A Quadruply Azulene‐Fused Porphyrin with Intense Near‐IR Absorption and a Large Two‐Photon Absorption Cross Section

Extending conjugation: Azulene-fused porphyrins (see example) are synthesized through the oxidation of meso-(4-azulenyl)porphyrins with FeCl3. The azulene-fused strategy allowed highly π-conjugated porphyrinic electronic systems, which are promising two-photon absorption pigments, to be realized.