Extremely long-distance electron transfer in porphyrin or phthalocyanine systems directly functionalized by an oligo(phenyleneethynylene) spacer

This review focuses on a new strategy to design covalently linked and electronically coupled porphyrin systems to achieve long-range photoinduced electron transfer. We show that the attachment of a π-conjugated bridge directly on the meso position of the porphyrin via an ethynyl or ethenyl linkage affords significant electronic coupling both on the ground- and excited-states and that oligophenyleneethynylenes represent suitable spacers to assist charge separation between porphyrins. They can indeed exhibit wire-like behaviour and promote fast interchromophore charge separation over distances up to 4.5 nm. These recent electronically coupled dyads represent attractive photochemical systems to build more complex arrays for solar energy conversion or for molecular electronic applications.