Strong enhancement of two-photon absorption properties in synergic ‘semi-disconnected’ multiporphyrin assemblies designed for combined imaging and photodynamic therapy

The synthesis and photophysical properties of new multiporphyrin assemblies are described. Their design, based on a smooth electronic disconnection between two-photon absorbing (2PA) octupolar or quadrupolar cores and the peripheral porphyrins, leads to a major increase in (non-resonant) 2PA responses in the NIR, while fully retaining the fluorescence and photosensitization properties of isolated porphyrins. This approach, which involves electronic coupling of semi-disconnected moieties in the higher excited states of the synergic systems, is of interest to fully benefit from the advantages of selective 2PA for application in combined two-photon high resolution imaging and photodynamic therapy.