Synthesis of New Porphyrin-Fullerene Dyads Capable of Forming Charge-Separated States on a Microsecond Lifetime Scale

A series of covalently linked axially symmetric porphyrin–fullerene dyads with a rigid pyrrolo[3,4‐c]pyrrolic linker enabling a fixed and orthogonal arrangement of the chromophores has been synthesized and studied by means of transient absorption spectroscopy and cyclic voltammetry. The lifetime of the charge‐separated state has been found to depend on the substituents on the porphyrin core, reaching up to 4 μs for a species with meso‐(p‐MeOC6H4) substituents. The ground and excited electronic states of model compounds have been calculated at the DFT and TD‐DFT B3LYP(6‐31G(d)) levels of theory and analyzed with regard to the effect of the substituent on the stabilization of the charge‐separated state in the porphyrin–fullerene ensemble with a view to explaining the observed dependence. Here′s to a long life! New porphyrin–fullerene dyads with a rigid pyrrolo[3,4‐c]pyrrolic linker have been found to be capable of forming charge‐separated states with lifetimes of up to 4 μs upon irradiation with visible light (see graphic).