Water-soluble carbon nanotubes through sugar azide functionalization

In this work we report a covalent functionalization of pristine single-walled carbon nanotubes (SWCNTs) directly with three sugar azides, 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl, 2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl or 2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl azide. Microwave-assisted functionalization was carried out for SWCNTs prepared with the HiPCO method. The as-prepared, new type of sugar-functionalized SWCNTs were analyzed by Raman and IR spectroscopy. Deacetylation of the functionalized tubes by sodium methoxide yielded nitrogen-linked, sugar-functionalized carbon nanotubes (CNTs) that formed stable dispersions in water. Reactivity of the sugar azides towards SWCNTs was estimated from the solubility experiments. The water solubility was found to be highest for galactopyranosyl and lowest for gluco- and mannopyranosyl derivatives.