Farbstofforganisate: Biomimetik und funktionelle Materialien

Oxidative cyclodehydrogenation of a perylene derivative: different reagents give different products

Oxidative cyclodehydrogenation of 3-(4-fluoronaphthalen-1-yl)perylene gives, by reaction with AlCl₃, 3-fluoroterrylene and by reaction with DDQ/TfOH, its isomer 10-fluorobenzo[4,5]indeno[1,2,3-cd]perylene.

Bichromophoric perylene derivatives: energy transfer from non-fluorescent chromophores

The energy of excitation at non-fluorescent chromophores such as fluorenone and anthraquinone has been trapped by a fast energy transfer to the highly fluorescent perylene bisimides. To this end, anthraquinone, fluorenone and anthracene derivatives have been linked to the perylene bisimides by non-conjugating spacers and fluorescence quantum yield of such assemblies have been determined as a function of the wavelengths of excitation. Energy transfer in such assemblies is strongly influenced by the orientation of the two chromophores. This is of interest for the construction of fluorescence switches.

Synthesis of diazadibenzoperylenes and characterization of their structural, optical, redox, and coordination properties

Tetraphenoxy-substituted diazadibenzoperylenes 5a,b were synthesized from tetrachloroperylene tetracarboxylic acid bisanhydride 1 through imidization with benzylamine, nucleophilic displacement of the four chlorine atoms by phenolates, carbonyl group reduction by LiAlH(4)/AlCl(3), and subsequent Pd/C-promoted debenzylation-dehydrogenation. The structural properties of these extended diazaarenes are discussed on the basis of a X-ray crystal structure of the N,N'-dibutylated diazadibenzoperylenium dication 6, which revealed a 25 degrees twist of the central six-membered ring leading to an atropisomeric pi-conjugated backbone. The chromophoric systems of 5 and 6 were characterized by optical absorption and fluorescence spectroscopy, which revealed an intense fluorescence with a quantum yield of 75% for 5 and 50% for 6. Cyclic voltammetry showed reversible oxidation and reduction waves for 6, whereas the oxidation of 5 afforded the irreversible deposition of a conductive film on the electrode surface. Finally, the potential use of ligands 5 in supramolecular chemistry has been evaluated by complexation experiments with carboxylic acids and zinc tetraphenylporphyrin (ZnTPP).