This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Ministry of Science and the ICP (No. NRF-2020R1A2C3008908 and 2016R1A5A1009405).

CAUTION: Before conducting the experiment, thoroughly read and comprehend the material safety data sheets (MSDSs) of the chemicals used in this protocol. Wear appropriate protective gear. Utilize a fume hood for all synthesis procedures.
1. Synthesis of cubic HKUST-1
NOTE: The experimental procedure was based on a previously reported method14. For core-shell synthesis, 10 pots were synthesized at a time. Therefore, 10 pots of the solution were prepared at one time and then distributed.
<ol>
	<li>Add 4.72 g (20.3 mmol) of Cu(NO3)2&#183;2.5H2O to a 100 mL Erlenmeyer flask and dissolve in 60 mL of a deionized (D.I.) water and N,N-dimethylformamide (DMF) mixture (1:1, v/v), swirling the flask manually.</li>
	<li>Add 1.76 g (8.38 mmol) of 1,3,5-benzenetricarboxylic acid (H3BTC) and 22 mL of ethanol to a 50 mL Erlenmeyer flask, and stir the solution at 90 &#176;C on a heated hotplate until dissolution.</li>
	<li>Place 6 mL of solution 1.1 (solution prepared in step 1.1) into each 20 mL vial.</li>
	<li>While stirring and heating, add 2.2 mL of solution 1.2 (solution prepared in step 1.2) to a vial containing solution 1.1, and immediately add 12 mL of acetic acid. 
	NOTE: 12 mL of acetic acid should be added at once.</li>
	<li>Close the lid of the vial and place it in a convection oven heated to 55 &#176;C for 60 h.</li>
	<li>After 60 h, quickly decant the mother liquor and wash the crystals by adding and removing fresh ethanol (sufficient volume to fill the vial) three times using a dropper.</li>
	<li>For core-shell synthesis, store the cubic crystals of HKUST-1 in a 20 mL vial full of N,N-diethylformamide (DEF) solvent.</li>
</ol>
2. Synthesis of octahedral HKUST-1
<ol>
	<li>Combine 4.72 g (20.3 mmol) of Cu(NO3)2&#183;2.5H2O and 30 mL of D.I. water in a 100 mL Erlenmeyer flask, swirl the flask to dissolve the solid, and add 30 mL of DMF after dissolving.</li>
	<li>Add 3.60 g (17.1 mmol) of H3BTC to 45 mL of ethanol in a 100 mL Erlenmeyer flask, and stir the solution at 90 &#176;C on a heated hotplate until dissolution.</li>
	<li>Place 6 mL of solution 2.1 (solution prepared in step 2.1) into each 50 mL vial.</li>
	<li>While stirring and heating, add 4.5 mL of solution 2.2 (solution prepared in step 2.2) to a vial containing solution 2.1, and immediately add 12 mL of acetic acid. 
	NOTE: 12 mL of acetic acid should be added at once without dividing.</li>
	<li>Close the lid of the vial and place in a convection oven heated to 55 &#176;C for 22 h.</li>
	<li>After 22 h, quickly decant the mother liquor and wash the crystals by adding and removing fresh ethanol three times using a dropper.</li>
	<li>For core-shell synthesis, store octahedral crystals of HKUST-1 in a 20 mL vial full of DEF solvent.</li>
</ol>
3. Synthesis of HKUST-1@MOF-5 core-shell
NOTE: The core-shell synthesis method is the same for both octahedral and cubic HKUST-1.
<ol>
	<li>Dissolve 0.760 g (2.55 mmol) of Zn(NO3)2&#183;6H2O and 0.132 g (0.795 mmol) of terephthalic acid&#160;separately in 10 mL of DEF in a 20 mL vial, using a sonicator.</li>
	<li>Mix the total volume of both solutions in a 35 mL glass jar.</li>
	<li>Quickly weigh the filtered HKUST-1 crystals (5 mg), and place the crystals in the glass jar containing the mixed solution. To prevent static electricity, use a filter paper to weigh. Seal the jar tightly with a silicon cap.</li>
	<li>After spreading the HKUST-1 crystals well on the bottom of the glass jar, place the jar in a convection oven and heat at 85 &#176;C for 36 h.</li>
	<li>After 36 h, quickly decant the mother liquor and wash the resultant crystals by adding and removing fresh ethanol three times using a dropper.</li>
</ol>
4. Solvent exchange of HKUST-1@MOF-5 core-shell
<ol>
	<li>Discard the storing solvent, DEF, from the vial containing HKUST-1@MOF-5.</li>
	<li>Add dichloromethane (DCM) (volume to fill the vial) into the vial and shake it manually for effective exchange.</li>
	<li>Change the DCM solvent 3-4 times every 4 h.</li>
</ol>

<ol>
	<li>Liu, C., Wang, J., Wan, J., Yu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MOF-on-MOF+hybrids:+Synthesis+and+applications.">MOF-on-MOF hybrids: Synthesis and applications.</a> Coordination Chemistry Reviews. 432, 213743 (2021).</li><li>Hong, D. H., Shim, H. S., Ha, J., Moon, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MOF-on-MOF+architectures:+Applications+in+separation,+catalysis,+and+sensing.">MOF-on-MOF architectures: Applications in separation, catalysis, and sensing.</a> Bulletin of the Korean Chemical Society. 42 (7), 956-969 (2021).</li><li>Ha, J., Moon, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+MOF-on-MOF+architectures+in+the+context+of+interfacial+lattice+matching.">Synthesis of MOF-on-MOF architectures in the context of interfacial lattice matching.</a> CrystEngComm. 23 (12), 2337-2354 (2021).</li><li>Lee, S., Oh, S., Oh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atypical+hybrid+metal-organic+frameworks+(MOFs):+A+combinative+process+for+MOF-on-MOF+growth,+etching,+and+structure+transformation.">Atypical hybrid metal-organic frameworks (MOFs): A combinative process for MOF-on-MOF growth, etching, and structure transformation.</a> Angewandte Chemie International Edition. 59 (3), 1327-1333 (2020).</li><li>Li, T., Sullivan, J. E., Rosi, N. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+preparation+of+a+core-shell+metal-organic+framework+for+selective+CO2+capture.">Design and preparation of a core-shell metal-organic framework for selective CO2 capture.</a> Journal of the American Chemical Society. 135 (27), 9984-9987 (2013).</li><li>Cho, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interface-sensitized+chemiresistor:+Integrated+conductive+and+porous+metal-organic+frameworks.">Interface-sensitized chemiresistor: Integrated conductive and porous metal-organic frameworks.</a> Chemical Engineering Journal. 449, 137780 (2022).</li><li>Faustini, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+approach+toward+continuous+and+ultrafast+synthesis+of+metal-organic+framework+crystals+and+hetero+structures+in+confined+microdroplets.">Microfluidic approach toward continuous and ultrafast synthesis of metal-organic framework crystals and hetero structures in confined microdroplets.</a> Journal of the American Chemical Society. 135 (39), 14619-14626 (2013).</li><li>Boone, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Designing+optimal+core-shell+MOFs+for+direct+air+capture.">Designing optimal core-shell MOFs for direct air capture.</a> Nanoscale. 14 (43), 16085-16096 (2022).</li><li>Yang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+synthesis+of+hybrid+core-shell+metal-organic+frameworks.">One-step synthesis of hybrid core-shell metal-organic frameworks.</a> Angewandte Chemie Edition. 57 (15), 3927-3932 (2018).</li><li>Kim, S., Lee, J., Jeoung, S., Moon, H. R., Kim, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-deactivated+core-shell+metal-organic+framework+by+simple+ligand+exchange+for+enhanced+size+discrimination+in+aerobic+oxidation+of+alcohols.">Surface-deactivated core-shell metal-organic framework by simple ligand exchange for enhanced size discrimination in aerobic oxidation of alcohols.</a> Chemistry. 26 (34), 7568-7572 (2020).</li><li>Koh, K., Wong-Foy, A. G., Matzger, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MOF@MOF:+microporous+core-shell+architectures.">MOF@MOF: microporous core-shell architectures.</a> Chemical Communications. (41), 6162-6164 (2009).</li><li>Luo, T. -. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multivariate+stratified+metal-organic+frameworks:+diversification+using+domain+building+blocks.">Multivariate stratified metal-organic frameworks: diversification using domain building blocks.</a> Journal of the American Chemical Society. 141 (5), 2161-2168 (2019).</li><li>Tang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+conversion+of+core-shell+metal-organic+frameworks:+a+new+method+for+selectively+functionalized+nanoporous+hybrid+carbon.">Thermal conversion of core-shell metal-organic frameworks: a new method for selectively functionalized nanoporous hybrid carbon.</a> Journal of the American Chemical Society. 137 (4), 1572-1580 (2015).</li><li>Kwon, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer-aided+discovery+of+connected+metal-organic+frameworks.">Computer-aided discovery of connected metal-organic frameworks.</a> Nature Communications. 10 (1), 3620 (2019).</li><li>Yuan, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stable+metal-organic+frameworks:+Design,+synthesis,+and+applications.">Stable metal-organic frameworks: Design, synthesis, and applications.</a> Advanced Materials. 30 (37), 1704303 (2018).</li><li>Feng, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uncovering+two+principles+of+multivariate+hierarchical+metal-organic+framework+synthesis+via+retrosynthetic+design.">Uncovering two principles of multivariate hierarchical metal-organic framework synthesis via retrosynthetic design.</a> ACS Central Science. 4 (12), 1719-1726 (2018).</li><li>Furukawa, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneously+hybridized+porous+coordination+polymer+crystals:+fabrication+of+heterometallic+core-shell+single+crystals+with+an+in-plane+rotational+epitaxial+relationship.">Heterogeneously hybridized porous coordination polymer crystals: fabrication of heterometallic core-shell single crystals with an in-plane rotational epitaxial relationship.</a> Angewandte Chemie International Edition. 48 (10), 1766-1770 (2009).</li><li>Guo, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+core-shell+ZIF-67@Co-MOF-74+catalyst+with+controllable+shell+thickness+and+enhanced+photocatalytic+activity+for+visible+light-driven+water+oxidation.">Synthesis of core-shell ZIF-67@Co-MOF-74 catalyst with controllable shell thickness and enhanced photocatalytic activity for visible light-driven water oxidation.</a> CrystEngComm. 20 (47), 7659-7665 (2018).</li></ol>

The authors have nothing to disclose.

In this protocol, cubic- and octahedral-shaped HKUST-1 crystals were synthesized, referring to a previously reported method14. For the synthesis of HKUST-1, H3BTC solution was added while heating and stirring the solution of Cu(NO3)2&#183;2.5H2O to prevent the precipitation of H3BTC as the temperature decreased. Subsequently, acetic acid was added immediately to prevent fast nucleation and ensure the growth of a large single crystal. As soon a...

MOF-on-MOF is a type of hybrid material comprising two or more different metal-organic frameworks (MOFs)1,2,3. Owing to the various possible combinations of constituents and structures, MOF-on-MOFs provide varied novel composites with remarkable properties, which have not been achieved in single MOFs, offering great potential in many applications4,5,6. Among the various types of MOF-on-MOFs, a core-shell structure in which one MOF surrounds another has the advantage of optimizing the characteristics of both MOFs by designing a more elaborated system5,6,7,8,9,10. Although many examples of core-shell MOFs have been reported, single-crystalline core-shell MOFs are uncommon and have been successfully synthesized mostly from isostructural pairs11,12,13. Moreover, single crystalline core-shell MOFs constructed using non-isostructural MOF pairs have seldom been reported, owing to the difficulty in selecting a pair that exhibit a well-matched crystal lattice3. To achieve seamless interfaces of the single-crystalline core-shell MOFs, a well-matched crystal lattice and chemical connection points between the two MOFs are critical. Here, the chemical connection point is defined as the spatial location where the linker/metal node of one MOF meets the metal node/linker of the second MOF through a coordination bond. In our previous reports14, the computational algorithm was used to screen for optimal targets for synthesis, and six suggested MOF pairs were successfully synthesized.
This paper demonstrates a protocol for synthesizing a single-crystalline core-shell MOF of an HKUST-1 and MOF-5 pair, which are iconic MOFs composed of totally different constituents and topologies. HKUST-1 was chosen as the core because it is more stable than MOF-5 under solvothermal reaction conditions15,16. Furthermore, because the chemical connection points between MOF-5 and HKUST-1 are well-matched in both the (001) and (111) planes, cubic and octahedral HKUST-1 crystals in which each plane is exposed were used as the core MOF. This protocol suggests the possibility of synthesizing more diverse core-shell MOFs with lattice-matching.

<table><tbody><tr><td>Acetic acid</td><td>DAEJUNG</td><td>1002-4400</td><td>Synthesis of HKUST-1 (protocol steps 1.4, and 2.4)</td></tr><tr><td>Copper(II) nitrate hemipentahydrate</td><td>Sigma Aldrich</td><td>223395-100G</td><td>Synthesis of HKUST-1 (protocol steps 1.1, and 2.1)</td></tr><tr><td>D2 PHASER</td><td>Bruker AXS</td><td>DOC-B88-EXS017-V3</td><td>Powder X-ray diffraction&amp;nbsp;</td></tr><tr><td>Digital stirring hot plate</td><td>Thermo Scientific</td><td>SP131320-33Q</td><td>Hotplate for heating and stirring (protocol steps 1.2, and 2.2)</td></tr><tr><td>Direct-Q3UV water purification system</td><td>MILLIPORE</td><td>ZRQSVP030</td><td>Deionized water (protocol steps 1.1, and 2.1)</td></tr><tr><td>Ethyl alcohol anhydrous, 99.9%</td><td>DAEJUNG</td><td>4023-4100</td><td>Synthesis of HKUST-1 (protocol steps 1.2, and 2.2)</td></tr><tr><td>Forced convection oven (OF-02P/PW)</td><td>JEIO TECH</td><td>EDA8136</td><td>Oven for heating reaction (protocol steps 1.5, 2.5, and 3.4)</td></tr><tr><td>N,N-diethylformamide</td><td>TCI</td><td>D0506</td><td>Synthesis of HKUST-1@MOF-5 (protocol step 3.1)</td></tr><tr><td>N,N&#039;-Dimethylformamide</td><td>DAEJUNG</td><td>6057-4400</td><td>Synthesis of HKUST-1 (protocol steps 1.1, and 2.1)</td></tr><tr><td>Stereo microscopes</td><td>Nikon</td><td>SMZ745T</td><td>Optical Microscope&amp;nbsp;</td></tr><tr><td>Terephthalic acid</td><td>Sigma Aldrich</td><td>185361-500G</td><td>Synthesis of HKUST-1@MOF-5 (protocol step 3.1)</td></tr><tr><td>Trimesic acid</td><td>Sigma Aldrich</td><td>482749-100G</td><td>Synthesis of HKUST-1 (protocol steps 1.2, and 2.2)</td></tr><tr><td>Ultrasonic cleaner</td><td>BRANSONIC</td><td>CPX-952-338R</td><td>Sonicator with bath for dissolving solution (protocol step 3.1)</td></tr><tr><td>Zinc nitrate hexahydrate</td><td>Sigma Aldrich</td><td>228737-100G</td><td>Synthesis of HKUST-1@MOF-5 (protocol step 3.1)</td></tr></tbody></table>

synthesis of single-crystalline core-shell metal-organic frameworks

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. However, the synthesis of single-crystalline core-shell MOFs is very challenging, and thus a limited number of examples have been reported. Here, we suggest a method of synthesizing single-crystalline HKUST-1@MOF-5 core-shells, which is HKUST-1 at the center of MOF-5. Through the computational algorithm, this pair of MOFs was predicted to have the matched lattice parameters and chemical connection points at the interface. To construct the core-shell structure, we prepared the octahedral- and cubic-shaped HKUST-1 crystals as a core MOF, in which the (111) and (001) facets were mainly exposed, respectively. Via the sequential reaction, the MOF-5 shell was well-grown on the exposed surface, showing a seamless connect interface, which resulted in the successful synthesis of single-crystalline HKUST-1@MOF-5. Their pure phase formation was proved by optical microscopic images and powder X-ray diffraction (PXRD) patterns. This method presents the potential of and insights into the single-crystalline core-shell synthesis with different kinds of MOFs.

According to the two calculated structures of the HKUST-1@MOF-5 core-shell system14, in both the (001) and (111) planes, the Cu sites from the metal nodes of HKUST-1 and the oxygen sites from the carboxylates of MOF-5 are well-matched as the chemical connection points at the interface between the two MOFs (Figure 1). Therefore, cubic and octahedral crystals of HKUST-1, in which the (001) and (111) planes are exposed, respectively, were synthesized as the core MOFs for...

Watch this Scientific Journal Video about Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks at JoVE.com

Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks

Here, we demonstrate a protocol for the two-step synthesis of single-crystalline core-shells using a non-isostructural metal-organic framework (MOF) pair, HKUST-1 and MOF-5, which have well-matched crystal lattices.

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. ...

synthesis-of-single-crystalline-core-shell-metal-organic-frameworks

Research

JoVE Journal

Chemistry

2.4K Views.  Ulsan National Institute of Science and Technology (UNIST). Ons protocol suggereert de mogelijkheid om diverse rooster-matched, core-shell MOF's te synthetiseren, en kan worden uitgebreid tot meerdere paren. Niet-isostructureel MOF-paar kan worden geïntegreerd in enkelkristallijne kern-schil MOF's met een naadloze interface door de solvothermische reactie. Door gebruik te maken van MOF's met verschillende pro-milieus, kunnen kern-shell-materialen voor efficiënte gasscheiding of katalytische toepassing worden ontworpen en gesynthetiseerd.Voeg ...

Video: Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Microfluidic-based Synthesis of Covalent Organic Frameworks (COFs): A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The first COF was reported in 2005 with much effort centered on the establishment of new synthetic routes for its preparation. To date, most available synthetic methods for COF synthesis are based on bulk mixing under solvothermal conditions. Therefore, there is increasing interest in developing systematic protocols for COF synthesis that provide for fine control over reaction conditions and improve COF processability on surfaces, which is essential for their use in practical applications. Herein, we present a novel microfluidic-based method for COF synthesis where the reaction between two constituent building blocks, 1,3,5-benzenetricarbaldehyde (BTCA) and 1,3,5-tris(4-aminophenyl)benzene (TAPB), takes place under controlled diffusion conditions and at room temperature. Using such an approach yields sponge-like, crystalline fibers of a COF material, hereafter called MF-COF. The mechanical properties of MF-COF and the dynamic nature of the approach allow the continuous production of MF-COF fibers and their direct printing onto surfaces. The general method opens new potential applications requiring advanced printing of 2D or 3D COF structures on flexible or rigid surfaces.

Microfluidic-based Synthesis of Covalent Organic Frameworks COFs: A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface

We present a novel microfluidic-based method for synthesis of covalent organic frameworks (COFs). We demonstrate how this approach can be used to produce continuous COF fibers, and also 2D or 3D COF structures on surfaces.

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The ...

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and non-porous supports (polymer, ceramic, metal, carbon, and graphene). We developed a novel crystallization technique, which is termed the ENACT approach: the electrophoretic nuclei assembly for the crystallization of highly intergrown thin films (ENACT). This approach allows for a high density of heterogeneous nucleation of MOFs on a chosen substrate via the electrophoretic deposition (EPD) directly from the precursor sol. The growth of well-packed MOF nuclei leads to a highly intergrown polycrystalline MOF film. We show that this simple approach can be used for the synthesis of thin, intergrown zeolite imidazole framework (ZIF)-7 and ZIF-8 films. The resulting 500 nm-thick ZIF-8 membranes show a considerably high H2 permeance (8.3 x 10-6 mol m-2 s-1 Pa-1) and ideal gas selectivities (7.3 for H2/CO2, 15.5 for H2/N2, 16.2 for H2/CH4, and 2655 for H2/C3H8). An attractive performance for C3H6/C3H8 separation is also achieved (a C3H6 permeance of 9.9 x 10-8 mol m-2 s-1 Pa-1 and a C3H6/C3H8 ideal selectivity of 31.6 at 25 &#176;C). Overall, the ENACT process, owing to its simplicity, can be extended to synthesize intergrown thin films of a wide range of nanoporous crystalline materials.

A simple, reproducible, and versatile approach for the synthesis of intergrown, polycrystalline metal-organic framework membranes on a wide range of unmodified porous and non-porous supports is presented.

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

Synthesis of Low-Valent MOFs from Multitopic Phosphine Linkers

Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers

Metal-organic frameworks (MOFs) are the subject of intense research focus due to their potential applications in gas storage and separation, biomedicine, energy, and catalysis. Recently, low-valent MOFs (LVMOFs) have been explored for their potential use as heterogeneous catalysts, and multitopic phosphine linkers have been shown to be a useful building block for the formation of LVMOFs. However, the synthesis of LVMOFs using phosphine linkers requires conditions that are distinct from those in the majority of the MOF synthetic literature, including the exclusion of air and water and the use of unconventional modulators and solvents, making it somewhat more challenging to access these materials. This work serves as a general tutorial for the synthesis of LVMOFs with phosphine linkers, including information on the following: 1) the judicious choice of the metal precursor, modulator, and solvent; 2) the experimental procedures, air-free techniques, and required equipment; 3) the proper storage and handling of the resultant LVMOFs; and 4) useful characterization methods for these materials. The intention of this report is to lower the barrier to this new subfield of MOF research and facilitate advancements toward novel catalytic materials.

Author Spotlight: Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers  

Here, we describe a protocol for the synthesis of low-valent metal-organic frameworks (LVMOFs) from low-valent metals and multitopic phosphine linkers under air-free conditions. The resulting materials have potential applications as heterogeneous catalyst mimics of low-valent metal-based homogeneous catalysts.

Metal-organic frameworks (MOFs) are the subject of intense research focus due to their potential applications in gas storage and separation, biomedicine, ...

Triazole and Tetrazole Functionalized Zr-MOFs Synthesis and Characterization

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.

Author Spotlight: Functionalizing Metal-Organic Frameworks: Advancements, Challenges, and the Power of Post-Synthetic Ligand Exchange 

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. ...

Synthesis and Discovery of Phosphonate-Based MOFs: A Solvothermal Approach

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 manuscript describes the synthesis of metal-organic frameworks (MOFs) from solution using an HT reactor system, resulting in the discovery of various phosphonate-based MOFs of the composition [Al2H12-x(PMP)3]Clx&#8729;6H2O (H4PMP = N,N &#39;-piperazine bis(methylenephosphonic acid)) for x = 4, 6, denoted as Al-CAU-60-xHCl, containing trivalent aluminum ions. This was accomplished under solvothermal reaction conditions by systematically screening the impact of the molar ratio of the linker to the metal and the pH of the reaction mixture on the product formation. The protocol for the HT investigation includes six steps: a) synthesis planning (DOE = design of&#160;experiment) within the HT methodology, b) dosing and working with in-house developed HT reactors, c) solvothermal synthesis, d) synthesis workup using in-house developed filtration blocks, e) characterization by HT powder X-ray diffraction, and f) evaluation of the data. The HT methodology was first used to study the influence of acidity on the product formation, leading to the discovery of Al-CAU-60&#8729;xHCl (x = 4 or 6).

Author Spotlight: Accelerating Discovery in Microporous Material Chemistry 

The targeted synthesis of new metal-organic frameworks (MOFs) is difficult, and their discovery depends on the knowledge and creativity of the chemist. High-throughput methods allow complex synthetic parameter fields to be explored quickly and efficiently, accelerating the process of finding crystalline compounds and identifying synthetic and structural trends.

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

Self-Assembly of Polymer-Grafted Metal Organic Framework Monolayers

Synthesis and Characterization of Self-Assembled Metal-Organic Framework Monolayers Using Polymer-Coated Particles

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. Attempts to enhance the utility of MOFs have involved the preparation of various composites, including polymer-grafted MOFs. By directly grafting polymers to the external surface of MOFs, issues of incompatibility between polymers and MOFs can be overcome. Polymer brushes grafted from the surface of MOFs can serve to stabilize the MOF while enabling particle assembly into self-assembled metal-organic framework monolayers (SAMMs) via polymer-polymer interactions.
Control over the chemical composition and molecular weight of the grafted polymer can allow for tuning of the SAMM characteristics. In this work, instructions are provided on how to immobilize a chain transfer agent (CTA) onto the surface of the MOF UiO-66 (UiO = Universitetet i Oslo). The CTA&#160;serves as initiation sites for the growth of polymers. Once polymer chains are grown from the MOF surface, the formation of SAMMs is achieved through self-assembly at an air-water interface. The resulting SAMMs are characterized and shown to be freestanding by scanning electron microscopy imaging. The methods presented in this paper are expected to make the preparation of SAMMs more accessible to the research community and thereby expand their potential use as a&#160;MOF-polymer composite.

Author Spotlight: Exploring Self-Assembled MOF-Polymer Composites

A protocol for the synthesis and characterization of self-assembled metal-organic framework monolayers is provided using polymer-grafted, metal-organic framework (MOF) crystals. The procedure shows that polymer-grafted MOF particles can be self-assembled at an air-water interface resulting in well-formed, free-standing, monolayer structures as evidenced by scanning electron microscopy imaging.

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. ...

Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks

Samenvatting

Meer video's verkennen