High-field EPR of irradiated inclusion compounds

High-field EPR can be successfully used to study the dynamics of guest molecules in inclusion compounds. A radical guest has been obtained by γ-irradiation of the inclusion compound nonadecan-10-one in perhydrotriphenylene. The rotational motion of the radicals inside the host channels is fast and the relaxation effect on the X-band EPR line shapes is small. The line widths of the W-band EPR spectra (108 GHz) are significantly larger since the molecular rotation modulates the g-tensor of the radical. Analysis of the relaxation effects shows that the X-band and W-band EPR are complementary. The former gives the maximum information at low temperature, while the latter is useful at higher temperatures.