Amine-linked Covalent Organic Frameworks as a Powerful Platform for Post-Synthetic Modification: Structure Interconversion and Combined Linkage- and Pore-Wall-Modification

22 September 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart-Wallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks, or directly from corresponding linkers in a one-pot crystallisation-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive-sites on the pore wall, enable further post-synthetic functionalisation to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts.


Covalent Organic Framework
Imine-Linked Covalent Organic Framework
Post-Synthetic Modification
One-Pot Approach
Amine-linked Covalent Organic Framework
Leuckart–Wallach reaction
Solid state NMR experiments
pair-distribution functions
X-ray Powder Diffraction
2D Materials

Supplementary materials



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