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.

Liquids with permanent porosity


Porous solids such as zeolites1 and metal–organic frameworks2,3 are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption–desorption cycles4, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids5. Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules6,7 that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities8,9,10, resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble ‘scrambled’ porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities.

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

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Preparation of the porous liquid.
Figure 2: Molecular simulations for the porous liquid show unoccupied molecular-sized pores.
Figure 3: Dissolution of methane in the porous liquid.
Figure 4: Porous liquids based on scrambled cages.


  1. Wright, P. A. Microporous Framework Solids (Royal Society of Chemistry, 2007)

  2. Cheetham, A. K., Férey, G. & Loiseau, T. Open-framework inorganic materials. Angew. Chem. Int. Edn 38, 3268–3292 (1999)

    Article  CAS  Google Scholar 

  3. Kitagawa, S., Kitaura, R. & Noro, S. Functional porous coordination polymers. Angew. Chem. Int. Edn 43, 2334–2375 (2004)

    Article  CAS  Google Scholar 

  4. D'Alessandro, D. M., Smit, B. & Long, J. R. Carbon dioxide capture: prospects for new materials. Angew. Chem. Int. Edn 49, 6058–6082 (2010)

    Article  CAS  Google Scholar 

  5. O’Reilly, N., Giri, N. & James, S. L. Porous liquids. Chem. Eur. J. 13, 3020–3025 (2007)

    Article  Google Scholar 

  6. Tozawa, T. et al. Porous organic cages. Nature Mater. 8, 973–978 (2009)

    Article  ADS  CAS  Google Scholar 

  7. Jones, J. T. A. et al. Modular and predictable assembly of porous organic molecular crystals. Nature 474, 367–371 (2011)

    Article  CAS  Google Scholar 

  8. Robbins, T. A., Knobler, C. B., Bellew, D. R. & Cram, D. J. A highly adaptive and strongly binding hemicarcerand. J. Am. Chem. Soc. 116, 111–122 (1994)

    Article  CAS  Google Scholar 

  9. Chaffee, K. E., Fogarty, H. A., Brotin, T., Goodson, B. M. & Dutasta, J.-P. Encapsulation of small gas molecules by cryptophane-111 in organic solution. 1. Size- and shape-selective complexation of simple hydrocarbons. J. Phys. Chem. A 113, 13675–13684 (2009)

    Article  CAS  Google Scholar 

  10. Little, M. A. et al. Synthesis and methane-binding properties of disulfide-linked cryptophane-0.0.0. Angew. Chem. Int. Edn 51, 764–766 (2012)

    Article  CAS  Google Scholar 

  11. Pohorille, A. & Pratt, L. R. Cavities in molecular liquids and the theory of hydrophobic solubilities. J. Am. Chem. Soc. 112, 5066–5074 (1990)

    Article  CAS  Google Scholar 

  12. Pierotti, R. A. The solubility of gases in liquids. J. Phys. Chem. 67, 1840–1845 (1963)

    Article  CAS  Google Scholar 

  13. Pierotti, R. A. A scaled particle theory of aqueous and non-aqueous solutions. Chem. Rev. 76, 717–726 (1976)

    Article  CAS  Google Scholar 

  14. Giri, N. et al. Alkylated organic cages: from porous crystals to neat liquids. Chem. Sci. 3, 2153–2157 (2012)

    Article  CAS  Google Scholar 

  15. Melaugh, G., Giri, N., Davidson, C. E., James, S. L. & Del Pópolo, M. G. Designing and understanding permanent microporosity in liquids. Phys. Chem. Chem. Phys. 16, 9422–9431 (2014)

    Article  CAS  Google Scholar 

  16. Mogensen, O. E. (ed.) Positron Annihilation in Chemistry (Springer Series in Chemical Physics 58, Springer, 1995)

  17. Mahmood, T., Cheng, K. L. & Yean, Y. C. Microanalysis of open spaces in crown ethers by using a novel probe: positron annihilation spectroscopy. In Third International Workshop on Positron and Positronium Chemistry (ed. Jean, Y. C. ) 640 (World Scientific, 1990)

  18. Lannung, A. & Gjaldbæk, J. C. The solubility of methane in hydrocarbons, alcohols, water and other solvents. Acta Chem. Scand. 14, 1124–1128 (1960)

    Article  CAS  Google Scholar 

  19. Darwish, N. A., Gasem, K. A. M. & Robinson, R. L. Jr. Solubility of methane in benzene, naphthalene, phenanthrene and pyrene at temperatures from 323 to 433 K and pressures to 11.3 MPa. J. Chem. Eng. Data 39, 781–784 (1994)

    Article  CAS  Google Scholar 

  20. Houndonougbo, Y. et al. A combined experimental–computational investigation of methane adsorption and selectivity in a series of isoreticular zeolitic imidazolate frameworks. J. Phys. Chem. C 117, 10326–10335 (2013)

    Article  CAS  Google Scholar 

  21. Zhang, J. et al. Porous liquids: a promising class of media for gas separation. Angew. Chem. Int. Edn 54, 932–936 (2015)

    Article  CAS  Google Scholar 

  22. Jiang, S. et al. Porous organic molecular solids by dynamic covalent scrambling. Nature Commun. 2, 207 (2011)

    Article  ADS  Google Scholar 

  23. Hasell, T. et al. Controlling the crystallization of porous organic cages: molecular analogs of isoreticular frameworks using shape-specific directing solvents. J. Am. Chem. Soc. 136, 1438–1448 (2014)

    Article  CAS  Google Scholar 

  24. Chen, L. et al. Separation of rare gases and chiral molecules by selective binding in porous organic cages. Nature Mater. 13, 954–960 (2014)

    Article  ADS  CAS  Google Scholar 

  25. Jorgensen, W. L., Maxwell, D. S. & Tirado-Rives, J. Development and testing of the OPLS all-atom force field on conformational energetics and properties of organic liquids. J. Am. Chem. Soc. 118, 11225 (1996)

    Article  CAS  Google Scholar 

  26. Roux, B. The calculation of the potential of mean force using computer simulations. Comput. Phys. Commun. 91, 275 (1995)

    Article  ADS  CAS  Google Scholar 

  27. Kumar, S., Rosenberg, J. M., Bouzida, D., Swendsen,R. H. & Kollman, P. A. Multidimensional free-energy calculations using the weighted histogram analysis method. J. Comput. Chem. 13, 1011 (1992)

    Article  CAS  Google Scholar 

  28. Hess, B., Kutzner, C., van der Spoel, D. & Lindahl, E. GROMACS 4: algorithms for highly efficient, load-balanced, and scalable molecular simulation. J. Chem. Theory Comput. 4, 435 (2008)

    Article  CAS  Google Scholar 

  29. Nosé, S. A molecular-dynamics methods for simulations in the canonical ensemble. Mol. Phys. 52, 255 (1984)

    Article  ADS  Google Scholar 

  30. Hoover, W. G. Canonical dynamics: equilibrium phase-space distributions. Phys. Rev. A 31, 1695 (1985)

    Article  ADS  CAS  Google Scholar 

  31. Parrinello, M. & Rahman, A. Polymorphic transitions in single crystals: a new molecular dynamics method. J. Appl. Phys. 52, 7182 (1981)

    Article  ADS  CAS  Google Scholar 

  32. Essmann, U. et al. A smooth particle mesh Ewald method. J. Chem. Phys. 103, 8577 (1995)

    Article  ADS  CAS  Google Scholar 

  33. Harms, S. et al. Free volume of interphases in model nanocomposites studied by positron annihilation lifetime spectroscopy. Macromolecules 43, 10505 (2010)

    Article  ADS  CAS  Google Scholar 

  34. Jacquemin, J., Costa Gomes, M. F., Husson, P. & Majer, V. Solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon, and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate between temperatures 283 K and 343 K and at pressures close to atmospheric. J. Chem. Thermodyn. 38, 490 (2006)

    Article  CAS  Google Scholar 

Download references


This work was funded by the Leverhulme Trust (F/00 203/T) and by EPSRC (EP/C511794/1). M.G.D.P. acknowledges financial support from ANPCyT (PICT-2011-2128) and from the EC-H2020, MSCRISE-2014 programme, through project 643998 ENACT. L.P. and M.C.G. acknowledge support from the Contrat d’Objectifs Partagés (CNRS, Blaise Pascal University, and the Auvergne Regional Government, France). A.I.C. acknowledges the European Research Council under the European Union’s Seventh Framework Programme/ERC Grant Agreement no. 321156 for financial support. We thank M. E. Briggs for assistance with the cage syntheses.

Author information

Authors and Affiliations



N.G. and R.L.G. synthesized the porous crown cage. M.D.P. and G.M. carried out the molecular simulations. K.R. and T.K. performed the PALS measurements. M.C.G. and L.P. measured the methane gas solubilities for the crown cage porous liquid. R.L.G. and A.I.C. conceived the synthesis of the scrambled porous imine cages. R.L.G synthesized and characterized the scrambled cage porous liquid and measured its gas solubilities. S.L.J. led the project overall and conceived the design of the porous liquid based on the crown-ether cage together with N.G. S.L.J. and A.I.C. led the writing of the manuscript with contributions from all co-authors.

Corresponding author

Correspondence to Stuart L. James.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Related audio

Supplementary information

Supplementary Information

This file contains Synthetic and analytical methods, with full synthesis details and characterisation. Molecular Simulations, positron annihilation lifetime spectroscopy (PALS), gas solubility and guest selectivities. (PDF 4891 kb)

Guest selectivity in ‘scrambled’ porous liquids

Two batches of porous liquid prepared in vials (200 mg scrambled cage dissolved in 1 mL hexachloropropene) and both were saturated with xenon (5 mins bubbling at 50-60 mL/min), followed by the addition of a stirrer bar. To one sample was added chloroform (16 μL, 1.0 mol. eq. based on cage) and to the other was added 1-t-butyl-3,5-dimethylbenzene (36 μL, 1.0 mol. eq.), in both cases being careful not to mix the solvents. Stirring was started to mix the solvent layers – as can be observed in the video, chloroform displaces the xenon gas whereas the large, bulky solvent does not. (MP4 29264 kb)

PowerPoint slides

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Giri, N., Del Pópolo, M., Melaugh, G. et al. Liquids with permanent porosity. Nature 527, 216–220 (2015).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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.


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