Contorted Heteroannulated Tetraareno[a,d,j,m]coronenes

Substituent Effects in Scholl-Type Reactions of 1,2-Terphenyls to Triphenylenes

A series of 3,3''- and 4,4''-dimethoxy terphenyls with different second substituents on their ortho-positions have been synthesized and investigated upon the possibility to be oxidatively cyclodehydrogenated to the corresponding triphenylenes under Scholl-type conditions. The experimentally obtained selectivities were supported and explained by quantum chemical calculations and conclusions on the involved mechanisms (acid catalyzed arenium-ion mechanism (AIM) vs radical cation mechanism) were drawn.

Synthesis and properties of thienonaphtho[bc]pyridines and thienonaphtho[bc]quinolines

The incorporation of heteroatoms within polycyclic aromatic compounds has gained significant interest due to its potential to effectively alter the inherent physicochemical properties of compounds without the need for profound structural changes. We herein report the development of a modular synthesis of hitherto unknown thienonaphtho[bc]pyridines and thienonaphtho[bc]quinolines in very good yields by Brønsted acid mediated cycloisomerization, permitting selective access to two isomeric products that are isoelectronic to the parent dibenzopyrene. The photophysical and electrochemical properties of the desired compounds were extensively studied and further complemented by DFT calculations.

In Silico Screening and Experimental Verification of Near-Infrared-Emissive Two-Boron-Doped Polycyclic Aromatic Hydrocarbons

Embedding two boron atoms into a polycyclic aromatic hydrocarbon (PAH) leads to the formation of a neutral analogue that is isoelectronic to the corresponding dicationic PAH skeleton, which can significantly alter its electronic structure. Based on this concept, we explore herein the identification of near-infrared (NIR)-emissive PAHs with the aid of an in silico screening method. Using perylene as the PAH scaffold, we embedded two boron atoms and fused two thiophene rings to it. Based on this design concept, all possible structures (ca. 2500 entities) were generated using a comprehensive structure generator. Time-dependent DFT calculations were conducted on all these structures, and promising candidates were extracted based on the vertical excitation energy, transition dipole moment, and atomization energy per bond. One of the extracted dithieno-diboraperylene candidates was synthesized and indeed exhibited emission at 724 nm with a quantum yield of 0.40 in toluene, demonstrating the validity of this screening method. This modification was further applied to other PAHs, and a series of thienobora-modified PAHs was synthesized.

Rubicene, an Unusual Contorted Core for Discotic Liquid Crystals

Rubicene, an unusual contorted polycyclic aromatic hydrocarbon, was realized to function as a novel core fragment for discotic liquid crystals. The central π-conjugated motif was prepared from dialkoxyiodobenzene via Sonagashira coupling followed by pentannulation and Scholl cyclodehydrogenation. The synthesized rubicene derivatives were found to be thermally stable and exhibit enantiotropic columnar mesophases. The columnar arrangement of these derivatives has been validated using polarising optical microscopy, differential scanning calorimetry & small-angle X-ray scattering.