Contradistinct Thermoresponsive Behavior of Isostructural MIL-53 Type Metal-Organic Frameworks by Modifying the Framework Inorganic Anion
Contradistinct Thermoresponsive Behavior of Isostructural MIL-53 Type Metal-Organic Frameworks by Modifying the Framework Inorganic Anion
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DOI：
10.1021/cm503311x
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发表时间：
2015-01-13
影响因子：
8.6
通讯作者：
Attfield, Martin P.
中科院分区：
文献类型：
--
作者：
Nanthamathee, Chompoonoot;Ling, Sanliang;Attfield, Martin P.
简单骨架无机阴离子对同构 MIL-53 型金属有机骨架 [AlF(bdc)] 和 [Al(OH)(bdc)] 热响应行为的影响已通过衍射和计算技术的组合确定。 [AlF(bdc)] 在 500 到大约 175 K 的温度范围内具有斜方晶系大孔结构，此时它会发生细微的变形，形成单斜晶系大孔结构，并在 11 K 下保持稳定。[AlF(bdc)] 的斜方晶系大孔结构在 175-500 K 范围内表现出负热膨胀。[Al(OH)(bdc)] 具有斜方晶系大孔结构。孔隙结构从 500 到 125 K，此时它会经历位移相变（呼吸效应），形成无孔单斜晶结构。 [Al(OH)(bdc)] 的斜方大孔形式在 150 至 500 K 范围内表现出正热膨胀。[Al(OH)(bdc)]（而不是 [AlF(bdc)]）中存在的呼吸效应与氢氧化物基团的存在所提供的跨孔最短尺寸的吸引力相互作用的额外贡献有关。任一材料的正交大孔结构的正热膨胀或负热膨胀的显示与AlO4X2八面体的共享角链的刚性有关，刚性较高的AlO4F2八面体有利于一种类型的静态或动态位移，而刚性较低的AlO4(OH)(2)八面体有利于不同类型的静态位移。通过控制该材料族中简单无机阴离子的特性和数量，可以预测具有受控膨胀和位移相变特性或同时包含混合热响应特性的金属有机框架的形成。这项工作表明在设计金属有机框架的热机械性能时考虑最简单物种的重要性。
The influence of simple framework inorganic anions on the thermoresponsive behavior of the isostructural MIL-53 type metal-organic frameworks [AlF(bdc)] and [Al(OH)(bdc)] has been determined using a combination of diffraction and computational techniques. [AlF(bdc)] has an orthorhombic large pore structure from 500 to similar to 175 K at which point it undergoes a subtle distortion to form a monoclinic large pore structure that remains stable to 11 K. The orthorhombic large pore form of [AlF(bdc)] exhibits negative thermal expansion from 175-500 K. [Al(OH)(bdc)] has an orthorhombic large pore structure from 500 to 125 K at which point it undergoes a displacive phase transition, a breathing effect, to form a nonporous monoclinic structure. The orthorhombic large pore form of [Al(OH)(bdc)] exhibits positive thermal expansion from 150 to 500 K. The presence of a breathing effect in [Al(OH)(bdc)], and not [AlF(bdc)], is related to the additional contributions to attractive interactions across the shortest dimension of the pore provided by the presence of the hydroxide groups. The display of positive or negative thermal expansion of the orthorhombic large pore structure of either material is related to the rigidity of the constituent corner-sharing chain of AlO4X2 octahedra with the more rigid AlO4F2 octahedra favoring one type of static or dynamic displacement and the less rigid AlO4(OH)(2) octahedra favoring a different type of static displacement. Formation of metal-organic frameworks with controlled expansion and displacive phase transition properties, or simultaneously containing mixed thermoresponsive properties, is predicted through control of the identity and amount of the simple inorganic anions in this family of material. The work indicates the importance of considering the simplest species when designing the thermo-mechanical properties of metal-organic frameworks.