Beyond perylene diimides: synthesis, assembly and function of higher rylene chromophores

Perylene diimides are among the most important chromophores in dyestuff chemistry. They do not only have excellent thermal, chemical and photochemical stability, high absorption coefficients and fluorescence quantum yields but also permit various chemical functionalizations. Over the last decades, academic and industrial interest in this class of chromophores has steadily increased due to their favourable properties and potential application in various research fields like organic electronics, biochemistry, photophysics and supramolecular chemistry. Higher rylene diimide dyes (e.g. 2-6), however, are still in their infancy and must be further explored by combining more research efforts of chemists, physicists, biologists, and material scientists since these dyes possess unique optical, electrochemical, and electronic properties. One of the main obstacles in such rylene based dyes seems to be their synthetic challenges. Thus, in this feature article, we summarize the latest advances in the field of rylene diimide dyes focusing on synthetic strategies toward their preparation. The self-assembly behaviour and applications of larger rylene chromophores are discussed as well.