Journal of Physical Chemistry B, Vol.118, No.7, 1932-1942, 2014
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.