Direct ab initio mapping of induced current density in the pi system of the expanded porphyrin amethyrin shows a picture at variance with the conventional 4npi ascription of antiaromaticity. The ipsocentric orbital model interprets the pattern of currents as a superposition of shell contributions: an intense paratropic ring current concentrated on the inner 20-site cycle, counteracted by a weaker diatropic circulation on a 24-site conjugation pathway and a combination of local 5-site diatropic circulations on the six pyrrolic rings.
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Steiner et al. (2006) studied this question.