title: Synthesis and ultrafast excited-state dynamics of zinc and palladium triply fused diporphyrins.
abstract: We report the synthesis and ultrafast excited-state dynamics of two new meso-meso, β-β, β-β triply fused diporphyrins, Zn-3DP and Pd-3DP. Both compounds were found to have short excited-state lifetimes: Zn-3DP possessed an average S1 lifetime of 14 ps before nonradiative deactivation to the ground state, whereas Pd-3DP displayed a longer average S1 lifetime of 18 ps before crossing to the T1 state, which itself possessed a very short triplet lifetime of 1.7 ns. The excited-state dynamics of Zn-3DP, compared to similar zinc(II) diporphyrins reported in the literature, suggests that a conical intersection of the S1 and S0 potential energy surfaces plays a major role as a deactivation pathway of these molecules. Furthermore, the short triplet lifetime of Pd-3DP, compared to other diporphyrins that also exploit the intramolecular heavy atom effect, reveals that the position of the heavy atom within the diporphyrin framework influences the strength of spin-orbit coupling. The implications for employing triply fused diporphyrins as NIR-absorbing triplet sensitizers are discussed.
authors: School of Chemistry, The University of Sydney , Sydney, NSW 2006, Australia.
authors: Derrick A
authors: DA
authors: Roberts
authors: Burkhard
authors: B
authors: Fückel
authors: Raphaël G C R
authors: RG
authors: Clady
authors: Yuen Yap
authors: YY
authors: Cheng
authors: Maxwell J
authors: MJ
authors: Crossley
authors: Timothy W
authors: TW
authors: Schmidt