Fullerene purification
Fullerene purification is the process of obtaining a
fullerene compound free of contamination. In fullerene production mixtures of C
60, C
70 and higher homologues are always formed. Fullerene purification is key to
fullerene science and determines fullerene prices and the success of practical applications of fullerenes. The first available purification method for C
60 fullerene was by
HPLC from which small amounts could be generated at large expense.
* A recent kilogram scale fullerene purification strategy was demonstrated by Nagata et al . In this method C
60 was separated from a mixture of C
60, C
70 and higher fullerene compounds by first adding the
amidine compound
DBU to a solution of the mixture in
1,2,3-trimethylbenzene. DBU as it turns out only reacts to C
70 fullerenes and higher which reaction products separate out and can be removed by filtration. C
60 fullerenes do not have any affinity for DBU and are subsequently isolated. Other diamine compounds like
DABCO do not share this selectivity.
* C
60 but not C
70 forms a 1:2
inclusion compound with
cyclodextrin (CD). A separation method for both fullerenes based on this principle is made possible by anchoring cyclodextrin to
colloidal gold particles through a
sulfur - sulfur bridge . The Au/CD compound is very stable and soluble in water and selectively extracts C
60 from the insoluble mixture after
refluxing for several days. The C
70 fullerene component is then removed by simple
filtration. C
60 is driven out from the Au/CD compound by adding
adamantol which has a higher affinity for the cyclodextrin cavity. Au/CD is completely
recycled when adamantol in turn is driven out by adding
ethanol and ethanol removed by evaporation. 50
mg of Au/CD captures 5 mg of C
60 fullerene.
#
Kilogram-scale [60]Fullerene Separation from a Fullerene Mixture: Selective Complexation of Fullerenes with 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) Koichi Nagata, Eiji Dejima, Yasuharu Kikuchi, Masahiko Hashiguchi Chemistry Letters Vol. 34
2005, No. 2 p.178.
Abstract#
Thio[2-(benzoylamino)ethylamino]--CD fragment modified gold nanoparticles as recycling extractors for [60]fullerene Yu Liu, Ying-Wei Yang and Yong Chen
Chemical Communications,
2005, (33), 4208 - 4210
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