Synthesis of ultrasmall magnetic iron oxide nanoparticles and study of their colloid and surface chemistry

Colloidal nanoparticles of Fe3O4 (4nm) were synthesized by high-temperature hydrolysis of chelated iron (II) and (III) diethylene glycol alkoxide complexes in a solution of the parent alcohol (H(2)DEG) without using capping ligands or surfactants:[Fe(DEG)Cl-2](2-)+2[Fe(DEG)Cl-3](2-)+2H(2)O+2OH(-)-> Fe3O4+3H(2)DEG+8Cl(-) The obtained particles were reacted with different small-molecule polydentate ligands, and the resulting adducts were tested for aqueous colloid formation. Both the carboxyl and a-hydroxyl groups of the hydroxyacids are involved in coordination to the nanoparticles' surface. This coordination provides the major contribution to the stability of the ligand-coated nanoparticles against hydrolysis. (C) 2009 Elsevier B.V. All rights reserved.