New linkage chemistry will endow covalent organic frameworks (COFs) with not only structural diversity but also fascinating properties. However, to develop a new type of linkages has been a great challenge. We herein report the first two COFs using aminal as the linkages. These two COFs have been synthesized by condensation of secondary amine and aldehyde. They crystallize in cpi net, which is a new topology for COFs. The aminal linkage is found to favor reservation of photophysical property of the monomers due to its tetrahedral geometry and nonconjugated feature. These aminal-COFs exhibit good thermal stability and high chemical stability under neutral and basic conditions.

Amide-linked covalent organic frameworks (amide COFs) possess enormous potentials in practical applications benefiting from their high stability and polyamide structures. However, they suffer from very limited accessibility. Herein, we report a new linkage conversion method to rapidly synthesize crystalline amide COFs through oxidation of imine linkages in their corresponding imine-linked frameworks with KHSO 5 as an oxidant under very mild conditions. This synthetic strategy is general, facile, efficient, and scalable, as demonstrated by the procedure of simply stirring mixtures of imine-linked COFs (seven examples) and KHSO 5 in anhydrous dimethylformamide for several hours to complete the conversions and gram-scale synthesis. The high efficiency of this approach enables facile production of amide COFs from widely available imine-linked COFs, which lays the foundation for exploring practical applications of this unique type of polyamide material.

A gaseous hydrogen chloride chemosensor has been developed based on a 2D covalent organic framework (COF), which exhibits a very fast response and high sensitivity to gaseous HCl through distinct changes in fluorescence emission and color.

Covalent organic framework nanosheets (COF NSs or CONs), as compared to their bulk counterparts two-dimensional (2D) covalent organic frameworks (COFs), exhibit superior performance in many aspects due to their fully...

Covalent organic frameworks (COFs) have emerged as a new class of cathode materials for energy storage in recent years. However, they are limited to two‐dimensional (2D) or three‐dimensional (3D) framework structures. Herein, this work reports designed synthesis of a redox‐active one‐dimensional (1D) COF and its composites with 1D carbon nanotubes (CNTs) via in situ growth. Used as cathode materials for Li‐ion batteries, the 1D COF@CNT composites with unique dendritic core–shell structure can provide abundant and easily accessible redox‐active sites, which contribute to improve diffusion rate of lithium ions and the corresponding specific capacity. This synergistic structural design enables excellent electrochemical performance of the cathodes, giving rise to 95% utilization of redox‐active sites, high rate capability (81% capacity retention at 10 C), and long cycling stability (86% retention after 600 cycles at 5 C). As the first example to explore the application of 1D COFs in the field of energy storage, this study demonstrates the great potential of this novel type of linear crystalline porous polymers in battery technologies.

Oily water caused in the process of industry leads to not only the waste of resources, but also environmental pollution. Membrane separation, as a facile and efficient separation technology, has attracted widespread attention in the field of oil/water separation. The development of membrane materials with high separation performance is one of the key elements to improve separation efficiency. In this work, a superhydrophobic membrane composited with a trifluoromethyl‐containing covalent organic framework (COF) is prepared, which exhibits excellent performance on separations of oil/water mixtures and water‐in‐oil emulsions. For different composition of oil/water mixtures, the highest flux of oil is up to 32 000 L m−2 h−1 and oil/water separation efficiency is above 99%. Moreover, the high oil/water separation efficiency remains unchanged after successive cycles. This work provides a feasible scheme for the design of high‐efficiency oil/water separation membranes.

Boron‐based covalent organic frameworks (COFs) are susceptible to nucleophilic attack by water at the electron‐deficient boron sites and even slightly humid air could destroy the integrity of their porous frameworks within hours. Such instability is a major limitation to the practical applications of boron‐based COFs. Herein we report a significant enhancement of hydrostability of boroxine‐linked COFs (COF‐1 as representative) by modification with an oligoamine (tetraethylenepentamine, TEPA), which leads to survival of the modified COF in water and long‐time stability under humid atmosphere. Meanwhile, the TEPA modification also results in a considerable increase in CO2 adsorption capacity up to 13 times and a dramatic improvement in CO2/N2 selectivity in low pressure region, which make the modified COF suitable for capturing CO2 from flue gas. This work provides a facile, efficient, and scalable method to greatly improve hydrostability of boroxine‐linked COFs and reshape them into high‐performance CO2 adsorbents.