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<p>Proton conduction pathways and mechanisms in covalent organic frameworks (COFs) have long been obscured by polycrystalline disorder. Here we report a solvent-free melt-phase post-synthetic modification (PSM) strategy that enables precise functionalization of three-dimensional single-crystalline COFs while preserving crystallinity. This methodology overcomes the limitations of solvent-mediated PSM by operating above the melting point of azole reagents, ensuring homogeneous pore accessibility without solvent occlusion. Applied to archetypal imine-linked COF-300, the method achieves crystallographically resolved conversion of fragile imine bonds (C = N, 1.245 Å) into robust amine linkages (C–N, 1.415 Å), concurrently covalently anchoring of proton-conductive azoles (C–N, 1.487 Å) on the COFs skeleton. The resulting azole-functionalized COFs (COF-300-1,2,3-triazole, COF-300-1,2,4-triazole, COF-300-pyrazole) exhibit intrinsic anhydrous superprotonic conductivity reaching 4.35 × 10<sup>−3</sup> S cm<sup>−1</sup> at 170 °C, with low activation energies (0.153–0.186 eV). Atomic-resolution crystallography and DFT calculations reveal that rigid hydrogen-bond networks eliminate thermal barriers for proton hopping, establishing a definitive structure-property correlation for proton transport in single-crystal COFs. This work pioneers a versatile platform for functionalizing 3D crystalline porous materials under solvent-free conditions.</p>

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Enhanced proton conductivity in azole-functionalized three-dimensional crystalline covalent organic frameworks

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月19日

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  • Aiping Yao,
  • Changyan Zhu,
  • Jun Liu,
  • Hongliang Xu,
  • Kuizhan Shao,
  • Chunyi Sun,
  • Chao Qin,
  • Xinlong Wang,
  • Hongying Zang,
  • Zhongmin Su,
  • Donglin Jiang

摘要

Proton conduction pathways and mechanisms in covalent organic frameworks (COFs) have long been obscured by polycrystalline disorder. Here we report a solvent-free melt-phase post-synthetic modification (PSM) strategy that enables precise functionalization of three-dimensional single-crystalline COFs while preserving crystallinity. This methodology overcomes the limitations of solvent-mediated PSM by operating above the melting point of azole reagents, ensuring homogeneous pore accessibility without solvent occlusion. Applied to archetypal imine-linked COF-300, the method achieves crystallographically resolved conversion of fragile imine bonds (C = N, 1.245 Å) into robust amine linkages (C–N, 1.415 Å), concurrently covalently anchoring of proton-conductive azoles (C–N, 1.487 Å) on the COFs skeleton. The resulting azole-functionalized COFs (COF-300-1,2,3-triazole, COF-300-1,2,4-triazole, COF-300-pyrazole) exhibit intrinsic anhydrous superprotonic conductivity reaching 4.35 × 10−3 S cm−1 at 170 °C, with low activation energies (0.153–0.186 eV). Atomic-resolution crystallography and DFT calculations reveal that rigid hydrogen-bond networks eliminate thermal barriers for proton hopping, establishing a definitive structure-property correlation for proton transport in single-crystal COFs. This work pioneers a versatile platform for functionalizing 3D crystalline porous materials under solvent-free conditions.