Zitronensäureether als Liganden für die zuverlässige Funktionalisierung von magnetischen Nanopartikeln

Two long-chain citric acid ethers have been synthesized. These ligands are used for the functionalization of magnetite- and alloyed iron/cobalt nanoparticles. These new particles are analysed by a combination of AGM, XRD, TEM, determination of the iron content, IR- and 1H-NMR-spectroscopy. It is demonstrated that all carbon acid groups are attached to the particles' surface. Nevertheless the required space of one ligand on the surface is quite small (40 A²). Due to the chelate effect the ligands are hardly exchanged by competing molecules: the bonds between particles and ligands are very reliable. It is shown that particles covered with citric acid ethers with terminal unsaturated alkyl chains can be further functionalized by hydrosilylation. By this simple type of reaction it is possible to integrate magnetic nanoparticles via covalent bonds into (bio)organic systems. Complex compounds of an analog short-chain ligand were used to study the coordination chemistry of the here described new class of compounds in detail. Surprisingly only minor differences were found in comparison with complex compounds of citric acid.