Synthesis of Denser Energetic Metal-Organic Frameworks via a Tandem Anion-Ligand Exchange Strategy
Synthesis of Denser Energetic Metal-Organic Frameworks via a Tandem Anion-Ligand Exchange Strategy
复制标题
通过串联阴离子-配体交换策略合成更致密的高能金属有机框架
DOI：
10.1021/acs.inorgchem.7b01122
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发表时间：
2017
影响因子：
4.6
通讯作者：
Pang Siping
中科院分区：
文献类型：
--
作者：
Zhang Jichuan;Su Hui;Dong Yalu;Zhang Pengcheng;Du Yao;Li Shenghua;Gozin Michael;Pang Siping
高密度材料因其广泛的应用而受到广泛关注。然而，提高 MOF 密度和制备更致密 MOF 的策略几乎尚未探索。在此，我们提出了一种串联阴离子-配体交换策略，通过使用具有柱状层状结构的三维阳离子MOF（3D CMOF）作为前体，以高密度阴离子和小单位配体作为外源客体来合成更致密的MOF。通过该策略，我们选择高密度硝基甲酸根离子[C(NO2)3–]作为外源阴离子，水作为外源配体，成功合成了两层状CMOFs。单晶 X 射线衍射表明，经过这种转变，框架外阴离子被 C(NO2)3 阴离子取代，二维 (2D) 网络中相邻层之间的距离比其 3D 前驱体短 3.70 Å 以上。所得材料具有更高的密度、更高的爆炸热、更高的氮和氧含量以及更低的金属含量。特别是，{Cu(atrz)2[C(NO2)3]2(H2O)2·atrz·2H2O}n(2b, ρ = 1.76 g cm–3, atrz = 4,4'-偶氮-1,2,4-三唑)的密度与其3D前体{2a, [Cu(atrz)3(NO3)2·2H2O]n, ρ = 1.64 g cm–3}，其爆热也增强至1900 kJ kg–1以上。由此产生的二维层状 CMOF 也是新的潜在高能量密度材料。这项工作可能为高密度 MOF 的设计和合成提供新的见解。此外，我们预计这里报道的方法将有助于制备新的 MOF，特别是通过传统合成途径很难或不可行的方法。
High-density materials have attracted extensive attention because of their broad applications. However, strategies for improving the densities of MOFs and preparing denser MOFs remain almost unexplored. Herein, we propose a tandem anion–ligand exchange strategy for synthesizing denser MOFs by using three-dimensional cationic MOFs (3D CMOFs) with pillared layered structures as precursors and high-density anions and small monotopic ligands as exogenous guests. By means of this strategy, we choose the high-density nitroformate ion [C(NO2)3–] as an exogenous anion and water as an exogenous ligand to successfully synthesize two layered CMOFs. Single-crystal X-ray diffraction showed that after this transformation, the extra-framework anions are replaced with the C(NO2)3–anions, and the distances between adjacent layers in the two-dimensional (2D) networks are more than 3.70 Å shorter than those of their 3D precursors. The resultant materials exhibit higher densities, higher heats of detonation, higher nitrogen and oxygen contents, and lower metal contents. In particular, the density of {Cu(atrz)2[C(NO2)3]2(H2O)2·atrz·2H2O}n(2b, ρ = 1.76 g cm–3, atrz = 4,4′-azo-1,2,4-triazole) is increased by 0.12 g cm–3compared to its 3D precursor {2a, [Cu(atrz)3(NO3)2·2H2O]n, ρ = 1.64 g cm–3}, and its heat of detonation is also enhanced to more than 1900 kJ kg–1. The resultant 2D layered CMOFs are also new potential high-energy density materials. This work may provide new insights into the design and synthesis of high-density MOFs. Moreover, we anticipate that the approach reported here would be useful for the preparation of new MOFs, in particular, which are otherwise difficult or unfeasible through traditional synthetic routes.