Stable antiaromatic expanded porphyrins were designed by the judicious implementation of meso-imidazolyl groups, which cause stabilization through the creation of a hydrogen-bonding network (see structures) that overcomes antiaromatic electronic destabilization. Both the hexaphyrin 1 and the octaphyrin 2, which contain imidazolyl groups at two opposite meso positions, are shown to be stable Hückel antiaromatic species.
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