Functionalization of SWNTs to facilitate the coordination of metal ions, compounds and clusters

Abstract

The carboxylate residues of the open ends of aryl-tert-butyl and arylsulfonic acid side-walled functionalized single walled carbon nanotubes (SWNTs) have been investigated for the complexation conditions of the iron–molybdenum cluster [H_xPMo₁₂O₄₀CH₄Mo₇₂Fe₃₀(O₂CMe)₁₅O₂₅₄(H₂O)₉₈] (“FeMoC”). A range of alternative donor groups for the attachment of FeMoC have been investigated for piranha etched SWNTs, dodecyl side-walled functionalized SWNTs (DD-SWNTs) and ultra-short SWNTs (US-SWNTs), including include pyridines, thiols and phosphines, using coupling reactions to either the carboxylate or hydroxide residues of the SWNTs' open ends. The functionalized SWNTs have been characterized by XPS, uptake of Fe³⁺ and, where appropriate, MAS ³¹P NMR. The efficacy of binding is dependent on the presence and identity of the ligand moiety. TEM and AFM of the SWNT–FeMoC conjugates show the presence of a 2–3 nm spherical feature on the tip of individual SWNTs.