Pitfalls in the synthesis of polyimide-linked two-dimensional covalent organic frameworks

Abstract

The well-known reaction of amines with anhydrides to produce highly stable imide moieties has been extended to the synthesis of two dimensional polyimide-linked covalent organic frameworks (2D-COFs) by others. We...

Dual redox-active porous polyimides as high performance and versatile electrode material for next-generation batteries

“…The decarboxylation scenario aligns with recent reports of decarboxylation of aromatic carboxylic acid species under mild hydrothermal (150-230 1C) conditions, 23 and has also been put forward recently for polyimide framework syntheses under classical conditions. 24 Overall, from all chemical analyses, i.e., ATR-FT-IR and ssNMR spectroscopy, and EA, we can at this point only conclude that the product shows dominant imide as well as thiazine functions, which means the redox active functions are intact and no residue of intermediate monomer salts are present. Rather, we hypothesize, but cannot claim from the data with certainty, that some degree of inhomogeneous decarboxylation occurs during PI MTA-MPT's synthesis, which would lead to organic Bertholide-like compounds.…”

“…The decarboxylation scenario aligns with recent reports of decarboxylation of aromatic carboxylic acid species under mild hydrothermal (150–230 °C) conditions, 23 and has also been put forward recently for polyimide framework syntheses under classical conditions. 24 …”

Direct and Linker-Exchange Alcohol-Assisted Hydrothermal Synthesis of Imide-Linked Covalent Organic Frameworks

“…Two additional signals at −254 ppm and −318 ppm appear in the 15 N spectrum of the Py-imide COF. These signals can be assigned to unreacted or dangling amine functional groups and to the amic acid intermediate described previously for the imide-COF condensation reaction (Figure c,d) . Note that the ssNMR spectra are measured using N–H cross-polarization methods and are therefore not quantitative.…”

Crystallinity of Imide-Linked Two-Dimensional Polymers Depends on the Nucleophilicity of Triamine Building Blocks

“…20 For example, a PI-2DP synthesized from the reaction between 2,4,6-tris(4aminophenyl)benzene (TAPB, triamine monomer) and pyromellitic dianhydride (PMDA, dianhydride monomer) showed either crystalline or amorphous material, depending on the reaction conditions. 16,21,22 The synthesis of PI-2DPs generally proceeds by a stepwise reaction, including the formation of amic acid intermediates followed by dehydration into imide rings. 18 In the first step, amine groups in triamine monomers (denoted as triamines) attack carbonyl groups in the anhydride monomers (denoted as dianhydrides), opening the anhydride groups into amic acid (amide + carboxylic acid) linkages.…”

“…As a result, the synthesis of crystalline PI-2DPs largely depends on controlling the reaction conditions . For example, a PI-2DP synthesized from the reaction between 2,4,6-tris­(4-aminophenyl)­benzene (TAPB, triamine monomer) and pyromellitic dianhydride (PMDA, dianhydride monomer) showed either crystalline or amorphous material, depending on the reaction conditions. ,, …”