The use of two different classes of covalent organic frameworks (covalent triazine and imine linked frameworks) as supports for molecular Ni²⁺ catalysts is presented. For COFs, a large concentration of N heteroatoms, either in the form of quasi bipyridine or as diiminopyridine moieties, allows for the coordination of NiBr₂ to the scaffold of the porous polymers. When applied as catalysts in the oligomerization of ethylene under mild reaction conditions (15 bar, 50 °C), these new catalysts display an activity comparable to those of their homogeneous counterpart and a fivefold higher selectivity to C₆ ⁺ olefins. Accumulation of long chain hydrocarbons within the porosity of the COFs leads to reversible deactivation. Full activity and selectivity of the best catalysts can be recovered upon washing with dichlorobenzene.

Covalent triazine frameworks (CTFs) are porous organic materials promising for applications in catalysis and separation due to their high stability, adjustable porosity, and intrinsic nitrogen functionalities. CTFs are prepared by ionothermal trimerization of aromatic nitriles; however, multiple side reactions also occur under synthesis conditions, and their influence on the material properties is still poorly described. Here we report the systematic characterization of nitrogen in CTFs using X-ray photoelectron spectroscopy. With the use of model compounds, we could distinguish several types of nitrogen species. By combining these data with textural properties, we unravel the influence that the reaction temperature, the catalyst, and the monomer structure and composition have on the properties of the resulting CTF materials.

Chemical clocks are often used as exciting classroom experiments, where an induction time is followed by rapidly changing colours that expose oscillating concentration patterns. This type of reaction belongs to a class of nonlinear chemical kinetics also linked to chaos, wave propagation and Turing patterns. Despite its vastness in occurrence and applicability, the clock reaction is only well understood for liquid-state processes. Here we report a chemical clock reaction, in which a solidifying entity, metal-organic framework UiO-66, displays oscillations in crystal dimension and number, as shown by X-ray scattering. In rationalizing this result, we introduce a computational approach, the metal-organic molecular orbital methodology, to pinpoint interaction between the tectonic building blocks that construct the metal-organic framework material. In this way, we show that hydrochloric acid plays the role of autocatalyst, bridging separate processes of condensation and crystallization.

A facile one-step method to shape covalent triazine frameworks (CTFs) for catalytic applications is reported. Phase inversion of the CTF powder by using a polyimide as a binder in a microfluidic device results in the formation of composite spheres with accessible CTF porosity and a high mechanical and thermal stability. The fabricated spheres can be used to host organometallic complexes. The obtained shaped catalysts, Ir@CTF spheres, are active and fully recyclable in the direct hydrogenation of carbon dioxide into formic acid under mild reaction conditions (20 bar and 50–90 °C) and in the dehydrogenation of formic acid.