Walenszus Francesco, Evans Jack D, Bon Volodymyr, Schwotzer Friedrich, Senkovska Irena, Kaskel Stefan
Anorganische Chemie I, Fakultät Chemie und Lebensmittelchemie, Technische Universität Dresden, Bergstrasse 66, 01062 Dresden, Germany.
Chem Mater. 2021 Oct 26;33(20):7964-7971. doi: 10.1021/acs.chemmater.1c01804. Epub 2021 Oct 6.
The flexibility of soft porous crystals, i.e., their ability to respond to external stimuli with structural changes, is one of the most fascinating features of metal-organic frameworks (MOFs). In addition to breathing and swelling phenomena of flexible MOFs, negative gas adsorption (NGA) and pressure amplification (PA) are the more recent discoveries in this field initially observed in the cubic DUT-49 framework. In recent years, the structural contraction was monitored by physisorption, X-ray diffraction, nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) techniques, providing only limited information about the electronic structure of the ligand. In this work, we designed a new ligand with a fluorescent core in the linker backbone and synthesized three new MOFs, isoreticular to DUT-49, denoted as DUT-140(M) (M-Cu, Co, Zn), crystallizing in the space group 3̅. DUT-140(Cu) can be desolvated and is highly porous with an accessible apparent surface area of 4870 m g and a pore volume of 2.59 cm g. Furthermore, it shows flexibility and NGA upon adsorption of subcritical gases. DUT-140(Zn), synthesized using postsynthetic metal exchange, could only be studied with guests in the pores. In addition to the investigation of the adsorption behavior of DUT-140(Cu), spectroscopic and computational methods were used to study the light absorption properties.
柔性多孔晶体的灵活性，即它们通过结构变化对外部刺激做出响应的能力，是金属有机框架（MOF）最引人入胜的特征之一。除了柔性MOF的呼吸和膨胀现象外，负气体吸附（NGA）和压力放大（PA）是该领域最近的发现，最初在立方DUT-49框架中观察到。近年来，通过物理吸附、X射线衍射、核磁共振（NMR）和电子顺磁共振（EPR）技术监测结构收缩，仅提供了关于配体电子结构的有限信息。在这项工作中，我们设计了一种在连接体主链中具有荧光核心的新配体，并合成了三种与DUT-49等规的新MOF，命名为DUT-140（M）（M = Cu、Co、Zn），结晶于空间群3̅。DUT-140（Cu）可以去溶剂化，具有高度多孔性，可及表观表面积为4870 m²/g，孔体积为2.59 cm³/g。此外，它在吸附亚临界气体时表现出灵活性和NGA。使用后合成金属交换合成的DUT-140（Zn），只能在孔中有客体的情况下进行研究。除了研究DUT-140（Cu）的吸附行为外，还使用光谱和计算方法研究了光吸收特性。
