First hyperpolarizability orientation in asymmetric pyrrole-based polyene chromophores

Novel, asymmetrically shaped, pyrrole-based polyene chromophores were designed to obtain a large angle θ(μ,βmax) between the directions of the maximum first hyperpolarizability βmax and the dipole moment μ, by introducing an asymmetric core pyrrole into the π-conjugated polyene bridge of the chromophore. Asymmetric N-substituted pyrrolic nonlinear optical chromophores based on configurationally locked polyene (CLP) were synthesized and their first hyperpolarizabilities were theoretically determined using density functional theory (DFT). High asymmetry with an angle θ(μ,βmax) between the dipole moment μ and the main direction of the charge-transfer transition βmax of up to 48° was achieved.