Electric birefringence of discotic benzene-hexa-n-heptanoate in isotropic solution phase

Abstract

The electric birefringence of solutions of oblate discogen and prolate nematogen in dioxane has been examined. Discotic benzene-hexa-n-heptanoate (BH7) exhibits negative birefringence, while nematic 5CB and MBBA exhibit positive birefringences at low concentrations. Possible modes of solute orientation, compatible with the observed birefringence sign, are discussed. For BH7, it is suggested that the in-plane axes with larger optical polarizabilities align perpendicular to the field direction. The dependence of the specific Kerr constant on the solution concentration is also reported.