All‐Fullerene Electron Donor–Acceptor Conjugates

The synthesis and characterization of a covalent all‐fullerene C 60 ‐Lu 3 N@I h ‐C 80 electron donor–acceptor conjugate has been realized by sequential 1,3‐dipolar cycloaddition reactions of azomethine ylides on Lu 3 N@I h ‐C 80 and C 60 . To the best of our knowledge, this is the first time that two fullerenes behaving as both electron donor (Lu 3 N@I h ‐C 80 ) and acceptor (C 60 ) 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 C 60 ⋅− ‐Lu 3 N@I h ‐C 80 ⋅+ charge‐separated state is formed. Spin conversion from the charge‐separated singlet state C 60 ⋅− ‐Lu 3 N@I h ‐C 80 ⋅+ into the corresponding triplet state is facilitated by the heavy‐atom effect stemming from the Lu 3 N‐cluster, which, in turn, slows down the charge recombination by one order of magnitude.