Fabrication of Hydrazone-Linked Covalent Organic Frameworks Using Alkyl Amine as Building Block for High Adsorption Capacity of Metal Ions

Abstract

There are several researches on the preparation and application of hydrazone-linked covalent organic frameworks (COFs), and all of them generally necessitate rigid aromatic amines. Herein, we report a strategy for design and synthesis of COF with flexible alkyl amine as a building block and intramolecular hydrogen bonding as a knot in the network. The proof-of-concept design was demonstrated by exploring 1,3,5-triformylphloroglucinol and oxalyldihydrazide (ODH) as precursors to synthesize a novel COF material (TpODH), in which different organic building units are combined through hydrazone bonds to form twodimensional porous frameworks. It should be pointed that irreversible enol-to-keto tautomerism and intramolecular N−H•••OC hydrogen bonding of TpODH would enhance the crystallinity and chemical stability, leading to large specific surface area of 835 m 2 g −1 . However, another COF synthesized with 1,3,5-triformylbenzene and ODH exhibited less crystallinity and low special surface area (94 m 2 g −1 ). Representatively, the resulting TpODH afforded Cu(II) and Hg(II) capacities of 324 and 1692 mg g −1 , respectively, which exceeded that of most COFs previously reported. Moreover, the Fourier-transform infrared and X-ray photoelectron spectroscopy spectra analyses were taken to demonstrate the adsorption mechanism. These results suggested that the materials could be applied to the removal of metallic ions in the future.

Covalent Organic Frameworks (COFs) for Cancer Therapeutics

“…As a promising alternative to MOFs, COFs can essentially be considered as nanomedicine candidates for cancer treatment . Although a series of two‐dimensional (2D) and three‐dimensional (3D) COFs connected by covalent boronate, hydrazone, imine, ether, and olefin linkages have been reported so far, only a handful of COFs have been successfully scaled down to the nanoregime. However, some unique advantages possessed by nanoscale COFs (NCOFs) make them more suitable for biomedical applications (Figure ), as exemplified here by LZU‐1 …”

Regenerable and stable sp2 carbon-conjugated covalent organic frameworks for selective detection and extraction of uranium

“…Covalent organic frameworks (COFs) are a class of porous crystalline polymers with significant advantages for application in catalysis [14][15][16][17][18] , gas storage [19][20][21][22] , and metal ion extraction [23][24][25][26][27] owing to excellent chemical and thermal stability, flexible topological connectivity, and tunable functionality [28][29][30] . COFs with tunable porosity and large specific surface area might be ideal for extracting radionuclides such as UO 2 2+ .…”

Adsorption Processing for the Removal of Toxic Hg(II) from Liquid Effluents: Advances in the 2019 Year

“…No data were included on desorption step. A strategy for the design and synthesis of covalent organic frameworks (COF) with flexible alkyl-amine as a building block and intramolecular hydrogen bonding as a knot in the network was proposed [55]. Thus, by using 1,3,5-triformylphloroglucinol and oxalyldihydrazide (ODH) as initiators, a COF material, TpODH, in which various organic building units were combined, through hydrazone bonds, to form two-dimensional porous frameworks was developed.…”