Bottom‐Up Preparation of Twisted Graphene Nanoribbons by Cu‐Catalyzed Deoxygenative Coupling

Abstract

Graphene nanoribbons (GNRs) are promising in organic optoelectronic materials, and their properties largely depend on the size, edge, and conformation. Herein, the fully armchair-edged GNRs (AGNRs) with lengths up to 2.65 nm by using a Cu-catalyzed deoxygenative coupling as a key step. The resulting AGNRs (2HBT, 3HBT, and 4HBT) possess highly twisted πscaffolds, and the torsion angles between the adjacent triphenylene moieties are larger than 32°, as proved by crystallographic analyses. Theoretical and spectroscopic studies show that the butoxy groups endow AGNRs with electron-rich features, the extension of the π-system from 2HBT to 4HBT reinforces S 0 !S 1 excitation, and the distortion of the π-scaffold enhances the fluorescence quantum yield (Φ F ). In particular, 4HBT has the lowest oxidation potential (E ox 1 = 0.55 V vs. SCE) and displays red fluorescence with a Φ F value of 81 %.