Photoactive self-assembled arrays based on porphyrins

Non-covalent supramolecular structures can be obtained via self-assembly of porphyrinic systems and suitably designed hosts or bridging units. These structures represent an important challenge for the mimicry of bacterial photosynthesis and for applications in molecular electronics and photocatalysis. Here we report on some recently explored examples, in particular cages formed by the self-assembly of Zn-trisporphyrin platforms by axial coordination with dipyridyl containing photoactive units; arrays formed by the coordination of Zn-bisporphyrin clips with a host (either poprhyrin or fullerene); porphyrinic cages assembled through metal mediated interactions, of potential use as nanoreactors; bisporphyrin macrocycles including fullerene hosts; porphyrin-fullerene couples assembled via hydrogen-bonding interactions through cyclopeptide scaffolds. The binding constants have been derived by means of spectrophotometric and spectrofluorimetric titrations and the photophysical investigations of the complexes have been carried out by means of steady-state and time-resolved optical techniques. All the examined supramolecular structures show interesting photophysical properties and in most cases photoinduced processes within the complexes, such as energy or electron transfer, have been proven to take place [1-4].