setting up the post-synthetic ligand exchange (pse) process, exchanged mof isolation and washing process

Síntesis y caracterización de Zr-MOFs funcionalizados con triazol y tetrazol

Metal-organic frameworks (MOFs) are three-dimensional porous materials that are formed through coordination bonds between metal clusters and multi-topic organic ligands. MOFs have garnered significant attention due to their permanent porosity, low density, and ability to associate organic and inorganic components, which enables diverse applications1,2. Moreover, the vast range of metal nodes and strut organic linkers offer MOFs theoretically unlimited structural combinations. Even with identical framework structures, MOFs&#39; physical and chemical properties can be modified through ligand functionalization with chemical tags. This modification process offers a promising route to tailor the properties of MOFs for specific applications3,4,5,6,7,8,9.
Both the pre-functionalization of ligands prior to MOF synthesis and post-synthetic modification (PSM) of MOFs have been employed to introduce and/or modify functional groups in MOF ligands10,11. In particular, covalent PSMs have been extensively studied to introduce new functional groups and generate a range of MOFs with diverse functionalities12,13,14. For instance, UiO-66-NH2 can be converted to amide-functionalized UiO-66-AMs with different chain lengths (ranging from the shortest acetamide to the longest n-hexyl amide) through acylation reactions with appropriate acyl halides (such as acetyl chloride or n-hexanoyl chloride)15,16. This approach demonstrates the versatility of covalent PSMs to introduce specific functional groups onto MOF ligands, paving the way for a broad range of applications.
In addition to covalent PSMs, post-synthetic ligand exchange (PSE) is a promising strategy for modifying MOFs (Figure 1). Since MOFs are composed of coordination bonds between metals and ligands (such as carboxylates), these coordination bonds can be replaced with external ligands from a solution. Exposing MOFs to a solution containing the desired ligand with chemical tags can be incorporated into the MOFs via PSE17,18,19,20,21,22. Since the PSE process is accelerated by the existence of coordinative solvents, the phenomenon is also called solvent-assisted ligand exchange (SALE)23,24. This approach offers a flexible and facile method for functionalizing MOFs with a wide range of external ligands, enabling a broad spectrum of applications25,26,27,28,29.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65619/65619fig01.jpg" /> 
Figure 1: Synthesis of triazole and tetrazole-functionalized H2BDC ligands and preparation of triazole- and tetrazole-functionalized UiO-66 MOF through PSE. <a href="https://www.jove.com/files/ftp_upload/65619/65619fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The progress of the PSE process can be controlled by adjusting the ligand ratio, exchange temperature, and time. Notably, room temperature PSE can be employed to obtain functionalized MOFs by exchanging ligands from a solution into MOF solids20. The PSE strategy is particularly useful for introducing both thermally unstable functional groups (such as azido groups) and coordinative functional groups (such as phenol groups) into MOF structures18. In addition, the PSE strategy has been applied to various MOFs with metal and coordination bond variations. This exchange is a universal process in the chemistry of MOFs30,31,32. In this study, we present a detailed protocol for PSE to obtain functionalized MOFs from pristine, non-functionalized MOFs, and we provide a characterization strategy to confirm successful functionalization of the MOFs. This method demonstrates the versatility and convenience of PSE for modifying MOFs with diverse functional groups.
Tetrazole-containing benzene-1,4-dicarboxylic acid (H2BDC-Tetrazole)33, and triazole-containing benzene-1,4-dicarboxylic acid (H2BDC-Triazole) are synthesized as target ligands and utilized in the PSE of UiO-66 MOFs to obtain novel, coordination-free, triazole-containing MOFs. Both triazoles and tetrazoles possess acidic N-H protons on their heterocyclic rings and can coordinate with metal cations, thus enabling their use in constructing MOFs34,35. However, there are limited studies on incorporating coordination-free tetrazoles and triazoles into MOFs and related structures. In case of triazole-functionalized Zr-MOFs, UiO-68 type MOFs were investigated to photophysical properties through direct solvothermal synthesis with benzotriazole functionalities36. For tetrazole-functionalized Zr-MOFs, the mixed direct synthesis was employed33. These heterocycle-functionalized MOFs could provide potential coordinating sites in MOF pores for catalysis, selective molecular uptake by binding affinity, and energy-related applications, such as proton conduction in fuel cells.

Autor destacado: Funcionalización de marcos metal-orgánicos: avances, desafíos y el poder del intercambio de ligandos possintéticos 

Síntesis de estructuras metal-orgánicas basadas en Zr funcionalizadas con triazol y tetrazol a través del intercambio de ligandos postsintéticos

Watch this Scientific Journal Video about Setting up the Post-synthetic Ligand Exchange PSE Process, Exchanged MOF Isolation and Washing Process at JoVE.com

Setting up the Post-synthetic Ligand Exchange (PSE) Process, Exchanged MOF Isolation and Washing Process  

Configuración del proceso de intercambio de ligandos postsintéticos (PSE), aislamiento MOF intercambiado y proceso de lavado

Comience midiendo 23.3 miligramos de triazol H2BDC y colóquelo en el vial de centelleo. Para disolver el ligando H2BDC en la solución acuosa, transfiera 1,0 mililitros de la solución de hidróxido de potasio al 4% en el vial utilizando una pipeta de vidrio. A continuación, sonicar la mezcla hasta que todos los sólidos se disuelvan por completo.Añadir una solución molar de ácido clorhídrico en el vial que contiene descarboxilato y agitar hasta alcanzar un pH de 7. Añadir 33 miligramos de UiO-66 MOF al vial de centelleo. Luego incubar el vial con el MOF y el ligando a temperatura ambiente y 120 RPM en un agitador durante 24 horas.A continuación, aísle el MOF sólido de la mezcla por centrifugación a 1166 g durante cinco minutos. a temperatura ambiente. Agregue 10 mililitros de metanol fresco al MOF sólido obtenido y agite el vial, creando una mezcla heterogénea para disolver cualquier ligando BDC inalterado restante.Aísle el sólido una vez más centrifugando la mezcla a 1166 g durante cinco minutos a temperatura ambiente y séquela.

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Chemistry

Setting up the Post-synthetic Ligand Exchange (PSE) Process, Exchanged MOF Isolation and Washing Process

312 vistas. Comience midiendo 23.3 miligramos de triazol H2BDC y colóquelo en el vial de centelleo. Para disolver el ligando H2BDC en la solución acuosa, transfiera 1,0 mililitros de la solución de hidróxido de potasio al 4% en el vial utilizando una pipeta de vidrio. A continuación, sonicar la mezcla hasta que todos los sólidos se disuelvan por completo.Añadir una solución molar de ácido clorhídrico en el vial que contiene descarboxilato y agitar hasta alcanzar un pH de 7. Añadir 33 mi...

Video: Setting up the Post-synthetic Ligand Exchange (PSE) Process, Exchanged MOF Isolation and Washing Process  

Synthesis of Triazole and Tetrazole-Functionalized Zr-Based Metal-Organic Frameworks Through Post-Synthetic Ligand Exchange

Metal-organic frameworks (MOFs) are a class of porous materials that are formed through coordination bonds between metal clusters and organic ligands. Given their coordinative nature, the organic ligands and strut framework can be readily removed from the MOF and/or exchanged with other coordinative molecules. By introducing target ligands to MOF-containing solutions, functionalized MOFs can be obtained with new chemical tags via a process called post-synthetic ligand exchange (PSE). PSE is a straightforward and practical approach that enables the preparation of a wide range of MOFs with new chemical tags via a solid-solution equilibrium process. Furthermore, PSE can be performed at room temperature, allowing the incorporation of thermally unstable ligands into MOFs. In this work, we demonstrate the practicality of PSE by using heterocyclic triazole- and tetrazole-containing ligands to functionalize a Zr-based MOF (UiO-66; UiO = University of Oslo). After digestion, the functionalized MOFs are characterized via various techniques, including powder X-ray diffraction and nuclear magnetic resonance spectroscopy.

Post-synthetic ligand exchange (PSE) is a versatile and powerful tool for installing functional groups into metal-organic frameworks (MOFs). Exposing MOFs to solutions containing triazole- and tetrazole-functionalized ligands can incorporate these heterocyclic moieties into Zr-MOFs through PSE processes.

Metal-organic frameworks (MOFs) are a class of porous materials that are formed through coordination bonds between metal clusters and organic ligands. ...