Golden molecular tweezers: dinuclear corannulene–Au(I) acetylide hosts for fullerene binding

Abstract

A series of homonuclear bimetallic organometallic complexes bearing two Au(I) atoms and two corannulene fragments have been synthesized, and their fullerene recognition properties were extensively studied in solution. The tether groups were diphosphine ligands with variable rigidity (namely, dppe, dppf, dppbenz, and xantphos) to cover a range of potential semisupported intramolecular aurophilic interactions. Experimental results showed that neither extreme flexibility nor rigidity favors fullerene binding, and in those cases where the metallophilic contact is present and assured by ligand design, this force might hinder the supramolecular assembly formation. Computational calculations clearly indicate that the aurophilic interaction is just another force that is playing a moderate role within the manifold forces involved in the recognition process. The most notable finding corresponded to host CAudppf, which exhibited the highest experimental performance toward fullerene binding within the studied family due to its good preorganization in a tweezer-like conformation despite the lack of proper aurophilic contact. Thorough theoretical studies strongly suggested that the Au(I)–Au(I) distance can be shortened upon complexation, effectively turning on the metallophilic interactions.