Self-Assembled Cofacial Zinc-Porphyrin Supramolecular Nanocapsules as Tuneable O-1(2) Photosensitizers

We demonstrate the benefits of using cofacial Zn-porphyrins as structural synthons in coordination-driven self-assembled prisms to produce cage-like singlet oxygen (O-1(2)) photosensitizers with tunable properties. In particular, we describe the photosensitizing and emission properties of palladium- and copper-based supramolecular capsules, and demonstrate that the nature of the bridging metal nodes in these discrete self-assembled prisms strongly influences O-1(2) generation at the Zn-porphyrin centers. The Pd-II-based prism is a particularly robust photosensitizer, whereas the Cu-II self-assembled prism is a dormant photosensitizer that could be switched to a ON state upon disassembly of the suprastructure. Furthermore, the well-defined cavity within the prisms allowed encapsulation of pyridine-based ligands and fullerene derivatives, which led to a remarkable guest tuning of the O-1(2) production.