Synthesis of fully π-conjugated non-alternant carbon nanobelts

Synthesizing carbon nanobelts (CNBs) with more delocalized electronic structures and enhanced π-conjugation remains challenging yet fundamentally important. Here we address this challenge and present the synthesis and characterization of fully π-conjugated, pentagon-embedded non-alternant CNBs. The nanobelts are meticulously designed with optimal strain and reactive site protection. The compounds are synthesized using an iterative Diels–Alder reaction followed by deoxygenative aromatization. Compared with all-benzenoid alternant CNBs, these CNBs exhibit smaller band gaps, stronger red emission and more effective π-conjugation owing to the incorporation of non-alternant moieties. Notably, one of the CNBs can be oxidized into its dication with an open-shell singlet ground state. Additionally, theoretical calculations indicate that the dication exhibits global aromaticity, characterized by two weakly coupled [32]annulenes with Baird-type aromaticity along its edges. This work opens avenues for synthesizing complex carbon nanostructures with enhanced electronic properties. The synthesis of fully π-conjugated, pentagon-embedded non-alternant carbon nanobelts is realized using an iterative Diels–Alder reaction followed by deoxygenative aromatization. Compared with all-benzenoid alternant counterparts, these carbon nanobelts have smaller band gaps, stronger red emission and more effective π-conjugation.