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

Abstract

A number of non-covalently bound donor-acceptor dyads, consisting of C60 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+@C60. To explore this anomalous effect, we study inclusion complexes [10]CPP⊃Li+@C60-MP, [10]CPP⊃C60-MPH+, and [10]CPP⊃C60-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

We are grateful for financial support from the Spanish MINECO (Network RED2018-102815-T, project CTQ2017-85341-P, and Juan de la Cierva contracts IJC2019-039846-I to A.J.S. and FJCI-2017-32757 to O.A.S.) and the Catalan DIUE (2017SGR39)