The orientational behaviour of dichlorobenzenes in nematic liquid crystal solvents

Abstract

. Can. J. Chem. 67, 54 (1989). The orientational order parameters of ortho-, meta-, and para-dichlorobenzene, dissolved in the nematic solvents EBBA and 1132, have been measured as functions of temperature and concentration, and used to determine the values of the potential energy parameters for each solute-solvent pair. These potentials have been interpreted in terms of a short-range contribution, which depends upon the shape and size of the solute molecule, plus a long-range term due to the interaction between the average electric field gradient from the solvent and the molecular quadmpole moment of the solute.

Prediction from Molecular Shape of Solute Orientational Order in Liquid Crystals

“…In an independent development 47 the linear dimensions of molecular solutes were approximated by Stuart's “Wirkungsradien” . Later the linear dimensions were estimated on the basis of van der Waals radii. ,,, The predictions of the above early models have been compared to experimental orientation parameters obtained in “pure” liquid crystals. Since it is now known that in these “pure” liquid crystals more than one orientation mechanism is usually operative, it is not surprising that comparisons between theory and experiment were often not very satisfactory.…”

“…It is interesting to note that a similar situation prevails in ordinary liquid crystals for saturated aliphatic and cyclic hydrocarbon solutes whose long-range electrostatic interactions with the solvent are relatively unimportant. Several phenomenological schemes for modeling short-range interactions have been proposed. ,,,,,− …”