A Pyrrole–Pyridine-Embedded Buckybowl: Synthesis and Application for Rapid Sulfur Mustard Imaging

Buckybowls, also known as π-bowls, have attracted growing research interest due to their unique curved π-surfaces and associated properties. However, the development of this field faces challenges, primarily the need for reliable synthetic strategies and more demonstrated practical applications. In this work, we have synthesized a pyrrole/pyridine-embedded buckybowl, triazahomosumanene (TAHS), through a “twisted precursor → notched shallow bowl → deep bowl” strategy for the progressive accumulation of high strain energy. TAHS exhibits highly acid-sensitive photophysical properties: substoichiometric protonation induces dramatic fluorescence changes, including a large bathochromic shift (Δλmax = 110 nm) and significant emission enhancement, features not observed for conventional pyridine-based polycyclic aromatics. Further investigations identified TAHS as a fluorescent probe for sulfur mustard with a fast response (5 s), high sensitivity (LOD < 100 nM), and high stability, capable of imaging in both live cells and mice. This work establishes a paradigm for the molecular design and functional application of curved aromatic systems.