Ground State Electronic Interactions in Macrocyclic Fullerene Bis‐Adducts Functionalized with Bridging Conjugated Oligomers

Macrocyclic C 60 ‐(π‐conjugated oligomer) dyads have been prepared from the corresponding bis‐malonates by a macrocyclization reaction on the C 60 sphere. In both multicomponent systems, the fullerene moiety and the π‐conjugated oligomer subunit are at the van der Waals contact due to the cyclic structure. Interestingly, the characteristic π‐π* electronic transition band of the conjugated system is significantly red‐shifted in both dyads with respect to the corresponding model compounds lacking the fullerene unit (Δ λ max = 24 to 34 nm). Whereas the absorption properties are dramatically affected by the intramolecular electronic interactions between the conjugated bridging system and the accepting C 60 spheroid, cyclic voltammetry revealed only small changes in their redox potentials. However, these intramolecular interactions have a significant influence on the electronic coupling of the two terminal aniline redox units of the conjugated system in the dyads. Actually, when compared to the corresponding model compound 14 ·+ , delocalization of the positive charge in the mixed‐valence species derived from the dyad 1 is more difficult due to the π‐π interactions of the conjugated system with the electron‐withdrawing fullerene group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)