Name: Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60
Uploaded: 2023-10-06T14:20:00
Description: Watch this Scientific Journal Video about Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60 at JoVE.com

solvothermal synthesis and isolation of the crystalline material al-cau-60

基于膦酸盐的 MOF 的合成和发现：一种溶热方法

Metal-organic frameworks (MOFs) are porous, crystalline compounds whose structures consist of metal-containing nodes, like metal ions or metal-oxygen clusters, which are connected by organic molecules (linkers)1. By varying the metal-containing nodes as well as the linker, a variety of compounds can be obtained that exhibit a wide range of properties and therefore have potential applications in different fields1.
The stability of a material is important for its application1,2,3. Therefore, MOFs containing tri- or tetravalent metal ions, such as Al3+, Cr3+, Ti4+, or Zr4+, with carboxylate2 or phosphonate4 linker molecules have been the focus of many investigations5,6,7. In addition to the direct synthesis of stable MOFs, the enhancement of stability through post-synthetic modifications as well as the formation of composites is a field of interest2. Phosphonate-based MOFs have been less often reported compared to carboxylate-based MOFs8. One reason is the higher coordination flexibility of the CPO32- group compared to the -CO2- group, which often leads to the formation of dense structures and greater structural diversity8,9,10,11. In addition, phosphonic acids often must be synthesized, as they are rarely available on the market. While some metal phosphonates exhibit exceptional chemical stability10, systematic access to isoreticular metal phosphonate MOFs, which allows the tuning of properties, is still a topic of high relevance12,13. Different strategies for the synthesis of porous metal phosphonates have been investigated, such as incorporating defects into otherwise dense layers, for example, by partially replacing phosphonate with phosphate ligands4,14. However, as defective structures are poorly reproducible, and the pores are not uniform, other strategies have been developed. In recent years, the use of sterically demanding or orthogonalized phosphonic acids as linker molecules have emerged as a suitable strategy for the preparation of porous metal phosphonates4,8,10,11,13,15,16,17,18. However, a universal synthesis route for porous metal phosphonates has not yet been discovered. As a result, the synthesis of metal phosphonates is often a process of trial and error, requiring the investigation of many synthesis parameters.
The parameter space of a reaction system includes chemical and process parameters and can be vast19. It consists of parameters such as the type of starting material (metal salt), molar ratios of starting materials, additives for pH adjustment, modulators, type of solvent, solvent mixtures, volumes, reaction temperatures, times, etc.19,20. A moderate number of parameter variations can easily result in several hundred individual reactions, making a carefully considered synthesis plan and well-chosen parameter space necessary. For example, a simple study using six molar ratios of the linker to the metal (e.g., M:L = 1:1, 1:2, ... to 1:6) and four different concentrations of an additive and keeping the other parameter constant, leads already to 6 x 4 = 24 experiments. Using four concentrations, five solvents, and three reaction temperatures would necessitate carrying out the 24 experiments 60 times, resulting in 1,440 individual reactions.
High-throughput (HT) methods are based on the concepts of miniaturization, parallelization, and automation, to varying degrees depending on the scientific question being addressed19,20. As such, they can be used to accelerate the investigation of multi-parameter systems and are an ideal tool for the discovery of new compounds, as well as synthesis optimization19,20. HT methods have been used successfully in different fields, ranging from drug discovery to materials science20. They have also been used for the investigation of porous materials such as zeolites and MOFs in solvothermal reactions, as recently summarized20. A typical HT workflow for solvothermal synthesis consists of six steps (Figure 1)19,20,21: a) selection of the parameter space of interest (i.e., the design of experiment [DOE]), which can be done manually or by using software; b) dosing of the reagents into the vessels; c) solvothermal synthesis; d) isolation and workup; e) characterization, which is typically done with powder X-ray diffraction (PXRD); and f) data evaluation, which is followed by step one again.
Parallelization and miniaturization are achieved in solvothermal reactions through the use of multiclaves, often based on the well-established 96-well plate format most commonly used in biochemistry and pharmacy19,20,22,23. Various reactor designs have been reported and several groups have constructed their own reactors19,20. Reactor choice depends on the chemical system of interest, especially the reaction temperature, (autogenous) pressure, and reactor stability19,20. For example, in a systematic study of zeolitic imidazolate frameworks (ZIFs), Banerjee et al.25 used the 96-well glass plate format to perform over 9600 reactions24. For reactions under solvothermal conditions, customized polytetrafluoroethylene (PTFE) blocks, or multiclaves with 24 or 48 individual PTFE inserts, have been described among others by the Stock group19,20.&#160;They are routinely employed, for example, in the synthesis of metal carboxylates and phosphonates. As such, Reinsch et al.25 reported the advantages of the methodology in the field of porous aluminum MOFs25. The in-house made HT reactor systems (Figure 2), which allow 24 or 48 reactions to be studied simultaneously, contain PTFE inserts with a total volume of 2.655 mL and 0.404 mL, respectively (Figure 2A,B). Usually, no more than 1 mL or 0.1 mL, respectively, is used. While these reactors are used in conventional ovens, microwave-assisted heating using SiC blocks and small glass vessels has also been reported26.
The automation of studies leads to time savings and improved reproducibility, as influence of the human factor is minimized20. The degree to which automation has been used varies strongly19,20. Fully automated commercial systems, including pipetting20 or weighting capabilities20, are known. A recent example is the use of a liquid-handling robot to study ZrMOFs, reported by the group of Rosseinsky27. Automated analysis can be performed by PXRD using a diffractometer equipped with an xy stage. In another example, a plate reader was used to screen solid-state catalysts, mainly MOFs, for HT screening of nerve agent degradation28. Samples can be characterized in a single run without the need for manual sample or position changes. Automation does not eliminate human error, but it reduces the possibility of its occurring19,20.
Ideally, all steps in a HT workflow should be adapted in terms of parallelization, miniaturization, and automation to eliminate possible bottlenecks and maximize efficiency. However, if it is not possible to establish a HT workflow in its entirety, it may be helpful to adopt selected steps/tools for one&#39;s own research. The use of multiclaves for 24 reactions is particularly useful here. The technical drawings of the in-house made equipment used in this study (as well as others) are published for the first time and can be found in Supplementary File 1, Supplementary File 2, Supplementary File 3, and Supplementary File 4.

作者聚焦：加速微孔材料化学的发现 

基于高通量方法的等网状Al（III）膦酸盐基金属有机骨架化合物的发现与合成优化

I see the periodic table as a huge playground, and in our research, we focus on the synthesis of new materials, porous materials, such as this here. That's a structural model, and we see holes in the framework. and that can be used to store molecules or also to separate molecules based on the size of these.And in addition to that kind of studies, we also develop new reactor systems in order to accelerate the discovery process. The current experimental challenges are to further accelerate the synthesis and characterization process with additional high throughput instrumentation, such as high throughput absorption characterization device. The lack of detail in publications regarding the synthesis and characterization procedure affecting reproducibility is a well-known problem in chemistry.By providing a thorough description of our method and setup, we aim to encourage other groups to adopt the described methodology, thereby increasing the reproducibility of experimental studies. We do not know what the future will bring since we work on the discovery of new materials, and we never know what kind of properties these materials will have. Nevertheless, I think that the use of linker molecules from renewable feedstocks will play a major role.And regarding the application, the use in sensing and the separation of gas molecules will be very important.

Watch this Scientific Journal Video about Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60 at JoVE.com

Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60  

溶剂热合成与分离结晶材料Al-CAU-60

首先，将接头H4PMP作为固体添加到Al-CAU-60的聚四氟乙烯或PTFE插入件中。然后使用移液管将氯化铝溶液、软化水和添加剂溶液添加到插入物中。将圆盘插入样品板，然后将填充的PTFE插件放入样品板中。以允许识别PTFE插件的方式标记反应器的接地板，并将带有填充PTFE插件的样品板插入接地板。准备两张PTFE片并将它们放在样品板上，以确保完全覆盖。确保PTFE板正确定位并使用导销安装顶板。添加螺钉并用手拧紧。然后在机械或液压机的帮助下密封最初封闭的反应器，并再次用手拧紧螺钉。将多盘釜放入可编程强制对流烤箱中。对于Al-CAU-60，设置屏幕上显示的温度时间程序。然后启动温度时间程序。从烤箱中取出多盘。冷却到室温后，将其放在机械或液压机上并轻轻压缩，直到可以用手松开螺钉。将多盘釜放入通风橱内，然后拆下反应器的顶板。然后从反应器的接地板上取下PTFE板和带有PTFE插件的样品板。现在，通过两个清洗瓶将过滤器块连接到真空泵来组装高通量过滤块。将两张滤纸放在两个硅胶密封垫之间，过滤器块中带有相应的凹槽。然后将 PTFE 填充块放在顶部，确保适当的凹槽与天花板垫和过滤器块相匹配。使用夹紧框架拧紧各层，该夹紧架由六个双头螺栓固定到位。要正确密封设备，请在双头螺栓上使用翼形螺母并用手拧紧。关闭填充块中不加塞的凹槽。打开膜真空泵并将其设置为将泵送至最佳真空的模式。用一次性移液器将PTFE插入物的内容物转移到填充块的指定孔中。一旦所有插入物都为空，再次寻找晶体并隔离它们（如果存在）。一旦所有孔都排干，请小心地拆卸过滤块。产品库现在以滤纸形式提供。让它在通风橱内风干。将产品库放置在底板和盖板之间，以便稍后通过粉末X射线衍射表征获得的产品。确保凹槽和板与产品位置匹配。对齐板后，用两个螺钉固定它们。将产品库插入衍射仪的样品架中。小心地将装载的样品架放入衍射仪的XY平台中。在开始测量之前关闭仪器。参数空间如下图所示。以氢氧化钠为添加剂的合成以蓝色突出显示，无添加剂的合成以绿色突出显示，用添加剂盐酸合成以橙色和红色突出显示。试剂的摩尔比显示在左侧和顶部。该图显示了所有测量的粉末X射线衍射图的堆叠图。在这里，添加剂氢氧化钠以蓝色突出显示，没有添加剂以绿色突出显示，添加剂盐酸以红色突出显示。此处显示的样品名称与合成混合物中使用的起始材料的摩尔比相关。这些结果表明，合成中得到的结晶度低的产物是氢氧化钠与铝的摩尔比为1：1，或不存在氢氧化钠或盐酸。从盐酸作为添加剂的合成中获得结晶度较高的产品。

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JoVE Journal

Chemistry

Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60

Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods

High-throughput (HT) methods are an important tool for the fast and efficient screening of synthesis parameters and the discovery of new materials. This ...