Rational and controllable syntheses of variants of modified N-confused N-fused porphodimethenes and a porphotrimethene with adaptive properties

Retrosynthetic design and synthesis with structural isolation of two unprecedented core modified
N-confused N-fused porphodimethene-like porphyrinoids possessing a [5.5.5.5] tetracyclic ring with
tunable photophysical properties is reported. The solid-state X-ray crystal structure reveals the expected
cis geometry for the meso-sp3 carbons. Controlled chemical oxidation of the porphodimethene analogue
11 bearing the N-confused pyrrole moiety to the corresponding porphotrimethene 12 has been achieved
in quantitative yield, while 10 bearing the N-methyl N-confused pyrrole moiety remained unsusceptible
to chemical oxidation. All three S2N3 hybrid N-confused N-fused porphodi(tri)methene-like porphyri-
noids 10–12 could recognize the fluoride anion with high selectivity; however, porphodimethene 10 and
porphotrimethene 12 do so via deprotonation rather than an anion recognition based mechanism as has
been anticipated in the case of porphodimethene 11.