3,7,23,27-Tetrabromooctaphyrin 2 was synthesized as a novel octaphyrin bearing two meso-free positions. Surprisingly, its ZnII and NiII complexation reactions produced a directly fused porphyrin(188.8.131.52) 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 Möbius aromaticity, 7 shows a paratropic ring-current effect due to the global Hückel 36π antiaromaticity. In addition, the oxidation of 7 with PbO2 allowed for formation of its two-electron oxidized species 9 that exhibited a diatropic ring-current effect due to the global Hückel 34π aromaticity. This work has demonstrated that meso-free large expanded porphyrins can be a promising platform to produce novel fused porphyrinoids.
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