Surface Modification of Ultrafine Magnetic Iron Oxide Particles

Ligand-exchange reactions between the caprylate units of capped γ-Fe2O3 nanoparticles, highly soluble in organic solvents, and multifunctional carboxylic compounds, like betaine·HCl and 2,5-dihydroxybenzoic acid, lead to reconstructed magnetic derivatives in which the magnetic properties of the inorganic support are combined with the chemical properties of the inserted ligands. Thus, the betaine derivative is highly hydrophilic, possessing interesting ion-exchange properties, while the 2,5-dihydroxybenzoate analogue inherits the recognition properties of its electron-rich aromatic constituent.