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

Abstract

AbstractMacrocyclic C60‐(π‐conjugated oligomer) dyads have been prepared from the corresponding bis‐malonates by a macrocyclization reaction on the C60 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 (Δλmax = 24 to 34 nm). Whereas the absorption properties are dramatically affected by the intramolecular electronic interactions between the conjugated bridging system and the accepting C60 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)