Incorporation of the 1,5-Naphthalene Subunit into Heteroporphyrin Structure: Toward Helical Aceneporphyrinoids

5,10,15,20-Tetraaryl-22-hetero-1,5-naphthiporphyrins,
which contain
a 1,5-naphthylene moiety instead of one pyrrole embedded in the macrocyclic
framework of heteroporphyrins, were obtained by the [3 + 1] approach
using the 1,5-naphthylene analogue of tripyrrane (1,5-bis­(phenyl­(2-pyrolyl)­methyl)­naphthalene)
and 2,5-bis­(arylhydroxymethyl)­heterocyclopentadiene (heterocyclopentadiene:
thiophene, selenophene, tellurophene). The steric constraints, imposed
by the substitution mode of the 1,5-naphthylene building block, resulted
in the specific helical conformation of 22-hetero-1,5-naphthiporphyrins.
The spectroscopic and structural properties of these aceneporphyrinoids
indicate a lack of macrocycle aromaticity. Their protonation yielded
solely dicationic species.