Zhang Xiaomin, Li Wenliang, Guan Yiran, Zhou Baolei, Zhang Jingping
Faculty of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun, 130024, China.
Chemistry. 2019 May 7;25(26):6569-6574. doi: 10.1002/chem.201806400. Epub 2019 Apr 17.
A novel type of ionic covalent organic framework (ICOF) with a spiroborate linkage has been recently designed and synthesized by Zhang and co-workers (Ionic Covalent Organic Frameworks with Spiroborate Linkage, Angew. Chem. Int. Ed. 2016, 55, 1737-1741). The spiroborate-linked ICOFs exhibit high Brunauer-Emmett-Teller (BET) surface areas and significant amounts of H and CH uptakes, combined with excellent thermal and chemical stabilities. Inspired by the novel properties of ICOFs, with the aim of gaining better understanding of the structure of such spiroborate-linked ICOFs, a series of potential 3D network configurations of ICOFs connected with tetrahedral [BO ] nodes were proposed, assuming the [BO ] node in spiroborate segments takes a tetrahedral configuration. These ICOFs, in terms of 2D and 3D topology through torsional energy of the [BO ] fragment, pore-size distribution, total energy of the framework, and gas adsorption properties were compared and systematically investigated by density functional theory calculations, molecular mechanics, and well-established Grand canonical Monte Carlo simulations. The results indicate that spiroborate-linked ICOFs are likely a mixture of various topologies. Among these architectures, the five-fold interpenetrating model shows the lowest energy and reasonable gas uptakes, therefore, it is considered to be the most possible structure. More importantly, the five-fold interpenetrating model, showing high CH uptakes compared with several classic porous materials, represents a promising CH storage material.
最近，张及其同事设计并合成了一种新型的具有螺硼酸酯键的离子共价有机骨架（ICOF）（《具有螺硼酸酯键的离子共价有机骨架》，《德国应用化学》，2016年，第55卷，1737 - 1741页）。螺硼酸酯连接的ICOF具有高比表面积（Brunauer - Emmett - Teller，BET）以及大量的氢气和甲烷吸附量，同时具备出色的热稳定性和化学稳定性。受ICOF这些新颖特性的启发，为了更好地理解此类螺硼酸酯连接的ICOF的结构，提出了一系列与四面体[BO₃]节点相连的ICOF的潜在三维网络构型，假设螺硼酸酯片段中的[BO₃]节点呈四面体构型。通过密度泛函理论计算、分子力学以及成熟的巨正则蒙特卡罗模拟，对这些ICOF在二维和三维拓扑结构方面，通过[BO₃]片段的扭转能、孔径分布、骨架总能量以及气体吸附特性进行了比较和系统研究。结果表明，螺硼酸酯连接的ICOF可能是多种拓扑结构的混合物。在这些结构中，五重互穿模型显示出最低的能量和合理的气体吸附量，因此，它被认为是最可能的结构。更重要的是，与几种经典多孔材料相比，五重互穿模型显示出高甲烷吸附量，是一种很有前景的甲烷储存材料。
