In-Depth Experimental and Computational Investigations for Remarkable Gas/Vapor Sorption, Selectivity, and Affinity by a Porous Nitrogen-Rich Covalent Organic Framework
In-Depth Experimental and Computational Investigations for Remarkable Gas/Vapor Sorption, Selectivity, and Affinity by a Porous Nitrogen-Rich Covalent Organic Framework
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DOI：
10.1021/acs.chemmater.8b04683
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发表时间：
2019-03-12
影响因子：
8.6
通讯作者：
Mandal, Sanjay K.
中科院分区：
文献类型：
--
作者：
Das, Prasenjit;Mandal, Sanjay K.
多孔富氮共价有机骨架（COFs）是选择性捕集、分离和转化CO2的最具挑战性的材料，对环境和清洁能源应用具有实质性影响。另一方面，通过COF中的π-富电子和π-缺电子中心的主客体相互作用分离工业环状同系物（苯/环己烷）是关键。在此基础上，在缩聚反应条件下合成了一种三嗪基苯并双咪唑桥联的COF（TBICOF），并通过多种分析手段对其结构进行了表征。由于苯并-双（咪唑）环的存在下，TBICOF表现出永久的稳定性和多孔性的存在下的酸和碱监测的广角X-射线图案和N-2吸附研究。在195 K下的377.14 cm（3）g（-1）（73.4 wt %）的增强的CO2吸收证实了其对骨架的高亲和力。CO2吸附是高度选择性的N-2和CH 4，因为非常强的相互作用之间的CO2和三嗪和苯并-双（咪唑）功能化的孔壁的TBICOF的吸附热和理想吸附溶液理论计算清楚地表明，这是高于其他报道的功能化的金属有机框架或COF。有趣的是，TBICOF也表现为在环境条件下将CO2化学固定为环状碳酸酯的非均相有机催化剂。π-缺电子三嗪和苯并双（咪唑）结构已被用于苯（641.9 cm（3）g（-1））在环己烷（186.2 cm（3）g（-1））上的选择性吸附和分离。基于密度泛函理论和巨正则蒙特卡罗分子模拟的计算研究进一步支持CO2（超过N-2和CH 4）和苯（超过环己烷）的选择性。
Porous nitrogen-rich covalent organic frameworks (COFs) are most challenging materials for selective CO2 capture, separation, and conversion for a substantive impact on the environment and clean energy application. On the other hand, separation of industrial cyclic congeners (benzene/cyclohexane) by the host-guest interaction through pi-electron-rich and -deficient centers in a COF is the key. On the basis of the strategic design, a triazine-based benzbis(imidazole)-bridged COF (TBICOF) has been synthesized under polycondensation conditions and structurally characterized by various analytical techniques. Because of the presence of a benz-bis(imidazole) ring, TBICOF exhibits permanent stability and porosity in the presence of acid and base monitored by the wide-angle X-ray pattern and N-2 sorption studies. The enhanced CO2 uptake of 377.14 cm(3) g(-1) (73.4 wt %) at 195 K confirms its high affinity toward the framework. CO2 sorption is highly selective over N-2 and CH4 because of very strong interactions between CO2 and triazine and benz-bis(imidazole)-functionalized pore walls of TBICOF as clearly evident from the isosteric heat of adsorption and ideal adsorbed solution theory calculation, which is higher than other reported functionalized metal-organic frameworks or COFs. Interestingly, TBICOF also behaves as a heterogeneous organocatalyst for chemical fixation of CO2 into cyclic carbonates under ambient conditions. The pi-electron-deficient triazine and benz-bis(imidazole) moieties have been utilized for selective sorption and separation of benzene (641.9 cm(3) g(-1)) over cyclohexane (186.2 cm(3) g(-1)). Computational studies based on density functional theory and grand canonical Monte Carlo molecular simulations further support the selectivity of CO2 (over N-2 and CH4) and benzene (over cyclohexane).