Rigid and flexible: A highly porous metal-organic framework with unusual guest-dependent dynamic behavior
Rigid and flexible: A highly porous metal-organic framework with unusual guest-dependent dynamic behavior
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DOI：
10.1002/anie.200460712
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发表时间：
2004-01-01
影响因子：
16.6
通讯作者：
Kim, K
中科院分区：
文献类型：
--
作者：
Dybtsev, DN;Chun, H;Kim, K
近年来，多孔金属有机材料[1]引起了人们的极大关注，因为它们在许多领域具有潜在的应用，包括气体储存[2]分离[3]和催化。[4]由于高骨架稳定性对于许多实际应用是必不可少的，因此对具有刚性骨架的金属有机材料的探索一直是激烈研究的主题。自从首次报道具有永久孔隙率的金属有机框架以来，[5]许多金属有机框架已被报道具有稳定的多孔结构;然而，只有少数这些材料具有高表面积，[6]这是这类材料的另一个重要优点。人们对具有柔性和动态框架的金属有机材料也越来越感兴趣，[7]特别是那些响应外部刺激而可逆地改变其结构和性质的材料，因为它们可能会在传感器等领域找到应用。[8]然而，同时具有高骨架稳定性和骨架柔性的多孔材料是罕见的。[9]在这里，我们报告了一种新的金属有机框架，永久孔隙率和高表面积，这也显示出不寻常的客人依赖的动态行为：框架收缩后，客户包合和扩大后，客户释放明确证明了单晶X-射线晶体学。这些变化是完全可逆的，取决于客人的性质。将Zn（NO3）2、对苯二甲酸（或1，4-苯二甲酸，H2bdc）和1，4-二氮杂双环[2.2. 2]正辛烷（dabco）在1108 ℃反应2d，得到晶体[Zn_2（1，4-bdc）_2（dabco）]·4DMF·1/2H_2O（1·4DMF·1/2H_2O），产率超过80%。[10]通过单晶X射线衍射确定了1·4DMF·1/2H2O的结构，并通过粉末X射线衍射（XRD）、热重分析（TGA）和元素分析分别确认了本体材料的相纯度。在1·4DMF·1/2H2O中，Zn2的骨架由具有桨轮结构的双核Zn2单元组成，并由1，4-bdc二价阴离子桥接形成扭曲的二维正方形网格{Zn2（1，4-bdc）2}. Zn2桨轮的轴向位置被dabco占据，dabco充当将2D层延伸成3D结构的柱（方案1）。在1·4 DMF·1/2H2O中，骨架的整体拓扑结构最好描述为压缩的原始立方（α-Po）网（图1a）。dabco柱沿沿着
Porous metal–organic materials [1] have attracted considerable attention in recent years because of their potential applications in many areas including gas storage,[2] separation,[3] and catalysis.[4] Because high framework stability is essential for many practical applications, the quest for metal–organic materials with rigid frameworks has been a subject of intense research. Since the first reports of metal–organic frameworks with permanent porosity,[5] many metal–organic frameworks have been reported to have stable porous structures; however, only a handful of these materials have a high surface area,[6] which is another important virtue of this class of materials. There is also growing interest in metal–organic materials with flexible and dynamic frameworks,[7] in particular, those that reversibly change their structures and properties in response to external stimuli as they may find applications, for example, in sensors.[8] However, porous materials that have both high framework stability and framework flexibility are rare.[9] Herein we report a novel metal–organic framework with permanent porosity and a high surface area, which also shows unusual guest-dependent dynamic behavior: the framework shrinks upon guest inclusion and expands upon guest release as proved unequivocally by single-crystal X-ray crystallography. These changes are fully reversible and depend on the nature of guests. Heating a dimethylformamide (DMF) solution of Zn (NO3) 2, terephthalic acid (or 1, 4-benzenedicarboxylic acid, H2bdc) and 1, 4-diazabicyclo [2.2. 2] octane (dabco) at 1108C for 2days gave the crystalline product [Zn2 (1, 4-bdc) 2 (dabco)]· 4 DMF· 1/2H2O (1· 4 DMF· 1/2H2O) in over 80% yield.[10] The structure of 1· 4 DMF· 1/2H2O was determined by single-crystal X-ray diffraction and the phase purity of the bulk material was independently confirmed by powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and elemental analysis. The framework in 1· 4 DMF· 1/2H2O is composed of dinuclear Zn2 units with a paddle wheel structure, which are bridged by 1, 4-bdc dianions to form a distorted 2D square-grid {Zn2 (1, 4-bdc) 2}. The axial sites of the Zn2 paddle wheels are occupied by dabco, which act as pillars to extend the 2D layers into a 3D structure (Scheme 1). The overall topology of the framework in 1· 4 DMF· 1/2H2O is best described as a compressed primitive cubic (α-Po) net (Figure1a). The dabco pillars are disordered along the