Carbon-70 fullerenes finally link up

Science News, August 25, 2001 by J.G.

Carbon-60 fullerenes--cagelike molecules of 60 carbon atoms ([C.sub.60])--are easily coaxed into polymer chains. Trying to do the same for less-symmetrical [C.sub.70] fullerenes has proven so frustrating, however, that some scientists have speculated that it can't be done.

Never say never. In the July 27 SCIENCE, Alexander V. Soldatov, now of Harvard University, and researchers in Germany, Russia, Austria, and Sweden describe how they managed the feat.

Computer modeling enabled the researchers to identify a crystal form of [C.sub.70] in which the molecules align in an orientation that could lead to polymerization.

After exposing a single crystal to high pressures and temperatures to trigger such a reaction, the researchers used spectroscopy, X-ray diffraction, and nuclear magnetic resonance imaging to examine the result. Their data showed that they indeed had created zigzagging polymeric chains of [C.sub.70].

This is the first time that researchers have determined the atomic positions in a fullerene polymer, claims Soldatov. Such molecular-scale detail might help researchers find ways to use high pressure to convert fullerenes into superhard materials, he says.