Two-Dimensional Coalescence Dynamics of Encapsulated Metallofullerenes in Carbon Nanotubes.

Christopher S. Allen†*, Yasuhiro Ito†, Alex W. Robertson†, Hisanori Shinohara‡, and Jamie H. Warner†*

† Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom ‡ Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.

ACS Nano, 2011, 5 (12), pp 10084–10089

We report on the coalescence of a two-dimensional (2D) chain of La@C82 metallofullerene molecules encapsulated inside a single-wall carbon nanotube (SWNT). 2D packing of metallofullerenes is known to adopt a zigzag arrangement and cause elliptical distortion to the cross-section of the SWNT host. We show that after coalescence of the metallofullerenes into an inner nanotube the carbon nanotube host returns to its original circular cross-section. This is due to a relaxation of the strain caused by the packing of the encapsulated La@C82 molecules into the nanotube. We identify the formation of some novel but transient fullerene-based structures formed during the intermediate stages of coalescence of the La@C82 into an inner nanotube. These results highlight the flexible nature of SWNTs and their ability to adapt their cross-sectional profile depending upon forces induced by material encapsulated within.