Carbene Zipper Reaction for Cascade π-Extension

The unique electronic, thermal, and mechanical properties of nanographenes structured with polycyclic aromatic hydrocarbons (PAHs) can be finely tuned via modulation of the π-length, π-width, π-shape, π-edge, and π-curvature topology. However, the programmable construction of such architectures remains a formidable challenge, drastically hindering the systematic exploration of structure–property relationships in graphene-based materials. In this study, a cascade π-extension strategy has been established for the precise synthesis of PAHs through a copper-catalyzed domino carbene transfer process, enabling determinate structural control with tunable lengths, facilitating the construction of versatile twisted π-systems with local aromaticity variations.