Coordination Geometry Changes in Amorphous Cyanide-Bridged Metal Organic Frameworks upon Water Adsorption
Coordination Geometry Changes in Amorphous Cyanide-Bridged Metal Organic Frameworks upon Water Adsorption
复制标题
非晶态氰化物桥金属有机骨架在吸水后的配位几何变化
DOI：
10.1021/acs.inorgchem.0c03742
复制
发表时间：
2021
影响因子：
4.6
通讯作者：
Ohba Masaaki
中科院分区：
文献类型：
--
作者：
Yoshino Haruka;Yamagami Kohei;Wadati Hiroki;Yamagishi Hirona;Setoyama Hiroyuki;Shimoda Sayuri;Mishima Akio;Le Ouay Benjamin;Ohtani Ryo;Ohba Masaaki
无定形配位聚合物和金属有机骨架（MOFs）因其功能多样而备受关注。在这里，我们展示了一系列具有不同金属（M[Ni（CN）4]：MNi; M = Mn，Fe和Co）的无定形氰化物桥接的MOFs的可调水吸附行为。所有三种化合物在一定的蒸气压（Pads）下吸附多达六个水分子，并转化为结晶霍夫曼型MOFs，M（H2O）2[Ni（CN）4]·4 H2O（MNi-H2O; M = Mn，Fe和Co）。MnNi、FeNi和CoNi的水吸附垫分别为P/P0= 0.4、0.6和0.9。虽然这些材料的无定形性质阻止了使用X射线晶体学技术的结构解析，但使用L2，3-，K-边X射线吸收精细结构和磁性测量分析了N-配位M2+中心周围的局部尺度结构。水合后，这些金属中心的配位几何形状从四面体变为八面体，导致MOF局部结构的显著重组。另一方面，Ni[Ni（CN）4]（NiNi）含有正方形平面Ni 2+中心没有经历显著的结构转变，因此在低压区域突然吸附H2O。因此，我们可以定义键长和配位几何形状的变化是如何与无定形MOF系统的吸附性能。
Amorphous coordination polymers and metal–organic frameworks (MOFs) have attracted much attention owing to their various functionalities. Here, we demonstrate the tunable water adsorption behavior of a series of amorphous cyanide-bridged MOFs with different metals (M[Ni(CN)4]:MNi; M = Mn, Fe, and Co). All three compounds adsorb up to six water molecules at a certain vapor pressure (Pads) and undergo conversion to crystalline Hofmann-type MOFs, M(H2O)2[Ni(CN)4]·4H2O (MNi–H2O; M = Mn, Fe, and Co). ThePadsofMnNi,FeNi, andCoNifor water adsorption isP/P0= 0.4, 0.6, and 0.9, respectively. Although the amorphous nature of these materials prevented structural elucidation using X-ray crystallography techniques, the local-scale structure around the N-coordinated M2+centers was analyzed using L2,3-, K-edge X-ray absorption fine structure, and magnetic measurements. Upon hydration, the coordination geometry of these metal centers changed from tetrahedral to octahedral, resulting in significant reorganization of the MOF local structure. On the other hand, Ni[Ni(CN)4] (NiNi) containing square-planar Ni2+centers did not undergo significant structural transformation and therefore abruptly adsorbed H2O in the low-pressure region. We could thus define how changes in the bond lengths and coordination geometry are related to the adsorption properties of amorphous MOF systems.