Magnetic Chemistry

Highly magnetic carbon coated metal nanoparticles can act as semi-heterogeneous support for protecting groups, reagents, transition metal complexes or organocatalysts. Compounds covalently attached to the graphene coating are amenable to rapid separation from the reaction mixture with the aid of an external magnet. Especially potentially noxious and expensive catalysts can be recycled by this means, thus complying with the goals of “green chemistry”.

Next to the magnetic properties of the metal core, hybrid structures comprising of “smart” polymers enable an additional trigger, e.g. for a thermally controlled phase switch. Moreover, amphiphilic coatings tremendously increase the stability of nanoparticle dispersions.

Sketch of a functionalized carbon coated metal nanoparticle.


Further reading:

• A. Schaetz, W.J. Stark, R.N. Grass, Magnetic cobalt[0]-graphene nanospheres, e-EROS, online available (2011).
• Q.M. Kainz, A. Schaetz, A. Zoepfl, W.J. Stark, O. Reiser, Combined Covalent and Noncovalent Functionalization of Nanomagnetic Carbon Surfaces with Dendrimers and BODIPY Fluorescent Dye, Chem. Mater., 23, 3606-3613 (2011).
• A. Schaetz, M. Zeltner, T.D. Michl, M. Rossier, R. Fuhrer, W.J. Stark, Magnetic Silyl Scaffold Enables Efficient Recycling of Protecting Groups, Chem. Eur. J., 17, 10566 – 10573 (2011) .
  DOI: 10.1002/chem.201101165
• M. Zeltner, A. Schaetz, M.L. Hefti, W.J. Stark, Magneto-thermally responsive C/Co@PNIPAM-nanoparticles enable preparation of self-separating, phase-switching palladium catalysts, J. Mater. Chem., 21, 2991-2996 (2011).
  DOI: 10.1039/C0JM03338C
  
• A. Schaetz, T.R. Long, R.N. Grass, W.J. Stark, P.R. Hanson, O. Reiser, Immobilization on a Nanomagnetic Co/C Surface using ROM Polymerization: Generation of a Novel Hybrid Material as Support for a Recyclable Palladium Catalyst, Adv. Funct. Mater., 20, 4323–4328 (2010).
  DOI: 10.1002/adfm.201000959
• A. Schaetz, R.N. Grass, W.J. Stark, Magnetische Chemie: Winzig und mit metallischem Kern, Nachrichten aus der Chemie, 58, 857 (September 2010).
  
• A. Schaetz, O. Reiser, W. J. Stark, Nanoparticles as Semi-Heterogeneous Catalyst Supports, Chem. Eur. J. 2010, in print.
  DOI: 10.1002/chem.200903462
  
• A. Schaetz, R.N. Grass, Q. Kainz, W.J. Stark, O. Reiser, Cu(II)-Azabis(oxazoline)-complexes immobilized on magnetic Co/C-Nanoparticles: Kinetic Resolution of 1,2-Diols under batch and continuous-flow conditions Chem. Mater., 22(2), 305–310 (2010).
  DOI: 10.1021/cm9019099
  
• A. Schaetz, O. Reiser, W.J. Stark, Nanoparticles as Semi-Heterogeneous Catalyst Supports, Chem. Eur. J., 16(30), 8950-67 (2010).
  DOI: 10.1002/chem.200903462