Structure-property relationships and nonlinear optical effects in donor-substituted dicyanopyrazine-derived push-pull chromophores with enlarged and varied π-linkers

Abstract

Thirteen new, stable, push-pull systems featuring dimethylamino and pyrazine-2,3-dicarbonitrile moieties as the donor and acceptor, respectively, and systematically extended and varied π-linkers were prepared and investigated. Evaluation of the measured UV/Vis spectra, electrochemical data (cyclic voltammetry, rotating disc voltammetry, and polarography), X-ray data, and experimentally determined and calculated hyperpolarizability values enabled structure-property studies; these revealed some important structural features that affected the efficiency of intramolecular charge-transfer and nonlinear optical properties in this class ofheterocyclic push-pull chromophores. The charge-transfer transition was most significantly affected by structuralfeatures such as π-linker length, chromophore planarity, and the number of 1,4-phenylene/ethynylene subunits in the π-linker. Linear and nonlinear optical properties of push-pull chromophores featuring a pyrazine-2,3- dicarbonitrile acceptor moiety and dimethylamino donors were modulated by systematic extension and variation of the π-linker. The length and character of the π-linker used significantly influenced the efficiency of the donor-acceptor conjugation and nonlinear responses. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.