Boffins synthesise Bucky's baby brother

Carbon-50 made solid

A group of physical chemists have made carbon-50 molecules in a solid state for the first time. Previous attempts to synthesise the molecule have been successful, but only in the gaseous phase. The researchers describe it as the long-sought-after little brother of Carbon-60.

Carbon-50 is an interesting molecule because it is a non-standard fullerene, and should therefore have unusual properties. It could also pave the way for the creation of other low number fullerenes.

Standard fullerenes obey the isolated pentagon rule, or IPR. This says that the most stable arrangement is a pentagon surrounded by five hexagons. The most common standard fullerene, and the most widely known, is Carbon-60: the Bucky Ball. This was first created artificially in 1985. It is composed on pentagons and hexagons of carbon atoms arranged in a sphere, just like a football (or soccer ball for US readers).

Molecules with up to 500 carbon atoms have been made, and all obey the IPR. If you have fewer than 60 carbon atoms, however, the IPR cannot be satisfied. Until now, molecules with fewer than 60 carbon atoms have only been made in the gaseous phase.

The team, headed by Lan-Sun Zheng at Xiamen University and joined by researchers at the Chinese Academy of Sciences in Beijing and Wuhan, used a graphite arc discharge technique to make the molecule. The Institute of Physics describes the method as follows:

"They added 0.013 atmospheres of carbon tetrachloride vapour to 0.395 atmospheres of helium in a sealed stainless steel vessel and then applied an electric field of 24 Volts.

After purifying around 90 grams of soot that contained carbon-50 chloride (C50Cl10), they obtained about 2 milligrams of C50Cl10 that was 99.5% pure. "

Xie says that carbon-50 could easily react with a variety of organic groups to form new compounds with interesting chemical and physical properties. It is composed of a central ball, with ten carbon-chlorine arms sticking out, making it potentially very reactive.

The work was orignially published in Science. (S-Y Xie et al. 2004 Science 304 699). ®

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