This work is partially supported by NSF (DMR-1006870) and NASA (NASA-NNX13AQ60G). X. Z. Wang acknowledges support from the Mary Kay O'Connor Process Safety Center (MKOPSC) at Texas A&amp;M University. We also thank Min Shuai for her guidance.

1. Synthese von α-ZrP Verwendung hydrothermale Method <ol><li> Man löst 6 g Zirkonylchlorid octahydrate (ZrOCl 2 · 8 H 2 O) in 3,75 ml entionisiertem (DI) Wasser in einem 150 ml - Rundkolben. </li><li> Hinzufügen 48 ml 15 M Phosphorsäure (H 3 PO 4) der Lösung tropfenweise ZrOCl 2 , hergestellt in Schritt 1.1 , gefolgt von Zugabe von 8,25 ml entionisiertes (DI) Wasser unter kräftigem Rühren. </li><li> Gießen resultierende gelartige Mischung in Teflon-ausgekleideten Druckbehälter von 80 ml Volumen. Das Gefäß wird in hydrothermalen Autoklaven besteht aus Edelstahl-Schale und Deckel, Druckplatte und dann gut festziehen. </li><li> Setzen Sie den hydrothermalen Autoklaven in Umluftofen bei 200 ° C für 24 Stunden. </li><li> Nach der Reaktion kann der hydrothermalen Autoklaven 8 Stunden auf Raumtemperatur unter Umgebungskühlung abzukühlen. </li><li> Sammeln α-ZrP Scheiben in Zentrifugenröhrchen nach dem Abkühlen bei 2 unter Verwendung von Zentrifuge,500 xg für 10 min. Sammeln Sie flüssige Anteil in Entsorgungsbehälter Abfall, da der Überstand nicht umgesetzte Phosphorsäure enthält, die korrosiv ist. <ol><li> Danach werden 40 ml Wasser zu a-ZrP, Wirbel für 1 min und Zentrifuge bei 2500 × g für 10 min wieder. Wiederholen Sie diesen Schritt 3 Mal, um sicherzustellen, dass die gesamte Säure abgewaschen. </li></ol></li><li> Trockene ZrP-Wasser klebrige Mischung im Ofen bei 65 ° C für 8 Stunden und dann mahlen ein Mörsers. </li></ol> 2. Synthese von α-ZrP durch Reflux Method <ol><li> Mischen Sie 6 g ZrOCl 2 · 8 H 2 O mit 50 ml 12 M Phosphatsäure in einem 150 ml - Rundkolben. </li><li> Die Mischung in Stufe 2.1 ist Rückfluß im Ölbad bei 94 ° C für 24 Std. </li><li> Waschen Sie das Produkt mit entionisiertem Wasser dreimal folgenden gleiche Protokoll in Schritt 1.6, und dann im Ofen bei 65 ° C getrocknet, um 8 Stunden. </li><li> Grind getrocknet sperrigen Probe zu einem Pulver mit einem Mörser und Stößel und Lager foder höher verwenden. </li></ol> 3. Synthese von α-ZrP durch Mikrowellen-unterstützte Methode <ol><li> 1 g ZrOCl 2 · 8 H 2 O in 9 ml 12 M Phosphorsäurelösung und gut umrühren das entstehende Gemisch in einem Glasfläschchen 20 ml Scintillations. </li><li> Pour 5 ml des obigen Gemisches in ein Gefäß 10 ml Glas für Mikrowellenreaktor angegeben. </li><li> Eingestellt Reaktionstemperatur bei 150 ° C, Druckgrenze bei 300 psi und ermöglichen die Reaktion für 1 Stunde passieren. </li><li> Nach der Reaktion ließ das Glasgefäß für etwa 15 min abkühlen und anschließend das gleiche Verfahren wie in den Schritten 1,6-1,7 Absäuern und Trocknen von α-ZrP Kristalle folgen. </li></ol> 4. Exfoliation von Layered α-ZrP in Monoschichten <ol><li> Disperse 1 g α-ZrP in 10 ml DI-Wasser in einem 20 ml Szintillationsgefß. </li><li> In 2,2 ml TBAOH (40 Gew.%), Um es und Wirbel für mindestens 40 Sekunden. Beachten Sie, dass molare Verhältnis von Zr: TBAOH gehalten wird als 1: 1. </li><li> Beschallen die resultierende konzentrierte Suspension für 1-2 h und lassen für 3 Tage voller Einlagerung von TBA + -Ionen und vollständige Ablösung von Kristallen zu ermöglichen. Gegebenenfalls können konzentrierte Suspension (2 bis 3-fache Verdünnung) mit Wasser verdünnt werden, um bessere Exfoliation zu erhalten. </li><li> Zentrifugieren der abgeblätterte Proben bei hoher Drehzahl (2.500 xg) für 1 Stunde zur Entfernung teilweise abgeblättert Kristalle am Boden abgesetzt. Sammeln Sie den oberen Teil (abgeblättert ZrP) in einen anderen Behälter, und wiederholen Sie den Vorgang, bis kein Sediment gefunden wird. </li></ol>

<ol>
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There is nothing to disclose.

Die Reflux-Methode ist eine gute Option für eine kleinere Größe von α-ZrP mit einem einheitlichen Durchmesser und Dicke zu machen. Ähnlich wie bei der hydrothermischen Verfahren wird die Rückflussverfahrens durch die Vorbereitungszeit begrenzt. Im Allgemeinen dauert es längere Zeit, damit die Kristalle wachsen. Die längere Reaktionszeit für Reflux-Verfahren erforderlich ist, kann in Nanoscheiben mit einer größeren Größe zur Folge haben. Die durchschnittliche Größe der abgeblä...

Diskotischen Kolloide sind natürlich reichlich in Form von Ton, Asphalten-, rote Blutkörperchen und Perlmutter. Eine Reihe von Anwendungen in vielen technischen Systemen, einschließlich Polymer - Nanokomposite 1, biomimetischen Materialien, funktionelle Membranen 2, diskotischen Flüssigkristall Studien 3 und Pickering - Emulsion Stabilisatoren 4 auf diskotischen kolloidalen Nanoscheiben entwickelt gegründet. Nanoscheiben mit Homogenität und geringer Polydispersität ist wichtig für die Phasen und Transformationen von Flüssigkristallen zu studieren. Zirkoniumphosphat (ZrP) ist ein synthetisches Nanoscheiben mit gut geordnete Schichtstruktur und kontrollierbaren Aspektverhältnis (Dicke über Durchmesser). Daher hilft die Erforschung verschiedener Synthese von ZrP fundamentales Verständnis der diskotischen Flüssigkristallsystem zu etablieren. Die Struktur von ZrP wurde 1964 5 von Clearfield und Stynes ​​erläutert. Für die Synthese von geschichteten Kristalle von ZrP, hydrothermale undReflux - Verfahren werden 6,7 gemeinhin angenommen. Die hydrothermale Verfahren gibt eine gute Kontrolle auf der Größe von 400 bis 1500 nm reichen und Uneinheitlichkeit innerhalb von 25% 6, während Reflux - Verfahren kleinere Kristalle Zeit für die gleiche Dauer gibt. Mikrowellenerwärmung ist nachgewiesen worden , eine vielversprechende Methode zur Synthese von Nanomaterialien 8. Allerdings gibt es keine Papiere beschreiben die Synthese von ZrP anhand von Mikrowellen-unterstützten Route. Die effektive Kontrolle über die Größe, Seitenverhältnis, und der Mechanismus des Kristallwachstums durch hydrothermale Verfahren wurde von unserer Gruppe 6 systematisch untersucht. ZrP kann leicht in Monolayern in wässrige Suspensionen exfolierten werden, und die abgeblätterte ZrP wurden als Flüssigkristallmaterialien in Cheng Gruppe 3,9-13 gut etabliert. Bisher abgeblättert ZrP Nanoscheiben mit verschiedenen Durchmessern, sagen verschiedene Seitenverhältnisse, wurden untersucht, zu dem Schluss, dass größere ZrP die ich hatte (isotrop) -N (Nematic) Übergang zu niedrigeren contration im Vergleich zu kleineren ZrP 3. Die Polydispersität 3, Salz 9 und die Temperatur 10,11 Effekte auf die Bildung der nematischen Flüssigkristallphase wurden ebenfalls berücksichtigt. Darüber hinaus können andere Phasen, wie sematischen Flüssigkristallphase, wurden ebenfalls untersucht 13,14. In diesem Artikel zeigen wir experimentelle Realisierung eines solchen kolloidalen ZrP Nanoscheiben Suspension. Layered ZrP Kristalle werden durch verschiedene Verfahren synthetisiert und anschließend in wässrigen Medien exfoliert sind einschichtige Nanoscheiben zu erhalten. Am Ende zeigen wir, Flüssigkristallphasenübergänge durch dieses System gezeigt. Ein bemerkenswerter Aspekt dieser Platten ist ihre stark anisotropen Natur , dass die Dicke zu Durchmesser - Verhältnis im Bereich von 0,0007 bis 0,05 liegt , je nach Größe der Platten 3. Die stark anisotropen einschichtige Nanoscheiben ein Modellsystem etablieren, um Phasenübergänge in den Suspensionen von Nanoscheiben studieren.

<table border="0" cellpadding="0" cellspacing="0" height="202" width="928">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:209px;">Material</td>
			<td style="width:208px;"></td>
			<td style="width:164px;"></td>
			<td style="width:352px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zirconyl Chloride Octahydrate</td>
			<td>Fischer Scientific (Acros Organics)</td>
			<td>AC20837-5000</td>
			<td>98% +&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">o-Phosphoric Acid</td>
			<td>Fischer Scientific</td>
			<td>A242-1</td>
			<td>&#62;= 85 %</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tetra Butyl Ammonium Hydroxide</td>
			<td>Acros Organics (Acros Organics)</td>
			<td>AC176610025</td>
			<td>40% wt. (1.5M)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Reaction Oven</td>
			<td>Fischer Scientific</td>
			<td>CL2 centrifuge</td>
			<td>Isotemperature Oven (Temperature Upto 350&#160;C)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge&#160;</td>
			<td>Thermo Scientific</td>
			<td>Not Available&#160;</td>
			<td>Rotation Speed : 100 - 4000 rpm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microwave Reactor</td>
			<td>CEM Corporation</td>
			<td>Discover and Explorer SP</td>
			<td>Temp. Upto 300oC, Power upto 300W, Pressure upto 30bar</td>
		</tr>
	</tbody>
</table>

synthesis and exfoliation of discotic zirconium phosphates to obtain colloidal liquid crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

Abbildung 1a-c zeigen REM - Aufnahmen von α-ZrP Nanoscheiben aus hydrothermalen erhalten, Reflux und Mikrowellen-unterstützte Methoden zur Verfügung . Es wurde beobachtet, dass α-ZrP Nanoscheiben hexagonal zeigen in Form und unterschiedlicher Dicke je nach Synthesebedingungen und vorbereiteten Verfahren. Eine zuvor berichtete Studie aus unserer Gruppe schlägt vor , 6 , dass für das Kristallwachstum Zeit 48 Stunden oder über die Kante der Scheiben schär...

Watch this Scientific Journal Video about Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals at JoVE.com

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

Synthese und Exfoliation von diskotischen Zirkoniumphosphaten Erhalten Kolloidales Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

synthesis-exfoliation-discotic-zirconium-phosphates-to-obtain

Research

JoVE Journal

Chemistry

8.4K Aufrufe.  Texas A&M University. A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers. 

Serie: Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Nucleoside Triphosphates - From Synthesis to Biochemical Characterization

The traditional strategy for the introduction of chemical functionalities is the use of solid-phase synthesis by appending suitably modified phosphoramidite precursors to the nascent chain. However, the conditions used during the synthesis and the restriction to rather short sequences hamper the applicability of this methodology. On the other hand, modified nucleoside triphosphates are activated building blocks that have been employed for the mild introduction of numerous functional groups into nucleic acids, a strategy that paves the way for the use of modified nucleic acids in a wide-ranging palette of practical applications such as functional tagging and generation of ribozymes and DNAzymes. One of the major challenges resides in the intricacy of the methodology leading to the isolation and characterization of these nucleoside analogues.
	
	In this video article, we present a detailed protocol for the synthesis of these modified analogues using phosphorous(III)-based reagents. In addition, the procedure for their biochemical characterization is divulged, with a special emphasis on primer extension reactions and TdT tailing polymerization. This detailed protocol will be of use for the crafting of modified dNTPs and their further use in chemical biology.

The protocol described herein aims to explain and abridge the numerous obstacles in the way of the intricate route leading to modified nucleoside triphosphates. Consequently, this protocol facilitates both the synthesis of these activated building-blocks and their availability for practical applications.

Nucleosidtriphosphaten - von der Synthese zur biochemischen Charakterisierung

The  traditional strategy for the introduction of chemical functionalities is the  use of solid-phase synthesis by appending suitably modified ...

Forschung

Chemie

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi4O10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi4O10 and BaCuSi4O10 are strong near infrared emitters. Aqueous CaCuSi4O10 and BaCuSi4O10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

The preparation and exfoliation of CaCuSi4O10&#160;and BaCuSi4O10 are described. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayers, whereas BaCuSi4O10&#160;requires ultrasonication in organic solvents. Near infrared (NIR) imaging illustrates the NIR emission properties of these materials, and aqueous dispersions of these nanomaterials are useful for solution processing.

Exfoliation von Ägyptisch Blau-und Han-Blau, zwei Alkali Erde Kupfer-Silikatpigmente

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the ...

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate using the Atomic Force Microscope (AFM), can provide key insights into physical interactions present within colloidal systems. Colloidal systems are widely existent in several applications including, pharmaceuticals, foods, paints, paper, soil and minerals, detergents, printing and much more.1-3 Furthermore, colloids can exist in many states such as emulsions, foams and suspensions. Using colloidal probe nanoscopy one can obtain key information on the adhesive properties, binding energies and even gain insight into the physical stability and coagulation kinetics of the colloids present within. Additionally, colloidal probe nanoscopy can be used with biological cells to aid in drug discovery and formulation development. In this paper we describe a method for conducting colloidal probe nanoscopy, discuss key factors that are important to consider during the measurement, and show that both quantitative and qualitative data that can be obtained from such measurements.

Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.

Quantitative und qualitative Untersuchung der Partikel-Partikel Wechselwirkungen mit Kolloidales Probe Nanoskopie

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate ...

From Constructs to Crystals &#8211; Towards Structure Determination of &#946;-barrel Outer Membrane Proteins

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% percent of known structures. There are two types of membrane proteins, &#945;-helical and &#946;-barrel. While &#945;-helical membrane proteins can be found in nearly all cellular membranes, &#946;-barrel membrane proteins can only be found in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. One common bottleneck in structural studies of membrane proteins in general is getting enough pure sample for analysis. In hopes of assisting those interested in solving the structure of their favorite &#946;-barrel outer membrane protein (OMP), general protocols are presented for the production of target &#946;-barrel OMPs at levels useful for structure determination by either X-ray crystallography and/or NMR spectroscopy. Here, we outline construct design for both native expression and for expression into inclusion bodies, purification using an affinity tag, and crystallization using detergent screening, bicelle, and lipidic cubic phase techniques. These protocols have been tested and found to work for most OMPs from Gram-negative bacteria; however, there are some targets, particularly for mitochondria and chloroplasts that may require other methods for expression and purification. As such, the methods here should be applicable for most projects that involve OMPs from Gram-negative bacteria, yet the expression levels and amount of purified sample will vary depending on the target OMP.

&#946;-barrel outer membrane proteins (OMPs) serve many functions within the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Here, we hope to alleviate a known bottleneck in structural studies by presenting protocols for the production of &#946;-barrel OMPs in sufficient quantities for structure determination by X-ray crystallography or NMR spectroscopy.

Von Konstrukten Crystals - Auf dem Weg zu Strukturbestimmung von β-Fass-Außenmembranproteine

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% ...

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.

Synthese von Programmierbare Hauptkettenflüssigkristalline Elastomere unter Verwendung eines Zwei-Stufen-Thiol-Acrylat-Reaktions

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline ...

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.

Synthese und Charakterisierung von supramolekularen Kolloid-

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

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid crystals (ILCs). Taking advantages of the high specificity of XB for haloperfluorocarbons and the ability of anions to act as XB-acceptors, we obtained supramolecular complexes based on 1-alkyl-3-methylimidazolium iodides and iodoperfluorocarbons, overcoming the well-known immiscibility between hydrocarbons (HCs) and perfluorocarbons (PFCs). The high directionality of the XB combined with the fluorophobic effect, allowed us to obtain enantiotropic liquid crystals where a rigid, non-aromatic, XB supramolecular anion acts as mesogenic core.
X-ray structure analysis of the complex between 1-ethyl-3-methylimidazolium iodide and iodoperfluorooctane showed the presence of a layered structure, which is a manifestation of the well-known tendency to segregation of perfluoroalkyl chains. This is consistent with the observation of smectic mesophases. Moreover, all the reported complexes melt below 100 &#176;C, and most are mesomorphic even at room temperature, despite that the starting materials were non-mesomorphic in nature.
The supramolecular strategy reported here provides new design principles for mesogen design allowing a totally new class of functional materials.

A protocol for the synthesis of a new type of mesogens, based on the halogen-bonded supramolecular anion [CnF2n+1-I&#183;&#183;&#183;I&#183;&#183;&#183;I-CnF2n+1]&#8722;, is reported.

Von Molekülen zu Materialien: neue ionische Flüssigkristalle durch Halogen-Bonding Technik

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

Facette für Facette Verknüpfung von Form-anisotropen kolloidales Cadmium Chalkogenid Nanostrukturen

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

Neuartige Techniken zur Beobachtung von Strukturdynamik von Photoresponsive Flüssigkristallen

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Exfoliation and Analysis of Large-area, Air-Sensitive Two-Dimensional Materials

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals crystals are produced using mechanical exfoliation, in which layers are peeled off a bulk crystal using adhesive tape. This method produces high-quality flakes, but they are often small and can be hard to find, particularly for materials with relatively high cleavage energies such as black phosphorus. By heating the substrate and the tape, two-dimensional material adhesion to the substrate is promoted, and the flake yield can be increased by up to a factor of ten. After exfoliation, it is necessary to image or otherwise analyze these flakes but some two-dimensional materials are sensitive to oxygen or water and will degrade when exposed air. We have designed and tested a hermetic transfer cell to temporarily maintain the inert environment of a glovebox so that air-sensitive flakes can be imaged and analyzed with minimal degradation. The compact design of the transfer cell is such that optical analysis of sensitive materials can be performed outside of a glovebox without specialized equipment or modifications to existing equipment.

A method for exfoliating large thin flakes of air sensitive two-dimensional materials and safely transporting them for analysis outside of a glovebox is presented.

Peeling und Analyse der großflächige, luftempfindlichen zweidimensionale Materialien

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals ...