Presentation Speech by Professor Lennart Eberson of the Royal Swedish Academy of Sciences
Translation of the Swedish text
Majesties, Your Royal Highness, Ladies and Gentlemen,
We like to think that everything worth knowing about the chemical elements is already known, and that carbon – one of our most thoroughly researched elements – could not possibly yield further important discoveries. Carbon has been known since prehistoric times as soot, coal and charcoal. By the late 18th century, graphite and diamonds had been shown to be different forms of the element carbon. We employ carbon in countless ways: the large-scale burning of coal as a fuel; the use of coke in steel production; the use of graphite in lubricants, pencils, brake linings, etc. That rare form of carbon known as a diamond has many applications, aside from its aesthetic function. An ordinary automobile tire contains 3 kilograms of carbon black, and activated carbon is highly useful in a wide variety of fields. Carbon is the basis of life processes; it is extremely important to all of us.
It was therefore a first-class scientific sensation when this year’s Laureates in Chemistry – Robert Curl, Harold Kroto and Richard Smalley – together with graduate students James Heath and Sean O’Brien, reported in 1985 that they had discovered a new, stable form of carbon in which sixty carbon atoms are arranged in a closed shell. They named this new carbon molecule buckminsterfullerene after the American architect R. Buckminster Fuller, inventor of the “geodesic dome”, a building perhaps internationally best known from the United States pavilion at the 1967 world’s fair in Montreal. To understand how the carbon atoms in buckminsterfullerene are connected to each other, we need only recall the pattern on the surface of a soccer ball, or European football. This ball is stitched together from 12 black pentagons and 20 white hexagons, in such a way that no pentagon comes into contact with another pentagon. The result is a highly symmetrical structure with sixty corners. If we now imagine that we place a carbon atom at each one of these 60 corners, we know how buckminsterfullerene looks. Although it is 300 million times smaller than a soccer ball!
The discovery of buckminsterfullerene – or C60 – was made by using an advanced instrument, in which a laser vaporized a very small quantity of carbon in one five billionth of a second. When the hot carbon gas condensed, it formed clusters containing different numbers of carbon atoms. The one with 60 carbon atoms was the most common. Many of these various carbon molecules were shown to have the same stability as C60 and were therefore also assumed to be closed; the collective name for such clusters was fullerenes It was also possible to produce fullerenes that enclosed a metal atom inside, for example potassium or cesium.
The problem with these experiments was that fullerenes were available in such small quantities that their postulated structure could not be rigorously verified. The years from 1985 to 1990 were filled with scientific disputes, in which the stubbornness, ingenuity and enthusiasm of the fullerenes’ discoverers kept their hypothesis alive despite rather severe criticism. Only in 1990 were physicists Donald Huffman and Wolfgang Krätschmer able to produce gram-sized quantities of C60 using a method that could be quickly and inexpensively duplicated in any laboratory. This made it possible to apply the whole battery of structural determination methods and show that C60 really had the structure its discoverers had hypothesized. Chemists now quickly went to work studying the chemistry of fullerenes. They were able to try out various applications of the chemistry and physics of fullerenes.
So why are the fullerenes so interesting? To understand this, we must look at the structure of other forms of carbon. Graphite consists of carbon atoms attached together in very large flat networks that are piled on top of each other, whereas diamonds consist of carbon atoms bound into endless three-dimensional networks. Both are examples of what we usually call polymers. The chemistry that can be done using these forms of carbon is rather limited – and not entirely inexpensive, in the case of diamonds! A fullerene, on the other hand, has a closed, low-molecular structure that can be chemically processed and modified in an almost infinite number of ways.
This year’s Nobel Prize in Chemistry has implications for all the natural sciences. The seeds of the discovery were sowed by a desire to understand the behavior of carbon in red giant stars and interstellar gas clouds. The discovery of fullerenes has expanded our knowledge and changed our thinking in chemistry and physics. It has given us new hypotheses on the occurrence of carbon in the universe. It has also led us to discover small quantities of fullerenes in geological formations. Fullerenes are probably present in much larger amounts on earth than previously believed. It has been shown that most sooty flames contain small quantities of fullerenes. Think of this the next time you light a candle!
The symmetry concept has played an important role in the history of ideas and the natural sciences. Ideas of symmetry dominate many important theories and comprise a strong driving force behind scientific thinking. We are fascinated by the beautiful structure of C60 – and this feeling has existed ever since humans began to reflect on natural phenomena. In the Timaeus dialogue, Plato described his theory of the four elementary particles for fire, earth, air and water:
“And next we have to determine what are the four most beautiful bodies which are unlike one another, and of which some are capable of resolution into one another; for having discovered thus much, we shall know the true origin of earth and fire and of the proportionate and intermediate elements. And then we shall not be willing to allow that there are any distinct kinds of visible bodies fairer than these…”
He went on to describe four of the five regular polyhedrons – the tetrahedron (fire), the cube (earth), the octahedron (air) and the icosahedron (water). The dodecahedron represents the cosmos because it is closest to that most perfect of forms, the sphere. Plato would certainly have found the structure of C60 – an expanded dodecahedron, which is about as close to a sphere as you can get – to be an unusually beautiful body.
Professors Curl, Kroto and Smalley,
You have been awarded the 1996 Nobel Prize in Chemistry for your discovery of a new form of the element carbon, the fullerenes. It is a privilege and a great pleasure for me to congratulate you on behalf of the Royal Swedish Academy of Sciences, and I now ask you to receive your Nobel Prizes from the hands of His Majesty the King.