Photochemical Hydroboration−Oxidation of Single-Walled Carbon Nanotubes

Abstract

The products of photochemical hydroboration−oxidation of single-walled carbon nanotubes (SWCNTs) with a variety of borane complexes have been analyzed using FTIR, UV/vis/NIR, and Raman spectroscopies. Analysis of reaction intermediates suggests that the reaction proceeds by attaching H and BH₂ groups, similar to the hydroboration of an alkene. Attempts to hydroborate SWCNTs at temperatures from 0 to 100 °C yielded no functionalization, suggesting that photochemical activation is necessary. The use of optical filters indicates that light in the wavelength range of 250−300 nm is necessary to hydroborate SWCNTs. Treatment with hydrogen peroxide in basic solution resulted in the attachment of OH groups to the hydroborated SWCNTs. UV/vis/NIR spectra of the resulting hydroxylated SWCNTs are similar to those of pristine nanotubes, indicating that the functionalization is not extensive and that the SWCNTs remain largely intact after the functionalization. This reaction process could lead to new pathways of functionalizing SWCNTs.