Inclusion of methano[60]fullerene derivatives in cavitand-based coordination cages

Abstract The X-ray study of self-assembled coordination cage 1 , constituted of two tetrapyridyl-substituted resorcin[4]arene cavitands coupled through four square-planar palladium complexes is reported. The coordination cage, embracing an internal cavity of ca. 840 A 3 , reveals to have the right size for the inclusion of large molecules such as fullerenes. Cage 1 forms 1:1 complexes with methano[60]fullerene derivatives 3 and 4 bearing a dimethyl and a diethyl malonate addend, respectively. Evidence for inclusion complexation was provided by 1 H NMR spectroscopic studies and ESI-MS investigations, which unambiguously showed the formation of 1:1 fullerene–cage complexes. The association constants ( K a ) were experimentally determined to be ca. 150 M −1 at 298 K in CD 2 Cl 2 . In both complexes 1 · 3 and 1 · 4 , the malonate residue is threaded through one of the four lateral portals, as clearly shown by docking simulations.