Nitride Cluster Fullerene Spin Shuttle: the role of cluster composition for single molecule magnet behavior

• Applicants: Professor Dr. Bernd Büchner, since 11/2013; Professor Dr. Lothar Dunsch, until 11/2013 (†)
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 237010132

• Final Report Year: 2018

Final Report Abstract

The project was focused on the synthesis and the studies of magnetic properties of endohedral metallofullerenes (EMFs), in particular those with trimetal nitride clusters. Initiated by the discovery of single molecule magnetism (SMM) in DySc2N@C80, this study aimed at screening different lanthanides, endohedral cluster compositions, and fullerenes cages with the goal to find the best combination for the enhanced SMM properties. It was shown that the nitride ion in the M3N cluster bears large negative charge and imposes strong magnetic anisotropy on lanthanide ions in the cluster. Paramagnetic NMR study of MSc2N@C80 molecules (M = Ce, Pr, Nd, Tb, Dy, Ho, Er, Tm) accompanied by point charge calculations revealed that Dy has the largest magnetic anisotropy and is therefore the most promising lanthanide for fullerene-SMMs. We have shown that the best SMM properties are found for DyM 2N and Dy2MN clusters (M = Sc, Lu) encapsulated within C80-Ih cages. Combination of Dy with other magnetic metals such as Gd or Er leads to much lower blocking temperatures of magnetization. Likewise, other fullerene cages also lead to lowering of the blocking temperature. The number of the Dy ions in the nitride cluster also has a strong influence on the SMM behavior. When only one Dy ion is present, DyM 2N@C2n molecules exhibit fast relaxation of magnetization in zero magnetic field via the quantum tunneling mechanism. The tunneling is suppressed in the molecule with two Dy ions in the nitride cluster, because their ferromagnetic exchange and dipolar coupling creates an additional energy barrier towards relaxation of magnetization.

Publications

• "Cluster-size dependent internal dynamics and magnetic anisotropy of Ho ions in HoM2N@C80 and Ho2MN@C80 families (M = Sc, Lu, Y)." Nanoscale 2014, 6 (19), 11431- 11438
  Y. Zhang, D. Krylov, S. Schiemenz, M. Rosenkranz, R. Westerström, J. Dreiser, T. Greber, B. Büchner, A. A. Popov
  
• "The Metallofullerene Field-Induced Single-Ion Magnet HoSc2N@C80." Chem. Eur. J. 2014, 20 (42), 13536-13540
  J. Dreiser, R. Westerström, Y. Zhang, A. A. Popov, L. Dunsch, K. Krämer, S.-X. Liu, S. Decurtins, T. Greber
  
• "X-ray induced demagnetization of single-molecule magnets." Appl. Phys. Lett. 2014, 105 (3), 032411
  J. Dreiser, R. Westerström, C. Piamonteze, F. Nolting, S. Rusponi, H. Brune, S. Yang, A. A. Popov, L. Dunsch, T. Greber
  
• "Magnetic Anisotropy of Endohedral Lanthanide Ions: Paramagnetic NMR Study of MSc2N@C80-Ih with M running through the Whole 4f Row." Chem. Sci. 2015, 6, 2328-2341
  Y. Zhang, D. Krylov, M. Rosenkranz, S. Schiemenz, A. A. Popov
  
• "Methane as a selectivity booster in the synthesis of endohedral fullerenes: towards selective synthesis of the single molecule magnet Dy2TiC@C80 and its congener Dy2TiC2@C80". Angew. Chem. Int. Ed. 2015, 54 (45), 13411-13415
  K. Junghans, C. Schlesier, A. Kostanyan, N. A. Samoylova, Q. Deng, M. Rosenkranz, S. Schiemenz, R. Westerström, T. Greber, B. Büchner, A. A. Popov
  
• "Triangular Monometallic Cyanide Cluster Entrapped in Carbon Cage with Geometry-Dependent Molecular Magnetism." J. Am. Chem. Soc. 2016, 138, 14764-14771
  F. Liu, C.-L. Gao, Q. Deng, X. Zhu, A. Kostanyan, R. Westerström, S. Wang, Y.-Z. Tan, J. Tao, S.-Y. Xie, A. A. Popov, T. Greber, S. Yang