Crafting Crystalline Materials with Unconventional Electronic and Magnetic Properties Based on Metallofullerenes with Metal-Metal Bonds

• Applicant: Dr. Evgenia Dmitrieva, since 1/2024
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Synthesis and Properties of Functional Materials
• Term: from 2021 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461222691

• Final Report Year: 2025

Final Report Abstract

Endohedral metallofullerenes (EMFs) are a class of unique molecules with metal ions encapsulated inside a fullerene cage. The fullerene cage acts as a unique coordinating ligand for the metal ions while protecting them from disturbance by the outer environment. These molecules are promising candidates for magnetic resonance imaging agents, single molecule devices for advancing technologies etc. Specifically, we synthesized a class of dimetallofullerenes with single electron-occupied metal–metal bonds, which are remarkable single-molecule magnets (SMM). However, the structure-property relations of EMFs as single-molecule magnets were unclear; the nature of the coordination bonds between metal ions and the fullerene cages was in debate; the charge transporting mechanism of crystalline materials containing EMFs was unclear. Financially supported by this project, we made three aspects of advancements as follows: (1) The toolbox of fullerene ligand engineering including surface modification, shape diversification, and interior engineering to harness the ligand field of metal ions was systematically studied, paving the way for rational ligand field engineering to tailor the molecular magnetism; (2) The coordination bonds between metal ions and the fullerene cages were deeply studied by variable temperature single crystal X-ray diffraction, unravelling the non-trivial role of small molecules in the crystal lattices, defining the labile coordination between metal ions and fullerene cages; (3) Charge transporting of organic single crystal was successfully conducted, disclosing extremely broad exciton bands originating from close contact between tightly packing molecules with strong interactions. The above results deepened our understanding of metal ion–fullerene cage coordination bonds, clarifying the strategy of ligand field engineering to tailor the molecular magnetism, paving the way to the reality application of fullerene-based single-molecule magnets. This project has been successfully finished, marked with 13 papers published in high-quality peer-reviewed journals, e.g., Journal of the American Chemical Society (2), Nature Communications, Chemical Science, Advanced Science, Inorganic Chemistry Frontiers (5), Chemical Communications, Nanoscale, and several papers in revision.

Publications

• Electrophilic Trifluoromethylation of Dimetallofullerene Anions en Route to Air-Stable Single-Molecule Magnets with High Blocking Temperature of Magnetization. Journal of the American Chemical Society, 143(43), 18139-18149.
  Wang, Yaofeng; Velkos, Georgios; Israel, Noel Jens; Rosenkranz, Marco; Büchner, Bernd; Liu, Fupin & Popov, Alexey A.
  
• Directed exciton transport highways in organic semiconductors. Nature Communications, 14(1).
  Müller, Kai; Schellhammer, Karl S.; Gräßler, Nico; Debnath, Bipasha; Liu, Fupin; Krupskaya, Yulia; Leo, Karl; Knupfer, Martin & Ortmann, Frank
  
• Nd─Nd Bond in Ih and D5h Cage Isomers of Nd2@C80 Stabilized by Electrophilic CF3 Addition. Advanced Science, 11(1).
  Yang, Wei; Velkos, Georgios; Rosenkranz, Marco; Schiemenz, Sandra; Liu, Fupin & Popov, Alexey A.
  
• Using internal strain and mass to modulate Dy⋯Dy coupling and relaxation of magnetization in heterobimetallic metallofullerenes DyM2N@C80and Dy2MN@C80(M = Sc, Y, La, Lu). Inorganic Chemistry Frontiers, 10(2), 468-484.
  Hao, Yajuan; Velkos, Georgios; Schiemenz, Sandra; Rosenkranz, Marco; Wang, Yaofeng; Büchner, Bernd; Avdoshenko, Stanislav M.; Popov, Alexey A. & Liu, Fupin
  
• Capturing Unstable Metallofullerenes. Inorganics, 12(2), 48.
  Liu, Fupin & Popov, Alexey A.
  
• Covalency versus magnetic axiality in Nd molecular magnets: Nd-photoluminescence, strong ligand-field, and unprecedented nephelauxetic effect in fullerenes NdM 2 N@C 80 (M = Sc, Lu, Y). Chemical Science, 15(6), 2141-2157.
  Yang, Wei; Rosenkranz, Marco; Velkos, Georgios; Ziegs, Frank; Dubrovin, Vasilii; Schiemenz, Sandra; Spree, Lukas; de Souza Barbosa, Matheus Felipe; Guillemard, Charles; Valvidares, Manuel; Büchner, Bernd; Liu, Fupin; Avdoshenko, Stanislav M. & Popov, Alexey A.
  
• Fullerene rotation dictated by benzene–fullerene interactions. Inorganic Chemistry Frontiers, 11(12), 3458-3464.
  Wang, Yaofeng & Liu, Fupin
  
• The hidden features of fullerene rotation in the crystal lattice. Inorganic Chemistry Frontiers, 11(19), 6343-6349.
  Hao, Yajuan; Wang, Yaofeng; Feiler, Christian G.; Weiss, Manfred S.; Popov, Alexey A. & Liu, Fupin
  
• Thirty Years of Hide-and-Seek: Capturing Abundant but Elusive MIII@C3v(8)-C82 Isomer, and the Study of Magnetic Anisotropy Induced in Dy3+ Ion by the Fullerene π-Ligand. Journal of the American Chemical Society, 146(36), 25328-25342.
  Yang, Wei; Barbosa, Matheus Felipe de Souza; Alfonsov, Alexey; Rosenkranz, Marco; Israel, Noel; Büchner, Bernd; Avdoshenko, Stanislav M.; Liu, Fupin & Popov, Alexey A.
  
• Pyramidal Nd2ScN inside an icosahedral C80 cage. Inorganic Chemistry Frontiers, 12(6), 2453-2458.
  Yang, Wei; Wang, Yaofeng; Popov, Alexey A. & Liu, Fupin