(Invited) Isolation and Structure Determination of Trifluoromethylated Gadolinium metallofullerenes

摘要

Endohedral metallofullerenes have been extensively studied since the first experimental observation of La@C_(60) in a laser-vaporized supersonic beam in 1985. However, most of these studies have focused on metallofullerenes larger than C_(60) such as Ln@C_(82) (Ln: lanthanide). There are few examples for isolation of small-cage (C_(60), C_(70), C_(72), and C_(74)) lanthanide metallofullerenes because of their extremely high chemical reactivity. Recently, we developed an in situ trifluoromethylation method for the extraction and purification of these missing metallofullerenes. Here we report the isolation and structure determination of trifluoromethylated gadolinium metallofullerenes (Gd@C_(60)(CF_3)_3, Gd@C_(60)(CF_3)_5, Gd@C_(70)(CF_3)_3, Gd@C_(74)(CF_3), and Gd@C_(74)(CF_3)_3). Gd-metallofullerenes are promising as magnetic resonance imaging (MRI) contrast agents. The fully enclosing carbon cage completely prevents leaching of the Gd atoms, resulting in lower toxicity than commercially available metal chelate reagents such as Gd-DTPA.