By courtesy of:
Christopher W. Bielawski, Diego Benitez, Robert H. Grubbs*
Science 2002, 297, 2041
and a recent paper:
Synthesis of Macrocyclic Copolymer Brushes and Their Self-Assembly into Supramolecular Tubes
Michel Schappacher and Alain Deffieux*
Science 2008, 319, 1512Â