An ionic vinylene-linked three-dimensional covalent organic framework for selective and efficient trapping of ReO4− or 99TcO4−

Abstract

The synthesis of ionic olefin linked three-dimensional covalent organic frameworks (3D COFs) is greatly challenging given the hardness of the formation of stable carbon-carbon double bonds (–C = C–). Herein, we report a general strategy for designing porous positively charged sp2 carbon-linked 3D COFs through the Aldol condensation promoted by quaternization. The obtained 3D COFs, namely TFPM-PZI and TAPM-PZI, showed impressive chemical stability. Furthermore, the positively charged frameworks with regular porosity endow 3D ionic COFs with selective capture radioactive ReO4−/TcO4− and great removal efficiency in simulated Hanford waste. This research not only broadens the category of 3D COFs but also promotes the application of COFs as efficient functional materials.

Modulating Anion Nanotraps via Halogenation for High-Efficiency 99TcO4–/ReO4– Removal under Wide-Ranging pH Conditions

“…This approach offers easy operation and high efficiency. Commonly used ion exchange materials include resins, , molecular compounds, silica, − metal borates, , layered double hydroxide (LDH), , metal–organic frameworks (MOFs), − ionic polymers, − cationic covalent organic nanosheets (iCONs), and covalent organic frameworks (COFs), − among others . Resins, molecular compounds, and LDH-based adsorbents all have limitations due to their relatively low 99 TcO 4 – adsorption capacity and poor selectivity.…”

“…Resins, molecular compounds, and LDH-based adsorbents all have limitations due to their relatively low 99 TcO 4 – adsorption capacity and poor selectivity. Recently, MOFs and COFs have demonstrated excellent 99 TcO 4 – capture abilities, offering the advantages of a high uptake capacity, fast adsorption kinetics, and good selectivity. − ,,,− ,, Although MOFs and COFs display fast kinetics and high capacity under mild conditions, they are generally unsuitable for 99 TcO 4 – adsorption under strongly acidic, high ionic strength, or alkaline solutions due to instability issues (i.e., under conditions most relevant to the treatment of nuclear waste streams). , …”

“…Recently, MOFs and COFs have demonstrated excellent 99 TcO 4 − capture abilities, offering the advantages of a high uptake capacity, fast adsorption kinetics, and good selectivity. [27][28][29][30][31][32][33][34]36,37,[47][48][49]51,53 Although MOFs and COFs display fast kinetics and high capacity under mild conditions, they are generally unsuitable for 99 TcO 4 − adsorption under strongly acidic, high ionic strength, or alkaline solutions due to instability issues (i.e., under conditions most relevant to the treatment of nuclear waste streams). 38,54 In general, adsorbents differ widely in their relative affinities for 99 TcO 4 − and other competing ions.…”

Deposition of Silver Nanostructures on Covalent Organic Frameworks for Photocatalytic Degradation of Sulfur Mustard Simulants

“…Covalent organic frameworks (COFs) are emerging crystalline porous materials with network structures and preset skeletons, which are composed of lightweight organic building units through covalent bonds. – Due to their high thermal and chemical stability, large specific surface areas, low skeleton density, and controllable structures, COFs have been applied in various fields such as catalysis technology, , gas separation and storage, , photoelectric materials, , ion extraction, , and antibacterial therapy. , To strengthen the generation of ROS in the COF-mediated photocatalytic process, some postsynthetic strategies such as the backbone modification, , functional group interconversion, , and metal deposition have been proposed. Loading metal nanoparticles or nanoclusters is considered to be an effective strategy to improve the photocatalytic properties of COFs in the midst of aforementioned strategies. , For instance, Zhang et al reported that the COFs loaded with Pt nanoparticles showed excellent catalytic activities in the reduction of nitrophenol and the Suzuki–Miyaura coupling reaction .…”

Fabricating s-collidine-derived vinylene-linked covalent organic frameworks for photocatalysis

“…13,14 To date, only a few types of monomers have been explored for the construction of vinylene-linked COFs. 8–10,14–21 In addition, the synthesis of these monomers usually requires a complicated process and the utilization of toxic reagents (for instance, NaCN and CuCN) with high cost. 15 Therefore, it is urgently needed to develop monomers with low cost to construct vinylene-linked COFs.…”