Tetralithiated Tetraazaperopyrene as a Key Intermediate for the Synthesis of Functionalized Derivatives

A new synthetic approach to core-functionalized tetraazaperopyrenes (TAPP) is reported. In-situ reaction of 4-fold lithiated TAPP with electrophiles results in the formation of various unprecedented TAPP derivatives, which are highly emissive fluorophores, show promising photophysical and electrochemical properties and act as valuable starting materials. Thus, lithiation of the TAPP core opens up a facile way for developing new organic materials

(Oligo-)Thiophene Functionalized Tetraazaperopyrenes: Donor–Acceptor Dyes and Ambipolar Organic Semiconductors

Tetraazaperopyrenes (TAPPs) have been functionalized with thiophene and terthiophene units of different architecture resulting in a variety of organic donor–acceptor (D–A) compounds. The influence of the connection of the thiophenes to the TAPP core on their structural, photophysical and electrochemical properties has been studied in detail by a combination of X-ray crystallography, UV–vis and fluorescence spectroscopy as well as cyclic voltammetry, which allowed the establishment of structure–property relationships. The HOMO–LUMO gap is significantly decreased upon substitution of the TAPP core with electron-donating thiophene units, the extent of which is strongly influenced by the orientation of the thiophene units. The latter also crucially directs the molecular packing in the solid. Linkage at the α-position allows both inter- and intramolecular N···S interaction, whereas linkage in the β-position prevents intramolecular N···S interaction, resulting in a less pronounced conjugation of the TAPP core and the thiophene units. The new TAPP derivatives were processed as semiconductors in organic thin-film transistors (TFTs) that show ambipolar behavior. The insight into band gap and structure engineering may open up new possibilities to tailor the electronic properties of TAPP-based materials for certain desired applications