Wide-line 1H NMR study of mesomorphic states of 4′-(octyloxy)-4-biphenylcarbonitrile

A sample of 4′-(octyloxy)-4-cyanobiphenyl (8OCB) was studied in the temperature range −60–80°C by wide-line 1H NMR. The line shapes, half-widths, and second moments were determined. For the smectic phase of 8OCB, the relaxation times T 1 and T 2, the correlation time τc, and the degree of order were estimated. The 1H NMR spectral patterns and characteristics were found to be quite different for the crystalline, smectic, and nematic phases of 8OCB, which makes it possible to reliably identify the corresponding transitions and assess the molecular dynamics and molecular order of a structure. The temperature ranges, stability conditions, and other characteristics of the liquid crystalline phases that form on heating 8OCB were determined.