Quantum-mechanical studies of NMR properties of solutes in Liquid Crystals: a new strategy to determine orientational order parameters

We present a quantum-mechanical method to calculate the tensorial NMR magnetic properties of molecules in liquid crystals. The method exploits a density functional description for the solute and the integral equation formalism version of the polarizable continuum model to include the effects of the dielectric anisotropy of the solvent on the wave function of the solute molecule and on its response to an applied magnetic field. Taking into account the dependence of the calculated molecular tensors on the solute orientation, we have derived the necessary expressions to relate such tensors to the spectral observables. These equations are then used to determine order parameters by calculating the nuclear shieldings of various solutes in the nematic ZLI-1167. Comparisons with experimental data of the same parameters are finally presented