Determination of Structural Characteristics of All-Organic Radical Liquid Crystals Based on Analysis of the Dipole–Dipole Broadened EPR Spectra

The angular dependences of g-value and line width of EPR spectra of paramagnetic all-organic liquid crystalline (LC) materials were measured for the quantitative characterization of the nematic, cholesteric, and smectic C phases. The detailed molecular alignment in mesophases was determined by means of numerical spectra simulation focusing on spin exchange and dipole–dipole magnetic interactions of neighboring molecules. The obtained structural data indicate that the spin polarization mechanism between neighboring molecules rather than the direct through-space interactions between paramagnetic centers is responsible for the specific magnetic properties of the studied LC materials.