Journal of the American Chemical Society, Vol.131, No.21, 7240-7240, 2009
Facile Formation of a Benzopyrane-Fused [28]Hexaphyrin That Exhibits Distinct Mobius Aromaticity
A benzopyrane-fused [28]hexaphyrin, 2, was prepared by simple heating of [26]hexaphyrin 1 in acetic acid. Fused [28]hexaphyrin 2 features a molecular twist, a distinct diatropic ring current, a large HOMA value, a large negative NICS value, and a large two-photon absorption (TPA) cross section even at room temperature, all of which support the Mobius aromaticity of 2. To the best of our knowledge, 2 is the first macrocycle that acquires distinct Mobius aromaticity without any assistance from metal coordination, temperature control, or protonation.