Synthesis of a Face-to-Face Porphyrin Nanoring

New porphyrin dimers PD and PR were synthesized through a one-pot condensation reaction. PD forms a Z-shaped porphyrin dimer, while PR adopts an interesting face-to-face porphyrin nanocage configuration. NMR and ACID data indicate that both exhibit localized aromaticity rather than global 3D aromaticity. Steady-state fluorescence, TCSPR, and nanosecond TA analyses of PD and PR demonstrated no significant π-π interactions between their porphyrin units, attributed to the terphenylene linker's considerable length. Singlet-oxygen (¹O₂) generation assays under blue and red light irradiation revealed both compounds to be highly effective type II photosensitizers.