FULLERENE-LINKED PARTICLES AS LC CHROMATOGRAPHIC MEDIA AND MODIFICATION OF THEIR ELECTRON-DONOR ACCEPTOR PROPERTIES BY SECONDARY CHEMICAL-REACTIONS

Fullerenes (C60 and C70) linked to small silica or polymer particles p rovide novel chromatographic stationary phases with electron donor/acc eptor surface interactions that may parallel those of aromatic carbons . Separations of fullerenes and aromatic compounds frequently encounte red as environmental contaminants were investigated using LC microcolu mns containing either particles prepared from BrHC60 linked to amino-s ilica (Spherisorb-NH2, Phenomenex) or porous polymers containing ca. 1 2% fullerene by weight. The polystyrene divinylbenzene (PSDVB)-C60/70H column had greater capacity (k') than the Si-NH-C60/70H column. Tolue ne and polycyclic aromatic hydrocarbons (PAHs), naphthalene, anthracen e, pyrene, and perylene, were retained in the order of increasing ring number; nitro-substituents increased retention; and chlorinated-diben zo-p-dioxins and -dibenzofurans were more strongly retained than their parent compounds. PCB congeners with no chlorine in the ortho, ortho' -positions are co-planar and are strongly retained; for these isomers, retention increased with higher chlorination. We demonstrate that sur face-linked fullerenes can also accommodate further chemical modificat ion through the addition of 2-(4-nitrophenyl)ethyl or -NH-CH2CH2NH2 mo ieties to yield altered electron donor/acceptor affinity. Separations appear to be derived primarily from aromatic electron induced dipole-d ipole or electron-pair donor or acceptor interactions (charge transfer complexes). Except for the fullerenes, surface interactions with comp ounds are largely suppressed with methylene chloride as the mobile pha se.