Marriage of an N‑Fused and a Regular Porphyrin in a Cofacial Ligand System

We present a straightforward synthetic route which allows
cofacial
stacking of N-fused porphyrins and regular porphyrins via an o-substituted
phenylene linker. The protocol comprises a crucial Suzuki–Miyaura
cross-coupling reaction to introduce the phenyl moiety at the tri-pentacyclic
ring of the N-fused porphyrin, paving the way to the first arrangement
that is capable of holding an N-fused porphyrin and a regular porphyrin
in spatial proximity. The ligand system was obtained with a 0.77%
yield in five steps, starting from pyrrole and benzaldehyde. The dimeric
ligand was investigated for further insights into sterical properties,
employing inter alia ion-mobility spectrometry, DFT calculations,
and metal coordination reactions. The molecular species were characterized
by 1H NMR, UV–vis, IR, high-resolution mass spectrometry,
and trapped ion-mobility measurements. The latter suggests that the
ligand system can stabilize two atoms of the same metal in different
oxidation states, such as in an Mn­(I)­Mn­(III) complex.