Erik Troschke

Topochemical conversion of an imine- into a thiazole-linked covalent organic framework enabling real structure analysis

Stabilization of covalent organic frameworks (COFs) by post-synthetic locking strategies is a powerful tool to push the limits of COF utilization, which are imposed by the reversible COF linkage. Here we introduce a sulfur-assisted chemical conversion of a two-dimensional imine-linked COF into a thiazole-linked COF, with full retention of crystallinity and porosity. This post-synthetic modification entails significantly enhanced chemical and electron beam stability, enabling investigation of the real framework structure at a high level of detail. An in-depth study by electron diffraction and transmission electron microscopy reveals a myriad of previously unknown or unverified structural features such as grain boundaries and edge dislocations, which are likely generic to the in-plane structure of 2D COFs. The visualization of such real structural features is key to understand, design and control structure–property relationships in COFs, which can have major implications for adsorption, catalytic, and transport properties of such crystalline porous polymers.Stabilization of covalent organic frameworks (COFs) by post-synthetic locking is a powerful tool to push the limits of COF utilization. Here the authors demonstrate a sulfur-assisted conversion of an imine-linked COF into a thiazole-linked COF, with retention of crystallinity and porosity, allowing for direct imaging of defects in COFs.

Solvent-free synthesis of a porous thiophene polymer by mechanochemical oxidative polymerization

This study elucidates a mechanochemical approach to synthesize a microporous thiophene polymer via oxidative polymerization. Utilizing a design of experiments approach we optimized the reaction conditions leading to complete conversion and a polymer with a surface area of up to 1850 m2 g−1 – almost twice as high as the material prepared by solution-based polymerization. Thus, our approach presents a solvent free, quick and scalable alternative for the production of porous polymers.

Integration of an N-heterocyclic carbene precursor into a covalent triazine framework for organocatalysis.

The successful incorporation of a thermally fragile imidazolium moiety into a covalent triazine framework resulted in a heterogeneous organocatalyst active in carbene-catalyzed umpolung reaction. The structural integrity of the imidazolium moiety was confirmed by combining solid-state NMR and XPS experiments.