A Green Fluorescent Nitrogen‐Doped Aromatic Belt Containing a [6]Cycloparaphenylene Skeleton

The design and synthesis of nitrogen‐doped aromatic belts with conjugated structures still remain a challenge. Here, we report the first nitrogen‐doped aromatic belt with a [6]cycloparaphenylene skeleton, which is conveniently synthesized from the easily available calix[3]carbazole. The aromatic belt has a rigid conjugated structure and deep cavity, and it can encapsulate one dichloromethane both in solution and in the solid state. Interestingly, the aromatic belt shows strong green fluorescence with a quantum yield of 0.39 and exhibits a narrow HOMO–LUMO energy gap of 2.02 eV. The belt‐shaped conjugated structure composed of three carbazole subunits has specific optoelectronic properties that will promote wide applications in supramolecular chemistry and materials science. The first nitrogen‐doped aromatic belt with a [6]cycloparaphenylene skeleton ([6]CPP) was conveniently synthesized from calix[3]carbazole. The aromatic belt showed an enhanced π‐conjugated structure and a deep cavity, and also exhibited strong green fluorescence and a narrow HOMO–LUMO energy gap.