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

Abstract EN

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-Fe2O3-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-Fe2O3-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-Fe2O3-nanoparticles with functional organic shells in a one-step procedure.