Effective, fast, and low temperature encapsulation of fullerene derivatives in single wall carbon nanotubes

High filling of single wall nanotubes (SWCNTs) with the typical exohedrally functionalized fullerene derivative of C60 N-methyl-3,4-fulleropyrrolidine C60–C3NH7 is reported at the temperature of refluxing hexane. The new peapod material is characterized by STM (scanning tunneling microscopy), TEM (transmission electron microscopy) and Raman spectroscopy. Atomically resolved STM scans on SWCNT show no excessive defects or sidewall functionalization as a result of this treatment. The radial breathing mode (RBM) mode of SWCNT at 165 cm−1 becomes weaker and shifted to 169 cm−1 indicating filled nanotubes. TEM studies show bundles of SWCNT are highly filled with derivative C60–C3NH7 and form the (C60–C3NH7)n peapods. Individual pyrrolidine-type functional groups attached to the fullerene cages are unambiguously visualized by a lower-dose observation.