Structure–Property Relationships and Nonlinear Optical Effects in Donor‐Substituted Dicyanopyrazine‐Derived Push–Pull Chromophores with Enlarged and Varied π‐Linkers

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.