jones writing as Daedalus. Aldersey-Williams does not mention him, but Baggott properly quotes from some of his remarkably imaginative writings in which the fullerenes were foreshadowed.

The two books have distinct approaches. Baggott's is far better illustrated than Aldersey-Williams's. For those who wish to see what the protagonists looked like, Baggott's is the book. It is written at a slightly higher scientific level, and is likely to appeal more to those with some real knowledge of chemistry. Aldersey-Williams has written an interesting book that seeks to explore the social side of the chase with more emphasis on personalities, but he falls into the trap that blocks the path of those who endeavour to popularise chemistry - he uses jargon too soon and in too great abundance. Nevertheless, the two books together do illuminate the story of this living discovery and help the general reader to share the demands, the pain and the delight of the scientific endeavour.

P. W. Atkins is a lecturer in physical chemistry, University of Oxford.

The Most Beautiful Molecule: An Adventure In Chemistry

Author - Hugh Aldersey-Williams
ISBN - 1 85410 303 2
Publisher - Aurum
Price - £18.95
Pages - 340pp

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