Amombo Noa Francoise M, Grape Erik Svensson, Åhlén Michelle, Reinholdsson William E, Göb Christian R, Coudert François-Xavier, Cheung Ocean, Inge A Ken, Öhrström Lars
Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-10691, Sweden.
J Am Chem Soc. 2022 May 18;144(19):8725-8733. doi: 10.1021/jacs.2c02351. Epub 2022 May 3.
A metal-organic framework (MOF) based on lanthanum(III) and the conformationally chiral linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)benzene, cpb: [La(cpb)]·1.5dmf was prepared by the solvothermal method in dimethylformamide (dmf) and characterized by variable-temperature X-ray powder diffraction (VTPXRD), variable-temperature X-ray single-crystal diffraction (SCXRD), and thermogravimetric analysis (TGA). is a rod-MOF with new topology . It has high-temperature stability with Sohncke space groups 622/622 at 90 K and 622 at 300 and 500 K, all phases characterized with SCXRD and at 293 K also with three-dimensional (3D) electron diffraction. VTPXRD indicates a third phase appearing after 620 K and stable up to 770 K. Gas sorption isotherms with N indicate a modest surface area of 231 m g for , roughly in agreement with the crystal structure. Carbon dioxide sorption reveals a gate-opening effect of where the structure opens up when the loading of CO reaches approximately ∼0.45 mmol g or 1 molecule per unit cell. Based on the SCXRD data, this is interpreted as flexibility based on the concerted movements of the propeller-like hexatopic cpb linkers, the movement intramolecularly transmitted by the π-π stacking of the cpb linkers and helped by the fluidity of the LaO coordination sphere. This was corroborated by density functional theory (DFT) calculations yielding the chiral phase (622) as the energy minimum and a completely racemic phase (6/), with symmetric cpb linkers representing a saddle point in a racemization process.
通过在二甲基甲酰胺（dmf）中采用溶剂热法制备了一种基于镧（III）和构象手性连接体1,2,3,4,5,6-六（4-羧基苯基）苯（cpb）的金属有机框架（MOF）：[La(cpb)]·1.5dmf，并通过变温X射线粉末衍射（VTPXRD）、变温X射线单晶衍射（SCXRD）和热重分析（TGA）对其进行了表征。它是一种具有新拓扑结构的棒状MOF。在90 K时，它具有 Sohncke 空间群 622/622，在 300 K 和 500 K 时具有 622，具有高温稳定性，所有相均通过 SCXRD 表征，在 293 K 时还通过三维（3D）电子衍射表征。VTPXRD 表明在 620 K 后出现第三相，并在高达 770 K 时保持稳定。N₂ 的气体吸附等温线表明其比表面积为 231 m²/g，大致与晶体结构相符。二氧化碳吸附显示出一种门控效应，当 CO₂ 的负载量达到约 0.45 mmol/g 或每晶胞 1 个分子时，结构会打开。基于 SCXRD 数据，这被解释为基于螺旋桨状六齿 cpb 连接体的协同运动的柔韧性，这种运动通过 cpb 连接体的 π-π 堆积在分子内传递，并得到 LaO 配位球流动性的帮助。密度泛函理论（DFT）计算证实了这一点，计算得出手性相（622）为能量最小值，而完全外消旋相（6/mmm），具有对称的 cpb 连接体，代表了外消旋化过程中的一个鞍点。
