Improved Production and Separation Processes for Gadolinium Metallofullerenes

A comprehensive scheme for processing all arc-produced gadolinium monometallofullerenes into separate quantified fractions is presented. As generated by the carbon arc process, endohedral metallofullerenes are entrained in a complex mixture of more abundant empty fullerenes and carbonaceous soot. The process described herein exploits the differences in solubility and redox reactivity between different classes of Gd@C2n and empty fullerenes to effect their separation from one another. Importantly, the processes not only facilitate use of the normally soluble metallofullerenes, such as Gd@C82, but also provide access to the normally insoluble metallofullerenes, such as Gd@C60. In quantifying the Gd@C2n contents of the different obtained fractions, the normally soluble Gd@C2n are found to be about a 10% minority of the total arc metallofullerene product, while the normally insoluble Gd@C2n comprise up to as much as 90% of the total amount of arc-produced Gd@C2n. Thus, new access to the insoluble class of Gd@C2n in addition to the soluble fullerenes now increases the total availability of monometal Gd endohedrals by up to an order of magnitude.