Novel expanded porphyrinoids with multiple-inner-ring-fusion and/or tunable aromaticity

Novel expanded porphyrinoids with advanced structure features (such as multiple-inner-ring-fusion) have a wide range of benefits (such as multi-metal coordination and facile tunable aromaticity) not offered by their normal porphyrin analogues, and have found wide applications as sensors, fluorescent probes, novel ligands and functionalized NIR organic dyes in various research fields. However, the structures of these expanded porphyrinoids are scarce due to their limited synthetic accessibility. Herein, we summarized the lately reported efficient synthesis of novel expanded porphyrinoids with multipleinner-ring-fusion (up to six-inner-ring-fusion) and smaragdyrins with tunable aromaticity. Their synthesis is either based on an oxidative ring cyclization on linear/macrocyclic oligopyrroles containing N-confused pyrrole unit(s) or a straightforward double S_NAr reaction on readily available 3,5-dibromoBODIPY, respectively.