Name: organic structure-directing agent-free synthesis for *bea-type zeolite membrane
Uploaded: 2020-02-22T12:30:00
Description: Watch this Scientific Journal Video about Organic Structure-directing Agent-free Synthesis for *BEA-type Zeolite Membrane at JoVE.com

This work was partially supported by JST CREST (Japan Science and Technology agency, Create REvolutionary technological seeds for Science and Technology innovation program), Grant Number JPMJCR1324, Japan.

1. Support preparation
<ol>
	<li>Pretreatment of support
	<ol>
		<li>Cut out a 3 cm long tubular porous &#945;-Al2O3 support (see Table of Materials).</li>
		<li>Wash the support with distilled water for 10 min. After that, wash the support with acetone for 10 min. Repeat this washing process 2x. 
		NOTE: Do not touch the outer surface of a support after the washing step. No other treatment was carried out (e.g., sonication, and rubbing by sandpaper, etc.)</li>
		<li>Dry the ...

<ol>
	<li>Ghaffour, N., Missimer, T. M., Amy, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technical+review+and+evaluation+of+the+economics+of+water+desalination:+Current+and+future+challenges+for+better+water+supply+sustainability.">Technical review and evaluation of the economics of water desalination: Current and future challenges for better water supply sustainability.</a> Desalination. 309, 197-207 (2013).</li><li>Hickenbottom, K. 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=Forward+osmosis+treatment+of+drilling+mud+and+fracturing+wastewater+from+oil+and+gas+operations.">Forward osmosis treatment of drilling mud and fracturing wastewater from oil and gas operations.</a> Desalination. 312, 60-66 (2013).</li><li>Kanezashi, M., Shazwani, W. N., Yoshioka, T., Tsuru, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separation+of+propylene/propane+binary+mixtures+by+bis(triethoxysilyl)+methane+(BTESM)-derived+silica+membranes+fabricated+at+different+calcination+temperatures.">Separation of propylene/propane binary mixtures by bis(triethoxysilyl) methane (BTESM)-derived silica membranes fabricated at different calcination temperatures.</a> Journal of Membrane Science. 415-416, 478-485 (2012).</li><li>Xu, L., Rungta, M., Koros, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrimid&#174;+derived+carbon+molecular+sieve+hollow+fiber+membranes+for+ethylene/ethane+separation.">Matrimid&#174; derived carbon molecular sieve hollow fiber membranes for ethylene/ethane separation.</a> Journal of Membrane Science. 380, 138-147 (2011).</li><li>Morigami, Y., Kondo, M., Abe, J., Kita, H., Okamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+first+large-scale+pervaporation+plant+using+tubular-type+module+with+zeolite+NaA+membrane.">The first large-scale pervaporation plant using tubular-type module with zeolite NaA membrane.</a> Separation and Purification Technology. 25, 251-260 (2001).</li><li>Kondo, M., Komori, M., Kita, H., Okamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tubular-type+pervaporation+module+with+zeolite+NaA+membrane.">Tubular-type pervaporation module with zeolite NaA membrane.</a> Journal of Membrane Science. 133, 133-141 (1997).</li><li>Hoof, V. V., Dotremont, C., Buekenhoudt, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+Mitsui+NaA+type+zeolite+membranes+for+the+dehydration+of+organic+solvents+in+comparison+with+commercial+polymeric+pervaporation+membranes.">Performance of Mitsui NaA type zeolite membranes for the dehydration of organic solvents in comparison with commercial polymeric pervaporation membranes.</a> Separation and Purification Technology. 48, 304-309 (2006).</li><li>Kamimura, Y., Chaikittisilp, W., Itabashi, K., Shimojima, A., Okubo, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Factors+in+the+Seed-Assisted+Synthesis+of+Zeolite+Beta+and+"Green+Beta"+from+OSDA-Free+Na+-Aluminosilicate+Gels.">Critical Factors in the Seed-Assisted Synthesis of Zeolite Beta and "Green Beta" from OSDA-Free Na+-Aluminosilicate Gels.</a> Chemistry An Asian Journal. 5, 2182-2191 (2010).</li><li>Majano, G., Delmotte, L., Valtchev, V., Mintova, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Al-Rich+Zeolite+Beta+by+Seeding+in+the+Absence+of+Organic+Template.">Al-Rich Zeolite Beta by Seeding in the Absence of Organic Template.</a> Chemistry of Materials. 21, 4184-4191 (2009).</li><li>Sakai, 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=Formation+process+of+*BEA-type+zeolite+membrane+under+OSDA-free+conditions+and+its+separation+property.">Formation process of *BEA-type zeolite membrane under OSDA-free conditions and its separation property.</a> Microporous and Mesoporous Materials. 284, 360-365 (2019).</li><li>Choi, 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=Grain+Boundary+Defect+Elimination+in+a+Zeolite+Membrane+by+Rapid+Thermal+Processing.">Grain Boundary Defect Elimination in a Zeolite Membrane by Rapid Thermal Processing.</a> Science. 325, 590-593 (2009).</li><li>Dong, J., Lin, Y. S., Hu, M. Z. -. C., Peascoe, R. A., Payzant, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Template-removal-associated+microstructural+development+of+porous-ceramic-supported+MFI+zeolite+membranes.">Template-removal-associated microstructural development of porous-ceramic-supported MFI zeolite membranes.</a> Microporous and Mesoporous Materials. 34, 241-253 (2000).</li><li>Schoeman, B. J., Babouchkina, E., Mintova, S., Valtchev, V. P., Sterte, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Synthesis+of+Discrete+Colloidal+Crystals+of+Zeolite+Beta+and+their+Application+in+the+Preparation+of+Thin+Microporous+Films.">The Synthesis of Discrete Colloidal Crystals of Zeolite Beta and their Application in the Preparation of Thin Microporous Films.</a> Journal of Porous Materials. 8, 13-22 (2001).</li><li>Sasaki, 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=Polytype+distributions+in+low-defect+zeolite+beta+crystals+synthesized+without+an+organic+structure-directing+agent.">Polytype distributions in low-defect zeolite beta crystals synthesized without an organic structure-directing agent.</a> Microporous and Mesoporous Materials. 225, 210-215 (2016).</li></ol>

There are many kinds of Si and Al sources for zeolite synthesis. However, we cannot change raw materials for preparation of this *BEA-type membrane. If raw materials are changed, the phase of zeolite crystallized and/or growth rate may be changed.
Glass beakers cannot be used for synthesis gel preparation because the synthesis gel has high alkalinity. Bottles and beakers made of polyethylene, polypropylene, and Teflon can be used instead.
To prepare a higher quality...

Membrane separation has drawn attention as novel-energy saving separation process. Many types of membranes have been developed for the past decades. Polymeric membranes have been widely used for gas separation, creating drinkable water from sea water1, and wastewater treatment2.
Inorganic membrane materials like silica3, carbon molecular sieve4, and zeolite have advantages for thermal, chemical, and mechanical strength compared with polymeric membranes. Therefore, inorganic membranes tend to be used under more severe conditions, such as hydrocarbon separation in petroleum and petrochemical fields.
Zeolite has unique adsorption and molecular sieving properties due to its micropores. In addition, zeolite has a cation exchange ability that contributes to control zeolite&#39;s adsorption and molecular sieving properties. The number of cations in zeolite is determined by the Si/Al ratio of the zeolite structure. Therefore, the size of the micropores and Si/Al ratio are key characteristics that determine the permeation and separation properties of zeolite membranes. For these reasons, zeolite is a promising type of inorganic membrane material. Some zeolite membranes have already been commercialized for dehydration of organic solvents due to their hydrophilicity and molecular sieving properties5,6,7,8.
*BEA-type zeolite is an interesting membrane material because of its large pore size and wide Si/Al range. *BEA has generally been prepared by hydrothermal treatment using tetraethylammonium hydroxide as organic structure-directing agent (OSDA). However, the synthesis method using OSDA has economic and environmental disadvantages. Recently, a seed-assisted method for *BEA synthesis without using OSDA was reported9,10.
*BEA is an intergrowth crystal of polymorph A and polymorph B. Thereby, &#34;*&#34; represents an intergrowth material. At present, no bulk materials consisting only of polymorph A or B is known.
We have successfully prepared *BEA membranes without using OSDA by a modified seed-assisted method11. The *BEA membrane had very few defects and exhibited high separation performance for hydrocarbons due to its molecular sieving effect. It is well known that calcination to remove OSDA after synthesis is one of the most common causes of defect formation in zeolite membranes12,13. Our *BEA membrane prepared without using OSDA showed good separation performance possibly because this calcination step was skipped.
The preparation of zeolite membranes is based on know-how and experience accumulated in the laboratory. Consequently, it is difficult for a beginner to synthesize zeolite membranes alone. Here, we would like to share a protocol for *BEA membrane preparation as a reference for everyone who wants to start membrane synthesis.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>a-Al2O3 support</td>
			<td>Noritake Co. Ltd.</td>
			<td>NS-1</td>
			<td>Average pore size, 150 nm; Outer diameter, 10 mm; Innar diameter, 7 mm</td>
		</tr>
		<tr>
			<td>Colloidal silica</td>
			<td>Nissan Chemical</td>
			<td>ST-S</td>
			<td>SiO2 30.5%, Na2O 0.44%, H2O 69.1%</td>
		</tr>
		<tr>
			<td>Mesh filter (PTFE membrane)</td>
			<td>Omnipore</td>
			<td>JGWP04700</td>
			<td>Pore size, 200 nm</td>
		</tr>
		<tr>
			<td>NaAl2O</td>
			<td>Kanto Chemical</td>
			<td>34095-01</td>
			<td>Na2O 31.0-35.0%; Al2O3 34.0-39.0%</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Kanto Chemical</td>
			<td>37184-00</td>
			<td>97%</td>
		</tr>
		<tr>
			<td>Tetraethylammonium hydroxide</td>
			<td>Sigma-Aldrich</td>
			<td>302929-500ML</td>
			<td>35 wt% solution</td>
		</tr>
	</tbody>
</table>

organic structure-directing agent-free synthesis for *bea-type zeolite membrane

Membrane separation has drawn attention as a novel-energy saving separation process. Zeolite membranes have great potential for hydrocarbon separation in petroleum and petrochemical fields because of their high thermal, chemical, and mechanical strength. A *BEA-type zeolite is an interesting membrane material because of its large pore size and wide Si/Al range. This manuscript presents a protocol for *BEA membrane preparation by a secondary growth method that does not use an organic structure-directing agent (OSDA). The preparation protocol consists of four steps: pretreatment of support, seed preparation, dip-coating, and membrane crystallization. First, the *BEA seed crystal is prepared by conventional hydrothermal synthesis using OSDA. The synthesized seed crystal is loaded on the outer surface of a 3 cm long tubular &#945;-Al2O3 support by a dip-coating method. The loaded seed layer is prepared with the secondary growth method using a hydrothermal treatment at 393 K for 7 days without using OSDA. A *BEA membrane having very few defects is successfully obtained. The seed preparation and dip-coating steps strongly affect the membrane quality.

Figure 1 shows the preparation procedure of the *BEA seed crystal. Figure 2 shows the X-ray diffraction (XRD) pattern of synthesized *BEA seed crystal. Typical strong reflection peaks of (101) and (302) around 2q = 7.7 and 22.1&#176; appeared. In addition, no obvious reflection peaks other than the *BEA-type zeolite were observed. These results showed that the pure phase of *BEA zeolite was successfully synthesized.
A typical...

Watch this Scientific Journal Video about Organic Structure-directing Agent-free Synthesis for *BEA-type Zeolite Membrane at JoVE.com

Organic Structure-directing Agent-free Synthesis for *BEA-type Zeolite Membrane

A *BEA seed crystal was loaded on a porous &#945;-Al2O3 support by the dip-coating method, and hydrothermally grown without using an organic structure-directing agent. A *BEA-type zeolite membrane having very few defects was successfully prepared by the secondary growth method.

Membrane separation has drawn attention as a novel-energy saving separation process. Zeolite membranes have great potential for hydrocarbon separation in ...

The preparation of zeolite membrane is based on knowhow and experience accumulated in the laboratory. We would like to share this protocol as a reference for everyone who wants to start membrane synthesis. This method enables us to obtain a BEA membrane, having a good separation performance without using organic structure-directing-agent.Operationally, equipment for zeolite membrane preparation are quite unique. This video can help you to run how to prepare zeolite membranes. Demonstrating the procedure will be Yuto Tsuzuki, a graduate student from our laboratory.To begin, cut out a three centimeter long tubular porous alpha aluminum oxide support. Wash the support with distilled water for 10 minutes. After that, wash the support with acetone for 10 minutes.Repeat this washing process twice. Use a beaker to transfer the washed support into an incubator to dry at 110 degrees Celsius overnight. In the morning, measure the weight of the support piece.First, add 26.2 grams of colloidal silica and 8.39 grams of tetraethylammonium hydroxide into a 250ml bottle made of polypropylene. Stir the mixture using a magnetic stirrer for 20 minutes in a 50 degrees Celsius water bath. After that, stir the mixture using a magnetic stirrer for 20 minutes at room temperature.Then, add 8.39 grams of tetraethylammonium hydroxide, 5.79 grams of distilled water, 1.08 grams of sodium hydroxide, and 0.186 grams of sodium aluminate into a Teflon beaker. Stir the mixture, by using a magnetic stirrer for 20 minutes at room temperature. Next, add solution B to solution A in a 250ml bottle.The mixture of solution A and B becomes milky. Cap the bottle, and shake it vigorously by hand for 5 minutes. After that, stir the mixture, using a magnetic stirrer, for 24 hours at room temperature.The next day, the gel obtained is the synthesis gel, with the final composition of 24 sodium oxide to one aluminum oxide to 200 silicon dioxide to 69 tetraethylammonium hydroxide to 2905 water. To perform crystallization, pour the synthesis gel into a Teflon-lined autoclave. Place the autoclave in an air oven at 100 degrees Celsius for seven days.Then, quench the autoclave with flowing water for 30 minutes. Remove the white sediment in the autoclave by a vacuum filtration apparatus with a 200 nanometer mesh filter. Wash the white sediment with 200ml of boiling water to remove amorphous and uncrystallized materials.Dry the washed sediment in a dish at 110 degrees Celsius overnight. The dried sediment is the seed crystal. To prepare BEA seed slurry, add 0.5g of the seed crystals into 100ml of distilled water in a bottle.Carry out sonication of the seed slurry for one hour to disperse the seed crystals. Then, fix a tubular support with a stainless steel rod, using Teflon tape, to plug the inside of the support. Pour the seed slurry into a glass tube, with a 19ml diameter.Immerse the fixed support into the poured seed slurry and wait for one minute. After that, withdraw the seed slurry vertically at approximately 3 centimeters per second through the silicon cap. Repeat the dip-coating process one more time.After dip-coating, dry the support at 70 degrees Celsius for two hours. Next, calsign the dip-coated support at 538 degrees Celsius for six hours with the increase and decrease temperature rates at 50 degrees Celsius per minute. This removes OSDA and chemically binds the seeds onto the support surface.After calcination, measure the weight of the support. Calculate the amount of seed crystal loaded, as the difference in the support weight, before and after dip-coating. Add 92.9 grams of distilled water, 9.39 grams of sodium hydroxide, and 1.15 grams of sodium aluminate into a 250ml polypropylene bottle.Stir the mixture using a magnetic stirrer for 30 minutes at 60 degrees Celsius in a water bath. After that, add 81.6 grams of colloidal silica in a step-wise manner of 1 drop per second into the mixture. Stir the mixture for another four hours at 60 degrees Celsius in a water bath.The gel obtained is the synthesis gel, having a final composition of 30 sodium oxide to one aluminum oxide to 100 silicon oxide to 2000 water. Then, pour the synthesis gel into a Teflon-lined autoclave in which the seeded support is placed vertically. Place the autoclave in an air oven at 120 degrees Celsius for seven days for crystallization.After crystallization, quench the autoclave with flowing water for 30 minutes. Wash the support with the membrane in boiling water for eight hours and dry overnight. This is the BEA membrane.After drying, measure the weight of the prepared support with membrane. Calculate the weight of the membrane by the difference in support weight before and after crystallization. The X-ray defraction pattern of synthesized BEA seed crystal, shows typical strong reflection peaks, around two theta, equaling 7.7 and 22.1 degrees.In addition, no obvious reflection peaks, other than the BEA type zeolite, were observed. Spherical seed crystals were observed through the FE-SEM image of the synthesized seed crystal and their size was uniformly approximately 200 nanometers. The X-ray defraction pattern of synthesized BEA membrane shows the same peaks observed in the seed crystals.In addition, reflection peaks of alpha aluminum oxide with two theta equaling 26, 35.5 and 38 degrees were observed. FE-SEM image of the synthesized membrane reveals that the crystals had truncated octohedral morphology, uniformly covering the support surface. There are many kinds of zircon and aluminum sources for zeolite synthesis.However, please do not change your materials for preparation of this BEA-type membrane.

organic-structure-directing-agent-free-synthesis-for-bea-type-zeolite

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Chemistry

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

Fluorescence sensors are powerful tools in life science. Here we describe a methodology to synthesize and use dendrimer-based fluorescent sensors to measure pH in living cells and in vivo. The dendritic scaffold enhances the properties of conjugated fluorescent dyes leading to improved sensing properties.

The development of  fluorescent indicators represented a revolution for life sciences. Genetically  encoded and synthetic fluorophores with sensing ...

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 ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

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A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Synthesis of a Water-soluble Metal&#8211;Organic Complex Array

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as Ru(II), Pt(II), and Rh(III). The compound, named as a water-soluble metal-organic complex array (WSMOCA), is obtained through 1) the conventional solution-chemistry-based preparation of the corresponding metal complex monomers having a 9-fluorenylmethyloxycarbonyl (Fmoc)-protected amino acid moiety and 2) their sequential coupling together with other water-soluble organic building units on the surface-functionalized polymeric resin by following the procedures originally developed for the solid-phase synthesis of polypeptides, with proper modifications. Traces of reactions determined by mass spectrometric analysis at the representative coupling steps in stage 2 confirm the selective construction of a predetermined sequence of metal centers along with the peptide backbone. The WSMOCA cleaved from the resin at the end of stage 2 has a certain level of solubility in aqueous media dependent on the pH value and/or salt content, which is useful for the purification of the compound.

Synthesis of a Water-soluble Metal&amp;#8211;Organic Complex Array

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We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as ...

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Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

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Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of &amp;#945;,&amp;#946;-Unsaturated Compounds and Alkynes

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Benzannulation reactions represent an effective protocol to transform acyclic building blocks into structurally varied benzene skeletons. Despite ...

Construction of Cyclic Cell-Penetrating Peptides for Enhanced Penetration of Biological Barriers

Cancer has been a grand challenge in global health. However, the complex tumor microenvironment generally limits the access of therapeutics to deeper tumor cells, leading to tumor recurrence. To conquer the limited penetration of biological barriers, cell-penetrating peptides (CPPs) have been discovered with excellent membrane translocation ability and have emerged as useful molecular transporters for delivering various cargoes into cells. However, conventional linear CPPs generally show compromised proteolytic stability, which limits their permeability across biological barriers. Thus, the development of novel molecular transporters that can penetrate biological barriers and exhibit enhanced proteolytic stability is highly desired to promote drug delivery efficiency in biomedical applications. We have previously synthesized a panel of short cyclic CPPs with aromatic crosslinks, which exhibited superior permeability in cancer cells and tissues compared to their linear counterparts. Here, a concise protocol is described for the synthesis of the fluorescently labeled cyclic polyarginine R8 peptide and its linear counterpart, as well as key steps for investigating their cell permeability.

This protocol describes the synthesis of cyclic cell-penetrating peptides with aromatic cross-links and the evaluation of their permeability across biological barriers.

Cancer has been a grand challenge in global health. However, the complex tumor microenvironment generally limits the access of therapeutics to deeper ...

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.

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 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, ...