Die Autoren erweitern ihre Anerkennung für Dr. Thomas J. Emge und Wei Liu von Rutgers University für ihre Analyse und Expertise in Kleinwinkel-Röntgenbeugung und Pulver Röntgenbeugung. Darüber hinaus erkennen die Autoren Hao Wang für seine Unterstützung mit den N 2 Adsorptionsexperimenten an.

1. Al (OH) 3 Nanopartikel-Synthese <ol><li> 1.40 g Aluminiumchloridhexahydrat in 5.822 g entionisiertem Wasser auflösen </li><li> 2.778 g L-Arginin zu der wässrigen Aluminiumchloridlösung unter magnetischem Rühren zugeben. Füge das L-Arginin langsam hinzu, so dass sich das hinzugefügte Arginin auflöst und keine großen Klumpen oder Klumpen bildet; Darüber hinaus reduziert eine langsame Zugabe lokale Konzentrationen der Alkalinität und liefert Bedingungen für eine kontrollierbarere Hydrolyse. </li><li> Sobald sich das Arginin in die Lösung auflöst, erhitze man die Lösung für 72 h bei 50 ° C; An dieser Stelle kann die Lösung als trübe Suspension erscheinen. </li></ol> 2. Präzipitieren von Al (OH) 3 mit NaCl <ol><li> Bereiten Sie eine GPC-Säule vor, die 49 in einem langen und 1.125 im Durchmesser ist. Packen Sie das Gel in aufeinanderfolgenden Schritten des Hinzufügens von Gel und lassen Sie Wasser durch die Säule fließen, um eine korrekte Verpackung zu gewährleisten, mit einem minimalen Raum zwischen den Gelperlen. Pack dieGel bis etwa 80% der Säule; Die Menge an gepacktem Gel variiert jedes Mal und wirkt sich nur auf die Retentionszeit der abgetrennten Spezies aus. </li><li> Führen Sie 10 mL as-synthetisierte Al (OH) 3 Nanopartikel-Suspension (hergestellt in Schritt 1.3) in die Säule unter Verwendung einer HPLC-Pumpe mit einer 10 mL Injektorschleife ein. Die Injektorschleife mit einem Außendurchmesser von ca. 0,125 Zoll und einer Länge, die kalibriert ist, um 10 ml injizierte Probe zu liefern, </li><li> Sammeln Sie die Säulenelution in Intervallen, die mit der dRI-Peak-Position korrelieren. Verbinden Sie den GPC-Ausgang mit dem Eingang eines Differential-Brechungsindex (dRI) -Detektors. HINWEIS: Da getrennte Spezies aus der GPC kommen, erscheinen sie auf dem dRI-Detektor als Peak und werden dann in 125 ml Flaschen gesammelt. Die GPC-Säule produziert zwei gut aufgelöste Peaks, die beide gesammelt und mit Größenausschlusschromatographie (SEC) und Elementaranalyse (EA) analysiert werden, um Arginin aus Aluminium spe zu erkennenCies Das gesammelte Gesamtvolumen hängt von der Größe der GPC-Säule, der Gesamtmenge des verwendeten Verpackungsmaterials und der Strömungsgeschwindigkeit des entionisierten Wassers ab, das verwendet wird, um die Säule zu eluieren. <ol><li> Sammeln Sie die Mehrheit der Peak-1-Fraktion über 100 min bei einer 0,2 ml / min Fließgeschwindigkeit. </li><li> Sammeln Sie das Elutionsmittel in 30-Minuten-Intervallen, sobald ein Peak auf dem RI-Detektor der GPC-Säule austritt. HINWEIS: Das Ändern des Intervallbereichs ändert die Konzentration und Reinheit des resultierenden gereinigten Peak 1-Materials. Es empfiehlt sich, zunächst kleine Intervalle des Peaks zu sammeln, um zu bestimmen, welcher Teil die höchste Konzentration und Reinheit der Peak-1-Spezies für eine bestimmte Säule enthält. </li></ol></li><li> 1 Gew .-% NaCl zubereiten. </li><li> Man gibt die hergestellte NaCl-Lösung tropfenweise zu 10 ml gereinigter Al (OH) 3 -Nanopartikel; Das unter Verwendung von NaCl-Präzipitation hergestellte Material wird für weitere Experimente nicht verwendet. </li></ol> 3. Vorbereitung von Al-MCM-41 <ol><li> AcTeste ca. 1,0 g MCM-41 bei 120 ° C unter Vakuum für 3 h in einem Vakuumofen. </li><li> 50,0 g Aluminiumchloridlösung durch Kombination von 9,6926 g AlCl &amp; sub3; · 6H &amp; sub2; O mit 40,3074 g entionisiertem Wasser zubereiten. </li><li> Füge 0,7 g aktiviertes MCM-41 zu 50,0 g Aluminiumchloridlösung (hergestellt in Schritt 3.2) zu. </li><li> Erlaube eine ausreichende Mischzeit (1 Std.), Um die Homogenität des AlCl 3 zu gewährleisten, die über die MCM-41 Kanäle diffundiert ist. </li><li> Füge L-Arginin zu der heterogenen Mischung zu einem Arg / Al-Molverhältnis von 2,75 unter magnetischem Rühren hinzu. Ähnlich wie bei Schritt 1.2 fügen Sie das Arginin langsam so hinzu, dass die sofort gebildeten Flockungsmittel wieder auflösen und das Verklumpen des Arginins reduzieren können, bevor die Zugabe fortgesetzt wird. </li><li> Nach der Homogenität die Mischung bei 50 ° C für 72 h erhitzen. </li><li> Filtriere die erhaltene heterogene Lösung unter Verwendung eines Buchner-Trichters unter Vakuum und wurde mit qualitativen 90-mm-Filterpapierkreisen ausgestattet(Oder andere geeignete Filterpapiere). </li><li> Waschen Sie das gefilterte weiße Pulver mit überschüssigem deionisiertem Wasser, um die Entfernung von nicht umgesetztem Aluminiumchlorid, Arginin oder wasserlöslichen Nebenprodukten aus dem hergestellten Al-MCM-41-Material zu gewährleisten. </li></ol>

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Mineral. 91 (1), 115-119 (2006).</li><li>Scherrer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bestimmung+der+Grosse+und+der+inneren+Struktur+von+Kolloidteilchen+mittels+Rontgenstrahlen+.">Bestimmung der Grosse und der inneren Struktur von Kolloidteilchen mittels Rontgenstrahlen .</a> Gottingen. 26, 98-100 (1918).</li><li>Langford, J. I., Wilson, A. J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scherrer+after+sixty+years:+a+survey+and+some+new+results+in+the+determination+of+crystallite+size.">Scherrer after sixty years: a survey and some new results in the determination of crystallite size.</a> J. Appl. Cryst. 11 (2), 102-113 (1978).</li><li>Swaddle, T. W., 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=Kinetic+Evidence+for+Five-Coordination+in+AlOH(aq)2++Ion.">Kinetic Evidence for Five-Coordination in AlOH(aq)2+ Ion.</a> Science. 308 (5727), 1450-1453 (2005).</li><li>Casey, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+Aqueous+Aluminum+Hydroxide+Molecules.">Large Aqueous Aluminum Hydroxide Molecules.</a> Chem. Rev. 106 (1), 1-16 (2006).</li><li>Lutzenkirchen, 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=Adsorption+of+Al13-Keggin+clusters+to+sapphire+c-plane+single+crystals:+Kinetic+observations+by+streaming+current+measurements.">Adsorption of Al13-Keggin clusters to sapphire c-plane single crystals: Kinetic observations by streaming current measurements.</a> Appl. Surf. Sci. 256 (17), 5406-5411 (2010).</li><li>Mokaya, R., Jones, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+post-synthesis+alumination+of+MCM-41+using+aluminum+chlorohydrate+containing+Al+polycations.">Efficient post-synthesis alumination of MCM-41 using aluminum chlorohydrate containing Al polycations.</a> J. Mater. Chem. 9 (2), 555-561 (1999).</li><li>Brunauer, S., Deming, L. S., Deming, W. E., Teller, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+a+Theory+of+the+van+der+Waals+adsorption+of+gases.">On a Theory of the van der Waals adsorption of gases.</a> J. Am. Chem. Soc. 62 (7), 1723-1732 (1940).</li><li>Kresge, C. T., Leonowicz, M. E., Roth, W. J., Vartuli, J. C., Beck, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ordered+mesoporous+molecular+sieves+synthesized+by+a+liquid-crystal+template+mechanism.">Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism.</a> Nature. 359 (6397), 710-712 (1992).</li><li>Zeng, Q., Nekvasil, H., Grey, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proton+Environments+in+Hydrous+Aluminosilicate+Glasses:+A+1H+MAS,+1H/27Al,+and+1H/23Na+TRAPDOR+NMR+Study.">Proton Environments in Hydrous Aluminosilicate Glasses: A 1H MAS, 1H/27Al, and 1H/23Na TRAPDOR NMR Study.</a> J. Phys. Chem. B. 103 (35), 7406-7415 (1999).</li><li>Kao, H. M., Grey, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+Bronsted+and+Lewis+acidity+of+zeolite+HY:+A+1H/27Al+and+15N/27Al+TRAPDOOR+NMR+study+of+mono-methylamine+adsorbed+on+HY.">Probing the Bronsted and Lewis acidity of zeolite HY: A 1H/27Al and 15N/27Al TRAPDOOR NMR study of mono-methylamine adsorbed on HY.</a> J. Phys. Chem. 100 (12), 5105-5117 (1996).</li><li>DeCanio, E. C., Edwards, J. C., Bruno, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solid-state+1H+MAS+NMR+characterization+of+&#947;-alumina+and+modified+&#947;-aluminas.">Solid-state 1H MAS NMR characterization of &#947;-alumina and modified &#947;-aluminas.</a> J. Catal. 148 (1), 76-83 (1994).</li><li>Shafran, K. L., Deschaume, O., Perry, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+static+anion+exchange+method+for+generation+of+high+purity+aluminium+polyoxocations+and+monodisperse+aluminum+hydroxide+nanoparticles.">The static anion exchange method for generation of high purity aluminium polyoxocations and monodisperse aluminum hydroxide nanoparticles.</a> J. Mater. Chem. 15 (33), 3415-3423 (2005).</li><li>Vogels, R. J. M. J., Kloprogge, J. T., Geus, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homogeneous+forced+hydrolysis+of+aluminum+through+the+thermal+decomposition+of+urea.">Homogeneous forced hydrolysis of aluminum through the thermal decomposition of urea.</a> J. Colloid Interface Sci. 285 (1), 86-93 (2005).</li></ol>

Die Autoren haben nichts zu offenbaren.

Die Herstellung einer wässrigen Aluminiumchloridlösung ergab die Verwendung eines kristallinen Hexahydratsalzes von Aluminiumchlorid. Obwohl die wasserfreie Form auch verwendet werden kann, ist es aufgrund ihrer signifikanten hygroskopischen Eigenschaften nicht bevorzugt, was es schwierig macht, mit der Konzentration von Aluminium zu arbeiten und diese zu kontrollieren. Es ist bemerkenswert, dass Aluminiumchloridlösung innerhalb von einigen Tagen nach der Herstellung verwendet werden sollte, da im Laufe der Zeit die ...

Materialien aus Aluminiumhydroxid sind vielversprechende Kandidaten für eine Vielzahl von industriellen Anwendungen, einschließlich Katalyse, Pharma, Wasseraufbereitung und Kosmetik. 1 , 2 , 3 , 4 Bei erhöhten Temperaturen absorbiert Aluminiumhydroxid eine wesentliche Menge an Wärme während der Zersetzung, um Aluminiumoxid (Al &amp; sub2; O &amp; sub3; ) zu ergeben, was es zu einem nützlichen flammhemmenden Mittel macht. 5 Die vier bekannten Polymorphe von Aluminiumhydroxid ( dh Gibbsit, Bayerit, Nordstrandit und Doyleit) wurden unter Verwendung von rechnerischen und experimentellen Techniken untersucht, um unser Verständnis der Entstehung und Strukturen zu verbessern 6 . Die Herstellung von nanoskaligen Partikeln ist aufgrund ihres Potentials, Quanteneffekte und Eigenschaften zu zeigen, die sich von denen der Thei unterscheiden, von besonderem InteresseR Bulk-Pendants. Nanogibbsit-Partikel mit Abmessungen in der Größenordnung von 100 nm werden unter verschiedenen Bedingungen 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 leicht hergestellt. Die Überwindung von inhärenten Herausforderungen, die mit der Verringerung der Partikelgrößen verbunden sind, ist schwierig; Daher gibt es nur wenige Fälle, wo Nanogibbsit-Partikel Dimensionen in der Größenordnung von 50 nm haben. 14 , 15 , 16 , 17 Nach unserem besten Wissen gab es keine Berichte über Nanogibbsit-Partikel kleiner als 50 nm. Dies ist zum Teil darauf zurückzuführen, dass Nanopartikel aufgrund elektrostatischer Instabilität dazu neigen, zu agglomerierenUnd die hohe Wahrscheinlichkeit für die Bildung von Wasserstoffbrücken zwischen den kolloidalen Partikeln, insbesondere in polaren protischen Lösungsmitteln. Unser Ziel war es, kleine Al (OH) 3 Nanopartikel unter Verwendung von ausschließlich sicheren Zutaten und Vorläufern zu synthetisieren. In der gegenwärtigen Arbeit wurde die wässrige Teilchenaggregation durch Einbringen einer Aminosäure ( dh L-Arginin) als Puffer und Stabilisator gehemmt. Darüber hinaus wird berichtet, dass das Guanidinium-haltige Arginin das Wachstum von Aluminiumhydroxid und die Aggregation verhinderte, um eine wässrige kolloidale Suspension mit durchschnittlichen Teilchengrößen von 10-30 nm zu ergeben. Es wird hier vorgeschlagen, dass die amphoteren und zwitterionischen Eigenschaften von Arginin die Oberflächenladung von Aluminiumhydroxid-Nanopartikeln während der milden Hydrolyse verminderten, um das Partikelwachstum über 30 nm zu verhindern. Obwohl Arginin nicht in der Lage war, die Teilchengröße unter 10 nm zu reduzieren, wurden solche Teilchen erreicht, indem der Vorteil des &quot;Käfig&quot; -Entwicklungseffekts ausgenutzt wurdeHin die mesoporen von MCM-41. Die Charakterisierung des Al-MCM-41-Verbundwerkstoffs ergab ultrafeine Aluminiumhydroxid-Nanopartikel innerhalb des mesoporösen Siliciumdioxids, das eine mittlere Porengröße von 2,7 nm aufweist.

<table border="0" cellpadding="0" cellspacing="0" width="650">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum chloride hexahydrate</td>
			<td style="width:103px;">Alfa Aesar</td>
			<td align="right" style="width:119px;">12297</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">L-arginine</td>
			<td style="width:103px;">BioKyowa</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum hydroxide</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">239186</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Bio-Gel P-4 Gel</td>
			<td style="width:103px;">Bio-Rad</td>
			<td style="width:119px;">150-4128</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Mesoporous siica (MCM-41 type)</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">643645</td>
			<td></td>
		</tr>
	</tbody>
</table>

facile preparation of ultrafine aluminum hydroxide particles with or without mesoporous mcm-41 in ambient environments

Eine wässrige Suspension von Nanogibbsit wurde über die Titration von Aluminium-Aqua-Säure [Al (H 2 O) 6 ] 3+ mit L-Arginin auf pH 4,6 synthetisiert. Da die Hydrolyse von wässrigen Aluminiumsalzen bekannt ist, eine breite Palette von Produkten mit einer breiten Palette von Größenverteilungen herzustellen, wurde eine Vielzahl von hochmodernen Instrumenten ( dh 27 Al / 1 H NMR, FTIR, ICP-OES) , TEM-EDX, XPS, XRD und BET) wurden zur Charakterisierung der Syntheseprodukte und zur Identifizierung von Nebenprodukten verwendet. Das Produkt, das aus Nanopartikeln (10-30 nm) bestand, wurde mittels Gelpermeationschromatographie (GPC) Säulentechnik isoliert. Fourier Transformation Infrarot (FTIR) Spektroskopie und Pulver Röntgenbeugung (PXRD) identifiziert das gereinigte Material als Gibbsit Polymorph von Aluminiumhydroxid. Die Zugabe von anorganischen Salzen ( zB NaCl) induzierte eine elektrostatische Destabilisierung der Suspension, wodurch die Nanopartikel zu yie agglomeriert wurdenLd Al (OH) 3 mit großen Teilchengrößen ausfallen. Unter Verwendung des hier beschriebenen neuartigen Syntheseverfahrens wurde Al (OH) 3 teilweise in das hochgeordnete mesoporöse Gerüst von MCM-41 mit mittleren Porenabmessungen von 2,7 nm geladen, wodurch ein Aluminosilikatmaterial mit sowohl oktaedrischem als auch tetraedrischem Al (O h / T d = 1,4). Der Gesamt-Al-Gehalt, gemessen unter Verwendung der energiedispersiven Röntgenspektrometrie (EDX), betrug 11% G / G mit einem Si / Al-Molverhältnis von 2,9. Ein Vergleich von Massen-EDX mit Oberflächen-Röntgen-Photoelektronenspektroskopie (XPS) Elementaranalyse lieferte Einblick in die Verteilung von Al innerhalb des Aluminosilikatmaterials. Weiterhin wurde ein höheres Verhältnis von Si / Al auf der äußeren Oberfläche (3.6) im Vergleich zur Masse (2.9) beobachtet. Approximationen von O / Al-Verhältnissen deuten auf eine höhere Konzentration von Al (O) 3 und Al (O) 4- Gruppen nahe dem Kern bzw. der äußeren Oberfläche hin. Die neu entwickelte Synthese von Al-MCM-41 ergibt eine Re-Licht hoher Al-Gehalt unter Beibehaltung der Integrität des geordneten Siliciumdioxidgerüsts und kann für Anwendungen verwendet werden, bei denen hydratisierte oder wasserfreie Al 2 O 3 -Nanopartikel vorteilhaft sind.

Nanogibbsit-Synthese Nanogibbsit wurde durch Titration von AlCl &amp; sub3; · 6H &amp; sub2; O (14 Gew .-%) mit L-Arginin zu einem endgültigen Arg / Al-Molverhältnis von 2,75 hergestellt. Die Synthese von Nanogibbsit-Partikeln wurde über SEC überwacht , was eine weit verbreitete Analysetechnik für partiell hydrolysierte Aluminiumchloridlösungen ist, die in der Lage ist, fünf Domäne...

Watch this Scientific Journal Video about Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments at JoVE.com

Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments

Eine ultrafeine Aluminiumhydroxid-Nanopartikel-Suspension wurde über die kontrollierte Titration von [Al (H 2 O)] 3+ mit L-Arginin auf pH 4,6 mit und ohne Käfigeffekt-Confinement in mesoporösen Kanälen von MCM-41 hergestellt.

Facile Vorbereitung von ultrafeinen Aluminiumhydroxidpartikeln mit oder ohne mesoporösem MCM-41 in Umgebungsbedingungen

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis ...

facile-preparation-ultrafine-aluminum-hydroxide-particles-with-or

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10.8K Aufrufe.  Colgate-Palmolive Company.  Eine ultrafeine Aluminiumhydroxid-Nanopartikel-Suspension wurde über die kontrollierte Titration von [Al (H 2 O)] 3+ mit L-Arginin auf pH 4,6 mit und ohne Käfigeffekt-Confinement in mesoporösen Kanälen von MCM-41 hergestellt. 

Serie: Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments

Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug delivery, biological imaging, and supported catalysis. In this report, we demonstrate parallel synthesis of brush-arm star polymer (BASP) nanoparticles by the &#34;brush-first&#34; method. In this method, a norbornene-terminated poly(ethylene glycol) (PEG) macromonomer (PEG-MM) is first polymerized via ring-opening metathesis polymerization (ROMP) to generate a living brush macroinitiator. Aliquots of this initiator stock solution are added to vials that contain varied amounts of a photodegradable bis-norbornene crosslinker. Exposure to crosslinker initiates a series of kinetically-controlled brush+brush and star+star coupling reactions that ultimately yields BASPs with cores comprised of the crosslinker and coronas comprised of PEG. The final BASP size depends on the amount of crosslinker added. We carry out the synthesis of three BASPs on the benchtop with no special precautions to remove air and moisture. The samples are characterized by gel permeation chromatography (GPC); results agreed closely with our previous report that utilized inert (glovebox) conditions. Key practical features, advantages, and potential disadvantages of the brush-first method are discussed.

Poly(ethylene glycol) (PEG) brush-arm star polymers (BASPs) with narrow mass distributions and tunable nanoscopic sizes are synthesized in via ring opening metathesis polymerization (ROMP) of a PEG-norbornene macromonomer followed by transfer of portions of the resulting living brush initiator to vials containing varied amounts of a rigid, photo-cleavable bis-norbornene crosslinker.

Partikel ohne Box: Bürsten erste Synthese von Photochemisch PEG-Sterne-Polymers unter Umgebungsbedingungen

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug ...

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Chemie

Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.

Aktivieren Moleküle, Ionen und Feststoffpartikeln mit Acoustic Cavitation

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic ...

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

Synthese und katalytische Aktivität von Gold-Intercalated in den Wänden der mesoporösen Silicat-

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and efficient synthesis of well-controlled fluorescent statistical glycopolymers using reversible addition-fragmentation chain-transfer (RAFT)-based polymerization is demonstrated. The synthesis starts with the preparation of &#946;-galactose-containing glycomonomer 2-lactobionamidoethyl methacrylamide obtained by reaction of lactobionolactone and N-(2-aminoethyl) methacrylamide (AEMA). 2-Gluconamidoethyl methacrylamide (GAEMA) is used as a structural analog lacking a terminal &#946;-galactoside. The following RAFT-mediated copolymerization reaction involves three different monomers: N-(2-hydroxyethyl) acrylamide as spacer, AEMA as target for further fluorescence labeling, and the glycomonomers. Tolerant of aqueous systems, the RAFT agent used in the reaction is (4-cyanopentanoic acid)-4-dithiobenzoate. Low dispersities (&#8804;1.32), predictable copolymer compositions, and high reproducibility of the polymerizations were observed among the products. Fluorescent polymers are obtained by modifying the glycopolymers with carboxyfluorescein succinimidyl ester targeting the primary amine functional groups on AEMA. Lectin-binding specificities of the resulting glycopolymers are verified by testing with corresponding agarose beads coated with specific glycoepitope recognizing lectins. Because of the ease of the synthesis, the tight control of the product compositions and the good reproducibility of the reaction, this protocol can be translated towards preparation of other RAFT-based glycopolymers with specific structures and compositions, as desired.

An efficient, three-step synthesis of RAFT-based fluorescent glycopolymers, consisting of glycomonomer preparation, copolymerization, and post-modification, is demonstrated. This protocol can be used to prepare RAFT-based statistical glycopolymers with desired structures.

Leichte und effiziente Herstellung von Tri-Komponente Fluorescent Glycopolymere über RAFT-kontrollierte Polymerisation

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and ...

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.

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.

Ausbau und Systematische Symmetric Studien auf eine Serie von supramolekularen Cluster mit binären oder ternären 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 ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

Facile Herstellung von Intern Selbstorganisierte Lipidpartikel stabilisiert durch Kohlenstoff-Nanoröhren

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Facile Preparation of 4-Substituted Quinazoline Derivatives

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted 2-aminobenzophenones and thiourea in the presence of dimethyl sulfoxide (DMSO). This is a unique complementary reaction system in which thiourea undergoes thermal decomposition to form carbodiimide and hydrogen sulfide, where the former reacts with 2-aminobenzophenone to form 4-phenylquinazolin-2(1H)-imine intermediate, whilst hydrogen sulfide reacts with DMSO to give methanethiol or other sulfur-containing molecule which then functions as a complementary reducing agent to reduce 4-phenylquinazolin-2(1H)-imine intermediate into 4-phenyl-1,2-dihydroquinazolin-2-amine. Subsequently, the elimination of ammonia from 4-phenyl-1,2-dihydroquinazolin-2-amine affords substituted quinazoline derivative. This reaction usually gives quinazoline derivative as a single product arising from 2-aminobenzophenone as monitored by GC/MS analysis, along with small amount of sulfur-containing molecules such as dimethyl disulfide, dimethyl trisulfide, etc. The reaction usually completes in 4-6 hr at 160 &#186;C in small scale but may last over 24 hr when carried out in large scale. The reaction product can be easily purified by means of washing off DMSO with water followed by column chromatography or thin layer chromatography.

A protocol for facile preparation of 4-substituted quinazoline derivatives from 2-aminobenzophenones, thiourea and dimethyl sulfoxide is presented.

Facile Herstellung von 4-substituierte Chinazolinderivate

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.

This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.

Visualisierung von Ambient-Massenspektrometrie mit der Verwendung von Schlieren Fotografie

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Einfache Synthese von wurmartigen Mizellen durch sichtbares Licht Mediated Dispersion Polymerisation mit Photoredox Katalysator

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high atomic and step economy. However, this functionality-directed cross-coupling reaction has not been developed, as there are still limited directing groups in practical use. In particular, a stoichiometric amount of oxidant is usually required, producing a large amount of waste. Due to our interest in novel 1,3-butadiene synthesis, we describe the ruthenium-catalyzed olefination of electron-deficient alkenes using allyl acetate and without external oxidant. The reaction of 2-phenyl acrylamide and allyl acetate was chosen as a model reaction, and the desired diene product was obtained in 80% isolated yield with good stereoselectivity (Z,E/Z,Z = 88:12) under optimal conditions: [Ru(p-cymene) Cl2]2 (3 mol %) and AgSbF6 (20 mol %) in DCE at 110 &#186;C for 16 h. With the optimized catalytic conditions in hand, representative &#945;- and/or &#946;-substituted acrylamides were investigated, and all reacted smoothly, regardless of aliphatic or aromatic groups. Also, differently N-substituted acrylamides have proven to be good substrates. Moreover, we examined the reactivity of different allyl derivatives, suggesting that the chelation of acetate oxygen to the metal is crucial for the catalytic process. Deuterium-labeled experiments were also conducted to investigate the reaction mechanism. Only Z-selective H/D exchanges on acrylamide were observed, indicating a reversible cyclometalation event. In addition, a kinetic isotope effect (KIE) of 3.2 was observed in the intermolecular isotopic study, suggesting that the olefinic C-H metalation step is probably involved in the rate-determining step.

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

The ruthenium-catalyzed olefination of electron-deficient alkenes with allyl acetate is described here. By using aminocarbonyl as a directing group, this external oxidant-free protocol has high efficiency and good stereo- and regioselectivity, opening a novel synthetic route to (Z,E)-butadiene skeletons.

Facile Vorbereitung von (2<em&gt; Z</em&gt;, 4<em&gt; E</em&gt;) - Dienamide durch Olefinierung von elektronenarmen Alkenen mit Allylacetat

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high ...