(191f) Covalent, Chemical Functionalization Of 1nm Carbon Coated Cobalt Nanoparticles – Linking Nano-Magnets And Molecules

Core-shell nanomaterials combine the beneficial properties of a core material with the surface properties of a second, shell material. We demonstrate how a metal/carbon core-shell material can significantly improve the magnetic properties of currently used magnetic nanoparticles.

Such increased magnetic properties can be achieved by the use of metallic compounds (Fe, Co, Ni) with an up to 3-fold increased mass magnetization. However, if the size of the metal is reduced to the nano-size range these materials usually become highly pyrophoric, impeding their application.

A way out of this problem is to coat the metallic nanoparticles with an inert shell material (see Figure). We present the one-step fabrication of 1-2 nm carbon coated cobalt nanomaterial at production rates of over 30 g/hr. Besides the protection of the metallic core at a wide pH and temperature range, the carbon layer offers the possibility to covalently functionalize the surface of the nanomagnets (Scheme). This not only allows influencing the dispersion properties of the material but also allows designing a material for the specific binding of ligands. These materials can now be used for the rapid magnetic separation of target compounds from liquid mixtures and offer a platform for new separation technologies in organic chemistry and biotechnology.

The Figure shows a photograph of as-prepared carbon coated cobalt nanoparticles (~5 g, left) and a transmission electron micrograph of an individual particle showing the metallic cobalt core, which is protected by several layers of graphene carbon.

The Scheme shows the chemistry applied in order to functionalize the surface of the nanomagnets with chloro- and amino- groups.

References:

[1] R. N. Grass, E. K. Athanassiou, W. J. Stark, Angew. Chem. Int. Ed. 2007, in print.

[2] R. N. Grass, W. J. Stark, J. Mater. Chem. 2006, 16, 1825.