Nanographenes, which are nanoscale (1–100 nm) graphene fragments, have been regarded as promising candidates for next-generation semiconductors. The bottom-up synthesis of nanographenes has enabled precise control over their sizes, topologies, and edge structures, giving rise to various nanographenes with appealing optical, electronic, and magnetic properties. During the past years, most studies have been focused on the improvement of glum and revealing the structure–property relationships. In contrast, rational design of strongly luminescent chiral nanographenes, which is as important as increasing glum, is still lacking.

Recently, Xiao-Ye Wang’ group proposed a strategy to access chiral nanographenes with excellent luminescent properties by helical π-extension of highly emissive chromophores under the condition of maintaining the frontier molecular orbital (FMO) distribution pattern. As a proof of concept, they choose perylene (Φ_F: 89–99 %) as the core to design and synthesize chiral nanographene 1, in which the FMO distribution of the central part is inherited from perylene and the orbital delocalization over the helicene moieties ensures the chiroptical responses. Consequently, the electronic transition responsible for the fluorescence process is nearly undisturbed, resulting in chiral nanographene 1 with a high Φ_F of 93 %, which is comparable to that of perylene and is the highest value among all the reported chiral nanographenes. In addition, the enantiomer of 1 exhibits CPL in the range 500–700 nm (|g_lum|: 0.8×10⁻³) with BCPL of 32 M⁻¹ cm⁻¹, rendering it an excellent luminescent chiral nanographene. This work thus provides a new design strategy of strongly emissive chiral nanographenes, which would stimulate their future chiroptical applications. Relevant achievements were published in Angew. Chem. Int. Ed., 2022, DOI: 10.1002/anie.202215367.