Through space singlet-singlet and triplet-triplet energy transfers in cofacial bisporphyrins held by the carbazoyl spacer

The through space singlet-singlet and triplet-triplet energy transfers in cofacial bis(etio-porphyrins) rigidly held by the carbazoyl spacer were investigated. The studies on singlet-singlet transfer, which operates via a Förster mechanism, were performed using the zinc porphyrin and free base chromophores as energy donor and acceptor, respectively, while the investigation on triplet-triplet processes was performed using the palladium porphyrin, and the zinc porphyrin and free base chromophores as donor and acceptors, respectively. The rate for singlet-singlet transfer ( k ET ( singlet )) is unexpectedly slower than that reported for other similar, rigidly held bisporphyrins such as H 2( D…