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Dynamical effects on the magnetic properties of dithiazolyl bistable materials

The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study (usually an X-ray crystal structure). Here, by means of a computational study, we compare the results obtained using such a static approach with th...

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Autores principales: Vela, Sergi, Deumal, Mercè, Shiga, Motoyuki, Novoa, Juan J., Ribas-Arino, Jordi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5645919/
https://www.ncbi.nlm.nih.gov/pubmed/29308151
http://dx.doi.org/10.1039/c4sc03930k
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author Vela, Sergi
Deumal, Mercè
Shiga, Motoyuki
Novoa, Juan J.
Ribas-Arino, Jordi
author_facet Vela, Sergi
Deumal, Mercè
Shiga, Motoyuki
Novoa, Juan J.
Ribas-Arino, Jordi
author_sort Vela, Sergi
collection PubMed
description The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study (usually an X-ray crystal structure). Here, by means of a computational study, we compare the results obtained using such a static approach with those obtained by explicitly accounting for thermal fluctuations, and uncover the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for the magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. For its high-temperature phase at 300 K, we show that nuclear dynamics induce large fluctuations in the magnetic exchange interactions (J (AB)) between spins (up to 1000% of the average value). These deviations result in a ∼20% difference between the 300 K magnetic susceptibility computed by explicitly considering the nuclear dynamics and that computed using the X-ray structure, the former being in better agreement with the experimental data. The unveiled strong coupling between J (AB) interactions and intermolecular vibrations reveals that considering J (AB) as a constant value at a given temperature (as always done in molecular magnetism) leads to a flawed description of the magnetism of TTTA. Instead, the physically relevant concept in this case is the statistical distribution of J (AB) values. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile π–π networks.
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spelling pubmed-56459192018-01-05 Dynamical effects on the magnetic properties of dithiazolyl bistable materials Vela, Sergi Deumal, Mercè Shiga, Motoyuki Novoa, Juan J. Ribas-Arino, Jordi Chem Sci Chemistry The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study (usually an X-ray crystal structure). Here, by means of a computational study, we compare the results obtained using such a static approach with those obtained by explicitly accounting for thermal fluctuations, and uncover the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for the magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. For its high-temperature phase at 300 K, we show that nuclear dynamics induce large fluctuations in the magnetic exchange interactions (J (AB)) between spins (up to 1000% of the average value). These deviations result in a ∼20% difference between the 300 K magnetic susceptibility computed by explicitly considering the nuclear dynamics and that computed using the X-ray structure, the former being in better agreement with the experimental data. The unveiled strong coupling between J (AB) interactions and intermolecular vibrations reveals that considering J (AB) as a constant value at a given temperature (as always done in molecular magnetism) leads to a flawed description of the magnetism of TTTA. Instead, the physically relevant concept in this case is the statistical distribution of J (AB) values. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile π–π networks. Royal Society of Chemistry 2015-04-01 2015-01-23 /pmc/articles/PMC5645919/ /pubmed/29308151 http://dx.doi.org/10.1039/c4sc03930k Text en This journal is © The Royal Society of Chemistry 2015 http://creativecommons.org/licenses/by/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Chemistry
Vela, Sergi
Deumal, Mercè
Shiga, Motoyuki
Novoa, Juan J.
Ribas-Arino, Jordi
Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title_full Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title_fullStr Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title_full_unstemmed Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title_short Dynamical effects on the magnetic properties of dithiazolyl bistable materials
title_sort dynamical effects on the magnetic properties of dithiazolyl bistable materials
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5645919/
https://www.ncbi.nlm.nih.gov/pubmed/29308151
http://dx.doi.org/10.1039/c4sc03930k
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