Solvatochromic solvent polarity parameters for the characterisation of some cyanobiphenyl nematic liquid crystals

Abstract

In application of liquid crystals (LCs) as solvents, it is required to obtain the polarity and solvatochromic polarity parameters such as the Kamlet–Abboud–Taft polarity functions. In this study, solvatochromic polarity parameters of some cyanobiphenyl nematic liquid crystals were acquired in different temperatures and phases, isotropic and anisotropic phases, using the Reichardt's dye and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate standard probe. In addition, to decrease the overlapping of the absorption band of probe with the absorption bands of LCs and to increase the solubility of the probe in LCs, a new azo dye was used as a probe for obtaining some solvatochromic polarity parameters. Finally, a new polarity parameter, the LC anisotropic matrix, is introduced.

Keywords:

• solvatochromism probe
• cyanobiphenyl liquid crystal
• matrix anisotropy
• Kamlet–Abboud–Taft polarity function