University of Oulu

Roukala, J., Straka, M., Taubert, S., Vaara, J., Lantto, P. (2017) Ratcheting rotation or speedy spinning: EPR and dynamics of Sc3C2@C80. Chemical Communications, 53 (64), 8992-8995. doi:10.1039/C7CC04695B

Ratcheting rotation or speedy spinning: EPR and dynamics of Sc₃C₂@C₈₀

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Author: Roukala, Juho1; Straka, Michal2; Taubert, Stefan3;
Organizations: 1NMR Research Unit, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland
2Institute of Organic Chemistry and Biochemistry, Flemingovo nam. 2, Prague, Czech Republic
3Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 13.9 MB)
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Language: English
Published: Royal Society of Chemistry, 2017
Publish Date: 2017-09-12


Besides their technological applications, endohedral fullerenes provide ideal conditions for investigating molecular dynamics in restricted geometries. A representative of this class of systems, Sc₃C₂@C₈₀ displays complex intramolecular dynamics. The motion of the ⁴⁵Sc trimer has a remarkable effect on its electron paramagnetic resonance (EPR) spectrum, which changes from a symmetric 22-peak pattern at high temperature to a single broad lineshape at low temperature. The scandium trimer consists of two equivalent and one inequivalent metal atom, due to the carbon dimer rocking through the Sc₃ triangle. We demonstrate through first-principles molecular dynamics (MD), EPR parameter tensor averaging, and spectral modelling that, at high temperatures, three-dimensional movement of the enclosed Sc₃C₂ moiety takes place, which renders the metal centers equivalent and their magnetic parameters effectively isotropic. In contrast, at low temperatures the dynamics becomes restricted to two dimensions within the equatorial belt of the Ih symmetric C₈₀ host fullerene. This restores the inequivalence of the scandium centers and causes their anisotropic hyperfine couplings to broaden the experimental spectrum.

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Series: Chemical communications
ISSN: 1359-7345
ISSN-E: 1364-548X
ISSN-L: 1359-7345
Volume: 53
Issue: 64
Pages: 8992 - 8995
DOI: 10.1039/C7CC04695B
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: JR acknowledges financial support from the Finnish Cultural Foundation, the National Doctoral Programme in Nanoscience (NGS-NANO), the Tauno Tönning Foundation, and the University of Oulu. Academy of Finland is acknowledged by JV (project no. 296292), PL (project no. 125316, 218191, 255641, and 285666) and ST (project no. 268251). MS was supported by the Czech Science Foundation, grant 17-07091S. Computational resources were provided by CSC – IT Center for Science and the Finnish Grid and Cloud Infrastructure (FGCI).
Academy of Finland Grant Number: 296292
Detailed Information: 296292 (Academy of Finland Funding decision)
125316 (Academy of Finland Funding decision)
218191 (Academy of Finland Funding decision)
255641 (Academy of Finland Funding decision)
285666 (Academy of Finland Funding decision)
Dataset Reference: Electronic supplementary information (ESI) available: Thorough discussion of the results, full average g- and A(45Sc) tensors and their isotropic values at T = 300 K and 100 K, time variation of the isotropic EPR and chosen geometrical parameters, average hyperfine tensor orientations at 100 K, full computational details including basis sets, and the equilibrium structure of Sc3C2@C80. See DOI: 10.1039/c7cc04695b
Copyright information: © Royal Society of Chemistry 2017. Published in this repository with kind permission from the publisher.