Symmetric 32π (1.0.1.0.1.0.1) Core-Modified Heptaphyrins from Asymmetric Building Block.

An asymmetrical precursor with three thiophene subunits on condensation with a thiophene/furan diol yield a symmetrical 32π heptaphyrin. Here are the first examples of pyrrole-free antiaromatic heptaphyrin synthesized by the acid assisted condensation reaction, followed by an oxidative α-α coupling between the terminal thiophene rings. The macrocycles attains a slightly bent configuration, which undergoes reversible two-electron oxidation between a neutral 4nπ and (4n + 2)π dication state.