Sidewall functionalization of single-walled carbon nanotubes by organometallic chromium-centered free radicals

The interaction of organometallic chromium-centered free radicals generated by the homolytic dissociation of (pentamethylcyclopentadienyl)chromium-tricarbonyl dimer in toluene with single-walled carbon nanotubes (SWNT) was investigated using ESR spectroscopy. Low values of g-factors of the radical species formed from chromium-centered free radicals and SWNT as well as invariability of disorder mode (D band) intensity in Raman spectra of pristine and functionalized SWNT after this reaction indicated that chromium-centered free radicals added to the surface of nanotubes through rather oxygen atoms than to sidewall carbon atoms. This is the first chromium-derivatization of carbon nanotubes.