First hyperpolarizability orientation in asymmetric pyrrole-based polyene chromophores

Abstract

Novel, asymmetrically shaped, pyrrole-based polyene chromophores were designed to obtain a large angle theta(mu,beta(max)) between the directions of the maximum first hyperpolarizability beta(max) and the dipole moment mu, by introducing an asymmetric core pyrrole into the pi-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 theta(mu,beta(max)) between the dipole moment mu and the main direction of the charge-transfer transition beta(max) of up to 48 degrees was achieved. (C) 2009 Elsevier Ltd. All rights reserved.