Faster Excited-State Intramolecular Electron Transfer from Perylenediimide Dianion Compared to Its Radical Anion

The properties of the excited perylenediimide dianion (PDI^2-∗) and its intramolecular electron transfer (ET) behavior were examined using femtosecond laser flash photolysis on PDI^2- and PDI^2--acceptor (A) dyads. Upon laser excitation, the dianion of PDI first generated a singlet (S₁) state, followed by a triplet (T₁) state. In all of the dyads, rate constants of the intramolecular ET from PDI^2-∗ (S₁) varied with the driving forces. Comparison of the PDI^2-∗-A and PDI^•-∗-A dyad systems revealed higher rate constants for the ET from PDI^2-∗ than from PDI^•-∗, which can be attributed to the difference in electronic coupling for the ET. These findings elucidate the previously unexplored photoinduced ET characteristics of PDI^2-, thereby advancing the groundwork for photochemical studies of excited multi-ions and their applications in related materials.