Ultrastable Imine‐Based Covalent Organic Frameworks for Sulfuric Acid Recovery: An Effect of Interlayer Hydrogen Bonding

Abstract

A rapid and scalable synthesis of six new imine-linked highly porous and crystalline COFs is presented that feature exceptionally high chemical stability in harsh environments including conc. H SO (18 m), conc. HCl (12 m), and NaOH (9 m). This is because of the presence of strong interlayer C-H⋅⋅⋅N hydrogen bonding among the individual layers, which provides significant steric hindrance and a hydrophobic environment around the imine (-C=N-) bonds, thus preventing their hydrolysis in such an abrasive environment. These COFs were further converted into porous, crystalline, self-standing, and crack-free COF membranes (COFMs) with extremely high chemical stability for their potential applications for sulfuric acid recovery. The as-synthesized COFMs exhibit unprecedented permeance for acetonitrile (280 Lm h bar ) and acetone (260 Lm h bar ).

Improved Photoreduction of CO2 with Water by Tuning the Valence Band of Covalent Organic Frameworks

“…The characteristic peaks of the obtained RXRD (Figure S6 in the Supporting Information) are still clear. This shows that the modified materials are stable in acid and alkali environments and can perform catalytic tasks in harsh environments …”

Tailoring Covalent Organic Frameworks To Capture Water Contaminants

“…[5] Bulky substituents next to the imine bonds have been shown to enhanceh ydrolytic stability by preventing access of water molecules near the linkage. [94,95] Additionally,i ncorporation of an intralayerh ydrogen-bonding interaction with the imine nitrogen, by positioning ah ydroxyl group in the a-position of the reactinga ldehyde, has been shown to enhance the hydrolytic stabilitye ven further. [96,97] On the other hand, placement of ah ydroxyl group in a-position to the amineh as been shownt ol ead to ultra-stable benzoxazole COFs.…”

“…al chemical stabilityu nder harsh acidic and basic conditions, as well as in boilingw ater,a nd common organic solvents fors everal days, broadening their application for the removal of toxic substances from water. [95] Additionally,i nterfacial polymerization, polymerization at the interface of two immiscible phases that contain the monomers, was used to obtain self-standing COF thin films with different thicknesses (Figures 7c-e). [144] Banerjeea nd co-workerss ynthesized ac rystalline porous2 Dn etwork at the liquid-liquid interface between dichloromethane and water.T he obtained COF thin film could be easily transferred onto as olid substrate, such as porous polyesterf abric, while retaining its physical shape and crystalline structure.…”

Proximity Effect in Crystalline Framework Materials: Stacking-Induced Functionality in MOFs and COFs

“…London dispersion interactions are commonly treated using an a posteriori correction [138,139] or the many-body dispersion (MBD) approach. [140] DFTB2 has been successfully applied to 2D COFs, [27,59,78,[141][142][143][144][145][146][147][148][149][150][151][152][153][154] DFTB3 has not yet been tested carefully with SOC and with periodic boundary conditions. Popular codes covering MOFs and COFs in periodic boundary conditions are dftb+ [155] and AMS/DFTB.…”