13C chemical shifts and spin-lattice relaxation in the nematic liquid crystal 4-cyano-4′-<i>n</i>-pentylbiphenyl

Abstract

The 13C chemical shifts and spin-lattice relaxation times were obtained for all the resolved resonances in the isotropic and nematic phases of 5CB. NOE measurements were also obtained for the isotropic phase. A study of these data indicates that a flexibility gradient exists along the n-pentyl chain and that D⊥, the rotational diffusion constant for the entire molecule, can be estimated. A study of the chemical shifts of 5CB shows that a single average shielding tensor is inadequate for a proper description of the chemical shifts of this liquid crystal molecule. These results are compared with those previously obtained for MBBA and PAA.