Guest species trapped inside carbon nanotubes

Taking the torsional motion of H2O2 inside a carbon nanotube as an example, the interaction between the encapsulated guest species and the cage is studied using density functional theoretical method with B3LYP functional and 6-31G∗∗ basis set. Depending upon its orientation inside the nanotube, H2O2 binds differently with the cage so that its torsional motion is inhibited. The binding due to the weak O-H⋯π interaction is discussed. The polarization of the nanotube because of the guest species suggests that the molecular motion through the nanotube may be influenced by polar solvents and external electric field.