Aromatic and Antiaromatic Cyclophane‐type Hexaphyrin Dimers

A peripherally strapped [28]hexaphyrin takes a rectangular conformation and exhibits antiaromatic character. A cyclophane‐type dimer consisting of such [28]hexaphyrins was synthesized from hexakis(pentafluorophenyl) [26]hexaphyrin via S_NAr reaction with allyl alcohol, one‐pot intra‐ and intermolecular olefin metathesis under improved Hoveyda–Grubbs catalysis, and final reduction with NaBH₄. The cyclophane‐type structures of [26]‐ and [28]hexaphyrin dimers have been revealed by X‐ray analysis. Studies on the structural, optical, and electronic properties have led to a conclusion that there is no favorable electronic interaction between the two [28]hexaphyrin segments and thus no indication of 3D aromaticity.