An extensive polycyclic -system with 23 fused rings is synthesized via a highly efficient borylation reaction, in which four B-N covalent bonds and four BN coordinate bonds are formed in one pot. BN coordinate bonds not only lock the backbone into a near-coplanar conformation but also decrease the LUMO energy level to around -3.82 eV, demonstrating the dual utility of this strategy for the synthesis of extensive rigid polycyclic molecules and the development of n-type conjugated materials for organic electronics and organic photovoltaics.
