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Linkage conversions in single-crystalline covalent organic frameworks

Nature Chemistry volume 16, pages 114–121 (2024)Cite this article

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Abstract

Single-crystal X-ray diffraction is a powerful characterization technique that enables the determination of atomic arrangements in crystalline materials. Growing or retaining large single crystals amenable to it has, however, remained challenging with covalent organic frameworks (COFs), especially suffering from post-synthetic modifications. Here we show the synthesis of a flexible COF with interpenetrated qtz topology by polymerization of tetra(phenyl)bimesityl-based tetraaldehyde and tetraamine building blocks. The material is shown to be flexible through its large, anisotropic positive thermal expansion along the c axis (αc = +491 × 10–6 K–1), as well as through a structural transformation on the removal of solvent molecules from its pores. The as-synthesized and desolvated materials undergo single-crystal-to-single-crystal transformation by reduction and oxidation of its imine linkages to amine and amide ones, respectively. These redox-induced linkage conversions endow the resulting COFs with improved stability towards strong acid; loading of phosphoric acid leads to anhydrous proton conductivity up to ca. 6.0 × 10−2 S cm−1.

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Fig. 1: Chemical conversion of single-crystalline imine COF to amine or amide COFs.
Fig. 2: Preparation and crystal structure of USTB-5 together with corresponding reversible structural transformation upon the removal/addition of solvent and chemically converted USTB-5r and USTB-5o.
Fig. 3: Comparison in PXRD patterns, spectroscopic data and N2 sorption behaviours of USTB-5 (grey), USTB-5r (red) and USTB-5o (cyan).
Fig. 4: Proton conductivity of H3PO4@USTB-5r and H3PO4@USTB-5o.

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Data availability

All data supporting the finding of this study are available within this article and its supplementary information. Crystallographic data for the structures in this article have been deposited at the Cambridge Crystallographic Data Centre under deposition nos. CCDC 2162845 (USTB-5), 2162846 (USTB-5r), 2162847 (USTB-5o), 2162848 (recovered USTB-5), 2162849 (USTB-5r obtained in bulky production) and 2234439 (H3PO4@USTB-5o). Copies of the data can be obtained free of charge from https://www.ccdc.cam.ac.uk/structures/. Source data are provided with this paper. In addition, the data that support the findings of this study and the raw data for all the figures have been uploaded to Figshare59 at https://doi.org/10.6084/m9.figshare.20446014.

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Acknowledgements

J.J. was supported by the Natural Science Foundation of China (nos. 22235001, 22175020 and 21631003), the Fundamental Research Funds for the Central Universities (no. FRF-BD-20-14A) and the University of Science and Technology Beijing. H. Wang was supported by the Natural Science Foundation of China (no. 22131005), Xiaomi Young Scholar Program, and University of the Science and Technology Beijing. R.-B.L. was supported by the Natural Science Foundation of China (nos. 22101307 and 22090061) and Hundred Talents Program of Sun Yat-Sen University. G.X. was supported by the Natural Science Foundation of China (nos. 22171263 and 91961115). S.L. was supported by the Natural Science Foundation of China (no. 22178012). We thank M. O’Keeffe at the Arizona State University for helpful discussion on structure expression. In addition, we also thank the staff from BL17B1 beamline of National Facility for Protein Science in Shanghai (NFPS) at Shanghai Synchrotron Radiation Facility for assistance during data collection.

Author information

Author notes

  1. These authors contributed equally: Baoqiu Yu, Rui-Biao Lin.

Authors and Affiliations

  1. Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, China

    Baoqiu Yu, Yucheng Jin, Hailong Wang, Xiaolin Liu, Kang Wang & Jianzhuang Jiang

  2. MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou, China

    Rui-Biao Lin & Jing-Hong Li

  3. State Key Laboratory of Structural Chemistry, Fujian Provincial Key Laboratory of Materials and Techniques toward Hydrogen Energy, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, China

    Gang Xu, Zhi-Hua Fu & Qian-Wen Li

  4. Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA

    Hui Wu & Wei Zhou

  5. Beijing Key Laboratory of Bio-Inspired Energy Materials and Devices, School of Space and Environment, Beihang University, Beijing, China

    Shanfu Lu & Zhenguo Zhang

  6. Rigaku Beijing Corporation, Beijing, China

    Zier Yan

  7. Fujian Provincial Key Laboratory of Polymer Materials, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, China

    Banglin Chen

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Contributions

B.Y., H. Wang, B.C. and J.J. conceived the subject and designed the experiments. B.Y. synthesized the materials and performed most of the characterization experiments with the help of X.L. and K.W. B.Y., Y.J. and H. Wang collected single-crystal X-ray diffraction data. B.Y., R.-B.L., J.-H.L., H. Wang and Z.Y. solved and analysed the crystal structures. G.X., Z.-H.F. and Q.-W.L. carried out impedance experiments. R.-B.L. and J.-H.L. collected PXRD measurements under in situ N2 loading. S.L. and Z.Z. carried out fuel cell experiments. H. Wu and W.Z. built the structure models for activated COFs. B.Y., R.-B.L., H. Wang, B.C. and J.J. interpreted the results and wrote the paper. All authors discussed the results and commented on the manuscript.

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Correspondence to Hailong Wang, Banglin Chen or Jianzhuang Jiang.

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Extended data

Extended Data Fig. 1 Optical microscopy and SEM photos of single crystals.

Optical microscopy photos of USTB-5 to show the crystallization kinetics together with the SEM photos of USTB-5a, USTB-5ra, and USTB-5oa. [Note]: It should be noted that, under the optimized reaction conditions, the single crystal size of USTB-5 amounts to ca. 50 μm after only 9 hours reaction, which quickly increases to ca. 200 μm after 24 hours. Five days later, single crystals of USTB-5 with the size up to ca. 450 μm and scalability over 0.4 g could be obtained.

Extended Data Fig. 2 Crystal structure of USTB-5.

(a) Asymmetric unit in the single-crystal structure of USTB-5 (2162845). Thermal ellipsoids are drawn with 50% probability. Carbon atom C1 and nitrogen atom N1 in an imine bond are co-occupancy disordered, and only a carbon hydrogen atom therefore appears around the co-occupancy position. (b) The complicated helical tube structure in USTB-5 is composed of two-strand helices and two single helices with atoms in individual helix shown in pink, green, and blue color, respectively. (c) Crystal structure of USTB-5 with three-fold interpenetration nets with all atoms in individual framework shown in pink, green, and blue color, respectively. (d) A qtz topology for USTB-5 with TFPB and TAPB simplified as the same 4-connected node. [Note]: The intercrossing voids between different interpenetrated nets shown in Extended Data Fig. 2b allow both the guest-induced dynamic transformation and post-synthetic chemical conversion depending on the reagent diffused to the imine sites.

Extended Data Fig. 3 Unit cell parameters of USTB-5.

Temperature-dependent unit cell parameters a, b, c, and V for USTB-5.

Source data

Extended Data Fig. 4 Crystal structure of USTB-5r.

(a) Asymmetric unit in the single-crystal structure of USTB-5r (2162846). Thermal ellipsoids are drawn with 50% probability. Carbon atom C1 and nitrogen atom N1 in amine bond are co-occupancy disordered, and two carbon hydrogen atoms and a nitrogen hydrogen atom therefore appear around the co-occupancy position. (b) Crystal structure of USTB-5r containing three-fold interpenetration nets with all atoms in individual framework shown in pink, green, and blue color, respectively. [Note]: The low diffraction resolution and structure disorder of USTB-5r prevent us from distinguishing the amine bond length in this compound and the imine bond length in USTB-5.

Extended Data Fig. 5 Crystal structure of USTB-5o.

(a, b) Asymmetric unit in the single-crystal structure of USTB-5o (2162847), which is divided into two parts for clarity. Thermal ellipsoids are drawn with 50% probability. For Extended Data Fig. 5a, carbon atoms C5 and C5A and nitrogen atoms N2 and N2A in amide bond are co-occupancy disordered, respectively, and hydrogen atom on amide nitrogen atom is obscured by oxygen atom in the present case. (c) Crystal structure of USTB-5o containing three-fold interpenetration nets with all atoms in individual framework shown in pink, green, and blue color, respectively.

Extended Data Fig. 6 Structural model of USTB-5a and corresponding N2 sorption isotherms.

(a) Structural model of USTB-5a containing three-fold interpenetration nets with all atoms in individual framework shown in pink, green, and blue color, respectively. Unit cell parameters are a = b = 32.6300 Å, c = 24.6860 Å, α = β = 90°, γ = 120°, and V = 22762.3 Å3 (Z = 18). (b) Hysteretic N2 sorption isotherms at 77 K with the first and second step corresponding to the flexible structure of USTB-5a and USTB-5, respectively. Inset: the structural difference between USTB-5a and USTB-5 along c axis, as mainly indicated by the different pitches for their double-strand helical secondary building blocks.

Extended Data Fig. 7 Structural model of USTB-5oa and corresponding N2 sorption isotherms.

(a) Structural model of USTB-5oa containing three-fold interpenetration nets with all atoms in individual framework shown in pink, green, and blue color, respectively. Unit cell parameters are a = b = 32.6000 Å, c = 25.3600 Å, α = β = 90°, γ = 120°, and V = 23340.8 (Z = 18). (b) Hysteretic N2 sorption isotherms at 77 K with the first and second step corresponding to the flexible structure of USTB-5oa and USTB-5o, respectively. Inset: the structural difference between USTB-5oa and USTB-5o along c axis, as indicated by the different pitches for their double-strand helical secondary building blocks.

Supplementary information

Supplementary Information

Supplementary Figs. 1–59, Tables 1–14, references and disclaimer.

Supplementary Data 1

Crystallographic data for USTB-5.

Supplementary Data 2

Crystallographic data for USTB-5r.

Supplementary Data 3

Crystallographic data for USTB-5o.

Supplementary Data 4

Crystallographic data for recovered USTB-5.

Supplementary Data 5

Crystallographic data for USTB-5r obtained in bulky production.

Supplementary Data 6

Crystallographic data for H3PO4@USTB-5o.

Supplementary Data 7

Data for Supplementary Figs. 19, 21–23, 24a, 42a,b, 44, 45 and 47–50.

Supplementary Data 8

Data for Supplementary Fig. 43.

Source data

Source Data Fig. 3

Source data for Fig. 3.

Source Data Fig. 4

Source data for Fig. 4.

Source Data Extended Data Fig. 3

Source data for Extended Data Fig. 3.

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Yu, B., Lin, RB., Xu, G. et al. Linkage conversions in single-crystalline covalent organic frameworks. Nat. Chem. 16, 114–121 (2024). https://doi.org/10.1038/s41557-023-01334-7

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