Fabrication of Hydrazone-Linked Covalent Organic Frameworks Using Alkyl Amine as Building Block for High Adsorption Capacity of Metal Ions
journal contributionposted on 08.03.2019, 00:00 authored by Ya Li, Chang Wang, Shujuan Ma, Haiyang Zhang, Junjie Ou, Yinmao Wei, Mingliang Ye
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 two-dimensional porous frameworks. It should be pointed that irreversible enol-to-keto tautomerism and intramolecular N–H···OC hydrogen bonding of TpODH would enhance the crystallinity and chemical stability, leading to large specific surface area of 835 m2 g–1. However, another COF synthesized with 1,3,5-triformylbenzene and ODH exhibited less crystallinity and low special surface area (94 m2 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.
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surface areaalkyl aminecrystallinityadsorption mechanismframeworkintramolecular hydrogenHigh Adsorption Capacityhydrazone bondsX-ray photoelectron spectroscopy spectra analysesenol-to-keto tautomerismproof-of-concept designbuilding unitsODHnovel COF materialhydrazone-linked covalentHydrazone-Linked Covalent Organic Frameworkschemical stabilitybuilding blockBuilding BlockTpODHMetal IonsAlkyl Amine