Large two-photon absorption (TPA) cross-section of directly linked fused diporphyrins.

The excited state dynamics and two-photon absorption properties of four novel triply linked porphyrin dimers in toluene have been investigated. The fused porphyrin dimers exhibit extremely increased two-photon absorption cross-section values (12 000−15 000 GM) compared with porphyrin monomers owing to much enhanced π-electron delocalization throughout the porphyrin dimer ring.