Photoinduced Intramolecular Electron Transfer Within Porphyrinic Rotaxanes

Photoinduced Intramolecular Electron Transfer Within Porphyrinic Rotaxanes 

In making rotaxanes usable as parts of molecular devices and with the purpose of studying long range election transfer processes within large molecular systems of well controlled geometries, the introduction of photoactive and electroactive compounds has been a valuable development. Photoinduced electron transfer between porphyrin species has a particular relevance to the primary events occurring in bacterial photosynthetic reaction center complexes, and so is a well studied phenomenon. 

Molecular systems in which two porphyrins are held apart by a covalently linked spacer function give rise to bis-porphyrins with flexible or constrained geometries. Rotaxane architectures incorporating similar or dissimilar porphyrins as stoppers have been widely developed in our group, with the goal of building such systems capable of allowing modulation of electron transfer. 

Specifically, light excitation of SP leads to very fast electron transfer to BPh, within 3 ps. In bis-porphyrin 1, the electron donor (the zinc porphyrin) is in its sing- 

The homoleptic Cu(l)2 complex and the bis-porphyrinic rotaxane 2+ both incorporate the same coordinating core Cu(dpp). In the rotaxane, one of the coordinating moieties (dpp) is incorporated in a macrocyde, which plays the role of a wheel. The second coordinating core is incorporated in the molecular thread - the axle of the rotaxane - the two ends of which bear the gold and the zinc porphyrin, respectively. 

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