Interfullerene Electronic Interactions and Excited-State Dynamics in Fullerene Dumbbell Conjugates.

Several dumbbell conjugates featuring M ₃ N@ I _h -C ₈₀ (M = Sc, Y) and C ₆₀ were prepared to systematically investigate interfullerene electronic interactions and excited state dynamics. From electrochemical investigations, we concluded that the redox potentials of our M ₃ N@ I _h -C ₈₀ (M = Sc, Y) dumbbells depend largely on the interfullerene electronic interactions. Assisted by DFT calculation, the unique role of metal atoms was highlighted. Most importantly, ultrafast spectroscopy experiments revealed symmetry-breaking charge separation in Sc ₃ N@C ₈₀ -dumbbell to yield an unprecedented (Sc ₃ N@C ₈₀ ) ^•+ -(Sc ₃ N@C ₈₀ ) ^•- charge separated state. This is, to the best of our knowledge, the first time that symmetry-breaking charge separation following photoexcitation is corroborated in a fullerene system. As such, our work shed light on the significance of interfullerene electronic interactions and their uniqueness for modulating excited state properties.