π-Aggregation-free, fused perylene pentamers: synthesis, narrowband far-red to near-infrared emission, and chiroptical properties

Chiral nanographenes have emerged as promising materials for chiral optoelectronics owing to their intrinsic chiroptical properties. However, their development remains constrained by synthetic challenges, strong π-aggregation, and low fluorescence quantum yields, while emission extending to the near-infrared (NIR) region is still rare. Here, we present a molecular design strategy that combines structural multiplicity with π-extension in a butterfly-shaped fused perylene pentamer scaffold to achieve active circularly polarized luminescence (CPL) emitters. By tuning the Scholl reaction conditions, we selectively obtained either racemic 1a (1a-rac) together with its meso-isomer (1a-meso) or an extended series of nanographenes (1a–1d). X-ray crystallography revealed contorted architectures featuring helicene subunits, while bulky aryl substituents improved solubility, enhanced stability, and enabled enantiomer separation. Owing to their extended π-conjugation, perylene-like frontier orbital distribution, and increased molecular symmetry and rigidity, these nanographenes exhibit highly tunable and remarkable optical and chiroptical properties. Notably, 1a demonstrates outstanding chiroptical performance (Φ_F = 65%; B_CPL = 66.7 M⁻¹ cm⁻¹), whereas 1d exhibits narrowband emission (FWHM = 37 nm) spanning the far-red to NIR region.