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Switching the magnetic hysteresis of an [Feii–NC–Wv]-based coordination polymer by photoinduced reversible spin crossover


Magnetic bistable materials that feature magnetic hysteresis are comparable to elementary binary units and promising for application in switches and memory devices. In this work, we report a material that consists of parallel cyanide-bridged [Feii–Wv] coordination chains linked together through rigid bis(imidazolyl)–benzene ligands and displays multiple magnetic states. The paramagnetic high-spin and diamagnetic low-spin states of the spin-crossover Feii ions can be interconverted by reversible light-induced excited spin state trapping (LIESST) by alternating between light irradiation of 808 and 473 nm. At 1.8 K, under 808-nm-light irradiation, magnetic interactions between the photogenerated paramagnetic high-spin Feii centres and the Wv centres lead to long fragments that exhibit single-chain magnet behaviour, with a wide magnetic hysteresis and a large coercive field of 19 kOe; under a 473 nm light, isolated Feii–Wv fragments behave as single-molecule magnets instead. At 3.3 K, the high-spin form still displays magnetic hysteresis, albeit narrower, whereas the low-spin one does not.

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Fig. 1: Crystal structure of complex 1.
Fig. 2: Temperature-dependent susceptibility of complex 1 under a d.c. field of 1 kOe.
Fig. 3: Light-induced magnetic property of complex 1.
Fig. 4: Mössbauer spectra of complex 1.
Fig. 5: Dynamic magnetic susceptibilities of complex 1 after 808-nm-light irradiation.
Fig. 6: Magnetic hysteresis loops after irradiation with different light.

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Data availability

All data supporting the finding of this study are available within this article and its Supplementary Information. The crystallographic data have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers CCDC 1967433 (for 1 at 200 K) and CCDC 1967426 (for 1 at 28 K) and can be obtained free of charge via Source data are provided with this paper.


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This work was supported by the National Natural Science Foundation of China (22025101, 91961114, 21871039, 22071017 and 21801037), the Liaoning Provincial Natural Science Foundation of China (2019-MS-318) and the Fundamental Research Funds for the Central Universities, China.

Author information

Authors and Affiliations



T.L. conceived the research and managed the project. L.Z. synthesized the complexes. L.Z. and Y.-S.M. performed the magnetic and spectroscopic measurements. Q.L., O.S. and H.O. carried out the 57Fe Mössbauer measurement and spectra analysis. Y.-S.M. and Q.S. carried out the heat capacity measurement and analysis. Y.-S.M. analysed the magnetic data. Y.-S.M., L.Z. and T.L. conducted the data interpretation and co-wrote the manuscript. L.Z. and Y.-S.M. contributed to this work equally. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Yin-Shan Meng or Tao Liu.

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The authors declare no competing interests.

Additional information

Peer review information Nature Chemistry thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–15, discussions and Tables 1–4.

Supplementary Data 1

CIF for complex 1 at 28 K; CCDC reference: 1967426.

Supplementary Data 2

CIF for complex 1 at 200 K; CCDC reference: 1967433.

Supplementary Data 3

Source data for Supplementary Fig. 11b,c. Extracted relaxation times at different temperatures and fitting results for complex 1 before irradiation; unprocessed in-phase signals at different temperatures and fitting results for complex 1 before irradiation.

Source data

Source Data Fig. 4

Source data for Fig. 4a–d. Unprocessed 57Fe Mössbauer spectra data and fitting data for complex 1 at 140 K (a), at 25 K (b), after 808-nm light irradiation at 25 K (c), and after 473-nm light irradiation at 25 K (d).

Source Data Fig. 5

Source data for Fig. 5b,c. Extracted relaxation times at different temperatures and fitting results for complex 1 after 808-nm light irradiation; unprocessed in-phase signals at different temperatures and fitting results for complex 1 after 808-nm light irradiation.

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Zhao, L., Meng, YS., Liu, Q. et al. Switching the magnetic hysteresis of an [Feii–NC–Wv]-based coordination polymer by photoinduced reversible spin crossover. Nat. Chem. 13, 698–704 (2021).

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