Investigation of the inner environment of carbon nanotubes with a fullerene-nitroxide probe.
A fulleropyrrolidine bearing a nitroxide free radical has been inserted into single-walled carbon nanotubes with the aid of supercritical CO2. Thanks to the encapsulated paramagnetic probes, it has been possible to detect and characterize the resulting peapod-like structure through electron paramagnetic resonance (EPR) spectroscopy. In particular, the analysis of spectral parameters derived from extensive EPR studies has elucidated the orientation and the residual rotational dynamics of the molecules embedded in the nanotubes. A limited anisotropic rotational freedom of the encapsulated fullerene nitroxide reveals a rather strong interaction of the probe with the surrounding nanotube walls. The interaction seems to involve the fullerene cage (as confirmed by Raman spectroscopy) and not the nitroxide moiety, whose EPR spectral characteristics, such as the isotropic hyperfine constant and the g-tensor, remain unaltered after encapsulation.
Campestrini
Sandro
S
Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo, 1, Padova 35131, Italy.
Corvaja
Carlo
C
De Nardi
Marco
M
Ducati
Caterina
C
Franco
Lorenzo
L
Maggini
Michele
M
Meneghetti
Moreno
M
Menna
Enzo
E
Ruaro
Giorgio
G
D025924:Chromatography, Supercritical Fluid; D004578:Electron Spin Resonance Spectroscopy; D037741:Fullerenes / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D015335:Molecular Probes; D037742:Nanotubes, Carbon; D009589:Nitrogen Oxides / Q000737:chemistry*; D013059:Spectrum Analysis, Raman
D037741:Fullerenes; D015335:Molecular Probes; D037742:Nanotubes, Carbon; D009589:Nitrogen Oxides; C039900:nitroxyl