A Self-Assembled Light-Harvesting Array of Seven Porphyrins in a Wheel and Spoke Architecture

A shape-persistent cyclic array of six zinc porphyrins provides an effective host for a dipyridyl-substituted free base porphyrin, yielding a self-assembled structure for studies of light harvesting. Energy transfer occurs essentially quantitatively from uncoordinated to pyridyl-coordinated zinc porphyrins in the cyclic array. Energy transfer from the coordinated zinc porphyrin to the guest free base porphyrin is less efficient (Φtrans ∼40%) and is attributed to a Forster through-space process.