N.M.R. relaxation in 18-crown-6 ether

N.M.R. relaxation times of the protons in 18-crown-6 ether have been measured as function of proton density in mixture with the perdeuterated crown ether, of the frequency and temperature. Intramolecular and intermolecular contributions to the relaxation were obtained. Some deuteron relaxation times and spin-echo self-diffusion constants were measured in addition. The intramolecular proton relaxation rate was analysed in terms of the anisotropic rotational diffusion model. The molecule reorients a factor 100 faster around the symmetry axis than perpendicular to it. The intermolecular proton relaxation rate was analysed in terms of three different theories which consider simple translational diffusion, the effect of intermolecular forces on translational diffusion, and rotational diffusion superimposed on translational diffusion. The measurements indicate that the latter effect is most important.