3D Energetic Metal-Organic Frameworks: Synthesis and Properties of High Energy Materials
3D Energetic Metal-Organic Frameworks: Synthesis and Properties of High Energy Materials
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DOI：
10.1002/anie.201307118
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发表时间：
2013-12-23
影响因子：
16.6
通讯作者：
Pang, Siping
中科院分区：
文献类型：
--
作者：
Li, Shenghua;Wang, Yuan;Pang, Siping
金属有机框架（MOFs）由于其有趣的分子拓扑结构和在化学分离、[1]气体储存、[2]药物递送、[3]催化[4]和化学传感器技术中的潜在应用而引起了极大的关注。[5]特别是，MOFs也可能是潜在的高能材料，因为它们的高密度和高爆热。例如，Hope-Weeks及其同事最近报道了两种肼-高氯酸盐1D MOFs [（Ni（NH 2NH 2）5（ClO 4）2）n（NHP），和（Co（NH 2NH 2）5（ClO 4）2）n（CHP）]具有线性聚合物结构，[6]被认为是迄今为止已知的最强大的金属基高能材料，爆炸热与六硝基六氮杂异伍兹烷（CL-20;约1.5千卡/升）相当。不幸的是，这些配位聚合物对源自此类线性聚合物结构的低刚性特性的冲击高度敏感，这使得实际应用不可行。为了降低灵敏度，同一作者还使用肼衍生物（肼-羧酸）作为配体构建具有2D片层结构的MOFs [（（Co2（N2 H4）4-（N2 H3 CO2）2）（ClO 4）2· H2O）n（CHHP）和（（Zn 2（N2 H4）3（N2 H3 CO2）2）（ClO 4）2· H2O）n（ZnHHP）]，其显示出感度的显著降低，然而，伴随着它们的爆热降低（图1）。[7]尽管取得了这些进展，但目前的协调框架仅限于一维或二维结构。与一维线性结构和二维层状结构相比，三维框架结构具有更为复杂的连接方式，可以进一步增强结构的补强性，从而提高结构的稳定性和能量性能。已经合成了许多具有有趣的磁性，[8]催化，[9]和发光特性的3D MOFs，[10]其中一些将各种高能部分如硝酸根阴离子（NO3-），[8b]高氯酸根阴离子（ClO 4-）[8 c]纳入3D框架。然而，它们作为含能材料的潜在应用尚未被公开或讨论;文献中也缺少有关含能特性的相关数据。此外，所报道的基于高氯酸根阴离子的1D和2D高能M0 F都已被美国环境保护署（EPA）仔细审查，因为它们促进甲状腺功能障碍并且是致畸的。[11]为了继续寻找新的高能量、环保的含能材料，我们探索了无卤含能3D MOFs的制备，其中两种聚合物[Cu（atrz）3（NO3）2] n（1）和[Ag（atrz）1.5（NO3）] n（2）通过用4，4 '-偶氮-1，2，4-三唑（atrz）取代肼配体而设计。[12]在这里，我们选择使用atrz作为配体，原因如下：1）作为富氮杂环骨架，[13] atrz具有高氮含量（N%= 100）。
Metal–organic frameworks (MOFs) have attracted great attention because of their intriguing molecular topologies and potential applications in chemical separation,[1] gas storage,[2] drug delivery,[3] catalysis [4] and chemical sensor technology.[5] Particularly, MOFs could also be potential energetic materials because of their high densities and high heats of detonation. For example, Hope-Weeks and co-workers recently reported two hydrazine-perchlorate 1D MOFs [(Ni (NH2NH2) 5 (ClO4) 2) n (NHP), and(Co (NH2NH2) 5 (ClO4) 2) n (CHP)] with linear polymeric structures,[6] which were regarded as possibly the most powerful metal-based energetic materials known to date, with heats of detonation comparable with that of hexanitrohexaazaisowutzitane (CL-20; about 1.5 kcalgÀ1). Unfortunately, these coordination polymers were highly sensitive to impact deriving from their low rigidity characteristic of such linear polymeric structures, which makes practical use infeasible. In order to decrease the sensitivities, the same authors also used a hydrazine derivative (hydrazine-carboxylate) as the ligand to construct MOFs with 2D sheet structures [((Co2 (N2H4) 4-(N2H3CO2) 2)(ClO4) 2· H2O) n(CHHP) and ((Zn2 (N2H4) 3 (N2H3CO2) 2)(ClO4) 2· H2O) n (ZnHHP)], which showed a considerable reduction to the sensitivity, however, concomitantly their heats of detonation decreased (Figure 1).[7]Despite these advances, current coordination frameworks are only limited to be a 1D or 2D structure. Compared with 1D linear and 2D layered structures, three-dimensional (3D) frameworks possess more complicated connection modes, which could further enhance structural reinforcement, hence improve the stabilities and energetic properties. A lot of 3D MOFs have been synthesized with interesting magnetic,[8] catalytic,[9] and luminescent properties,[10] some of them incorporate a variety of energetic moities such as nitrate anions (NO3 À),[8b] perchlorate anions (ClO4 À)[8c] into the 3D frameworks. However, their potential applications as energetic materials have not been disclosed or discussed; relevant data about energetic properties are also missing in the literature. Additionally, both reported 1D and 2D energetic MOFs based on the perchlorate anions, have been scrutinized by the US Environmental Protection Agency (EPA) because they promote thyroid dysfunction and are teratogenic.[11] Continuing our interest in finding new highly energetic, eco-friendly energetic materials, we explore the preparation of halogen-free energetic 3D MOFs, for which two polymers [Cu (atrz) 3 (NO3) 2] n (1) and [Ag (atrz) 1.5 (NO3)] n(2) were designed by replacing the hydrazine ligand with 4, 4’-azo-1, 2, 4-triazole (atrz).[12] Here, we chose to use atrz as a ligand for the following reasons: 1) as a nitrogen-rich heterocyclic backbone,[13] atrz possesses a high nitrogen content (N%=