A meso-Tetraaryl-21-carbaporphyrin: Incorporation of a Cyclopentadiene Unit into a Porphyrin Architecture.

Incorporation of a cyclopentadiene moiety into the meso-tetraarylporphyrin framework, using 1,3-bis(arylhydroxymethyl)ferrocene as a synthon, resulted in the rational synthesis of a meso-tetraaryl-21-carbaporphyrin. The molecular design preserves all essential virtues of the original tetrapyrrolic architecture of meso-tetraarylporphyrin, including the perfect match between the ionic radii of an inserted metal and the size of the macrocyclic (CNNN) core, and steric protection provided by thoughtfully chosen meso-aryl substituents. Its protonation of the inner core reveal an adjustable (trigonal versus tetrahedral) geometry.