X- and W-band ESR study on γ-cyclodextrin bicapped C60 after NH3-gas doping

Among the diverse topics of supramolecular chemistry of gamma -cyclodextrin (gamma -CyD) bicapped C-60 systems, electronic and magnetic properties induced by electron dopants have not been well elucidated yet. This paper describes the crystalline solid sample of C-60(gamma -CyD)(2). 24H(2)O treated by NH3-gas doping. Several open-shell species including an anionic C-60 have been detected and characterized by conventional cw-ESR spectroscopy. It has turned out that the monoanionic C-60 is extremely stable at room temperature for more than several months and it undergoes a symmetry reduction by the Jahn-Teller distortion to have an axial symmetry. W-band ESR spectroscopy has been invoked to resolve the g-anisotropy. In addition, the characteristic features appearing in the FV-band spectra has been explained by the possible occurrence of the dynamic behavior underlain by quantum tunneling between the distorted forms of NH3 radical cation due to the dynamic pseudo Jahn-Teller effect.