Proton NMR study of a discotic columnar mesophase

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Abstract
The molecular ordering and the dynamics of the isotropic and the discotic columnar liquid crystalline phase of hexapentoxy‐triphenylene have been studied by high resolution proton NMR, self‐diffusion measurements and spin–lattice relaxation in the laboratory (T1) and the rotating frame (T1ρ). The onset of the columnar ordering is accompanied by the gradual appearance of a short ’’liquid crystalline’’ component in the proton free induction decay (FID) in addition to the long component characteristic of the isotropic phase. The proton T1 is frequency dependent in the isotropic and in the columnar phase. It changes discontinuously at the clearing point at low frequencies where as it is continuous at 270 MHz. An analysis of the possible relaxation mechanisms is presented.