Temperature‐Controlled Synthesis of Corannulene‐Based Multi‐Helicenes: Highly Integrated Curvature/Planarity for Enhanced CPL Brightness and Solid‐State Luminescence

Abstract

Abstract Corannulene and hexabenzocoronene ( HBC ), as archetypal bowl‐shaped and planar nanographene, have attracted considerable interest. Highly integrating these complementary motifs into a single architecture, however, remains a challenge owing to considerable intramolecular strains. Here, we report a temperature‐controlled synthesis that enables selective hybridization between corannulene and multiple HBC ‐like motifs, yielding the anticipated quintuple [8]helicene ( Cor‐5H ) and an unexpected triple [8]helicene ( Cor‐4H ) incorporating a rare nonagon, likely involving a phenyl shift rearrangement mechanism. DFT calculations provide insights into the preferential formation of Cor‐5H at lower temperatures, while Cor‐4H predominates at elevated temperatures. Single‐crystal X‐ray diffraction confirms their hybrid bowl–helix topologies, in which a central corannulene is fused with four ( Cor‐4H ) or five ( Cor‐5H ) HBC ‐like blades. The significant steric constraint imposed by the curved core results in high strain energies. This synergistic integration of curvature and planarity endows both compounds with intense deep‐red to near‐infrared (NIR) fluorescence; enhanced chiroptical responses and high circularly polarized luminescence (CPL) brightness; as well as unusual solid‐state fluorescence due to suppressed π–π stacking. As the largest π‐extended corannulene‐based multiple [n]helicenes reported to date, Cor‐5H and Cor‐4H demonstrate the powerful potential of fusing curved and planar nanographene motifs to design materials with advanced chiroptical functions.