Team Leader
CHemistry
Lukas Spree
Before joining QNS, Lukas Spree’s work was focused on the synthesis, isolation, and characterization of endohedral fullerene based single molecule magnets. At QNS he is working on the chemical modification of spin qubit candidates, to facilitate their deposition on various substrates, while preserving spin coherence.
Since April 2024 he is leading his own research project supported by the IBS Young Scientist Fellowship.
“Freude am Schauen und Begreifen ist die schönste Gabe der Natur.”
“The joy in looking and understanding is the most beautiful gift of nature.”
Albert Einstein
- Education
- Work Experience
- Selected Publications
- Awards
| 2016 – 2020 | PhD in Applied Natural Science, Institute for Solid State and Materials Research Dresden |
| 2010 – 2016 | BS/MS in Applied Natural Science, Technische Universität Bergakademie Freiberg |
| 2021 – Current | Research Professor at Center for Quantum Nanoscience(QNS), Institute for Basic Science(IBS), Ewha Womans University, Seoul, Korea |
| 2020 – 2021 | Institute for Solid State and Materials Research Dresden, Research Assistant |
2021
Spree L; Liu F; Neu V; Rosenkranz M; Velkos G; Wang Y; Schiemenz S; Dreiser J; Gargiani P; Valvidares M; Chen C; Büchner B; Avdoshenko S M; Popov A A
Robust Single Molecule Magnet Monolayers on Graphene and Graphite with Magnetic Hysteresis up to 28 K Journal Article
In: Adv Funct Materials, vol. 31, no. 48, 2021, ISSN: 1616-3028.
@article{Spree2021,
title = {Robust Single Molecule Magnet Monolayers on Graphene and Graphite with Magnetic Hysteresis up to 28 K},
author = {Lukas Spree and Fupin Liu and Volker Neu and Marco Rosenkranz and Georgios Velkos and Yaofeng Wang and Sandra Schiemenz and Jan Dreiser and Pierluigi Gargiani and Manuel Valvidares and Chia‐Hsiang Chen and Bernd Büchner and Stanislav M. Avdoshenko and Alexey A. Popov},
doi = {10.1002/adfm.202105516},
issn = {1616-3028},
year = {2021},
date = {2021-09-01},
journal = {Adv Funct Materials},
volume = {31},
number = {48},
publisher = {Wiley},
abstract = {The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single-molecule magnets or qubit candidates.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single-molecule magnets or qubit candidates.
2019
Spree L; Popov A A
Recent advances in single molecule magnetism of dysprosium-metallofullerenes Journal Article
In: Dalton Trans., vol. 48, no. 9, pp. 2861–2871, 2019, ISSN: 1477-9234.
@article{Spree2019,
title = {Recent advances in single molecule magnetism of dysprosium-metallofullerenes},
author = {Lukas Spree and Alexey A. Popov},
doi = {10.1039/c8dt05153d},
issn = {1477-9234},
year = {2019},
date = {2019-02-26},
journal = {Dalton Trans.},
volume = {48},
number = {9},
pages = {2861--2871},
publisher = {Royal Society of Chemistry (RSC)},
abstract = {Encapsulation of dysprosium ions in fullerenes results in efficient air stable single molecule magnets, which can be used in preparation of various 1D, 2D, and 3D assemblies.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Encapsulation of dysprosium ions in fullerenes results in efficient air stable single molecule magnets, which can be used in preparation of various 1D, 2D, and 3D assemblies.
Liu F; Velkos G; Krylov D S; Spree L; Zalibera M; Ray R; Samoylova N A; Chen C; Rosenkranz M; Schiemenz S; Ziegs F; Nenkov K; Kostanyan A; Greber T; Wolter A U B; Richter M; Büchner B; Avdoshenko S M; Popov A A
Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond Journal Article
In: Nat Commun, vol. 10, no. 1, 2019, ISSN: 2041-1723.
@article{Liu2019b,
title = {Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond},
author = {Fupin Liu and Georgios Velkos and Denis S. Krylov and Lukas Spree and Michal Zalibera and Rajyavardhan Ray and Nataliya A. Samoylova and Chia-Hsiang Chen and Marco Rosenkranz and Sandra Schiemenz and Frank Ziegs and Konstantin Nenkov and Aram Kostanyan and Thomas Greber and Anja U. B. Wolter and Manuel Richter and Bernd Büchner and Stanislav M. Avdoshenko and Alexey A. Popov},
doi = {10.1038/s41467-019-08513-6},
issn = {2041-1723},
year = {2019},
date = {2019-02-04},
journal = {Nat Commun},
volume = {10},
number = {1},
publisher = {Springer Science and Business Media LLC},
abstract = {Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln2@C80(CH2Ph) dimetallofullerenes (Ln2 = Y2, Gd2, Tb2, Dy2, Ho2, Er2, TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal–metal bonding orbital. Tb2@C80(CH2Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln2@C80(CH2Ph) is redox active, enabling electrochemical tuning of the magnetism.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln2@C80(CH2Ph) dimetallofullerenes (Ln2 = Y2, Gd2, Tb2, Dy2, Ho2, Er2, TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal–metal bonding orbital. Tb2@C80(CH2Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln2@C80(CH2Ph) is redox active, enabling electrochemical tuning of the magnetism.
Liu F; Spree L; Krylov D S; Velkos G; Avdoshenko S M; Popov A A
Single-Electron Lanthanide-Lanthanide Bonds Inside Fullerenes toward Robust Redox-Active Molecular Magnets Journal Article
In: Accounts of Chemical Research, vol. 52, no. 10, pp. 2981–2993, 2019, ISSN: 15204898.
@article{Liu2019,
title = {Single-Electron Lanthanide-Lanthanide Bonds Inside Fullerenes toward Robust Redox-Active Molecular Magnets},
author = {Fupin Liu and Lukas Spree and Denis S Krylov and Georgios Velkos and Stanislav M Avdoshenko and Alexey A Popov},
doi = {10.1021/acs.accounts.9b00373},
issn = {15204898},
year = {2019},
date = {2019-10-01},
urldate = {2019-10-01},
journal = {Accounts of Chemical Research},
volume = {52},
number = {10},
pages = {2981–2993},
publisher = {American Chemical Society (ACS)},
abstract = {A characteristic phenomenon of lanthanide-fullerene interactions is the transfer of metal valence electrons to the carbon cage. With early lanthanides such as La, a complete transfer of six valence electrons takes place for the metal dimers encapsulated in the fullerene cage. However, the low energy of the σ-type Ln-Ln bonding orbital in the second half of the lanthanide row limits the Ln2 → fullerene transfer to only five electrons. One electron remains in the Ln-Ln bonding orbital, whereas the fullerene cage with a formal charge of -5 is left electron-deficient. Such Ln2@C80 molecules are unstable in the neutral form but can be stabilized by substitution of one carbon atom by nitrogen to give azafullerenes Ln2@C79N or by quenching the unpaired electron on the fullerene cage by reacting it with a chemical such as benzyl bromide, transforming one sp2 carbon into an sp3 carbon and yielding the monoadduct Ln2@C80(CH2Ph). Because of the presence of the Ln-Ln bonding molecular orbital with one electron, the Ln2@C79N and Ln2@C80(R) molecules feature a unique single-electron Ln-Ln bond and an unconventional +2.5 oxidation state of the lanthanides.In this Account, which brings together metallofullerenes, molecular magnets, and lanthanides in unconventional valence states, we review the progress in the studies of dimetallofullerenes with single-electron Ln-Ln bonds and highlight the consequences of the unpaired electron residing in the Ln-Ln bonding orbital for the magnetic interactions between Ln ions. Usually, Ln···Ln exchange coupling in polynuclear lanthanide compounds is weak because of the core nature of 4f electrons. However, when interactions between Ln centers are mediated by a radical bridge, stronger coupling may be achieved because of the diffuse nature of radical-based orbitals. Ultimately, when the role of a radical bridge is played by a single unpaired electron in the Ln-Ln bonding orbital, the strength of the exchange coupling is increased dramatically. Giant exchange coupling in endohedral Ln2 dimers is combined with a rather strong axial ligand field exerted on the lanthanide ions by the fullerene cage and the excess electron density localized between two Ln ions. As a result, Ln2@C79N and Ln2@C80(CH2Ph) compounds exhibit slow relaxation of magnetization and exceptionally high blocking temperatures for Ln = Dy and Tb. At low temperatures, the [Ln3+-e-Ln3+] fragment behaves as a single giant spin. Furthermore, the Ln-Ln bonding orbital in dimetallofullerenes is redox-active, which allows its population to be changed by electrochemical reactions, thus changing the magnetic properties because the change in the number of electrons residing in the Ln-Ln orbital affects the magnetic structure of the molecule.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A characteristic phenomenon of lanthanide-fullerene interactions is the transfer of metal valence electrons to the carbon cage. With early lanthanides such as La, a complete transfer of six valence electrons takes place for the metal dimers encapsulated in the fullerene cage. However, the low energy of the σ-type Ln-Ln bonding orbital in the second half of the lanthanide row limits the Ln2 → fullerene transfer to only five electrons. One electron remains in the Ln-Ln bonding orbital, whereas the fullerene cage with a formal charge of -5 is left electron-deficient. Such Ln2@C80 molecules are unstable in the neutral form but can be stabilized by substitution of one carbon atom by nitrogen to give azafullerenes Ln2@C79N or by quenching the unpaired electron on the fullerene cage by reacting it with a chemical such as benzyl bromide, transforming one sp2 carbon into an sp3 carbon and yielding the monoadduct Ln2@C80(CH2Ph). Because of the presence of the Ln-Ln bonding molecular orbital with one electron, the Ln2@C79N and Ln2@C80(R) molecules feature a unique single-electron Ln-Ln bond and an unconventional +2.5 oxidation state of the lanthanides.In this Account, which brings together metallofullerenes, molecular magnets, and lanthanides in unconventional valence states, we review the progress in the studies of dimetallofullerenes with single-electron Ln-Ln bonds and highlight the consequences of the unpaired electron residing in the Ln-Ln bonding orbital for the magnetic interactions between Ln ions. Usually, Ln···Ln exchange coupling in polynuclear lanthanide compounds is weak because of the core nature of 4f electrons. However, when interactions between Ln centers are mediated by a radical bridge, stronger coupling may be achieved because of the diffuse nature of radical-based orbitals. Ultimately, when the role of a radical bridge is played by a single unpaired electron in the Ln-Ln bonding orbital, the strength of the exchange coupling is increased dramatically. Giant exchange coupling in endohedral Ln2 dimers is combined with a rather strong axial ligand field exerted on the lanthanide ions by the fullerene cage and the excess electron density localized between two Ln ions. As a result, Ln2@C79N and Ln2@C80(CH2Ph) compounds exhibit slow relaxation of magnetization and exceptionally high blocking temperatures for Ln = Dy and Tb. At low temperatures, the [Ln3+-e-Ln3+] fragment behaves as a single giant spin. Furthermore, the Ln-Ln bonding orbital in dimetallofullerenes is redox-active, which allows its population to be changed by electrochemical reactions, thus changing the magnetic properties because the change in the number of electrons residing in the Ln-Ln orbital affects the magnetic structure of the molecule.
| 2024-2027 | IBS Young Scientist Fellowship |
| 2022-2024 | Feodor Lynen Fellowship by the Alexander von Humboldt-Foundation |