Porphyrin-Phthalocyanine/Pyridylfullerene Supramolecular Assemblies

The synthesis and photophysical properties of several porphyrin (P)–phthalocyanine (Pc) conjugates (P–Pc; 1–3) are described, in which the phthalocyanines are directly linked to the β‐pyrrolic position of a meso‐tetraphenylporphyrin. Photoinduced energy‐ and electron‐transfer processes were studied through the preparation of H2P–ZnPc, ZnP–ZnPc, and PdP–ZnPc conjugates, and their assembly through metal coordination with two different pyridylfulleropyrrolidines (4 and 5). The resulting electron‐donor–acceptor hybrids, which were formed by axial coordination of compounds 4 and 5 with the corresponding phthalocyanines, mimicked the fundamental processes of photosynthesis; that is, light harvesting, the transduction of excited‐state energy, and unidirectional electron transfer. In particular, photophysical studies confirmed that intramolecular energy‐transfer resulted from the S2 excited state as well as from the S1 excited state of the porphyrins to the energetically lower‐lying phthalocyanines, followed by an intramolecular charge‐transfer to yield P–Pc.+⋅C60.−. This unique sequence of processes opens the way for solar‐energy‐conversion processes. Alright PET? Photoinduced energy‐ and electron‐transfer processes were studied in several porphyrin (P)/phthalocyanine (Pc)/fullerene (C60) hybrids in which the phthalocyanines were directly linked to the β‐pyrrolic positions of the porphyrins and assembled through metal coordination with different pyridylfullerenes (see figure).