Purification of uranium-based endohedral metallofullerenes (EMFs) by selective supramolecular encapsulation and release

Supramolecular nanocapsule 1.(BArF)₈ is able to sequentially and selectively entrap recently discovered U₂ rate at C₈₀ and unprecedented Sc₂CU rate at C₈₀, simply by soaking crystals of 1.(BArF)₈ in a toluene solution of arc-produced soot. These species, selectively and stepwise absorbed by 1.(BArF)₈, are easily released, obtaining highly pure fractions of U₂ rate at C₈₀ and Sc₂CU rate at C₈₀ in one step. Sc₂CU rate at C₈₀ represents the first example of a mixed metal actinide-based endohedral metallofullerene (EMF). Remarkably, the host-guest studies revealed that 1.(BArF)₈ is able to discriminate EMFs with the same carbon cage but with different encapsulated cluster and computational studies provide support for these observations. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)