Non-Chromatographic Isolation of Mixed-Metal Nitride Clusters in Larger Carbon Cages

There is a growing interest in mixed-metal nitride metallofullerenes.  Prior to exploring their properties and applications, these mixed-metal endohedrals must first be purified.  To date, their isolation has been difficult.  Hurdles to overcome include their (1) low abundance in soot extract, (2) their co-synthesis with a complex mixture of many types of fullerenes and metallofullerenes, and (3) their HPLC co-elution with contaminant species.  In this presentation, we reveal a separation methodology to minimize and/or avoid HPLC (e.g., recycling HPLC), which is the conventional (i.e., literature) method for isolating mixed-metal nitride endohedral metallofullerenes.  We also discuss strategies and details of our purification approach, which exploits differences in their reactivity with Lewis acids and aminosilica for their selective removal from extracts and subsequent isolation.