Connecting two C60 stoppers to molecular wires: ultrafast intramolecular deactivation reactions

Abstract

A new series of soluble dumbbell-type architectures constituted by π-conjugated oligophenyleneethynylenes (OPEs) and two C₆₀ stoppers have been prepared by using a convergent synthetic strategy. In particular, we base our approach on the systematic cross-coupling, palladium catalyzed Hagihara–Sonogashira reaction between aryl iodides and alkynyl derivatives. The cyclic voltammetry of the correspondingly synthesized system reveals amphoteric redox behavior and the lack of significant electronic communication between the oligo-arylalkynyl bridge and the two C₆₀ moieties, which behave as two independent units. Excited state studies carried out by fluorescence and transition absorption spectroscopy show that, although a weak competitive electron transfer could operate in the deactivation process of the excited oligo-arylalkynyl bridges, their deactivation is mainly governed by energy transfer.