[10]CPP-Based Inclusion Complexes of Charged Fulleropyrrolidines. Effect of the Charge Location on the Photoinduced Electron Transfer.

A number of non-covalently bound donor-acceptor dyads, consisting of C ₆₀ as the electron acceptor and cycloparaphenylene (CPP) as the electron donor, have been reported. A hypsochromic shift of the charge transfer (CT) band in polar medium has been found in [10]CPP⊃Li ⁺ @C ₆₀ . To explore this anomalous effect, we study inclusion complexes [10]CPP⊃Li ⁺ @C ₆₀ -MP, [10]CPP⊃C ₆₀ -MPH ⁺ , and [10]CPP⊃C ₆₀ -PPyMe ⁺ formed by fulleropyrrolidine derivatives and [10]CPP using the DFT/TDDFT approach. We show that the introduction of a positively charged fragment into fullerene stabilizes CT states that become the lowest-lying excited states. These charge-separated states can be generated by the decay of locally excited states on a nanosecond to picosecond time scale. The distance of the charged fragment to the center of the fullerenic cage and its accessibility to the solvent determine the strength of the hypsochromic shift.
(© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)