High-field EPR of irradiated inclusion compounds

High-field EPR can be successfully used to study the dynamics of guest mole cules in inclusion compounds. A radical guest has been obtained by gamma-ir radiation of the inclusion compound nonadecan-10-one in perhydrotriphenylen e. The rotational motion of the radicals inside the host channels is fast a nd the relaxation effect on the X-band EPR line shapes is small. The line w idths of the W-band EPR spectra (108 GHz) are significantly larger since th e 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 lat ter is useful at higher temperatures. (C) 1999 Elsevier Science B.V. All ri ghts reserved.