Internally 2,5‐Thienylene‐Bridged [46]Decaphyrin: (Annuleno)annulene Network Consisting of Möbius Aromatic Thia[28]hexaphyrins and Strong Hückel Aromaticity of its Protonated Form

Internally 1,3‐phenylene‐ and 2,5‐thienylene‐bridged 46]decaphyrins 2 and 3 have been synthesized. While 2 shows modest aromatic character derived from the global 46π‐conjugated circuit, 3 displays larger aromatic character owing to the contribution of an (annuleno)annulene‐type network consisting of two twisted Möbius aromatic thia28]hexaphyrin segments in addition to the global 46π‐network. Upon protonation, these 46]decaphyrins underwent large structural changes to acquire strong aromaticity. Protonated 3 has been revealed to take on a planar structure composed of fused two triangular thia28]hexaphyrin segments.