The orientational behaviour of 1,4-difluorobenzene and p-benzoquinone in ZLI1132 and EBBA nematic solvents

The non-polar rigid molecules 1,4-difluorobenzene and p-benzoquinone dissolved in ZLI1132 and EBBA nematic solvents show a bizarre 'double face' rod-like or disk-like orientational behaviour, depending on the used solvent. In the present Letter it is shown that the observed effect, unpredictable on the basis of solely short-range orientating mechanisms, can be qualitatively accounted when also electrostatic long-range interactions are taken into account (in particular, the coupling between the solute quadrupole moment and the solvent electric field gradient). The obtained result confirms the non-negligible role played by electrostatic interactions, even in the case of non-polar molecules. (C) 2002 Elsevier Science B.V. All rights reserved.