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ERC Consolidator grant "GraM3"

Surface-grafted metallofullerene molecular magnets with controllable alignment of magnetic moments (PI: A. A. Popov)

This project has received funding from the European Research Council (ERC) under the Horizon 2020 research and innovation programme (grant agreement No. 648295).

 

 

The molecules retaining their magnetization in the absence of magnetic field are known as single molecule magnets (SMMs). Important problems to be solved on the way to the applications of SMMs in molecular spintronics is their deposition on surfaces and addressing their spins on the single molecular level. In this project we address these problems by designing SMMs based on endohedral metallofullerenes (EMFs) and their derivatives with surface-anchoring groups.Magnetic behaviour of the surface-grafted SMMs will be studied by bulk- and surface-sensitive techniques including X-ray magnetic circular dichroism and scanning tunneling microscopy.

PI: Dr. Alexey A. Popov


Group "Synthesis and Properties"

Dr. Fupin Liu, head of the group
Synthesis of EMFs, single crystal growth and analysis

Lukas Spree, PhD student
Synthesis of EMFs and derivatives, magnetometry

Yaofeng Wang, PhD student
Synthesis of EMFs and derivatives

Wei Yang, PhD student
Synthesis of EMFs and derivatives

 

Group "Theory"

Dr. Stanislav Avdoshenko, head of the group
Computational studies

Vasilii Dubrovin, PhD student
Quantum chemical calculations

Svetlana Sudarkova, visiting PhD student (Moscow State University)
Quantum chemical calculations

 

Group "Magnetism and Surface Studies"

Georgios Velkos, PhD student
Magnetometry, XMCD

Emmanouil Koutsouflakis, PhD student
Scanning tunneling microscopy

 

Alumni

Dr. Peter Machata, Postdoc (till 09.2019)
Electrochemistry and spectroelectrochemistry

Jimmy Kuo, visiting student (2-months DAAD Fellowship in 2018)
Synthesis of EMFs

Dr. Christin Schlesier, PhD student (defense in November 2018)
Synthesis of EMFs, magentic properties

Dr. Ariane Brandenburg, PhD student (defense in September 2018)
Synthesis of EMFs, chemical derivatization

Dr. Chia-Hsiang Chen, Postdoc (till 07.2018)
Synthesis of EMFs, chemical derivatization

Dr. Denis Krylov, PhD student (defense in June 2017)
Magnetometry, STM

Dr. Nataliya Samoylova, PhD student (defense in September 2017)
Fullerene derivatives, electrochemistry

Dr. Katrin Junghans, PhD student (defense in May 2017)
Synthesis of EMFs

Dr. Qingming Deng, PhD student (defense in May 2016)
Quantum chemical calculations

  1. L. Spree, C. Schlesier, A. Kostanyan, R. Westerström, T. Greber, B. Büchner,  S. Avdoshenko, A. A. Popov. Single molecule magnets DyM2N@C80 and Dy2MN@C80 (M = Sc, Lu): The impact of diamagnetic metals on the Dy3+ magnetic anisotropy, Dy∙∙∙Dy coupling, and mixing of molecular and lattice vibrations.  Chem. Eur. J.  2020, in press. DOI: 10.1002/chem.201904879

  2. F. Liu, L. Spree, D. S. Krylov, G. Velkos, S. M. Avdoshenko, A. A. Popov. Single-electron lanthanide-lanthanide bonds inside fullerenes toward robust redox-active molecular magnets.  Acc. Chem. Res. 2019, 52 (10), 2981-2993. DOI: 10.1021/acs.accounts.9b00373

  3. V. Dubrovin,  A. A. Popov, S. Avdoshenko. Magnetism in Ln molecular systems with 4f/valence-shell interplay (FV-magnetism).  Chem. Commun.  2019, 55, 13963-13966. DOI: 10.1039/C9CC06913E

  4. C. Schlesier, F. Liu, V. Dubrovin, L. Spree, B. Büchner, S. M. Avdoshenko, A. A Popov. Mixed dysprosium-lanthanide nitride clusterfullerenes DyM2N@C80-Ih and Dy2MN@C80-Ih (M = Gd, Er, Tm, and Lu): synthesis, molecular structure, and quantum motion of the endohedral nitrogen atom. Nanoscale 2019, 11, 13139. DOI: 10.1039/C9NR03593A

  5. W. Yang, G. Velkos, F. Liu, S. M. Sudarkova, Y. Wang, J. Zhuang, H. Zhang, X. Li, X. Zhang, B. Büchner, S. M. Avdoshenko, A. A. Popov, N. Chen. Single molecule magnetism with strong magnetic anisotropy and enhanced Dy∙∙∙Dy coupling in three isomers of Dy-oxide clusterfullerene Dy2O@C82.  Adv. Sci. 2019, 1901352. DOI: 10.1002/advs.201901352

  6. F. Liu, G. Velkos, D. S. Krylov, L. Spree, M. Zalibera, R. Ray, N. A. Samoylova, C.-H. Chen, M. Rosenkranz, S. Schiemenz, F. Ziegs, K. Nenkov, A. Kostanyan, T. Greber, A. U. B. Wolter, M. Richter, B. Büchner, S. M. Avdoshenko, A. A. Popov. Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal-metal bond.  Nat. Commun.  2019, 10, 571. DOI: 10.1038/s41467-019-08513-6

  7. G. Velkos, D. S. Krylov, K. Kirkpatrick, L. Spree, V. Dubrovin, B. Büchner, S. M. Avdoshenko, V. Bezmelnitsyn, S. Davis, P. Faust, J. Duchamp, H. C. Dorn, A. A. Popov. High blocking temperature of magnetization and giant coercivity in the azafullerene Tb2@C79N with a single-electron Tb–Tb bond.  Angew. Chem. Int. Ed.  2019, 58, 5891.  DOI: 10.1002/anie.201900943

  8. L. Spree, A. A. Popov. Recent advances in single molecule magnetism of dysprosium-metallofullerenes. Dalton Trans. 2019, 48, 2861. DOI: 10.1039/c8dt05153d

  9. V. Dubrovin, L.-H. Gan, B. Büchner, A. A. Popov, S. M. Avdoshenko. Endohedral metal-nitride cluster ordering in metallofullerene-NiII(OEP) complexes and crystals: a theoretical study. Phys. Chem. Chem. Phys.  2019, 21, 8197. DOI: 10.1039/C9CP00634F

  10. T. Greber, A. P. Seitsonen, A. Hemmi, J. Dreiser, R. Stania, F. Matsui, M. Muntwiler, A. A. Popov, R. Westerström. Circular dichroism and angular deviation in x-ray absorption spectra of Dy2ScN@C80 single molecule magnets on h-BN/Rh(111).  Phys. Rev. Materials 2019,  3, 014409.  DOI: 10.1103/PhysRevMaterials.3.014409

  11. S. M. Avdoshenko, F. Fritz, C. Schlesier, A. Kostanyan, J. Dreiser, M. Luysberg, A. A. Popov, C. Meyer, R. Westerström. Partial magnetic ordering in one-dimensional arrays of endofullerene single-molecule magnet peapods.  Nanoscale  2018, 10, 18153-18160. DOI: 10.1039/C8NR05386C

  12. A. Brandenburg, D. S. Krylov, A. Beger, A. U. B. Wolter, B. Büchner, A. A. Popov. Carbide clusterfullerene DyYTiC@C80 featuring three different metals in the endohedral cluster and its single-ion magnetism.  Chem. Commun.  2018, 54, 10683-10686. DOI: 10.1039/C8CC04736G

  13. C. Schlesier, L. Spree, A. Kostanyan, R. Westerström, A. Brandenburg, A. U. B. Wolter, S. Yang, T. Greber, A. A Popov. Strong carbon cage influence on the single molecule magnetism in Dy-Sc nitride clusterfullerenes.  Chem. Commun.  2018, 54, 9730-9733. DOI: 10.1039/C8CC05029E

  14. X. Zhang, W.-L. Li, L. Feng, X. Chen, A. Hansen, S. Grimme, S. Fortier, D.-C. Sergentu, T. Duignan, J. Autschbach, S. Wang, Y. Wang, G. Velkos, A. Popov, N. Aghdassi, S. Duhm, X. Li, J. Li, L. Echegoyen, W. H. E. Schwarz, N. Chen. A Diuranium Carbide Cluster Stabilized Inside a C80 Fullerene Cage. Nat. Commun. 2018, 9, 2753. DOI: 10.1038/s41467-018-05210-8

  15. R. Stania, A. P. Seitsonen, D. Kunhardt, B. Büchner, A. A. Popov, M. Muntwiler, T. Greber. Electrostatic Interaction Across a Single Layer Carbon Shell. J. Phys. Chem. Lett. 2018, 9, 3586-3590. DOI: 10.1021/acs.jpclett.8b01326

  16. C.-H. Chen, D. S. Krylov, S. M. Avdoshenko, F. Liu, L. Spree, R. Westerström, C. Bulbucan, M. Studniarek, J. Dreiser, A. U. B. Wolter, B. Büchner, A. A. Popov. Magnetic hysteresis in self-assembled monolayers of Dy-fullerene single molecule magnets on gold. Nanoscale 2018, 10, 11287-11292. DOI: 10.1039/C8NR00511G

  17. D. S. Krylov, F. Liu, A. Brandendurg, L. Spree, V. Bon, S. Kaskel, A. U. B. Wolter, B. Büchner, S. M. Avdoshenko, A. A. Popov. Magnetization relaxation in the single-ion magnet DySc2N@C80: quantum tunneling, magnetic dilution, and unconventional temperature dependence. Phys. Chem. Chem. Phys. 2018, 20, 11656-11672. DOI: 10.1039/C8CP01608A

  18. G. Velkos, D. S. Krylov, K. Kirkpatrick, X. Liu, L. Spree, A. U. B. Wolter, B. Büchner, H. C. Dorn, A. A. Popov. Giant exchange coupling and field-induced slow relaxation of magnetization in Gd2@C79N with a single-electron Gd–Gd bond. Chem. Commun. 2018, 54, 2902-2905. DOI: 10.1039/C8CC00112J

  19. B. J. Eleazer, M. D. Smith, A. A. Popov, D. V. Peryshkov. Expansion of the (BB)>Ru metallacycle with coinage metal cations: formation of B–M–Ru–B (M = Cu, Ag, Au) dimetalacyclodiboryls. Chem. Sci. 2018, 9, 2601-2608. DOI: 10.1039/C8SC00190A

  20. A. A. Popov. Redox-active metal–metal bonds between lanthanides in dimetallofullerenes. Curr. Opin. Electrochem. 2018, 8, 73-80. DOI: 10.1016/j.coelec.2017.12.003

  21. M. Zalibera, D. S. Krylov, D. Karagiannis, P.-A. Will, F. Ziegs, S. Schiemenz, W. Lubitz, S. Reineke, A. Savitsky, A. A. Popov. Thermally-activated delayed fluorescence in Y3N@C80 endohedral fullerene: time resolved luminescence and electron paramagnetic resonance studies. Angew. Chem. Int. Ed. 2018, 130 (1), 283–287. DOI: 10.1002/anie.201710637

  22. A. Kostanyan, R. Westerström, Y. Zhang, D. Kunhardt, R. Stania, B. Büchner, A. A. Popov, T. Greber. Switching molecular conformation with the torque on a single magnetic moment. Phys. Rev. Lett. 2017, 119 (23), 237202. DOI: 10.1103/PhysRevLett.119.237202

  23. F. Fritz, R. Westerström, A. Kostanyan, C. Schlesier, J. Dreiser, B. Watts, L. Houben, M. Luysberg, S. M Avdoshenko, A. A. Popov, C. M. Schneider, C. Meyer. Nanoscale X-ray investigation of magnetic metallofullerene peapods. Nanotechnology 2017, 28, 435703. DOI: 10.1088/1361-6528/aa8b4c

  24. F. Liu, D. S. Krylov, L. Spree, S. M. Avdoshenko, N. A. Samoylova, M. Rosenkranz, A. Kostanyan, T. Greber, A. U. B. Wolter, B. Büchner, A. A. Popov. Single molecule magnet with an unpaired electron trapped between two lanthanide ions inside a fullerene. Nat. Commun. 2017, 8, 16098. DOI: 10.1038/ncomms16098

  25. C.-H. Chen, D. S. Krylov, S. M. Avdoshenko, F. Liu, L. Spree, R. Yadav, A. Alvertis, L. Hozoi, K. Nenkov, A. Kostanyan, T. Greber, A. U. B. Wolter, A. A. Popov. Selective arc-discharge synthesis of Dy2S-clusterfullerenes and their isomer-dependent single molecule magnetism. Chem. Sci. 2017, 8, 6451-6465. DOI: 10.1039/C7SC02395B

  26. D. S. Krylov, F. Liu, S. M. Avdoshenko, L. Spree, B. Weise, A. Waske, A. U. B. Wolter, B. Büchner, A. A Popov. Record-high thermal barrier of the relaxation of magnetization in the nitride clusterfullerene Dy2ScN@C80-Ih. Chem. Commun. 2017, 53, 7901-7904. DOI: 10.1039/C7CC03580B

  27. S. Schimmel, Z. Sun, D. Baumann, D. Krylov, N. Samoylova, A. Popov, B. Büchner, C. Hess. Adsorption characteristics of Er3N@C80 on W(110) and Au(111) studied via STM/STS. Beilstein J. Nanotechnol. 2017, 8, 1127-1134. DOI: 10.3762/bjnano.8.114

  28. N. A. Samoylova, S. M. Avdoshenko, D. S. Krylov, H. R Thompson, A. Kirkhorn, M. Rosenkranz, S. Schiemenz, F. Ziegs, A. U. B. Wolter, S. Yang, S. Stevenson, A. A. Popov. Confining the spin between two metal atoms within the carbon cage: Redox-active metal-metal bonds in dimetallofullerenes and their stable cation radicals. Nanoscale 2017, 9, 7977-7990. DOI: 10.1039/C7NR02288C

  29. A. M. Rice, W. B. Fellows, E. A. Dolgopolova, A. B. Greytak, A. K. Vannucci, M. D. Smith, S. G. Karakalos, J. A. Krause, S. M. Avdoshenko, A. A. Popov, N. B. Shustova. Hierarchical Corannulene-Based Materials: Energy Transfer and Solid-State Photophysics. Angew. Chem. Int. Ed. 2017, 56 (16), 4525-4529. DOI: 10.1002/anie.201612199

  30. F. Liu, S. Wang, C.-L. Gao, Q. Deng, X. Zhu, A. Kostanyan, R. Westerström, F. Jin, S.-Y. Xie, A. A. Popov, T. Greber, S. Yang. Mononuclear Clusterfullerene Single-Molecule Magnet Containing Strained Fused-Pentagons Stabilized by a Nearly Linear Metal Cyanide Cluster. Angew. Chem. Int. Ed. 2017, 138, 14764-14771. DOI: 10.1002/anie.201611345

  31. 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. Triangular Monometallic Cyanide Cluster Entrapped in Carbon Cage with Geometry-Dependent Molecular Magnetism. J. Am. Chem. Soc. 2016, 138, 14764-14771. DOI: 10.1021/jacs.6b09329

  32.  B. J. Eleazer, M. D. Smith, A. A. Popov, D. V. Peryshkov. (BB)-Carboryne Complex of Ruthenium: Synthesis by Double B–H Activation at a Single Metal Center. J. Am. Chem. Soc. 2016, 138 (33), 10531–10538. DOI: 10.1021/jacs.6b05172

  33. K. Junghans, K. B. Ghiassi, N. A. Samoylova, Q. Deng, M. Rosenkranz, M. M. Olmstead, A. L. Balch, A. A. Popov. Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih-C80, Sc2TiC@D5h-C80 and Sc2TiC2@Ih-C80: Metal Size Tuning of the TiIV/TiIII Redox Potentials. Chem. Eur. J. 2016, 22 (37), 13098-13107. DOI: 10.1002/chem.201601655

  34. D. V. Konarev,   L. Zorina,   S. S. Khasanov,   A. A Popov,   A. Otsuka,   H. Yamochi,   G. Saito, R. N. Lyubovskaya.  Crystalline anionic complex of scandium nitride endometallo-fullerene: Experimental observation of single-bonded (Sc3N@Ih-C80−)2 dimers. Chem. Commun., 2016, 52, 10763-10766. DOI: 10.1039/C6CC05550H

  35. D. E. Williams, E. A. Dolgopolova, D. C. Godfrey, E. D. Ermolaeva, P. J. Pellechia, A. B. Greytak, M. D. Smith, S. M. Avdoshenko, A. A. Popov, N. B. Shustova. Fulleretic Well-Defined Scaffolds: Donor–Fullerene Alignment Through Metal Coordination and Its Effect on Photophysics. Angew. Chem. Int. Ed. 2016, 55, 9070-9074. DOI: 10.1002/anie.201603584.

  36. K. Junghans, M. Rosenkranz, A. A. Popov. Sc3CH@C80: selective 13C enrichment of the central carbon atom. Chem. Commun. 2016, 52, 6561-6564, DOI: 10.1039/C5CC10025A

  37. Q. Deng, T. Heine, S. Irle, A. A. Popov. Self-assembly of endohedral metallofullerenes: a decisive role of cooling gas and metal–carbon bonding. Nanoscale 2016, 8, 3796-3808. DOI: 10.1039/C5NR08645K

  38. K. Junghans, C. Schlesier, A. Kostanyan, N. A. Samoylova, Q. Deng, M. Rosenkranz, S. Schiemenz, R. Westerström, T. Greber, B. Büchner, 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, DOI: 10.1002/anie.201505870

  39. M. Zalibera, P. Machata, T. T. Clikeman, M. Rosenkranz, S. H. Strauss, O. V. Boltalina, A. A. Popov. 19F NMR-, ESR-, and vis-NIR-spectroelectrochemical study of the unconventional reduction behaviour of perfluoroalkylated fullerene: dimerization of the C70(CF3)10− radical anion. Analyst 2015, 140, 7209-7216. DOI: 10.1039/C5AN01129A

Endohedral Metallofullerenes

Closed carbon cages encapsulating different atoms, ions, clusters and even small molecules are known as "endohedral  fullerenes" (from Greek ἔνδον  – within and ἕδρα  – face of a geometrical figure). Endohedral metallofullerenes (EMFs) are thus  fullerenes with one or more metal atoms inside the carbon cage. In the chemical formulae, endohedral species are written first followed by the symbol “@” and then by the fullerene (e.g., "Sc3N@C80" denotes the fullerene C80 with endohedral cluster Sc3N). The Figure shows different types of EMFs, from mono- and di-metallofullerenes to complex clusterfullerenes comprising up to four metal atoms and one-two non-metals (C, N, O, S, etc).  Encapsulations of Lanthanide ions within the fullerene cage may lead to fullerene-based single molecule magnets.

Single Molecule Magnets

Single molecule magnets (SMMs) are molecular materials whose molecules can behave as tiny magnets, e.g. via preserving their magnetic state in the absence of magnetic field and exhibiting slow relaxation of magnetization. SMM behaviour is characterized by the presence of the spin-reversal barrier caused by the magnetic anisotropy. Realization of magnetism on a molecular level is very technologically attractive since it promises a dramatic increase of possible writing densities and offers a number of spintronics applications. Lanthanide and especially Dy-based SMMs constitute an important class of such materials providing high relaxation energy barriers and the highest temperatures at which hysteresis can be observed so far in SMMs.

Lanthanide-based EMFs provide a convenient possibility to stabilize metal atoms in unconventional clusters inside the carbon cage. In clusterfullerenes, such as Dy2ScN@C80 shown in the Figure, endohedral lantanide ions are coordinated to negatively charged non-metal ions, such as N3−, S2−, O2−, etc. The presence of such ions at a close distance to lanthanides creates strong axial ligand field and hence large magnetic anisotropy. Thus, many Dy-EMFs exhibit slow relaxation of magnetization at helium temperatures. For Dy2ScN@C80, the barrier of the reversal of magnetization is 1735 K, which is  one of the highest values among all SMMs. Relaxation of magnetization in this SMM follows the Orbach mechanism and proceeds via the 5th excited Kramers doublet.