Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Covalent organic framework atropisomers with multiple gas-triggered structural flexibilities


Covalent organic frameworks (COFs) are emerging crystalline porous polymers, showing great potential for applications but lacking gas-triggered flexibility. Atropisomerism was experimentally discovered in 1922 but has rarely been found in crystals with infinite framework structures. Here we report atropisomerism in COF single crystals. The obtained COF atropisomers, namely COF-320 and COF-320-A, have identical chemical and interpenetrated structures but differ in the spatial arrangement of repeating units. In contrast to the rigid COF-320 structure, its atropisomer (COF-320-A) exhibits unconventional gas sorption behaviours with one or more sorption steps in isotherms at different temperatures. Single-crystal structures determined from continuous rotation electron diffraction and in situ powder X-ray diffraction demonstrate that these adsorption steps originate from internal pore expansion with or without changing the crystal space group. COF-320-A recognizes different gases by expanding its internal pores continuously (crystal-to-amorphous transition) or discontinuously (crystal-to-crystal transition) or having mixed transition styles, distinguishing COF-320-A from existing soft/flexible porous crystals. These findings extend atropisomerism from molecules to crystals and propel COFs into the covalently linked soft porous crystal regime, further advancing applications of soft porous crystals in gas sorption, separation and storage.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Synthesis and characterization of COF-320-A.
Fig. 2: Gas sorption isotherms and in situ PXRD measurements of COF-320-A for C2H4 at 195 K.
Fig. 3: Gas sorption isotherms and in situ PXRD measurements of COF-320-A for CO2 at 195 K.
Fig. 4: Gas sorption isotherms and in situ PXRD measurements of COF-320-A for C2H2 at 195 K.
Fig. 5: Calculation of Edef, Eint and Etot during the gas sorption of COF-320-A.

Data availability

All data are available in the main text or the Supplementary Information. The crystallographic data for single-crystal COF-320-A and COF-320-A2 have been deposited at the Cambridge Crystallographic Data Centre (CCDC, free of charge at under deposition numbers CCDC 2111901 and 2111902, respectively. Correspondence and requests for materials should be addressed to the corresponding authors.


  1. Horike, S., Shimomura, S. & Kitagawa, S. Soft porous crystals. Nat. Chem. 1, 695–704 (2009).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  3. Hiraide, S. et al. High-throughput gas separation by flexible metal–organic frameworks with fast gating and thermal management capabilities. Nat. Commun. 11, 3867 (2020).

    Article  CAS  Google Scholar 

  4. Mason, J. A. et al. Methane storage in flexible metal–organic frameworks with intrinsic thermal management. Nature 527, 357–361 (2015).

    Article  CAS  Google Scholar 

  5. Zhou, H.-C. “Joe” & Kitagawa, S. Metal–organic frameworks (MOFs). Chem. Soc. Rev. 43, 5415–5418 (2014).

    Article  CAS  Google Scholar 

  6. Furukawa, H., Cordova, K. E., O’Keeffe, M. & Yaghi, O. M. The chemistry and applications of metal-organic frameworks. Science 341, 12304444 (2013).

    Article  Google Scholar 

  7. Yaghi, O. M. et al. Reticular synthesis and the design of new materials. Nature 423, 705–714 (2003).

    Article  CAS  Google Scholar 

  8. Xu, W. et al. Anisotropic reticular chemistry. Nat. Rev. Mater. 5, 764–779 (2020).

    Article  CAS  Google Scholar 

  9. Li, Y., Chen, W., Xing, G., Jiang, D. & Chen, L. New synthetic strategies toward covalent organic frameworks. Chem. Soc. Rev. 49, 2852–2868 (2020).

    Article  CAS  Google Scholar 

  10. Krause, S., Hosono, N. & Kitagawa, S. Chemistry of soft porous crystals: structural dynamics and gas adsorption properties. Angew. Chem. Int. Ed. 59, 15325–15341 (2020).

    Article  CAS  Google Scholar 

  11. Ortiz, A. U., Boutin, A., Fuchs, A. H. & Coudert, F.-X. Anisotropic elastic properties of flexible metal-organic frameworks: how soft are soft porous crystals? Phys. Rev. Lett. 109, 195502 (2012).

    Article  Google Scholar 

  12. Atkins, P. W. & Shriver, D. F. Shriver & Atkins Inorganic Chemistry 4th edn (W.H. Freeman and Co., 2006).

  13. Ding, M., Cai, X. & Jiang, H.-L. Improving MOF stability: approaches and applications. Chem. Sci. 10, 10209–10230 (2019).

    Article  CAS  Google Scholar 

  14. Guan, X., Chen, F., Fang, Q. & Qiu, S. Design and applications of three dimensional covalent organic frameworks. Chem. Soc. Rev. 49, 1357–1384 (2020).

    Article  CAS  Google Scholar 

  15. Feng, X., Ding, X. & Jiang, D. Covalent organic frameworks. Chem. Soc. Rev. 41, 6010–6022 (2012).

    Article  CAS  Google Scholar 

  16. Chen, Y. et al. Guest-dependent dynamics in a 3D covalent organic framework. J. Am. Chem. Soc. 141, 3298–3303 (2019).

    Article  CAS  Google Scholar 

  17. Liu, X. et al. A crystalline three-dimensional covalent organic framework with flexible building blocks. J. Am. Chem. Soc. 143, 2123–2129 (2021).

    Article  CAS  Google Scholar 

  18. Zhu, Q. et al. 3D cage COFs: a dynamic three-dimensional covalent organic framework with high-connectivity organic cage nodes. J. Am. Chem. Soc. 142, 16842–16848 (2020).

    Article  CAS  Google Scholar 

  19. Cheng, J. K., Xiang, S.-H., Li, S., Ye, L. & Tan, B. Recent advances in catalytic asymmetric construction of atropisomers. Chem. Rev. 121, 4805–4902 (2021).

    Article  CAS  Google Scholar 

  20. Christie, G. H. & Kenner, J. LXXI.—The molecular configurations of polynuclear aromatic compounds. Part I. The resolution of γ-6:6′-dinitro- and 4:6:4′:6′-tetranitro-diphenic acids into optically active components. J. Chem. Soc. Trans. 121, 614–620 (1922).

    Article  CAS  Google Scholar 

  21. Bringmann, G. et al. Atroposelective synthesis of axially chiral biaryl compounds. Angew. Chem. Int. Ed. 44, 5384–5427 (2005).

    Article  CAS  Google Scholar 

  22. Smyth, J. E., Butler, N. M. & Keller, P. A. A twist of nature – the significance of atropisomers in biological systems. Nat. Prod. Rep. 32, 1562–1583 (2015).

    Article  CAS  Google Scholar 

  23. Clayden, J., Moran, W. J., Edwards, P. J. & LaPlante, S. R. The challenge of atropisomerism in drug discovery. Angew. Chem. Int. Ed. 48, 6398–6401 (2009).

    Article  CAS  Google Scholar 

  24. Glunz, P. W. Recent encounters with atropisomerism in drug discovery. Bioorg. Med. Chem. Lett. 28, 53–60 (2018).

    Article  CAS  Google Scholar 

  25. Zhang, Y.-B. et al. Single-crystal structure of a covalent organic framework. J. Am. Chem. Soc. 135, 16336–16339 (2013).

    Article  CAS  Google Scholar 

  26. Geng, K. et al. Covalent organic frameworks: design, synthesis, and functions. Chem. Rev. 16, 8814–8933 (2020).

    Article  Google Scholar 

  27. Aitipamula, S. et al. Polymorphs, salts, and cocrystals: what’s in a name? Cryst. Growth Des. 12, 2147–2152 (2012).

    Article  CAS  Google Scholar 

  28. Piaggi, P. M. & Parrinello, M. Predicting polymorphism in molecular crystals using orientational entropy. Proc. Natl Acad. Sci. USA 115, 10251–10256 (2018).

    Article  CAS  Google Scholar 

  29. Widmer, R. N. et al. Rich polymorphism of a metal–organic framework in pressure–temperature space. J. Am. Chem. Soc. 141, 9330–9337 (2019).

    Article  CAS  Google Scholar 

  30. Li, Y. et al. Polymorphism of 2D imine covalent organic frameworks. Angew. Chem. Int. Ed. 60, 5363–5369 (2021).

    Article  CAS  Google Scholar 

  31. Jones, J. T. A. et al. On–off porosity switching in a molecular organic solid. Angew. Chem. Int. Ed. 50, 749–753 (2011).

    Article  CAS  Google Scholar 

  32. Serre, C. et al. Very large breathing effect in the first nanoporous chromium(III)-based solids: MIL-53 or CrIII(OH)·{O2C−C6H4−CO2}·{HO2C−C6H4−CO2H}x·H2Oy. J. Am. Chem. Soc. 124, 13519–13526 (2002).

    Article  CAS  Google Scholar 

  33. Wu, C.-D., Hu, A., Zhang, L. & Lin, W. A homochiral porous metal−organic framework for highly enantioselective heterogeneous asymmetric catalysis. J. Am. Chem. Soc. 127, 8940–8941 (2005).

    Article  CAS  Google Scholar 

  34. Gong, W., Chen, Z., Dong, J., Liu, Y. & Cui, Y. Chiral metal–organic frameworks. Chem. Rev. 122, 9078–9144 (2022).

    Article  CAS  Google Scholar 

  35. Shekunov, B. Y., Aulton, M. E., Adama-Acquah, R. W. & Grant, D. J. W. Effect of temperature on crystal growth and crystal properties of paracetamol. J. Chem. Soc. Faraday Trans. 92, 439–444 (1996).

    Article  CAS  Google Scholar 

  36. Judge, R. A., Jacobs, R. S., Frazier, T., Snell, E. H. & Pusey, M. L. The effect of temperature and solution pH on the nucleation of tetragonal lysozyme crystals. Biophys. J. 77, 1585–1593 (1999).

    Article  CAS  Google Scholar 

  37. Sun, Y.-X. & Sun, W.-Y. Influence of temperature on metal-organic frameworks. Chin. Chem. Lett. 25, 823–828 (2014).

    Article  CAS  Google Scholar 

  38. Krause, S. et al. A pressure-amplifying framework material with negative gas adsorption transitions. Nature 532, 348–352 (2016).

    Article  CAS  Google Scholar 

  39. Krause, S. et al. Towards general network architecture design criteria for negative gas adsorption transitions in ultraporous frameworks. Nat. Commun. 10, 3632 (2019).

    Article  Google Scholar 

  40. Garai, B. et al. Reversible switching between positive and negative thermal expansion in a metal–organic framework DUT-49. J. Mater. Chem. A 8, 20420–20428 (2020).

    Article  CAS  Google Scholar 

  41. Li, D. & Kaneko, K. Hydrogen bond-regulated microporous nature of copper complex-assembled microcrystals. Chem. Phys. Lett. 335, 50–56 (2001).

    Article  CAS  Google Scholar 

  42. Eguchi, R., Uchida, S. & Mizuno, N. Inverse and high CO2/C2H2 sorption selectivity in flexible organic–inorganic ionic crystals. Angew. Chem. Int. Ed. 51, 1635–1639 (2012).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  44. Cockayne, E. Thermodynamics of the flexible metal–organic framework material MIL-53(Cr) from first-principles. J. Phys. Chem. C 121, 4312–4317 (2017).

    Article  CAS  Google Scholar 

  45. Pallach, R. et al. Frustrated flexibility in metal-organic frameworks. Nat. Commun. 12, 4097 (2021).

    Article  CAS  Google Scholar 

  46. Sen, S. et al. Cooperative bond scission in a soft porous crystal enables discriminatory gate opening for ethylene over ethane. J. Am. Chem. Soc. 139, 18313–18321 (2017).

    Article  CAS  Google Scholar 

  47. Demuynck, R. et al. Efficient construction of free energy profiles of breathing metal–organic frameworks using advanced molecular dynamics simulations. J. Chem. Theory Comput. 13, 5861–5873 (2017).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  49. Uribe-Romo, F. J. et al. A crystalline imine-linked 3-D porous covalent organic framework. J. Am. Chem. Soc. 131, 4570–4571 (2009).

    Article  CAS  Google Scholar 

  50. Ma, Y.-X. et al. A dynamic three-dimensional covalent organic framework. J. Am. Chem. Soc. 139, 4995–4998 (2017).

    Article  CAS  Google Scholar 

  51. Poloni, R., Lee, K., Berger, R. F., Smit, B. & Neaton, J. B. Understanding trends in CO2 adsorption in metal–organic frameworks with open-metal sites. J. Phys. Chem. Lett. 5, 861–865 (2014).

    Article  CAS  Google Scholar 

  52. Ding, Q. et al. Exploiting equilibrium-kinetic synergetic effect for separation of ethylene and ethane in a microporous metal-organic framework. Sci. Adv. 6, eaaz4322 (2020).

  53. Akkermans, R. L. C., Spenley, N. A. & Robertson, S. H. Monte Carlo methods in Materials Studio. Mol. Simul. 39, 1153–1164 (2013).

    Article  CAS  Google Scholar 

  54. Cichocka, M. O., Ångström, J., Wang, B., Zou, X. & Smeets, S. High-throughput continuous rotation electron diffraction data acquisition via software automation. J. Appl. Crystallogr. 51, 1652–1661 (2018).

    Article  CAS  Google Scholar 

  55. Kabsch, W. XDS. Acta Crystallogr. D Biol. Crystallogr. 66, 125–132 (2010).

    Article  CAS  Google Scholar 

  56. Sheldrick, G. M. A short history of SHELX. Acta Crystallogr. A 64, 112–122 (2008).

    Article  CAS  Google Scholar 

Download references


This work was supported by ExxonMobil through the Singapore Energy Center (EM11161.TO4, EM11161.TO17), the Ministry of Education—Singapore (MOE2019-T2-1-093, MOE-T2EP10122-0002), the Energy Market Authority of Singapore (EMA-EP009-SEGC-020), the Agency for Science, Technology and Research (U2102d2004, U2102d2012), the National Research Foundation Singapore (NRF-CRP26-2021RS-0002), Japan Society for the Promotion of Science KAKENHI (JP19H02734, JP20H02575, JP20K20564), the Swedish Research Council (VR, 2016-04625; 2017-04321) and the Swedish Research Council Formas (2020-00831). We thank the staff from the test centre of the Department of Chemical and Biomolecular Engineering, National University of Singapore, for the assistance with scanning electron microscopy and Fourier-transform infrared spectroscopy measurements.

Author information

Authors and Affiliations



D.Z. formulated and supervised the project. C.K. performed the synthesis of COF-320-A crystals and analyses of its growth kinetics and gas sorption measurements. Z.Z. and C.K. performed simulations on the COF–gas interactions. S.K., K.N. and R.M. performed in situ PXRD measurements. Z.H. and X.Z. performed the structure resolving of COF-320-A and COF-320-A2 single crystals. C.K. and D.Z. wrote the manuscript. A.K.U., D.C.C., L.S.B., Y.W., Z.Z., S.K., K.N., X.Z., Z.H., and R.K. contributed to the data analysis, discussion and manuscript revision.

Corresponding authors

Correspondence to Zhehao Huang, Ryotaro Matsuda or Dan Zhao.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Materials thanks François-Xavier Coudert and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

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

Supplementary information

Supplementary Information

Supplementary Figs. 1–18 and Tables 1–7.

Supplementary Data 1

Crystal structure of COF-320-A.

Supplementary Data 2

Crystal structure of COF-320-A2.

Supplementary Data 3

Simulated and refined atomistic coordinates of COF-320-A2 during C2H4 adsorption.

Supplementary Data 4

Simulated and refined atomistic coordinates of COF-320-A2E1 during C2H4 adsorption.

Supplementary Data 5

Simulated and refined atomistic coordinates of COF-320-AE1 during CO2 adsorption.

Supplementary Data 6

Simulated and refined atomistic coordinates of COF-320-AE2 during CO2 adsorption.

Supplementary Data 7

Simulated and refined atomistic coordinates of COF-320-AE3 during CO2 adsorption.

Supplementary Data 8

Simulated and refined atomistic coordinates of COF-320-A2E2 during C2H2 adsorption.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Kang, C., Zhang, Z., Kusaka, S. et al. Covalent organic framework atropisomers with multiple gas-triggered structural flexibilities. Nat. Mater. 22, 636–643 (2023).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing