Entanglement of Square Nets in Covalent Organic Frameworks

作者：Fangying Jin, Ha L. Nguyen, Zhiye Zhong, Xing Han, Chenhui Zhu, Xiaokun Pei, Yanhang Ma, Omar M. Yaghi · 发表于：Journal of the American Chemical Society · 年份：2022 · DOI：10.1021/jacs.1c13468 · 被引用次数：59 · 研究领域：Covalent Organic Framework Applications、Metal-Organic Frameworks: Synthesis and Applications、Luminescence and Fluorescent Materials

Two entangled 2D square covalent organic frameworks (COFs) have been synthesized from 4,4′,4″,4‴-(9,9′-spirobi[fluorene]-2,2′,7,7′-tetrayl)-tetrabenzaldehhyde (SFTB) and p -phenylenediamine (PPA) and benzidine (BZD) to form COF-38, [(SFTB)(PPA) 2 ] imine, and its isoreticular form COF-39, [(SFTB)(BZD) 2 ] imine . We also report the single-crystal electron diffraction structure of COF-39 and find that it is composed of mutually entangled 2D square nets ( sql ). These COFs represent the first examples of entangled 2D COF structures, which, as we illustrate, were made possible by our strategy of using the distorted tetrahedral SFTB building unit. SFTB overcomes the propensity of 2D COFs to stack through π–π stacking and allows entanglements to form. This work significantly adds to the design principles of COFs.