High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks
We use first-principles calculations to show that the square symmetry of two-dimensional (2D) metal-organic frameworks (MOFs) made from octaamino-substituted phthalocyanines and square planar Ni²⁺ ions, which enable strong conjugation of π electrons, has a critical impact on the magnetic properties...
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| Format: | Article |
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Royal Society of Chemistry (RSC)
2018
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| Online Access: | http://hdl.handle.net/1721.1/113286 https://orcid.org/0000-0001-8217-8213 https://orcid.org/0000-0002-1262-1264 https://orcid.org/0000-0002-7841-8058 |
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| author | Li, Wenbin Sun, Lei Qi, Jingshan Jarillo-Herrero, Pablo Dinca, Mircea Li, Ju |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Li, Wenbin Sun, Lei Qi, Jingshan Jarillo-Herrero, Pablo Dinca, Mircea Li, Ju |
| author_sort | Li, Wenbin |
| collection | MIT |
| description | We use first-principles calculations to show that the square symmetry of two-dimensional (2D) metal-organic frameworks (MOFs) made from octaamino-substituted phthalocyanines and square planar Ni²⁺ ions, which enable strong conjugation of π electrons, has a critical impact on the magnetic properties of the lattice. In particular, we predict the unexpected emergence of a rare high-temperature ferromagnetic half-metallic ground state in one case. Among charge neutral MOFs made from (2,3,9,10,16,17,23,24)-octaiminophthalocyanine (OIPc) metallated with divalent first-row transition metal ions (M-OIPc; M = Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺) and connected through square planar Ni-bisphenylenediimine moieties, NiMn-OIPc exhibits a half-metallic and ferromagnetic ground state with a large exchange energy resulting from the unique strong hybridization between the d/π orbitals of Mn, the Pc ring, and the Ni-bisphenylenediimine nodes. Notably, we show that for NiMn-OIPc there is a considerable difference between the ferromagnetic ordering temperature (T[subscript c]) predicted by a 2D Ising model, which exceeds 600 K, and a T[subscript c] of 170 K predicted by our more realistic Monte Carlo simulation that includes magnetic anisotropy. Critically, our simulations adopt two spin models that incorporate magnetic anisotropy in the form of exchange anisotropy and single-ion anisotropy. We further show that in the bulk, 2D layers of NiMn-OIPc adopt a slipped-parallel stacking configuration, and exhibit interlayer magnetic coupling that is sensitive to the relative in-plane displacement between adjacent layers. These results highlight the critical role of magnetic anisotropy in modeling the properties of 2D magnetic systems. More generally, it demonstrates that strong hybridization between open-shell ions and delocalized aromatic π systems with appropriate symmetry, combined with large magnetic anisotropy, will be an effective design strategy to realize ferromagnetic 2D MOFs with high T[subscript c]. |
| first_indexed | 2024-09-23T08:12:13Z |
| format | Article |
| id | mit-1721.1/113286 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T08:12:13Z |
| publishDate | 2018 |
| publisher | Royal Society of Chemistry (RSC) |
| record_format | dspace |
| spelling | mit-1721.1/1132862022-09-30T08:17:48Z High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks Li, Wenbin Sun, Lei Qi, Jingshan Jarillo-Herrero, Pablo Dinca, Mircea Li, Ju Massachusetts Institute of Technology. Department of Chemistry Massachusetts Institute of Technology. Department of Materials Science and Engineering Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Massachusetts Institute of Technology. Department of Physics Massachusetts Institute of Technology. Research Laboratory of Electronics Li, Wenbin Sun, Lei Qi, Jingshan Jarillo-Herrero, Pablo Dinca, Mircea Li, Ju We use first-principles calculations to show that the square symmetry of two-dimensional (2D) metal-organic frameworks (MOFs) made from octaamino-substituted phthalocyanines and square planar Ni²⁺ ions, which enable strong conjugation of π electrons, has a critical impact on the magnetic properties of the lattice. In particular, we predict the unexpected emergence of a rare high-temperature ferromagnetic half-metallic ground state in one case. Among charge neutral MOFs made from (2,3,9,10,16,17,23,24)-octaiminophthalocyanine (OIPc) metallated with divalent first-row transition metal ions (M-OIPc; M = Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺) and connected through square planar Ni-bisphenylenediimine moieties, NiMn-OIPc exhibits a half-metallic and ferromagnetic ground state with a large exchange energy resulting from the unique strong hybridization between the d/π orbitals of Mn, the Pc ring, and the Ni-bisphenylenediimine nodes. Notably, we show that for NiMn-OIPc there is a considerable difference between the ferromagnetic ordering temperature (T[subscript c]) predicted by a 2D Ising model, which exceeds 600 K, and a T[subscript c] of 170 K predicted by our more realistic Monte Carlo simulation that includes magnetic anisotropy. Critically, our simulations adopt two spin models that incorporate magnetic anisotropy in the form of exchange anisotropy and single-ion anisotropy. We further show that in the bulk, 2D layers of NiMn-OIPc adopt a slipped-parallel stacking configuration, and exhibit interlayer magnetic coupling that is sensitive to the relative in-plane displacement between adjacent layers. These results highlight the critical role of magnetic anisotropy in modeling the properties of 2D magnetic systems. More generally, it demonstrates that strong hybridization between open-shell ions and delocalized aromatic π systems with appropriate symmetry, combined with large magnetic anisotropy, will be an effective design strategy to realize ferromagnetic 2D MOFs with high T[subscript c]. 2018-01-23T19:36:33Z 2018-01-23T19:36:33Z 2017-02 2016-11 2018-01-19T19:09:43Z Article http://purl.org/eprint/type/JournalArticle 2041-6520 2041-6539 http://hdl.handle.net/1721.1/113286 Li, Wenbin et al. “High Temperature Ferromagnetism in π-Conjugated Two-Dimensional Metal–organic Frameworks.” Chemical Science 8, 4 (2017): 2859–2867 © The Royal Society of Chemistry https://orcid.org/0000-0001-8217-8213 https://orcid.org/0000-0002-1262-1264 https://orcid.org/0000-0002-7841-8058 http://dx.doi.org/10.1039/C6SC05080H Chemical Science Creative Commons Attribution 3.0 Unported license http://creativecommons.org/licenses/by/3.0/ application/pdf Royal Society of Chemistry (RSC) Royal Society of Chemistry |
| spellingShingle | Li, Wenbin Sun, Lei Qi, Jingshan Jarillo-Herrero, Pablo Dinca, Mircea Li, Ju High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title | High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title_full | High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title_fullStr | High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title_full_unstemmed | High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title_short | High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks |
| title_sort | high temperature ferromagnetism in π conjugated two dimensional metal organic frameworks |
| url | http://hdl.handle.net/1721.1/113286 https://orcid.org/0000-0001-8217-8213 https://orcid.org/0000-0002-1262-1264 https://orcid.org/0000-0002-7841-8058 |
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