A spin transition mechanism for cooperative adsorption in metal–organic frameworks


Cooperative binding, whereby an initial binding event facilitates the uptake of additional substrate molecules, is common in biological systems such as haemoglobin1,2. It was recently shown that porous solids that exhibit cooperative binding have substantial energetic benefits over traditional adsorbents3, but few guidelines currently exist for the design of such materials. In principle, metal–organic frameworks that contain coordinatively unsaturated metal centres could act as both selective4,5,6,7 and cooperative adsorbents if guest binding at one site were to trigger an electronic transformation that subsequently altered the binding properties at neighbouring metal sites8,9,10. Here we illustrate this concept through the selective adsorption of carbon monoxide (CO) in a series of metal–organic frameworks featuring coordinatively unsaturated iron(ii) sites. Functioning via a mechanism by which neighbouring iron(ii) sites undergo a spin-state transition above a threshold CO pressure, these materials exhibit large CO separation capacities with only small changes in temperature. The very low regeneration energies that result may enable more efficient Fischer–Tropsch conversions and extraction of CO from industrial waste feeds, which currently underutilize this versatile carbon synthon11. The electronic basis for the cooperative adsorption demonstrated here could provide a general strategy for designing efficient and selective adsorbents suitable for various separations.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Idealized adsorption isotherms and the cooperative spin transition mechanism.
Figure 2: Solid state structures.
Figure 3: Characterization of the spin transition mechanism.
Figure 4: Gas adsorption isotherms, working capacities, and molar selectivity values.


  1. 1

    Perutz, M. F. Mechanism of Cooperativity and Allosteric Regulation in Proteins (Cambridge Univ. Press, 1990)

  2. 2

    Perrella, M. & Di Cera, E. CO ligation intermediates and the mechanism of hemoglobin cooperativity. J. Biol. Chem. 274, 2605–2608 (1999)

    CAS  Article  Google Scholar 

  3. 3

    McDonald, T. M. et al. Cooperative insertion of CO2 in diamine-appended metal-organic frameworks. Nature 519, 303–308 (2015)

    CAS  ADS  Article  Google Scholar 

  4. 4

    Caskey, S. R., Wong-Foy, A. G. & Matzger, A. J. Dramatic tuning of carbon dioxide uptake via metal substitution in a coordination polymer with cylindrical pores. J. Am. Chem. Soc. 130, 10870–10871 (2008)

    CAS  Article  Google Scholar 

  5. 5

    Sumida, K. et al. Carbon dioxide capture in metal–organic frameworks. Chem. Rev. 112, 724–781 (2012)

    CAS  Article  Google Scholar 

  6. 6

    Herm, Z. R., Bloch, E. D. & Long, J. R. Hydrocarbon separations in metal–organic frameworks. Chem. Mater. 26, 323–338 (2014)

    CAS  Article  Google Scholar 

  7. 7

    Xiao, D. J. et al. Selective, tunable O2 binding in cobalt(II)–triazolate/pyrazolate metal–organic frameworks. J. Am. Chem. Soc. 138, 7161–7170 (2016)

    CAS  Article  Google Scholar 

  8. 8

    Kahn, O. & Martinez, C. J. Spin-transition polymers: from molecular materials toward memory devices. Science 279, 44–48 (1998)

    CAS  ADS  Article  Google Scholar 

  9. 9

    Niel, V., Martinez-Agudo, J. M., Munoz, M. C., Gaspar, A. B. & Real, J. A. Cooperative spin crossover behavior in cyanide-bridged Fe(II)–M(II) bimetallic 3D Hofmann-like networks (M = Ni, Pd, Pt). Inorg. Chem. 40, 3838–3839 (2001)

    CAS  Article  Google Scholar 

  10. 10

    Foucher, D. A., Honeyman, C. H., Nelson, J. M., Tang, B. Z. & Manners, I. Organometallic ferrocenyl polymers displaying tunable cooperative interactions between transition metal centers. Angew. Chem. Int. Edn Engl. 32, 1709–1711 (1993)

    Article  Google Scholar 

  11. 11

    Kerry, F. G. Industrial Gas Handbook: Gas Separation and Purification Ch. 8 (CRC, 2007)

  12. 12

    Zhou, H. C., Long, J. R. & Yaghi, O. M. Introduction to metal–organic frameworks. Chem. Rev. 112, 673–674 (2012)

    CAS  Article  Google Scholar 

  13. 13

    Furukawa, H., Cordova, K. E., O’Keeffe, M. & Yaghi, O. M. The chemistry and applications of metal-organic frameworks. Science 341, 1230444 (2013)

    Article  Google Scholar 

  14. 14

    Li, J.-R., Kuppler, R. J. & Zhou, H.-C. Selective gas adsorption and separation. Chem. Soc. Rev. 38, 1477–1504 (2009)

    CAS  Article  Google Scholar 

  15. 15

    Schneemamn, A. et al. Flexible metal–organic frameworks. Chem. Soc. Rev. 43, 6062–6096 (2014)

    Article  Google Scholar 

  16. 16

    Serre, C. et al. An explanation for the very large breathing effect of a metal–organic framework during CO2 adsorption. Adv. Mater. 19, 2246–2251 (2007)

    CAS  Article  Google Scholar 

  17. 17

    Walton, K. S. et al. Understanding inflections and steps in carbon dioxide adsorption isotherms in metal–organic frameworks. J. Am. Chem. Soc. 130, 406–407 (2008)

    CAS  Article  Google Scholar 

  18. 18

    Benito-Garagorri, D., Lagoja, I., Veiros, L. F. & Kirchner, K. A. Reactivity of coordinatively unsaturated iron complexes towards carbon monoxide: to bind or not to bind? Dalton Trans. 40, 4778–4792 (2011)

    CAS  Article  Google Scholar 

  19. 19

    Reed, D. A. et al. Reversible CO scavenging via adsorbate-dependent spin state transitions in an iron(II)–triazolate metal–organic framework. J. Am. Chem. Soc. 138, 5594–5602 (2016)

    CAS  Article  Google Scholar 

  20. 20

    Liao, P.-Q. et al. Drastic enhancement of catalytic activity via post-oxidation of a porous MnII triazolate framework. Chem. Eur. J. 20, 11303–11307 (2014)

    CAS  Article  Google Scholar 

  21. 21

    Liao, P.-Q. et al. Monodentate hydroxide as a super strong yet reversible active site for CO2 capture from high-humidity flue gas. Energy Environ. Sci. 8, 1011–1016 (2015)

    CAS  Article  Google Scholar 

  22. 22

    Rieth, A. J., Tulchinsky, Y. & Dinca˘, M. High and reversible ammonia uptake in mesoporous azolate metal–organic frameworks with open Mn, Co, and Ni sites. J. Am. Chem. Soc. 138, 9401–9404 (2016)

    CAS  Article  Google Scholar 

  23. 23

    Garcia, Y., Niel, V., Munoz, M. C. & Real, J. A. Spin crossover in 1D, 2D, and 3D polymeric Fe(II) networks. Top. Curr. Chem. 233, 229–257 (2004)

    CAS  Article  Google Scholar 

  24. 24

    Bloch, E. D. et al. Reversible CO binding enables tunable CO/H2 and CO/N2 separations in metal-organic frameworks with exposed divalent metal cations. J. Am. Chem. Soc. 136, 10752–10761 (2014)

    CAS  Article  Google Scholar 

  25. 25

    International Energy Agency. Global Action to Advance Carbon Capture and Storage: A Focus on Industrial Applications http://www.iea.org/publications/freepublications/publication/CCS_Annex.pdf (IEA, 2013)

  26. 26

    Dutta, N. N. & Patil, G. S. Developments in CO separation. Gas. Sep. Purif. 9, 277–283 (1995)

    CAS  Article  Google Scholar 

  27. 27

    Sato, H. et al. Self-accelerating CO sorption in a soft nanoporous crystal. Science 343, 167–170 (2014)

    CAS  ADS  Article  Google Scholar 

  28. 28

    Peng, J. et al. A supported Cu(I)@MIL-100(Fe) adsorbent with high CO adsorption capacity and CO/N2 selectivity. Chem. Eng. J. 270, 282–289 (2015)

    CAS  Article  Google Scholar 

  29. 29

    Davis, R. A., Nicholas, D. M., Smith, D. D., Wang, S.-I. & Wright, R. A. Integrated reformer process for the production of carbon black. US patent 5,011,670 (1991)

    Google Scholar 

  30. 30

    Halder, G. J., Kepert, C. J., Moubaraki, B., Murray, K. S. & Cashion, J. D. Guest-dependent spin crossover in a nanoporous molecular framework material. Science 298, 1762–1765 (2002)

    CAS  ADS  Article  Google Scholar 

  31. 31

    Denysenko, D. et al. Elucidating gating effects for hydrogen sorption in MFU-4-type triazolate-based metal–organic frameworks featuring different pore sizes. Chem. Eur. J. 17, 1837–1848 (2011)

    CAS  Article  Google Scholar 

  32. 32

    Coelho, A. A. Indexing of powder diffraction patterns by iterative use of singular value decomposition. J. Appl. Cryst. 36, 86–95 (2003)

    CAS  Article  Google Scholar 

  33. 33

    Coelho, A. A. TOPAS-Academic, version 4.1 (Coelho Software, 2007)

Download references


This research was supported through the Center for Gas Separations Relevant to Clean Energy Technologies, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under award DE-SC0001015. Powder X-ray diffraction data were collected at Beamline 11-BM and Beamline 17-BM at the Advanced Photon Source, a DOE Office of Science User Facility, operated by Argonne National Laboratory under contract DE-AC02-06CH11357. We thank P. C. Bunting, R. L. Siegelman and J. E. Bachman for discussions, and H. Z. H. Jiang for experimental assistance. D.A.R., J.O., J.A.M., D.J.X. and L.E.D. thank the National Science Foundation for graduate fellowship support.

Author information




D.A.R., B.K.K. and J.R.L. formulated the project. D.A.R. and B.K.K. synthesized the compounds. D.A.R. and B.K.K. collected and analysed the gas adsorption data. J.O., J.A.M. and T.R. collected and analysed the X-ray diffraction data. D.J.X. collected and analysed the Mössbauer spectra. L.E.D. collected and analysed the magnetic susceptibility data. V.C. and S.B. collected and analysed the infrared spectra. D.A.R., B.K.K. and J.R.L. wrote the paper, and all authors contributed to revising it.

Corresponding author

Correspondence to Jeffrey R. Long.

Ethics declarations

Competing interests

J.R.L., D.A.R., B.K.K. and the University of California, Berkeley have filed for a patent on some of the results contained herein.

Additional information

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

This file contains supplementary discussion, tables S1-S10 and figures S1-S21. (PDF 3088 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Reed, D., Keitz, B., Oktawiec, J. et al. A spin transition mechanism for cooperative adsorption in metal–organic frameworks. Nature 550, 96–100 (2017). https://doi.org/10.1038/nature23674

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing