Superparamagnetic Ironoxide Nanoparticles via Ligand Exchange Reactions: Organic 1,2‐Diols as Versatile Building Blocks for Surface Engineering

Abstract

A method for the preparation of ligand‐covered superparamagnetic iron oxide nanoparticles via exchange reactions is described. 1,2‐diol‐ligands are used to provide a stable binding of the terminally modified organic ligands onto the surface of γ ‐Fe 2 O 3 ‐nanoparticles ( r ~ 4 nm). The 1,2‐diol‐ligands are equipped with variable terminal functional groups (i.e., hydrogen bonding moieties, azido‐ bromo‐, fluorescent moieties) and can be easily prepared via osmium tetroxide‐catalyzed 1,2‐dihydroxylation reactions of the corresponding terminal alkenes. Starting from octylamine‐covered γ ‐Fe 2 O 3 ‐nanoparticles, ligand exchange was effected at 50 ∘ C over 24–48 hours, whereupon complete ligand exchange is taking place as proven by thermogravimetric (TGA)‐ and IR‐spectroscopic measurements. A detailed kinetic analysis of the ligand exchange reaction was performed via TGA analysis, demonstrating a complete ligand exchange after 24 hours. The method offers a simple approach for the generation of various γ ‐Fe 2 O 3 ‐nanoparticles with functional organic shells in a one‐step procedure.