meso-N-Pyrrole as a Versatile Substituent Influencing the Optical Properties of Porphyrin.

A meso-N-pyrrole porphyrin converts into a π-extended porphyrin forming an indolizine-3-one motif. The indolizine-3-one frame opens a lactam subunit preserving a six-membered, heterocyclic structure fused with the main macrocycle. The optical properties of formed derivatives follow the structural modifications giving the absorbance and emission eventually modulated by the NH-centered modifications of the fused unit.