Covalent functionalization of carbon nanotubes through organometallic reduction and electrophilic attack

Organometallic reagents such as butyllithium are known to covalently functionalize the sidewalls of carbon nanotubes. The function grafted corresponds to the organic part of the alkali compound, while one negative charge is transferred to the nanotube for each function. Carbon nanotubes reduced by organolithium compounds were used here as nucleophilic reactive species through these transferred and delocalized charges. Various halogenated electrophiles in excess were reacted with them in anhydrous conditions. The grafting of the corresponding chemical function onto the carbon nanotubes through a Lewis metathetic exchange reaction was demonstrated by chemical, thermal, and spectroscopic analyses. This synthetic route applied successfully to both single-walled and multi-walled nanotubes and to a series of electrophiles. The extent of functionalization was found to depend on stoechiometries used, although a direct correlation could not be obtained.