Study of molecular dynamics in liquid-crystalline phases of CBOOA by high-resolution 13C NMR

High-resolution C-13 NMR experiments were performed in smectic Ad (SAd), nematic (N), and isotropic- liquid (1) phases of a liquid crystal, 4-octyloxy-N-(4-cyanobenzylidene)aniline (CBOOA). The temperature dependency of the spin-lattice relaxation times varied smoothly in the liquid-crystalline phases for almost all of the carbon atoms. However, for the carbon atom in the cyano-end group, a sharp change was detected at the SAd-N transition temperature. It is suggested that intermolecular interaction, which is not observed in the N phase, occurs in the SAd phase around the cyano-end group.