Name: Solvothermal Synthesis and Isolation of the Crystalline Material Al-CAU-60
Uploaded: 2023-10-06T14:20:00
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solvothermal synthesis and isolation of the crystalline material al-cau-60

Synthèse et découverte de MOF à base de phosphonates : une approche solvothermique

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.

Pleins feux sur l’auteur : Accélérer les découvertes en chimie des matériaux microporeux 

Découverte et optimisation de la synthèse de composés de cadre organométallique à base d’Al(III) phosphonate isoréticulaire à l’aide de méthodes à haut débit

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  

Synthèse solvothermique et isolement du matériau cristallin Al-CAU-60

Pour commencer, ajoutez l’agent de liaison H4PMP en tant que solide aux inserts en polytétrafluoroéthylène, ou PTFE, pour Al-CAU-60. Utilisez ensuite une pipette pour ajouter la solution de chlorure d’aluminium, l’eau déminéralisée et la solution d’additifs aux inserts. Insérez les disques dans la plaque d’échantillonnage et placez les inserts en PTFE remplis dans la plaque d’échantillonnage.Marquer la plaque de masse du réacteur de manière à permettre l’identification des inserts en PTFE et insérer la plaque d’échantillon avec les inserts en PTFE remplis dans la plaque de terre. Préparez deux feuilles de PTFE et placez-les sur les plaques d’échantillonnage en assurant une couverture complète. Assurez-vous que la feuille de PTFE est correctement positionnée et s’adapte à la plaque de tête à l’aide des broches de guidage.Ajoutez les vis et serrez-les à la main. Ensuite, scellez le réacteur initialement fermé à l’aide d’une presse mécanique ou hydraulique et serrez à nouveau les vis à la main. Placer le multiclave dans un four à convection forcée programmable.Pour Al-CAU-60, réglez le programme de temps de température affiché à l’écran. Démarrez ensuite le programme de temps de température. Retirez le multiclave du four.Une fois refroidi à température ambiante, placez-le sur une presse mécanique ou hydraulique et comprimez-le doucement jusqu’à ce que les vis puissent être desserrées à la main. Placez le multiclave à l’intérieur d’une hotte et retirez la plaque de tête du réacteur. Retirez ensuite les feuilles de PTFE et la plaque d’échantillonnage avec les inserts en PTFE de la plaque de terre du réacteur.Assemblez maintenant le bloc de filtration à haut débit en connectant le bloc filtrant à une pompe à vide via deux bouteilles de lavage. Placez deux papiers filtres entre deux tapis d’étanchéité en silicone avec les cavités correspondantes dans le bloc filtrant. Placez ensuite le bloc de remplissage en PTFE sur le dessus, en veillant à ce que les renfoncements appropriés correspondent aux tapis de plafond et au bloc filtrant.Serrez les couches à l’aide du cadre de serrage, qui est maintenu en place par six boulons à goujons. Pour bien sceller l’unité, utilisez des écrous d’aile sur les boulons de goujon et serrez-les à la main. Fermez les cavités du bloc de remplissage qui ne doivent pas être remplies de bouchons.Allumez la pompe à vide à membrane et réglez-la sur un mode dans lequel elle pompera au meilleur vide possible. Transférer le contenu des inserts en PTFE dans les puits désignés du bloc de remplissage à l’aide de pipettes jetables. Une fois que tous les inserts sont vides, jetez un second coup d’œil aux cristaux et isolez-les s’ils sont présents.Démontez soigneusement le bloc de filtration une fois tous les puits vidés. Une bibliothèque de produits est maintenant disponible sur papier filtre. Laissez-le sécher à l’air libre à l’intérieur de la hotte.Placez la bibliothèque de produits entre la plaque de base et la plaque de couverture pour caractériser ultérieurement le produit obtenu par diffraction des rayons X en poudre. Assurez-vous que les renfoncements et les plaques correspondent à l’emplacement des produits. Après avoir aligné les plaques, fixez-les avec deux vis.Insérez la bibliothèque de produits dans le porte-échantillon du diffractomètre. Placez délicatement le porte-échantillon chargé dans l’étage XY du diffractomètre. Fermez l’instrument avant de commencer les mesures.L’espace des paramètres est illustré dans cette figure. La synthèse avec l’hydroxyde de sodium comme additif est surlignée en bleu, la synthèse sans additif est surlignée en vert et la synthèse avec l’additif acide chlorhydrique est surlignée en orange et en rouge. Les rapports molaires des réactifs sont indiqués sur le côté gauche et sur le dessus.Le tracé empilé de tous les modèles de diffraction des rayons X de poudre mesurés est représenté sur cette figure. Ici, l’additif hydroxyde de sodium est surligné en bleu, aucun additif n’est surligné en vert et l’additif acide chlorhydrique est surligné en rouge. Les noms d’échantillons sont indiqués ici qui correspondent aux rapports molaires des matières premières utilisées dans le mélange de synthèse.Ces résultats suggèrent que les produits à faible cristallinité ont été obtenus à partir de la synthèse où le rapport molaire hydroxyde de sodium/aluminium était de un pour un, ou où aucun hydroxyde de sodium ou acide chlorhydrique n’était présent. Des produits de cristallinité plus élevée ont été obtenus à partir d’une synthèse où l’acide chlorhydrique a été utilisé comme additif.

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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 ...