Promising Molecules for Optoelectronic Applications: Synthesis of 5,10-Dihydrobenzo[a ]indolo[2,3-c ]carbazoles by Scholl Reaction of 1,2-Bis(indol-2-yl)benzenes

Entropy-Induced Selectivity Switch in Gold Catalysis: Fast Access to Indolo[1,2-a]quinolines

New N-heterocyclic compounds for organic functional materials and their efficient syntheses are highly demanded. A surprising entropy-induced selectivity switch in the gold-catalyzed intramolecular hydroarylation of 2-ethynyl N-aryl indoles was found and its exploitation led to straightforward syntheses of indolo[1,2-a]quinolines. Experimental and computational mechanistic investigations gave insight into this uncommon selectivity phenomenon and into the special reactivity of the indolo[1,2-a]quinolines. The high functional group tolerance of this methodology enabled access to a diverse scope with high yields. In addition, bidirectional approaches, post-functionalization reactions, and π-extension of the core structure were feasible. An in-depth study of the photophysical properties explored the structure-effect relationship for different derivatives and revealed a high potential of these compounds for future applications as functional materials.

Straight access to highly fluorescent angular indolocarbazoles via merging Au- and Mo-catalysis

A straightforward and efficient synthesis of the two less explored types of indolocarbazoles has been developed giving rise to highly fluorescent compounds with fluorescence quantum yields around 0.7.

Bay-Substituted Thiaza[5]helicenes: Synthesis and Implications on Structural and Spectroscopic Properties

A series of bay-substituted thiaza[5]helicenes was synthesized to investigate the effect of different substituents on the properties of these helicenes. These thiaza[5]helicenes with different substituents were prepared in a straightforward manner through indole- and benzo[b]thiophene synthesis, palladium-catalyzed Suzuki coupling, oxidative cyclization, and functional group interconversion reactions. We investigated the impact of these different bay area substituents compared to the unsubstituted thiaza[5]helicene on the structural parameters and studied the steady-state electronic spectroscopy of these thiaza[5]helicenes in toluene and acetonitrile. We found that different functional groups influence the solid state structure and spectroscopic properties, but a single substituent in the bay area of a thiaza[5]helicene was not enough to prevent enantiomerization at room temperature.

5,10-Dihydrobenzo[ a]indolo[2,3- c]carbazoles as Novel OLED Emitters

The excited-state dynamics of four 5,10-dihydrobenzo[ a]indolo[2,3- c]carbazoles in solution and in films were studied with stationary and time-resolved spectroscopies. The solvent dependency of the photophysics reveals no appreciable dipole moment in the ground state. In the excited state, electron-withdrawing substituents contribute to an outspoken charge-transfer character. In films, although the molecules are mostly present as monomers, the excited-state dynamics are characterized by a cascade of energy-transfer processes to excited dimers and aggregates which dominate the photoluminescence (PL) spectra. The properties of the aggregates depend on the used substituents. The electroluminescence spectra obtained from single-layer and multilayer devices mostly resemble the PL spectra, but show contributions from other species such as electromers or electroplexes. It is inferred that the different substituents lead to a different packing of the carbazole moieties, each of which has different mobilities and recombination probabilities.