Bay‐functionalized [7]Helicene Bilayer Nanographenes

Abstract Helical bilayer nanographenes (HBNGs) represent a promising class of materials for advanced optoelectronic and chiroptical applications, owing to their extended π ‐conjugation, intrinsic chirality, and tunable interlayer interactions. Here, the rational design and synthesis of bay ‐functionalized [7]HBNGs incorporating methoxy, diketone, and phenazine moieties is reported. These tailored modifications enable precise tuning of redox properties and significantly enhance photophysical properties, including pronounced spectral shifts, prolonged fluorescence lifetimes of up to 10 ns, and fluorescence quantum yields reaching 55%. Importantly, the resulting [7]HBNGs exhibit strong electronic circular dichroism and exceptional circularly polarized luminescence (CPL), with CPL brightness values as high as 110 M ⁻¹ cm ⁻¹ . The modular, convergent strategy enables versatile late‐stage modification of bay‐substituted HBNGs from a single scalable precursor, streamlining access to diverse derivatives and opening new opportunities for their application in molecular electronics, chiroptical devices, and advanced optoelectronic materials.