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  January 17,  2005
Volume 83, Number 3
p. 14
 

NANOSCIENCE

  Filling A Fullerene
Japanese group uses organic synthesis to make milligrams of H2-filled C60
 

BETHANY HALFORD
   
 
 

Using organic synthesis as a scalpel and stitches, Japanese researchers have performed "molecular surgery" on a buckyball. A group at Kyoto University creates an opening in the molecule, inserts H2 into the cavity, and then, in just four steps, closes up the C60 framework to construct the endohedral fullerene H2@C60 [Science, 307, 238 (2005)].

TRAPPED Komatsu and coworkers close a 13-membered-ring hole in four synthetic steps to make H2@C60 (C = gray, O = red, N = blue, S = yellow, H = blue spheres).

COURTESY OF KOICHI KOMATSU

The key point "is that we showed, for the first time, the great potential of organic synthesis for the production of endohedral fullerenes, which thus far has relied on hardly controllable physical methods under extreme conditions," says chemistry professor Koichi Komatsu, who spearheaded the effort.

Previously, Komatsu's group had prepared a C60 derivative containing a 13-membered-ring orifice that they quantitatively filled with H2 (C&EN, June 16, 2003, page 5). In the latest work, Komatsu and coworkers Michihisa Murata and Yasujiro Murata synthetically "sew" this hole to make the nanocontainer.

"Our success depends on the presence of a readily removable sulfur atom on the rim of the orifice," Komatsu says. Once the hydrogen is trapped within the fullerene, the researchers oxidize this sulfide group to a sulfoxide. The sulfoxide is then excised photochemically, shrinking the hole by one atom. Titanium-mediated coupling of carbonyl groups tightens the opening to an eight-membered ring.

The opening is then small enough that the team can heat the compound without losing the hydrogen cargo. The fullerene derivative rearranges--presumably via thermally allowed electrocyclization--restoring the C60 cage and eliminating 2-cyanopyridine and diphenylacetylene in the process.

 
     
  Chemical & Engineering News
ISSN 0009-2347
Copyright © 2005
 


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