| Abstract
| - The need for new photodynamic-therapy photosensitizers has stimulated the search of new families ofcompounds absorbing strongly in the 700−900 nm range, the region where tissue is most transparent toradiation capable to induce the photodynamic effect. Using computational chemistry techniques, 3,6,13,16-tetraazaporphycenes were previously identified as interesting target candidates. This work reports on thephotophysical and electrochemical properties of selected members of this new family of macrocycles. Comparedto porphycenes, the tetra-aza counterparts show stronger absorption in the near-infrared, lower-lying singletand triplet excited states, and substantially larger internal conversion quantum yield (ΦIC = 0.93). Energytransfer to oxygen is observed, which results in the formation of the cytotoxic species singlet oxygen. Theprocess is found to be reversible, consistent with a triplet-energy value close to that of singlet oxygen.
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