Property tuning in selected examples of D-p-A molecules has been discussed and summarized in this review article. The tuning and structure-property relationships have been demonstrated on the particular A, p and D parts of the push-pull molecule. Special emphasis has been put on the tuning of the FMO levels and optical properties. Further prospective applications of the given chromophore have also been considered.

A series of donor–acceptor chromophores was prepared in which the spacer separating 4‐dimethylanilino (DMA) donor and C(CN)2 acceptor moieties is systematically varied. All of the new push–pull systems, except 4 b, are thermally stable molecules. In series a, the DMA rings are directly attached to the central spacer, whereas in series b additional acetylene moieties are inserted. X‐ray crystal structures were obtained for seven of the new, intensely colored target compounds. In series a, the DMA rings are sterically forced out of the mean plane of the residual π system, whereas the entire conjugated π system in series b is nearly planar. Support for strong donor–acceptor interactions was obtained through evaluation of the quinoid character of the DMA ring and by NMR and IR spectroscopy. The UV/Vis spectra feature bathochromically shifted, intense charge‐transfer bands, with the lowest energy transitions and the smallest optical gap being measured for the two‐dimensionally extended chromophores 6 a and 6 b. The redox behavior of the push–pull molecules was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the series 1 b, 2 b, 4 b, 5 b, in which the spacer between donor and acceptor moieties is systematically enlarged, the electrochemical gap decreases steadily from 1.94 V (1 b) to 1.53 V (5 b). This decrease is shown to be a consequence of a reduction in the D–A conjugation with increasing spacer length. Degenerate four‐wave mixing experiments reveal high third‐order optical nonlinearities, pointing to potentially interesting applications of some of the new chromophores in optoelectronic devices.

Here, we report dicyanopyrazine (DPZ)-derived push–pull chromophores, easily prepared and tunable organic compounds, as new kinds of photoredox catalysts.

An efficient chemodivergent strategy for visible light photocatalysis is developed. In the presence of a dicyanopyrazine-derived chromophore (DPZ) photocatalyst, aerobic photooxygenation of indoles could produce either isatins or formylformanilides in satisfactory yields by judiciously selecting inorganic salts or modulating the reaction pH. The current chemodivergent method is also effective with 2-substituted indoles, opening straightforward synthetic routes to valuable 2,2-disubstituted 3-oxindoles, formylformanilide derivatives, and benzoxazinones. Mechanistic investigations involving cyclic voltammetry studies further confirm that reaction pH influences the electrochemical properties of DPZ, thus affecting the oxidative pathway by which indoles are being transformed.

SummaryResearch activities in the field of imidazole-derived push–pull systems featuring intramolecular charge transfer (ICT) are reviewed. Design, synthetic pathways, linear and nonlinear optical properties, electrochemistry, structure–property relationships, and the prospective application of such D-π-A organic materials are described. This review focuses on Y-shaped imidazoles, bi- and diimidazoles, benzimidazoles, bis(benzimidazoles), imidazole-4,5-dicarbonitriles, and imidazole-derived chromophores chemically bound to a polymer chain.