From industrial colorants to single photon sources and biolabels:: The fascination and function of rylene dyes

Perylene dyes are key chromophores in dyestuff chemistry. The solubility, absorption, and emission behavior of this class of materials can be efficiently controlled by functionalization using a variety of different synthetic procedures. Moreover, these chemical modifications have allowed their widespread application as functional dyes. New NIR-absorbers have been synthesized by introducing additional naphthalene units to the perylene scaffold to form the higher homologues of the series of rylenediimides. Such dyes can be used for laser welding and laser marking of polymers. Highly fluorescent nanoparticles containing multiple chromophores have been prepared by decorating polyphenylene dendrimers with rylenes on the surface. Depending on the chromophoric interactions, these types of materials can serve as single photon sources. When in addition to the surface, the interior and the dendritic scaffold are equipped with donor and acceptor dyes, synthetic light-harvesting complexes are obtained, which collect light from the whole visible spectrum. Due to the outstanding chemical and photochemical stabilities as well as their high fluorescence quantum yields, the perylene- and terrylenediimides have been established as key chromophores for single molecule spectroscopy allowing photophysical processes, e.g. energy and electron transfer to be studied on the single molecule level over extended periods of time. With water soluble rylene dyes single molecule measurements regarding biological problems can now be addressed as well. The same set of favorable proper-ties also makes the rylene dyes excellent candidates for applications in organic electronic devices.