Molecular Motions and Mesophases in Anhydrous Thallium (I) Soaps Studied by 1H- and 205TL-NMR. The 205TL Chemical Shift Tensor

The thermotropic phases of fatty acid (C12, C14, C22) thallium (I) salts were studied by the spin-1/2-pair dipolar echo 1H-NMR method and by 205Tl-NMR in the temperature range from 230 K to 480 K. For the first time the 205Tl chemical shift tensor in such soaps in the crystalline state was shown to be axially symmetric and to exhibit an anisotropy of −780 ± 8 ppm. Also for the first time, a detailed characterization of the dynamical properties of the liquid crystalline mesophases was performed; this allows some conclusions to be reached about the structure of the mesophases present in the C12 and C14 soaps below their isotropic states. The phases of the various soaps studied were unambiguously assigned.