All‐Fullerene Electron Donor–Acceptor Conjugates

AbstractThe synthesis and characterization of a covalent all‐fullerene C60‐Lu3N@Ih‐C80 electron donor–acceptor conjugate has been realized by sequential 1,3‐dipolar cycloaddition reactions of azomethine ylides on Lu3N@Ih‐C80 and C60. To the best of our knowledge, this is the first time that two fullerenes behaving as both electron donor (Lu3N@Ih‐C80) and acceptor (C60) are forming an electroactive dumbbell. DFT calculations reveal up to 16 diastereomeric pairs, that is, 8 with syn and 8 with anti orientation, with the anti‐RSSS isomer being the most stable. Spectroelectrochemical absorption and femtosecond transient absorption experiments support the notion that a C60⋅−‐Lu3N@Ih‐C80⋅+ charge‐separated state is formed. Spin conversion from the charge‐separated singlet state C60⋅−‐Lu3N@Ih‐C80⋅+ into the corresponding triplet state is facilitated by the heavy‐atom effect stemming from the Lu3N‐cluster, which, in turn, slows down the charge recombination by one order of magnitude.