Diazulenorubicene as a Non-benzenoid Isomer of peri-Tetracene with Two Sets of 5/7/5 Membered Rings Showing Good Semiconducting Properties

Angew Chem Int Ed Engl. 2023 Sep 25;62(39):e202304632. doi: 10.1002/anie.202304632. Epub 2023 Jul 3.

Abstract

Non-benzenoid polycyclic aromatic hydrocarbons (PAHs) have received a lot of attention because of their unique optical, electronic, and magnetic properties, but their synthesis remains challenging. Herein, we report a non-benzenoid isomer of peri-tetracene, diazulenorubicene (DAR), with two sets of 5/7/5 membered rings synthesized by a (3+2) annulation reaction. Compared with the precursor containing only 5/7 membered rings, the newly formed five membered rings switch the aromaticity of the original heptagon/pentagon from antiaromatic/aromatic to non-aromatic/antiaromatic respectively, modify the intermolecular packing modes, and lower the LUMO levels. Notably, compound 2 b (DAR-TMS) shows p-type semiconducting properties with a hole mobility up to 1.27 cm2 V-1 s-1 . Moreover, further extension to larger non-benzenoid PAHs with 19 rings was achieved through on-surface chemistry from the DAR derivative with one alkynyl group.

Keywords: Annulation; Aromaticity; Fused Ring Systems; Semiconducting Properties; on-Surface Synthesis.