NUCLEAR-SPIN RELAXATION AND TRANSLATIONAL DIFFUSION STUDY OF BENZENE-HEXA-N-ALKANOATES

The molecular dynamics of benzene-hexa-n-heptanoate (BHA7) have been s tudied in the isotropic liquid phase by multifield carbon-13 nuclear s pin relaxation of a carboxyl carbon labeled compound. The experimental data are analyzed with a dynamical model based on the assumption of t hree types of motion: a fast internal motion in the aliphatic chains, a slow overall reorientation of the molecule, and an intermediate proc ess connected with the flexibility of the carboxyl group. The first tw o motions occur clearly on different time scales, whereas the last pro cess is not time scale separated from the global molecular tumbling. P reviously reported carbon-13 line shapes in the mesophase and in the s lid state of BHA7 were used for verification of the results. Measureme nts of translational diffusion coefficients in isotropic and ordered p hases of BHA6 and BHA7 were performed using 'H pulsed field gradient N MR spin-echo techniques.