A co-functionalization approach to soluble and functional single-walled carbon nanotubes

A new class of single-walled carbon nanotube (SWNT) derivatives have been synthesized by means of an oxidation route that leads to shortened nanotubes bearing carboxylic acid end groups. The simultaneous attachment of poly(ethylene glycol)amine (PEG-NH2) and amine derivatives of aromatic fluorophores was achieved through the formation of amide bonds. Different soluble products have been obtained from 2-aminofluorene, 2-aminoanthracene and 1-aminomethyl-naphthalene. Basic spectroscopic characterization revealed peculiar features, such as quenching of the fluorescence, that suggest intramolecular interactions between the tubes and the attached aromatic moieties. The proposed co-functionalization procedure could be easily extended to obtain a wide range of soluble organic derivatives of SWNTs.