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Published online: 19 December 2007 | doi:10.1038/nchina.2007.268

Fullerenes: A water-bomb recipe

Anne Pichon

Introduction

© (2007) ACS

Fullerenes — C₆₀ molecules in the form of spherical cages — have enormous potential for pharmaceutical use, particularly in drug delivery. One method to insert drug molecules into a fullerene is to make an opening in the fullerene cage, but this requires the cleavage of selected carbon–carbon bonds, which is a difficult task owing to fullerene's unique spherical structure. Liangbing Gan, Zheming Wang and co-workers at Peking University in Beijing and the Chinese Academy of Sciences in Shanghai¹ have cleaved five consecutive fullerene bonds, which formed an opening large enough for a water molecule to be inserted (see image).

There were eight steps in the cage-opening method. The researchers began by marking a local fullerene bond with a tert-butyl radical for cleavage, and then cleaving it through peroxide-mediated photolysis. The adjacent fullerene bonds were cleaved through a series of steps, which involved oxidation and structural rearrangements, carried out under mild reaction conditions (at temperatures below 40 °C and in air). The resulting product, fullerenone (C₅₉), is a fullerene cage with an 18-membered-ring opening in place of a carbon atom.

Although the fullerenone has a large opening, the rim of the opening is completely blocked by amide groups that must be removed through decarboxylation. The researchers further widened the opening by inserting an oxygen atom into the rim through ferrocene treatment. The final fullerenone makes an excellent trap for water molecules.

The authors of this work are from:
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, China; State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.

Reference

1. Xiao, Z. et al. Synthesis of [59]fullerenones through peroxide-mediated stepwise cleavage of fullerene skeleton bonds and X-ray structures of their water-encapsulated open-cage complexes. J. Am. Chem. Soc. doi: 10.1021/ja0763798 (2007). | Article |