Ambient aqueous-phase synthesis of covalent organic frameworks for degradation of organic pollutants.

Yaozu Liu,Yushan Yan,Qianrong Fang,Valentin Valtchev,Shilun Qiu,Yujie Wang,Ming Xue,Liangkui Zhu,Hui Li,Xinyu Guan

doi:10.1039/c9sc03725j

Abstract

The development of a mild, low cost and green synthetic route for covalent organic frameworks (COFs) is highly desirable in order to open the door for practical uses of this new family of crystalline porous solids. Herein, we report a general and facile strategy to prepare a series of microporous or mesoporous COFs by a β-ketoenamine based Michael addition-elimination reaction in aqueous systems at ambient temperature and pressure. This synthesis method not only produces highly crystalline and porous COFs, but also can be carried out with a high reaction rate (only 30 min), high yields (as high as 93%) and large-scale preparation (up to 5.0 g). Furthermore, an Fe(ii)-doped COF shows impressive performance in the oxidative degradation of organic pollutants in aqueous medium. This research thus provides a promising pathway to large-scale green preparation of COFs and their potential application in environmental remediation.

Highlights

Covalent organic frameworks (COFs) as a new class of fascinating crystalline porous materials are composed of light elements, such as C, H, N, B and O, and connected by covalent bonds.[1]
We have exploited a fast, ambient temperature and pressure ionothermal synthesis of COFs;[14] the high cost of ionic liquids hinders the application of this method for large-scale preparation of COFs
The model reaction is implemented between 3-(dimethylamino)-1-phenyl-2-propen-1one (DPPO) and benzenamine (BA) to form 3-anilino-1-phenyl2-propen-1-one (APPO) and a by-product, dimethylamine (DMA, Scheme 1b)

Summary

Introduction

Covalent organic frameworks (COFs) as a new class of fascinating crystalline porous materials are composed of light elements, such as C, H, N, B and O, and connected by covalent bonds.[1]. Taking these considerations in mind, we report a general and environmentally benign approach to construct microporous and mesoporous COFs by a b-ketoenamine based Michael addition–elimination reaction in aqueous systems under ambient conditions. A metal-doped COF, JUC-521-Fe, shows impressive performance in the degradation of toxic organic pollutants in aqueous solution.

Results

Conclusion