A Doubly meso-Free Tetrabromo-[36]octaphyrin as a Promising Precursor of Directly Fused Porphyrin(2.1.1.1) Dimer and meso-α Fused N-Confused Porphyrin Dimer

3,7,23,27-Tetrabromo-[36]octaphyrin 2 was synthesized as a novel octaphyrin bearing two meso -free positions. Surprisingly, its Zn II and Ni II complexation reactions produced a directly fused porphyrin(2.1.1.1) dimer 6 , and a meso-α fused N-confused porphyrin (NCP) dimer 7 , as the first example of NCP tape, respectively, via transannular C-C bond formation. While 6 exhibits a diatropic ring-current effect owing to the global 36π Mobius aromaticity, 7 shows a paratropic ring-current effect due to the global Huckel 36π antiaromaticity. In addition, the oxidation of 7 with PbO 2 allowed for formation of its two-electron oxidized species 9 that exhibited a diatropic ring-current effect due to the global Huckel 34π aromaticity. This work has demonstrated that meso -free large expanded porphyrins can be a promising platform to produce novel fused porphyrinoids.