Cyclic porphyrin arrays as artificial photosynthetic antenna: synthesis and excitation energy transfer.

Covalently linked cyclic porphyrin arrays have been explored in recent years as artificial photosynthetic antenna. In this review we present the fundamental aspects of covalently linked cyclic porphyrin arrays by highlighting recent progress. The major emphasis of this tutorial review lies on the synthetic method, the structure, and the excitation energy transfer (EET) of such arrays. The final cyclization steps were often performed with the aid of templates. Efficient EET along the wheel is observed in these cyclic arrays, but ultrafast EET processes with rates of <1 ps, which rival those in the natural LH2, are rare and have been identified only in cyclic arrays 30-32 composed of directly meso-meso linked porphyrins.