Synthesis and Characterization of Eu-Metallofullerenes from Eu@C74 to Eu@C90 and Their Nanopeapods

A series of Eu-metallofullerenes from Eu@C74 to Eu@C90 have been successfully synthesized and isolated by multistep HPLC separation. We have used composite rods doped with nickel as the anode to improve the yield of europium metallofullerenes. All the newly isolated metallofullerenes are characterized by LD-TOF mass spectrometry, UV-vis-NIR absorption spectroscopy, and electron energy loss spectroscopy. We have also synthesized the nanopeapods encapsulating Eu@C82 fullerenes and characterized them with HRTEM. The results show that the entrapped Eu atoms have a divalent charge state in the intact Eu@C82 metallofullerene.