This work was financially supported by Grant-in-Aid for Scienti&#64257;c Research B (24350072, 25288036) and Grant-in-Aid for Scienti&#64257;c Research on Innovative Areas (24108723) from MEXT and JSPS, Japan. T.S. acknowledges Grant-in-Aid for JSPS Fellows (25763), the GCOE Program of Osaka University and Grants for Excellent Graduate Schools, MEXT, Japan.

1. Preparation of Single Crystals Composed of Primary Ammonium Triphenylacetates
<ol>
	<li>Prepare organic salts, primary ammonium triphenylacetates (Figure 1a).
	<ol>
		<li>Dissolve triphenylacetic acid (TPAA, 0.10 g, 0.35 mmol) and primary amine: n-butylamine (nBu, 2.5 x 10-2 g, 0.35 mmol), isobutylamine (isoBu, 2.5 x 10-2 g, 0.35 mmol), t-butylamine (tBu, 2.5 x 10-2 g, 0.35 mmol), or t-amylamine (tAm, 3.0 x 10-2 g, 0.35 mmol), together in methanol (20 ml) in TPAA : amine = 1:1 molar ratio for preparation of binary organic salts.</li>
		<li>In the case of ternary organic salts, dissolve TPAA (0.10 g, 0.35 mmol) and two kinds of primary amines: nBu (1.3 x 10-2 g, 0.17 mmol)-tBu (1.3 x 10-2 g, 0.17 mmol), nBu (1.3 x 10-2 g, 0.17 mmol)-tAm (1.5 x 10-2 g, 0.17 mmol), isoBu (1.3 x 10-2 g, 0.17 mmol)-tBu (1.3 x 10-2 g, 0.17 mmol), or isoBu (1.3 x 10-2 g, 0.17 mmol)-tAm (1.5 x 10-2 g, 0.17 mmol), together in methanol (20 ml) in TPAA : amine-1 : amine-2 = 2:1:1.</li>
		<li>Evaporate all of the solutions by rotary evaporators (40 &#176;C, 200 Torr), affording organic salts: TPAA-nBu, TPAA-isoBu, TPAA-tBu, TPAA-tAm, TPAA-nBu-tBu, TPAA-nBu-tAm, TPAA-isoBu-tBu, and TPAA-isoBu-tAm.</li>
	</ol>
	</li>
	<li>Prepare single crystals composed of supramolecular clusters.
	<ol>
		<li>Dissolve each of the organic salts (5.0 mg) in a glass vial in toluene (0.30 ml) as a non-polar good solvent, which was selected because the supramolecular clusters are preferably constructed in non-polar environment. For the organic salts TPAA-tBu, TPAA-tAm, TPAA-isoBu-tBu, and TPAA-isoBu-tAm, heat toluene up to 40 &#176;C to dissolve them.</li>
		<li>Add hexane: 0.5 ml, 0.5 ml, 0.5 ml, 2 ml, 2 ml, 1 ml, and 0.5 ml, to the solution of the organic salts of TPAA-nBu, TPAA-isoBu, TPAA-tAm, TPAA-nBu-tBu, TPAA-nBu-tAm, TPAA-isoBu-tBu, and TPAA-isoBu-tAm, respectively, as a poor solvent to decrease solubility of the organic salt, except for the solution of the organic salt TPAA-tBu.</li>
		<li>Keep the solution stable at room temperature in the glass vial, affording single crystals within a day.</li>
	</ol>
	</li>
	<li>Confirm the organic salt formation by Fourier transform infrared (FT-IR) spectra35,36.
	<ol>
		<li>Mix the single crystals of the organic salt with potassium bromide (KBr) in 1:100 weight ratio.</li>
		<li>Grind the mixture by an agate mortar until it becomes homogeneous powdered mixture.</li>
		<li>Fill up a round die (diameter: 5 mm) with the powdered mixture and make a pellet by pressing it with a pellet press.</li>
		<li>Put the pellet into a FT-IR spectrometer, and perform measurements (cumulative number: 16, resolution: 1 cm-1).</li>
	</ol>
	</li>
</ol>
2. Crystallographic Studies
<ol>
	<li>Pick up a high quality single crystal of the organic salt TPAA-tAm from the glass vial into paraffin on a glass plate. The crystal looks uniform under a stereomicroscope, meaning the crystal is not assemblies of multiple crystals but a single crystal,&#160; and has a crystal size around 0.3 to 1 mm without cracks.</li>
	<li>Put the single crystal on a loop.</li>
	<li>Set the loop with the single crystal in single crystal X-ray diffraction equipment.</li>
	<li>Select a collimator: 0.3, 0.5, 0.8, or 1 mm, depending on the maximum size of the single crystal.</li>
	<li>Start a preparatory measurement of single crystal X-ray diffraction to collect X-ray diffraction patterns37,38 from the single crystal using the single crystal X-ray diffraction equipment (radiation source: graphite monochromated CuK&#945; (&#955; = 1.54187 &#197;), exposure time: 30 sec (determine based on the crystal size), detector: e.g. imaging plate, crystal-to-detector distance: 127.40 mm, temperature: 213.1 K, number of frames: 3).</li>
	<li>Determine possible crystal parameters and set conditions: exposure time, angles of X-ray exposure: &#969;, &#967;, and &#966;, and number of frames, for following measurement based on the result of the above preparatory measurement.</li>
	<li>Start a regular measurement of single crystal X-ray diffraction to collect X-ray diffraction patterns37,38 from the single crystals using the single crystal X-ray diffraction equipment under the conditions (radiation source: graphite monochromated CuK&#945; (&#955; = 1.54187 &#197;), detector: e.g. imaging plate, crystal-to-detector distance: 127.40 mm, temperature: 213.1 K).</li>
	<li>Solve a crystal structure from the diffraction patterns by direct methods, SIR200439 or SHELXS9740, and refine by a full-matrix least-squares procedure using all the observed reflections based on F2. Refine all the non-hydrogen atoms with anisotropic displacement parameters, and place the hydrogen atoms in idealized positions with isotropic displacement parameters relative to the connected non-hydrogen atoms and not refined. Perform these calculations using a software such as the CrystalStructure41.</li>
	<li>Repeat the procedures from steps 2.1 to 2.8 with some modifications of the conditions: collimator size, exposure time of X-ray for preparatory measurements and regular measurements, and angles of X-ray exposure: &#969;, &#967;, and &#966;, and number of frames, for the single crystals of organic salts: TPAA-nBu-tBu, TPAA-nBu-tAm, TPAA-isoBu-tBu, and TPAA-isoBu-tAm to reveal their crystal structures.</li>
	<li>Retrieve crystal structures of the organic salts: TPAA-nBu (refcode: MIBTOH)22, TPAA-isoBu (refcode: GIVFEX)24, and TPAA-tBu (refcode: GIVFIB)23, from Cambridge Structural Database42 using a software, Conquest43, or a request form44.</li>
	<li>Investigate the supramolecular clusters in the crystal structures by computer graphics using software such as Mercury45-48&#160;and Pymol49; Determine point group symmetries of hydrogen-bonding patterns in the supramolecular clusters by comparing the obtained patterns with the previously classified ones (Figure 1b) and chiral conformations of the trityl groups as &#923; or &#916; (Figure 1a).</li>
	<li>Characterize polyhedral features of the supramolecular clusters in each of the crystal structures of the organic salts.
	<ol>
		<li>Delete all of the atoms in the supramolecular clusters except for carbon and nitrogen atoms of the component carboxylate anions and ammonium cations.</li>
		<li>Make bonds between the carbon and nitrogen atoms of which original carboxylate and ammonium cations are connected by hydrogen bonds.</li>
		<li>Measure distances between carbon-carbon and nitrogen-nitrogen atoms, and set boundaries for making further bonds (5.3 and 4.1 &#197; for carbon-carbon and nitrogen-nitrogen distances, respectively, in this study).</li>
		<li>Make further bonds between carbon-carbon and nitrogen-nitrogen atoms of which distances are less than 5.4 and 4.2 &#197;, respectively.</li>
		<li>Determine the resulting polyhedrons of the organic salts: TPAA-isoBu, TPAA-tBu, TPAA-tAm, TPAA-isoBu-tBu, and TPAA-isoBu-tAm, as trans-bicapped octahedron (tbo), triangular dodecahedron (td), td, td, and td, respectively, by considering rotational axis (C3 or C2) as well as numbers of sides of the polyhedrons.</li>
		<li>Make additional bonds to the resulting polyhedrons of the organic salts: TPAA-nBu, TPAA-nBu-tBu, and TPAA-nBu-tAm, by considering number of sides, symmetry elements, and intermolecular interactions in the supramolecular clusters because they have less sides than ideal ones: td, tbo, and square antiprism (sa).</li>
		<li>Determine the polyhedron of the TPAA-nBu salt as sa by making two addition bonds due to its C2 symmetry and 14 original bonds. Determine the other polyhedrons of the organic salts TPAA-nBu-tBu and TPAA-nBu-tAm as td based on their C2 symmetry and &#34;bands&#34; of the trityl groups around the supramolecular cluster. Namely, the trityl groups in the supramolecular clusters of the ternary organic salts form &#34;bands&#34; by intermeshing their three phenyl rings and the polyhedron td has sides connecting four acids (Figure 1c(ii)), meaning they have similar structural features.</li>
	</ol>
	</li>
</ol>

The authors have nothing to disclose.

A series of supramolecular clusters with closed hydrogen-bonding networks was successfully constructed and characterized from viewpoints of chirality and polyhedral features using organic salts of TPAA, which has a trityl group, and various kinds and combinations of primary amines. In this method, the critical steps are introduction of a molecule with a bulky trityl group and recrystallization of organic salts composed of the molecule and counter ions from non-polar solvents. This is because the supramolecular cluster ha...

Supramolecules are fascinating and important research targets because of their unique functions, such as construction of supramolecular architectures, sensing of ions and/or molecules, and chiral separations, originated from their molecular recognition abilities using flexible non-covalent bonds1-11. In molecular recognitions, symmetry of supramolecular assemblies is one of the most important factors. Despite the importance, it is still difficult to design supramolecules with desired symmetries due to flexibility in numbers and kinds of the components as well as angles and distances of non-covalent bonds.
Clarification of correlations between symmetries of supramolecules and their components based on systematical studies is useful strategy to achieve construction of desired supramolecules. For this purpose, supramolecular clusters were selected as research targets because they are composed of limited number of components and are evaluable theoretically12-14. However, contrary to metal complexes, there are a limited number of reports constructing supramolecular clusters due to low stability of non-covalent bonds for sustaining the supramolecular structures15,16. This low stability also becomes a problem in obtaining a series of supramolecular assemblies which have the same kinds of structures. In this study, charge-assisted hydrogen bonds of organic salts, which are one of the most robust non-covalent bonds17-20, are mainly employed to construct specific supramolecular assemblies preferentially21-32. It is also noteworthy that organic salts are composed of acids and bases, and thus numerous kinds of organic salts are easily obtained just by mixing different combinations of acids and bases. Especially, organic salts are useful for systematic studies because combinations of a specific component with various kinds of counter ions result in the same types of supramolecular assemblies. Therefore, it is possible to compare structural differences of supramolecular assemblies based on kinds of counter ions.
In previous works, supramolecules with 0-dimensional (0-D), 1-dimensional (1-D), and 2-dimensional (2-D) hydrogen-bonding networks by primary ammonium carboxylates were confirmed and characterized from a viewpoint of chirality32. These multi-dimensional supramolecules are important research targets in hierarchical crystal design27 as well as applications exploiting their dimensionality. In addition, characterization of the hydrogen-bonding networks would give important knowledge about roles of biological molecules because all of amino acids have ammonium and carboxylic groups. Providing guidelines to obtain these supramolecules separately gives them further opportunities in applications. In these supramolecules, construction of supramolecular clusters with 0-D hydrogen-bonding networks is relatively difficult as demonstrated in statistical study28. However, after clarification of factors for constructing the supramolecular clusters, they were selectively constructed, and a series of the supramolecular clusters was obtained21-25,32. These works make it possible to conduct systematical symmetric study on the supramolecular clusters to clarify component-dependent symmetric characteristics of the supramolecular clusters. For this purpose, the supramolecular clusters of primary ammonium triphenylacetates have interesting features, that is, their topological variety in hydrogen-bonding networks24,32, which would reflect their symmetric features as well as chiral conformations of the component trityl groups (Figure 1a and 1b). Here methodologies for constructing a series of supramolecular clusters using primary ammonium triphenylacetates and for characterizing symmetric features of the supramolecular clusters are demonstrated. Keys for the construction of the supramolecular clusters are introduction of bulky trityl groups and recrystallization of the organic salts from non-polar solvents. Binary and ternary primary ammonium triphenylacetates were prepared for the construction of the supramolecular clusters. Crystallographic studies from viewpoints of topologies of the hydrogen-bonding networks24,32, topographies (conformations) of trityl groups33,34, and molecular arrangements as analogues of octacoordinated polyhedrons12 (Figure 1c) revealed component-dependent symmetric characteristics of the supramolecular clusters25.

<table>
	<tbody>
		<tr>
			<td>Triphenylacetic acid</td>
			<td>Aldrich</td>
			<td>T81205-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Butylamine</td>
			<td>TCI</td>
			<td>B0707</td>
			<td></td>
		</tr>
		<tr>
			<td>Isobutylamine</td>
			<td>TCI</td>
			<td>I0095</td>
			<td></td>
		</tr>
		<tr>
			<td>tert-Butylamine</td>
			<td>TCI</td>
			<td>B0709</td>
			<td></td>
		</tr>
		<tr>
			<td>tert-Amylamine</td>
			<td>TCI</td>
			<td>A1002</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Wako</td>
			<td>131-01826</td>
			<td>hazardous substance</td>
		</tr>
		<tr>
			<td>Toluene</td>
			<td>Wako</td>
			<td>204-01866</td>
			<td>hazardous substance</td>
		</tr>
		<tr>
			<td>Hexane</td>
			<td>Wako</td>
			<td>085-00416</td>
			<td></td>
		</tr>
		<tr>
			<td>KBr</td>
			<td>Wako</td>
			<td>165-17111</td>
			<td></td>
		</tr>
	</tbody>
</table>

construction and systematical symmetric studies of a series of supramolecular clusters with binary or ternary ammonium triphenylacetates

Functions of clusters in nano or sub-nano scale significantly depend on not only kinds of their components but also arrangements, or symmetry, of their components. Therefore, the arrangements in the clusters have been precisely characterized, especially for metal complexes. Contrary to this, characterizations of molecular arrangements in supramolecular clusters composed of organic molecules are limited to a few cases. This is because construction of the supramolecular clusters, especially obtaining a series of the supramolecular clusters, is difficult due to low stability of non-covalent bonds compare to covalent bonds. From this viewpoint, utilization of organic salts is one of the most useful strategies. A series of the supramolecules could be constructed by combinations of a specific organic molecule with various counter ions. Especially, primary ammonium carboxylates are suitable as typical examples of supramolecules because various kinds of carboxylic acids and primary amines are commercially available, and it is easy to change their combinations. Previously, it was demonstrated that primary ammonium triphenylacetates using various kinds of primary amines specifically construct supramolecular clusters, which are composed of four ammoniums and four triphenylacetates assembled by charge-assisted hydrogen bonds, in crystals obtained from non-polar solvents. This study demonstrates an application of the specific construction of the supramolecular clusters as a strategy to conduct systematical symmetric study for clarification of correlations between molecular arrangements in supramolecules and kinds and numbers of their components. In the same way with binary salts composed of triphenylacetates and one kind of primary ammoniums, ternary organic salts composed of triphenylacetates and two kinds of ammoniums construct the supramolecular clusters, affording a series of the supramolecular clusters with various kinds and numbers of the components.

Organic salt formation of TPAA and primary amines were confirmed by FT-IR measurements. Crystal structures of the organic salts were analyzed by single crystal X-ray diffraction measurements. As a result, the same kinds of the supramolecular clusters, which are composed of four ammoniums and four triphenylacetates by charge-assisted hydrogen bonds (Figure 1a), were confirmed in all of the single crystals of the organic salts regardless of kinds and numbers of the componen...

Watch this Scientific Journal Video about Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates at JoVE.com

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates

This article describes construction of a series of hydrogen-bonding supramolecular clusters in crystals using primary ammonium triphenylacetates, which are recrystallized from non-polar solvents. This selective construction of the supramolecular clusters leads to effective systematical symmetric studies about a correlation between the supramolecular clusters and their components.

Functions of clusters in nano or sub-nano scale significantly depend on not only kinds of their components but also arrangements, or symmetry, of their ...

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8.0K Views.  Osaka University. This article describes construction of a series of hydrogen-bonding supramolecular clusters in crystals using primary ammonium triphenylacetates, which are recrystallized from non-polar solvents. This selective construction of the supramolecular clusters leads to effective systematical symmetric studies about a correlation between the supramolecular clusters and their components.

Video: Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates

Electrochemically and Bioelectrochemically Induced Ammonium Recovery

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ammonium from an ammonium-rich stream is demonstrated using an electrochemical and a bioelectrochemical system. Both systems are controlled by a potentiostat to either fix the current (for the electrochemical cell) or fix the potential of the working electrode (for the bioelectrochemical cell). In the bioelectrochemical cell, electroactive bacteria catalyze the anodic reaction, whereas in the electrochemical cell the potentiostat applies a higher voltage to produce a current. The current and consequent restoration of the charge balance across the cell allow the transport of cations, such as ammonium, across a cation exchange membrane from the anolyte to the catholyte. The high pH of the catholyte leads to formation of ammonia, which can be stripped from the medium and captured in an acid solution, thus enabling the recovery of a valuable nutrient. The flux of ammonium across the membrane is characterized at different anolyte ammonium concentrations and currents for both the abiotic and biotic reactor systems. Both systems are compared based on current and removal efficiencies for ammonium, as well as the energy input required to drive ammonium transfer across the cation exchange membrane. Finally, a comparative analysis considering key aspects such as reliability, electrode cost, and rate is made.
This video article and protocol provide the necessary information to conduct electrochemical and bioelectrochemical ammonia recovery experiments. The reactor setup for the two cases is explained, as well as the reactor operation. We elaborate on data analysis for both reactor types and on the advantages and disadvantages of bioelectrochemical and electrochemical systems.

We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ...

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the hydroxylmethylene phosphine precursor with ammonia in methanol under a nitrogen atmosphere. The N-triphosPh ligand precipitates from the solution after approximately 1 hr of reflux and can be isolated analytically pure via simple cannula filtration procedure under nitrogen. Reaction of the N-triphosPh ligand with [Ru3(CO)12] under reflux affords a deep red solution that show evolution of CO gas on ligand complexation. Orange crystals of the complex [Ru(CO)2{N(CH2PPh2)3}-&#954;3P] (2) were isolated on cooling to RT. The 31P{1H} NMR spectrum showed a characteristic single peak at lower frequency compared to the free ligand. Reaction of a toluene solution of complex 2 with oxygen resulted in the instantaneous precipitation of the carbonate complex [Ru(CO3)(CO){N(CH2PPh2)3}-&#954;3P] (3) as an air stable orange solid. Subsequent hydrogenation of 3 under 15 bar of hydrogen in a high-pressure reactor gave the dihydride complex [RuH2(CO){N(CH2PPh2)3}-&#954;3P] (4), which was fully characterized by X-ray crystallography and NMR spectroscopy. Complexes 3 and 4 are potentially useful catalyst precursors for a range of hydrogenation reactions, including biomass-derived products such as levulinic acid (LA). Complex 4 was found to cleanly react with LA in the presence of the proton source additive NH4PF6 to give [Ru(CO){N(CH2PPh2)3}-&#954;3P{CH3CO(CH2)2CO2H}-&#954;2O](PF6) (6).

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Ruthenium phosphine complexes are widely used for homogeneous catalytic reactions such as hydrogenations. The synthesis of a series of novel tridentate ruthenium complexes bearing the N-triphos ligand N(CH2PPh2)3 is reported. Additionally, the stoichiometric reaction of a dihydride Ru&#8211;N-triphos complex with levulinic acid is described.

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

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 ...

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, non-aqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of non-aqueous electrolytes. However, significant technical hurdles exist currently limiting non-aqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we recently reported a non-aqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox material exhibits an ambipolar electrochemical property, and therefore can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry. Moreover, we demonstrated that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC), as cross-validated by electron spin resonance (ESR) measurements. Herein we present a video protocol for the electrochemical evaluation and SOC diagnosis of the PTIO symmetric flow battery. With a detailed description, we experimentally demonstrated the route to achieve such purposes. This protocol aims to spark more interests and insights on the safety and reliability in the field of non-aqueous redox flow batteries.

We present the protocols for electrochemically evaluating a symmetric non-aqueous organic redox flow battery and for diagnosing its state of charge using FTIR.

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid ...

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol. The effects were studied under isothermal and varying temperature conditions.
We describe equipment and experimental strategies applicable for monitoring the stability of coexisting liquid domains in charged vesicles under symmetric and asymmetric high-salinity solution conditions. This includes an approach to prepare charged multicomponent GUVs in high-salinity buffer at high temperatures. The protocol entails the option to perform a partial exchange of the external solution by a simple dilution step while minimizing the vesicle dilution. An alternative approach is presented utilizing a microfluidic device that allows for a complete external solution exchange. The solution effects on phase separation were also studied under varying temperatures. To this end, we present the basic design and utility of an in-house built temperature control chamber. Furthermore, we reflect on the assessment of the GUV phase state, pitfalls associated with it and how to circumvent them.

Experiments on phase separated giant unilamellar vesicles (GUVs) frequently neglect physiological solution conditions. This work presents approaches to study the effect of high-salinity buffer on liquid-liquid phase separation in charged multicomponent GUVs as a function of trans-membrane solution asymmetry and temperature.

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...

Preparation of Binary and Ternary Deep Eutectic Systems

The preparation of deep eutectic systems (DES) is a priori a simple procedure. By definition, two or more components are mixed together at a given molar ratio to form a DES. However, from our experience in the laboratory, there is a need to standardize the procedure to prepare, characterize and report the methodologies followed by different researchers, so that the results published can be reproduced. In this work, we test different approaches reported in the literature to prepare eutectic systems and evaluated the importance of water in the successful preparation of liquid systems at room temperature. These published eutectic systems were composed of citric acid, glucose, sucrose, malic acid, &#946;-alanine, L-tartaric acid and betaine and not all of preparation methods described could be reproduced. However, in some cases, it was possible to reproduce the systems described, with the inclusion of water as a third component of the eutectic mixture.

This protocol aims to standardize the preparation of deep eutectic systems throughout the scientific community so that these systems can be reproduced.

The preparation of deep eutectic systems (DES) is a priori a simple procedure. By definition, two or more components are mixed together at a given molar ...

Directed Assembly of Elastin-like Proteins into defined Supramolecular Structures and Cargo Encapsulation In Vitro

Tailored proteinaceous building blocks are versatile candidates for the assembly of supramolecular structures such as minimal cells, drug delivery vehicles and enzyme scaffolds. Due to their biocompatibility and tunability on the genetic level, Elastin-like proteins (ELP) are ideal building blocks for biotechnological and biomedical applications. Nevertheless, the assembly of protein based supramolecular structures with distinct physiochemical properties and good encapsulation potential remains challenging.
Here we provide two efficient protocols for guided self-assembly of amphiphilic ELPs into supramolecular protein architectures such as spherical coacervates, fibers and stable vesicles. The presented assembly protocols generate Protein Membrane-Based Compartments (PMBCs) based on ELPs with adaptable physicochemical properties. PMBCs demonstrate phase separation behavior and reveal method dependent membrane fusion and are able to encapsulate chemically diverse fluorescent cargo molecules. The resulting PMBCs have a high application potential as a drug formulation and delivery platform, artificial cell, and compartmentalized reaction space.

At the interface of organic and aqueous solvents, tailored amphiphilic elastin-like proteins assemble into complex supramolecular structures such as vesicles, fibers and coacervates triggered by environmental parameters. The described assembly protocols yield Protein Membrane-Based Compartments (PMBCs) with tunable properties, enabling the encapsulation of various cargo.