Triplet state sensitization of covalently linked hybrid porphyrin dimers. Evidence for intramolecular triplet energy transfer

Triplet sensitization of covalently linked hybrid porphyrin dimers, in pulsed radiolysis solutions, allows monitoring intramolecular triplet energy transfer. Results for two dimers are reported: the para-para and ortho-ortho of Zn(-CH2-)3H2, where the Zn and H2 are the tetratosyl, zinc, and free base, porphyrin chromophores. The results for the intramolecular rates are k/sub et//sup para-para/ = (2.6-10) x 105 s-1 and k/sub et//sup ortho-ortho/ > 10 x 105 s-1. The pseudo-first-order rates for sensitization are k/sup ortho-ortho/ = 1.8 x 105 s-1 and k/sup para-para/ > 1.8 x 105 s-1