S. Stevenson et al., ISOLATION AND MONITORING OF THE ENDOHEDRAL METALLOFULLERENES Y-AT-C-82 AND SC3-AT-C-82 - ONLINE CHROMATOGRAPHIC-SEPARATION WITH EPR DETECTION, Analytical chemistry, 66(17), 1994, pp. 2680-2685
The direct coupling of high-performance liquid chromatography (HPLC) w
ith on-line electron paramagnetic resonance (EPR) detection is demonst
rated for monitoring separations of endohedral metallofullerenes (M@C-
2n). The HPLC-EPR approach readily permits detection of the paramagnet
ic species, such as Y@C-82 and Sc-3@C-82, in the presence of the domin
ant empty-cage fullerenes (C-60, C-70) and diamagnetic metallofulleren
es (e.g., M(2)@C-2n). The results indicate that on-line EPR provides a
noninvasive, selective detector for HPLC metallofullerene separations
that is readily adaptable to air-sensitive and/or labile compounds. S
pecifically, the ''EPR-active'' metallofullerenes, Y@C-82 and Sc-3@C-8
2, are selectively monitored on-line for an initial separation of the
metallofullerene fraction from the dominant empty-cage fullerenes util
izing a combination of polystyrene columns. This preparative ''cleanup
'' procedure is followed by HPLC-EPR separation and monitoring of Y@C-
82 and SC3@C-82 species using a selective tripodal pi-acidic-phase col
umn (Trident-Tri-DNP) for the final stages of isolation.