Solution-phase dielectric characterization of the 4-amino-4′-dicyanovinylazobenzene nonlinear-optical chromophore

Abstract

The dielectric constants of solutions of 4-amino-4′-dicyanovinylazobenzene chromophore (DCV) at a wide range of concentrations in dioxane were measured. The chromophore dipole moment was determined to be 9.4 D in dioxane and in methyl trimethylacetate. Somewhat smaller values for the dipole moment were obtained when the chromophore was dissolved in chloroform or when it was covalently attached to a polymethacrylate backbone. No significant nonlinearity was observed in plots of dielectric constant versus concentration, even at concentrations approaching the solubility limit. Theoretical modeling indicates that such nonlinearity would have been observed if appreciable aggregation had occurred. It is predicted that dipole-dipole aggregation should not diminish the electric-field-induced alignment achievable in macroscopically homogeneous DCV-containing materials.