Abstract
Our trifluoromethyl functionalization method enables the dissolution and isolation of missing metallofullerenes of Gd@C74(CF3)n. After multi-stage high-performance liquid chromatography purification, Gd@C74(CF3)3 and two regioisomers of Gd@C74(CF3) are isolated. X-ray crystallographic analysis reveals that all of the isolated metallofullerenes react with CF3 groups on pentagons of the D3 h-symmetry C74 cages. Highest occupied molecular orbital-lowest unoccupied molecular orbital gaps of these trifluoromethylated derivatives, estimated by absorption spectra, are in the range 0.71–1.06 eV, consistent with density functional calculations.
Highlights
Endohedral metallofullerenes M@C2m (M 1⁄4 rare earth metal), encapsulating metal atoms in the internal space of spherical carbon structures, have attracted much attention due to their unique properties [1,2]
The purity of the three metallofullerenes obtained by multi-stage High-performance liquid chromatography (HPLC) preparation was confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy
Addition of oddnumber CF3 groups to the carbon cage may result in a closed-shell configuration, which is more stable than an open-shell configuration of non-substituted Gd@C74
Summary
Endohedral metallofullerenes M@C2m (M 1⁄4 rare earth metal), encapsulating metal atoms in the internal space of spherical carbon structures, have attracted much attention due to their unique properties [1,2]. Gadolinium-encapsulated metallofullerenes have been widely investigated for biomedical applications [3,4,5,6,7,8]. With such high magnetic moments, Gd@C2m are of interest as novel magnetic resonance imaging (MRI) contrast agents [3,4,5,6].
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