Covalent organic frameworks (COFs) were prepared through imine condensation reaction of hydrazine hydrate with hydroxy-1,3,5-triformylbenzenes, containing a varying number of hydroxyl groups, affording the microporous materials called . The role of intramolecular hydrogen bonding formation (conformational locking effects) in the crystallinity of the resulting COFs was evaluated. The results indicate that the increase of the number of conformational locks increases the symmetry of moieties during nucleation and crystal growth, resulting in less defects in the product structure. The use of aniline as modulator, with in situ formation of an intermediate imine, was also evaluated and proved to be beneficial in the case where the number of conformational locks is insufficient to afford high crystallinity. The use of the modulator for RIO-11 resulted in greater crystallinity and a 5.3-fold increase of its pristine BET surface area. Narrower monomodal pore size distributions, with cylindrical pores, were shown to be responsible for the greater surface area in these cases.

Sustainability in chemistry heavily relies on heterogeneous catalysis. Enzymes, the main catalyst for biochemical reactions in nature, are an elegant choice to catalyze reactions due to their high activity and selectivity, although they usually suffer from lack of robustness. To overcome this drawback, enzyme‐decorated nanoporous heterogeneous catalysts were developed. Three different approaches for Candida antarctica lipase B (CAL‐B) immobilization on a covalent organic framework (PPF‐2) were employed: physical adsorption on the surface, covalent attachment of the enzyme in functional groups on the surface and covalent attachment into a linker added post‐synthesis. The influence of the immobilization strategy on the enzyme uptake, specific activity, thermal stability, and the possibility of its use through multiple cycles was explored. High specific activities were observed for PPF‐2‐supported CAL‐B in the esterification of oleic acid with ethanol, ranging from 58 to 283 U mg−1, which was 2.6 to 12.7 times greater than the observed for the commercial Novozyme 435.

Among various porous solids for gas separation and purification, metal-organic frameworks (MOFs) are promising materials that potentially combine high CO 2 uptake and CO 2 /N 2 selectivity. So far, within the hundreds of thousands of MOF structures known today, it remains a challenge to computationally identify the best suited species. First principle-based simulations of CO 2 adsorption in MOFs would provide the necessary accuracy; however, they are impractical due to the high computational cost. Classical force field-based simulations would be computationally feasible; however, they do not provide sufficient accuracy. Thus, the entropy contribution that requires both accurate force fields and sufficiently long computing time for sampling is difficult to obtain in simulations. Here, we report quantum-informed machine-learning force fields (QMLFFs) for atomistic simulations of CO 2 in MOFs. We demonstrate that the method has a much higher computational efficiency (∼1000×) than the first-principle one while maintaining the quantum-level accuracy. As a proof of concept, we show that the QMLFF-based molecular dynamics simulations of CO 2 in Mg-MOF-74 can predict the binding free energy landscape and the diffusion coefficient close to experimental values. The combination of machine learning and atomistic simulation helps achieve more accurate and efficient in silico evaluations of the chemisorption and diffusion of gas molecules in MOFs.

The development of efficient catalytic systems is a fundamental aspect for the straightforward production of chemicals. During the last years, covalent organic frameworks (COFs) emerged as an exciting class of organic nanoporous materials. Due to their pre‐designable structure, they can be prepared with distinct physicochemical characteristics, specific pore sizes, and tunable functional groups. Moreover, associated with their stability in different media, these materials are considered promising supports for enzyme immobilization. Herein, it is highlighted the recent literature of enzyme immobilization in COFs, the main immobilization strategies, and the catalytic applications of these composites.