Electron Beam Irradiation as a General Approach for the Rapid Synthesis of Covalent Organic Frameworks under Ambient Conditions

Abstract

Crystalline porous materials such as covalent organic frameworks (COFs) are advanced materials to tackle challenges of catalysis and separation in industrial processes. Their synthetic routes often require elevated temperatures, closed systems with high pressure, and long reaction times, hampering their industrial applications. Here we use a traditionally unperceived strategy to assemble highly crystalline COFs by electron beam irradiation with controlled received dosage, contrasting sharply with the previous observation that radiation damages the crystallinity of solids. Such synthesis by electron beam irradiation can be achieved under ambient conditions within minutes, and the process is amendable for large-scale production. The intense and targeted energy input to the reactants leads to new reaction pathways that favor COF formation in nearly quantitative yield. This strategy is applicable not only to known COFs but also to new series of flexible COFs that are difficult to obtain using traditional methods.

Electron Beam Irradiation‐Induced Formation of Defect‐Rich Zeolites under Ambient Condition within Minutes

“…Compared with laboratory‐scale irradiation source of gamma ray, electron beam provided by commercially available electron accelerator often exhibits higher dose rate and ionizing efficiency, leading to intrinsic advantages in energy deposition and activation of reaction systems. We recently demonstrated that electron beam irradiation assisted synthesis is a general approach to form different types of covalent organic frameworks including those typical ones reported in the literatures and several new ones that cannot be directly synthesized through conventional solvothermal method, showing distinct merits of ambient conditions, ultrarapid synthesis, quantitative yield, and high‐purity product [12] . Here we expand this synthetic strategy into the formation of a family of zeolites.…”

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

“…In addition to the aforementioned methods, other synthesis methods have also been developed, such as photochemical synthesis, 145,146 electron-beam irradiation synthesis, 147 and vapor-assisted synthesis. 148 Although these methods are probably not universal, they might be highly effective for the synthesis of task-specic COFs with specic structures.…”

Advanced Ordered Nanoporous Materials

“…Besides, those COFs also have high thermal stability (stable up to 400 °C) and crystallinity which make them a versatile platform in desired applications. A unique flexible structure (having AA eclipsed-and AB staggered-stacking architecture system) of imine-based COF was recently prepared by irradiating 2,4,6-tris(4formylphenoxy)-1,3,5-triazine and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine using 100 kGy of electron beam for 160 s, which later denoted as EB-COF 1 (Zhang et al 2020). This material possesses type I reversible isotherm which is determined by the N 2 adsorption-desorption method and also has 738 m 2 g −1 of BET surface area.…”