Clicking onto Nanofibers

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Science  20 Mar 2009:
Vol. 323, Issue 5921, pp. 1539
DOI: 10.1126/science.323.5921.1539b

Vertically aligned carbon nanofibers—stacked “cups” of grapheme—are of interest for electrochemistry because they expose a high fraction of edge sites with much faster electron transfer rates than the basal plane sites that predominate on carbon nanotubes. For applications such as sensing, it would be useful to attach redox-active groups to the surface of these materials. Landis and Hamers report that copper click chemistry can be used to attach groups such as ferrocene. The carbon nanofiber surfaces were functionalized with azide groups, and ethynyl-substituted ferrocenes were then covalently attached through the Cu(I)-catalyzed cyclization reaction. The attachment was quite stable—the redox couple could be cycled at least 1500 times. The rates through this pi-bonded bridge were similar to those for ferrocene groups attached through saturated alkyl linkages, suggesting that electron transfer occurs through the aqueous solvent rather than the hydrocarbon bridges. — PDS

Chem. Mater. 21, 724 (2009).

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