Dipole moment calculation in solution for some liquid crystalline molecules

• We computed geometry and dipole moment of four LC compounds in non-polar solvent.
• For highly polar molecules, PCM model is closer to experiment than Onsager model.
• Orientation of symmetric terminal polar groups affects the direction of dipole moment.
• Adding polar terminal groups changes the dielectric anisotropy in the LC phase.

Theoretical and experimental studies were used to determine the dipole moment for four liquid crystalline materials. Ab initio calculations in vacuum led to elimination of a few potential conformers in each molecule. These results were used as initial data to obtain the geometry of the molecules in non-polar solvent according to Onsager’s or PCM model. After employing both models, slight increase of the dipole moment was noticed for all the molecules. The results are similar for both the models, with one exception for the strongly polar molecule where the Onsager’s model led to much higher dipole moment. The dipole moment was also determined experimentally for all the materials. The experimental data were compared with the results from calculations. For the nematic materials, the theoretically predicted sign of the dielectric anisotropy was compared with experimental results.

Figure optionsDownload as PowerPoint slide