From Highly Crystalline to Outer Surface-Functionalized Covalent Organic Frameworks--A Modulation Approach.
From Highly Crystalline to Outer Surface-Functionalized Covalent Organic Frameworks--A Modulation Approach.
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DOI：
10.1021/jacs.5b10708
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发表时间：
2016-02-03
影响因子：
15
通讯作者：
Bein T
中科院分区：
文献类型：
--
作者：
Calik M;Sick T;Dogru M;Döblinger M;Datz S;Budde H;Hartschuh A;Auras F;Bein T
结晶度和孔隙率对于共价有机框架（COF）的许多性质（包括吸附、扩散和电子传输）至关重要。我们已经开发了一种新的方法，通过在合成中引入调节剂来强烈增强这两个方面。这种调制器在溶剂热COF生长过程中与其中一个构建块竞争，导致高度结晶的框架，其域尺寸大大增加，达到数百纳米。所获得的材料具有完全可进入的孔，内表面积超过2000 m2 g-1。通过NMR光谱的组成分析表明，COF-5结构可以在宽范围的硼酸与邻苯二酚的比例下形成，从而产生具有从高度缺乏硼酸到具有邻苯二酚空隙的网络的组成的框架。通过铱染色对− SH-官能化调节剂的可视化显示，COF结构域被调节剂终止。因此，使用官能化的调节剂，这种合成方法还提供了一种新的和简便的方法，用于COF结构域的外表面官能化，为合成后修饰反应提供了可接近的位点。我们证明了这一概念的可行性，通过共价连接荧光染料和亲水性聚合物的COF表面。我们预计，实现具有附加表面功能的选择的高度结晶的COF将使调制概念有利于一系列应用，包括气体分离、催化和光电子学。
Crystallinity and porosity are of central importance for many properties of covalent organic frameworks (COFs), including adsorption, diffusion, and electronic transport. We have developed a new method for strongly enhancing both aspects through the introduction of a modulating agent in the synthesis. This modulator competes with one of the building blocks during the solvothermal COF growth, resulting in highly crystalline frameworks with greatly increased domain sizes reaching several hundreds of nanometers. The obtained materials feature fully accessible pores with an internal surface area of over 2000 m2 g–1. Compositional analysis via NMR spectroscopy revealed that the COF-5 structure can form over a wide range of boronic acid-to-catechol ratios, thus producing frameworks with compositions ranging from highly boronic acid-deficient to networks with catechol voids. Visualization of an −SH-functionalized modulating agent via iridium staining revealed that the COF domains are terminated by the modulator. Using functionalized modulators, this synthetic approach thus also provides a new and facile method for the external surface functionalization of COF domains, providing accessible sites for post-synthetic modification reactions. We demonstrate the feasibility of this concept by covalently attaching fluorescent dyes and hydrophilic polymers to the COF surface. We anticipate that the realization of highly crystalline COFs with the option of additional surface functionality will render the modulation concept beneficial for a range of applications, including gas separations, catalysis, and optoelectronics.