Abstract

Gels formed via metal–ligand coordination typically have very low branch functionality, f, as they consist of 2–3 polymer chains linked to single metal ions that serve as junctions. Thus, these materials are very soft and unable to withstand network defects such as dangling ends and loops. We report here a new class of gels assembled from polymeric ligands and metal–organic cages (MOCs) as junctions. The resulting ‘polyMOC’ gels are precisely tunable and may feature increased branch functionality. We show two examples of such polyMOCs: a gel with a low f based on a M2L4 paddlewheel cluster junction and a compositionally isomeric one of higher f based on a M12L24 cage. The latter features large shear moduli, but also a very large number of elastically inactive loop defects that we subsequently exchanged for functional ligands, with no impact on the gel's shear modulus. Such a ligand substitution is not possible in gels of low f, including the M2L4-based polyMOC.

  • Compound C17H14N2O

    (3,5-di(pyridin-4-yl)phenyl)methanol

  • Compound C17H14N2O

    (3,5-di(pyridin-3-yl)phenyl)methanol

  • Compound C37H28N2O2

    (3,5-di(pyridin-4-yl)benzyl) 4-(pyren-1-yl)butanoate

  • Compound C132H218N4O52

    α,ω-omega-bis(carboxymethyl)poly(ethylene oxide) bis(3,5-di(pyridin-4-yl)benzyl ester)

  • Compound C132H218N4O52

    α,ω-bis(carboxymethyl)poly(ethylene oxide) bis(3,5-di(pyridin-3-yl)benzyl ester)

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References

  1. 1.

    , , , & Advanced Inorganic Chemistry Vol. 5 (Wiley, 1999).

  2. 2.

    & Reversible cross-linking by complex-formation. Polymers containing 2-hydroxybenzoic acid residues. Eur. Polym. J. 12, 525–528 (1976).

  3. 3.

    , & A stable metal coordination polymer gel based on a calix[4]arene and its ‘uptake’ of non-ionic organic molecules from the aqueous phase. Chem. Commun. 362–363 (2002).

  4. 4.

    & Multistimuli, multiresponsive metallo-supramolecular polymers. J. Am. Chem. Soc. 125, 13922–13923 (2003).

  5. 5.

    , , , & Cross-linked and functionalized ‘universal polymer backbones’ via simple, rapid, and orthogonal multi-site self-assembly. Tetrahedron 60, 7205–7215 (2004).

  6. 6.

    , & Rational control of viscoelastic properties in multicomponent associative polymer networks. Macromolecules 38, 10171–10177 (2005).

  7. 7.

    , & Strong means slow: dynamic contributions to the bulk mechanical properties of supramolecular networks. Angew. Chem. Int. Ed. 44, 2746–2748 (2005).

  8. 8.

    , & Small-molecule dynamics and mechanisms underlying the macroscopic mechanical properties of coordinatively cross-linked polymer networks. J. Am. Chem. Soc. 127, 14488–14496 (2005).

  9. 9.

    , , & Understanding the mechanism of gelation and stimuli-responsive nature of a class of metallo-supramolecular gels. J. Am. Chem. Soc. 128, 11663–11672 (2006).

  10. 10.

    , , , & Evolution of spherical assemblies to fibrous networked Pd(II) metallogels from a pyridine-based tripodal ligand and their catalytic property. Chem. Mater. 21, 557–563 (2009).

  11. 11.

    et al. pH-induced metal–ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli. Proc. Natl Acad. Sci. USA 108, 2651–2655 (2011).

  12. 12.

    et al. Optically healable supramolecular polymers. Nature 472, 334–338 (2011).

  13. 13.

    et al. Active cross-linkers that lead to active gels. Angew. Chem. Int. Ed. 52, 11494–11498 (2013).

  14. 14.

    & Metal–organic gels: from discrete metallogelators to coordination polymers. Coord. Chem. Rev. 257, 1373–1408 (2013).

  15. 15.

    , & Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands. Soft Matter 9, 10314–10323 (2013).

  16. 16.

    et al. Self-healing metallopolymers based on cadmium bis(terpyridine) complex containing polymer networks. Polym. Chem. 4, 4966–4973 (2013).

  17. 17.

    & Metallo/clusto hybridized supramolecular polymers. Soft Matter 10, 9038–9053 (2014).

  18. 18.

    , & Self-assembly of discrete cyclic nanostructures mediated by transition metals. Chem. Rev. 100, 853–908 (2000).

  19. 19.

    & Strategies for the construction of supramolecular compounds through coordination chemistry. Angew. Chem. Int. Ed. 40, 2022–2043 (2001).

  20. 20.

    , , & Multicomponent metal–ligand self-assembly. Curr. Opin. Chem. Biol. 6, 757–764 (2002).

  21. 21.

    From supramolecular chemistry towards constitutional dynamic chemistry and adaptive chemistry. Chem. Soc. Rev. 36, 151–160 (2007).

  22. 22.

    , , & Metal–organic container molecules through subcomponent self-assembly. Chem. Commun. 49, 2476–2490 (2013).

  23. 23.

    & Topologically complex molecules obtained by transition metal templation: it is the presentation that determines the synthesis strategy. New J. Chem. 37, 49–57 (2013).

  24. 24.

    , & Giant hollow MnL2n spherical complexes: structure, functionalisation and applications. Chem. Commun. 49, 6703–6712 (2013).

  25. 25.

    , , & Stimuli-responsive metal–ligand assemblies. Chem. Rev. 115, 7729–7793 (2015).

  26. 26.

    , & Introduction to metal–organic frameworks. Chem. Rev. 112, 673–674 (2012).

  27. 27.

    , , & The chemistry and applications of metal–organic frameworks. Science 341, 1230444 (2013).

  28. 28.

    , , , & Structuring of metal–organic frameworks at the mesoscopic/macroscopic scale. Chem. Soc. Rev. 43, 5700–5734 (2014).

  29. 29.

    et al. Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication. Nature Mater. 11, 717–723 (2012).

  30. 30.

    et al. A synthetic route to ultralight hierarchically micro/mesoporous Al(III)-carboxylate metal–organic aerogels. Nature Commun. 4, 1774 (2013).

  31. 31.

    , , & polyMOFs a class of interconvertible polymer–metal–organic-framework hybrid materials. Angew. Chem. Int. Ed. 54, 6152–6157 (2015).

  32. 32.

    & Polymer Physics (Oxford Univ. Press, 2003).

  33. 33.

    , & Soft porous crystals. Nature Chem. 1, 695–704 (2009).

  34. 34.

    , , & Supramolecular polymers. Chem. Rev. 101, 4071–4097 (2001).

  35. 35.

    , , & Supramolecular polymers: historical development, preparation, characterization, and functions. Chem. Rev. 115, 7196–7239 (2015).

  36. 36.

    , , & Generation of metallosupramolecular polymer gels from multiply functionalized grid-type complexes. New J. Chem. 36, 668–673 (2012).

  37. 37.

    et al. Ionic self-assembly of surface functionalized metal–organic polyhedra nanocages and their ordered honeycomb architecture at the air/water interface. Chem. Commun. 48, 7946–7948 (2012).

  38. 38.

    et al. Supramolecular polymers with tunable topologies via hierarchical coordination-driven self-assembly and hydrogen bonding interfaces. Proc. Natl Acad. Sci. USA 110, 15585–15590 (2013).

  39. 39.

    et al. Hierarchical self-assembly: well-defined supramolecular nanostructures and metallohydrogels via amphiphilic discrete organoplatinum(II) metallacycles. J. Am. Chem. Soc. 135, 14036–14039 (2013).

  40. 40.

    et al. Cross-linked supramolecular polymer gels constructed from discrete multi-pillar[5]arene metallacycles and their multiple stimuli-responsive behavior. J. Am. Chem. Soc. 136, 8577–8589 (2014).

  41. 41.

    et al. Responsive supramolecular polymer metallogel constructed by orthogonal coordination-driven self-assembly and host/guest interactions. J. Am. Chem. Soc. 136, 4460–4463 (2014).

  42. 42.

    et al. Creating coordination-based cavities in a multiresponsive supramolecular gel. Chem. Eur. J. 21, 7418–7427 (2015).

  43. 43.

    , , , & A dual role for 1,2,4,5-tetrazines in polymer networks combining Diels–Alder reactions and metal coordination to generate functional supramolecular gels. ACS Macro Lett. 4, 458–461 (2015).

  44. 44.

    et al. Differentially addressable cavities within metal–organic cage-cross-linked polymeric hydrogels. J. Am. Chem. Soc. 137, 9722–9729 (2015).

  45. 45.

    & Exploiting cavities in supramolecular gels. Angew. Chem. Int. Ed. 49, 6718–6724 (2010).

  46. 46.

    et al. Finite, spherical coordination networks that self-organize from 36 small components. Angew. Chem. Int. Ed. 43, 5621–5625 (2004).

  47. 47.

    et al. Self-assembled M24L48 polyhedra and their sharp structural switch upon subtle ligand variation. Science 328, 1144–1147 (2010).

  48. 48.

    , & Self-assembly of a novel macrotricyclic Pd(II) metallocage encapsulating a nitrate ion. Chem. Commun. 1652–1653 (2001).

  49. 49.

    et al. Two-component control of guest binding in a self-assembled cage molecule. Chem. Commun. 46, 4932–4934 (2010).

  50. 50.

    , , & Simulation of metal–ligand self-assembly into spherical complex M6L8. J. Am. Chem. Soc. 134, 14401–14407 (2012).

  51. 51.

    , , , & Coordination-directed self-assembly of M12L24 nanocage: effects of kinetic trapping on the assembly process. ACS Nano 8, 1290–1296 (2014).

  52. 52.

    Spatial inhomogeneity and dynamic fluctuations of polymer gels. Macromol. Chem. Phys. 199, 1–30 (1998).

  53. 53.

    , , , & Direct measurements of polymer brush conformation using small-angle neutron scattering (SANS) from highly grafted iron oxide nanoparticles in homopolymer melts. Macromolecules 46, 9341–9348 (2013).

  54. 54.

    & Elastic and thermoelastic properties of rubber like materials. Ind. Eng. Chem. 33, 624–629 (1941).

  55. 55.

    et al. Counting primary loops in polymer gels. Proc. Natl Acad. Sci. USA 109, 19119–19124 (2012).

  56. 56.

    et al. Crossover experiments applied to network formation reactions: improved strategies for counting elastically inactive molecular defects in PEG gels and hyperbranched polymers. J. Am. Chem. Soc. 136, 9464–9470 (2014).

  57. 57.

    et al. Beyond post-synthesis modification: evolution of metal–organic frameworks via building block replacement. Chem. Soc. Rev. 43, 5896–5912 (2014).

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Acknowledgements

J.A.J. thanks the National Science Foundation (NSF) (CHE-1334703 and CHE-1351646), the MIT Energy Initiative and the Deshpande Center for Technological Innovation for their support of this work. R.G.G. MAS NMR spectroscopy is supported through the National Institutes of Health, EB-002026. A.V.Z. thanks the Department of Defense National Defense Science and Engineering Graduate program and Intel for graduate fellowships in support of this work. V.K.M. is grateful to the Natural Sciences and Engineering Research Council of Canada and the Government of Canada for a Banting Postdoctoral Fellowship. This work made use of the DCIF Shared Experimental Facilities at the MIT (National Institutes of Health, 1S10RR013886–01; NSF, CHE-0234877), the MIT X-Ray Facility (NSF, CHE-0946721) and Shared Experimental Facilities supported in part by the Materials Research Science and Engineering Center program of the NSF (DMR-1419807). We acknowledge the support of the National Institute of Standards and Technology (NIST), US Department of Commerce, in providing the neutron research facilities used in this work. This work utilized facilities supported in part by the NSF under Agreement No. DMR-0944772. This manuscript was prepared under cooperative agreement 70NANB12H239 from NIST, US Department of Commerce. The statements, findings, conclusions and recommendations are those of the authors and do not necessarily reflect the views of NIST or the US Department of Commerce. We thank P. Müller for X-ray crystallography and M. MacLeod for assistance in processing the crystal structure data, S. Trauger for ESI-TOF-MS., E. Dreaden for cryo-TEM, T. M. Swager and G. Gutierrez for the use of a fluorimeter and N. Holten-Andersen, S. Grindy, K. Kawamoto and M. Glassman for helpful discussions.

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Affiliations

  1. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA

    • Aleksandr V. Zhukhovitskiy
    • , Mingjiang Zhong
    • , Eric G. Keeler
    • , Vladimir K. Michaelis
    • , Robert G. Griffin
    • , Adam P. Willard
    •  & Jeremiah A. Johnson
  2. Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA

    • Eric G. Keeler
    • , Vladimir K. Michaelis
    •  & Robert G. Griffin
  3. Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, Delaware 19716, USA

    • Jessie E. P. Sun
    •  & Darrin J. Pochan
  4. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA

    • Michael J. A. Hore

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Contributions

A.V.Z. and J.A.J. conceived the idea. A.V.Z. conducted the synthesis and characterization experiments. A.V.Z. and M.Z. conducted the mechanical testing experiments. A.V.Z., E.G.K. and V.K.M. conducted the MAS NMR experiments. J.E.P.S. and D.J.P. conducted the SANS experiments and analysed SANS data. M.J.A.H. provided the SANS model. A.P.W. developed the simulations. All authors analysed data. A.V.Z. and J.A.J. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Jeremiah A. Johnson.

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    Crystallographic data for compound (L2)4Pd(II)2

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DOI

https://doi.org/10.1038/nchem.2390

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