Fullerenes are a family of carbon allotropes, discovered in 1985 which form 3 D molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid, tube, or plane . Fullerenes are extraordinarily stable and heat-resistant, joining diamonds and graphite as the third form of pure carbon, yet are the only form of carbon that is soluble, leading to easy processing and a variety of chemical modifications for usable nanotechnology materials.
By far the most common fullerene is C60, also known as "buckyballs," which look like soccer balls - are spherical , hollow molecular cages of carbon atoms about a billionth of an inch in diameter. Other relatively common fullerenes are C70, C76, and C84. The architectural structure of fullerene molecules resembles the geodesic domes (like the Eden Project) created by architect and philosopher R. Buckminster Fuller.
The existence of a sperical C60 was predicted in 1970 by Eiji Osawa of Toyohashi University of Technology but not discovered until 2 teams at Sussex University in the UK and Rice University in Florida demonstrated their existence - for which Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry. "The discovery of carbon atoms bound in the form of a ball is rewarded" said the Press elease. Their discovery has opened up an amazing new new field of chemistry.
Curl, Kroto and Smalley performed the experiments together with graduate students J.R. Heath and S.C. OBrien during a period of eleven days in 1985 to produce the first synthesised fullerenes, discovering that modest changes in conditions could affect the size of molecules produced.see pic.
For chemists the proposed structure was uniquely beautiful and satisfying. It corresponds to an aromatic, three-dimensional system in which single and double bonds alternated, and was thus of great theoretical significance. Unsurprisingly 2 books published about the discovery reflect that excitement Jim Baggott, Perfect Symmetry: The Accidental Discovery of Buckminsterfullerene, Oxford University Press, 1994 and Hugh Aldersey-Williams, The Most Beautiful Molecule: An Adventure in Chemistry, Aurum Press, London, 1995,
Subsequently fullerenes have been discovered in such a mundane thing as candle soot and as a result of lightning discharges. Recently they have been found in naturally occuring minerals.
The commercial exploitation of these curious and fascinating 3 dimensional molecules is however still stalled as it has been difficult to produce large quantities for experimental , never mind commercial use. Nearly 2,000 patents already exist for a broad range of pharmaceutical, electronic and other commercial applications, including anticancer and anti-HIV therapies, drugs for neurodegenerative diseases, drug delivery systems, and cosmetic preparations that retard the aging of skin.
The common method of production so far has been by vapourizing graphite. This is a relatively primitive and uncontrolled method., which cannot be used for the more exotic fullerene derivatives or unusual fullerene compounds.
Current techniques are complicated and may require as many as 11 sequential steps, - with final results producing low yields of C60 molecules. This hasn't prevented some commercial exploitation Frontier Carbon Corporation (FCC), which is a joint venture between Mitsubishi Chemical Corporation and Mitsubishi Corporation, which started production an sales of fullerene in May 2002 with a capacity of 400 kg/year. In May 2003, FCC increased the capacity by 100-fold, to 40 ton/year, to supply fullerene and its derivatives with reasonable prices for commercial use. Fullerene-based products started to emerge in 2003 first in sports industry such as bowling balls and golf-club heads in Japan, both of which are of high performance and have become popular products.
In December 2004 FCC (operating under the brand name nanom) decided to begin production of fullerene materials in the U.S. starting in March 2005 in co-operation with TDA Research, Inc.( a U.S. corporation licensed by Massachusetts Institute of Technology to use combustion-based technology for the production of fullerenic products) for serving present and potential customers.
They supply Nanom Mix (mixed fullerenes, including C60 and C70); Nanom Purple (pure C60); Nanom Spectra (tailor-made, chemically functionalized fullerenes); and mixtures of fullerenic materials with unique properties.
A group from Spain led by José Martin-Gago of the Institute of Materials Science in Madrid have now published a better controlled and higher yielding method of production method using surface-catalyzed cyclodehydrogenation. The process produces the C60 molecules with roughly 100% yield.
Indeed, the researchers have used the process to synthesize a heterofullerene C57N3 for the first time.
The method involves depositing the final aromatic precursors (such as C57H33N3) onto a catalytic platinum surface and then heating it to 750 K. This transforms all of the precursors into fullerenes.
Martin-Gago talks of a form of molecular origami in which numerous planar molecules can form into complex structures as envisaged in the graphic shown above.
"The secret is ," he says, "to use the catalytic properties of a surface for inducing dehydrogenation of the precursor molecule."
The method might be used to functionalize standard fullerenes by using different precursor molecules, says the team. And it could be exploited to encapsulate atoms or small molecules to form endohedral fullerenes if the process is carried out in an atmosphere containing guest species.
"We will now use this methodology to encapsulate some magnetic clusters in these molecules and use them as biomarkers," revealed Martin-Gago.