Los autores extienden su agradecimiento al Dr. Thomas J. Emge y Wei Liu de la Universidad de Rutgers por su análisis y experiencia en difracción de rayos X de ángulo pequeño y difracción de rayos X en polvo. Además, los autores reconocen a Hao Wang por su apoyo con los experimentos de adsorción de N2.

1. Síntesis de nanopartículas de Al (OH) 3 <ol><li> Se disuelven 1,40 g de hexahidrato de cloruro de aluminio en 5,822 g de agua desionizada. </li><li> Se a~naden 2,778 g de L-arginina a la solución acuosa de cloruro de aluminio bajo agitación magnética. Agregue la L-arginina lentamente, de modo que la arginina añadida se disuelva y no forme grandes grupos o trozos; Además, una adición lenta reduce las concentraciones locales de alcalinidad y proporciona las condiciones para una hidrólisis más controlable. </li><li> Una vez que toda la arginina se disuelve en la solución, calentar la solución durante 72 h a 50 ° C; En este punto, la solución puede aparecer como una suspensión turbia. </li></ol> 2. Precipitación de Al (OH) 3 con NaCl <ol><li> Prepare una columna de GPC de 49 pulgadas de largo y 1.125 de diámetro. Empaquete el gel en pasos sucesivos de agregar el gel y de permitir que el agua fluya a través de la columna para asegurar el embalaje apropiado, con el espacio mínimo entre los granos del gel. Empaca elGel a aproximadamente 80% de la columna; La cantidad de gel embalado varía cada vez y sólo afecta el tiempo de retención de las especies separadas. </li><li> Introducir 10 ml de la suspensión de nanopartículas de Al (OH) 3 sintetizada (preparada en el paso 1.3) en la columna usando una bomba de HPLC con un bucle inyector de 10 ml. Hacer por encargo el bucle del inyector usando tubería con un diámetro externo de aproximadamente 0,125 pulgadas y una longitud que está calibrada para suministrar 10 mL de muestra inyectada. </li><li> Recoger la columna de elución en intervalos de correlación con la localización del pico de dRI. Conecte la salida GPC a la entrada de un detector de índice de refracción diferencial (dRI). NOTA: Como especies separadas salen del GPC, aparecen en el detector de dRI como un pico y luego se recogen en botellas de 125 mL. La columna GPC produce dos picos bien resueltos, que se recogen y se analizan con cromatografía de exclusión de tamaño (SEC) y análisis elemental (EA) para discernir arginina a partir de aluminio speCies El volumen total recogido dependerá del tamaño de la columna de GPC, de la cantidad total de material de envasado utilizado y del caudal del agua desionizada utilizada para eluir la columna. <ol><li> Recoger la mayoría de la fracción de pico 1 durante 100 min a una velocidad de flujo de 0,2 ml / min. </li><li> Recoger el eluyente en intervalos de 30 minutos una vez que un pico emerge en el detector RI de la columna GPC. NOTA: Al cambiar el rango de intervalos se cambiará la concentración y pureza del material de pico 1 purificado resultante. Es mejor recolectar pequeños intervalos del pico al principio para determinar qué porción contiene la concentración y pureza más altas de las especies de pico 1 para una columna específica. </li></ol></li><li> Preparar 1% en peso de NaCl. </li><li> Añadir la solución de NaCl preparada gota a gota a 10 ml de nanopartículas de Al (OH) 3 purificadas; El material preparado usando precipitación de NaCl no se usa para experimentos adicionales. </li></ol> 3. Preparación de Al-MCM-41 <ol><li> C.AAproximadamente 1,0 g de MCM-41 a 120 ° C bajo vacío durante 3 h en un horno de vacío. </li><li> Preparar 50,0 g de solución de cloruro de aluminio combinando 9,6926 g de AlCl $ ₃ $ 6H $ ₂ $ O con 40,3074 g de agua desionizada. </li><li> Se a~naden 0,7 g de MCM-41 activado a 50,0 g de solución de cloruro de aluminio (preparada en la etapa 3.2). </li><li> Dejar un tiempo de mezclado adecuado (1 h) para asegurar la homogeneidad del AlCl3 difundido a través de los canales MCM-41. </li><li> Añadir L-arginina a la mezcla heterogénea hasta una relación molar Arg / Al de 2,75 bajo agitación magnética. De forma similar al paso 1.2, a~nadir la arginina lo suficientemente lentamente para permitir que los floculados instantáneamente formados se redisolvan y reduzcan el aglomerado de la arginina antes de continuar la adición. </li><li> Una vez homogéneo, calentar la mezcla a 50 ° C durante 72 h. </li><li> Filtrar la solución heterogénea obtenida utilizando un embudo de Buchner, bajo vacío y equipado con círculos de papel de filtro de calidad de 90 mm(O cualquier otro papel de filtro apropiado). </li><li> Lavar el polvo blanco filtrado con agua desionizada en exceso para asegurar la eliminación del cloruro de aluminio, la arginina o los subproductos solubles en agua que no han reaccionado del material Al-MCM-41 producido. </li></ol>

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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>

Los autores no tienen nada que revelar.

La preparación de una solución acuosa de cloruro de aluminio implicó el uso de una sal de hexahidrato cristalino de cloruro de aluminio. Aunque también se puede usar la forma anhidra, no se prefiere debido a sus propiedades higroscópicas significativas, lo que hace difícil trabajar con y controlar la concentración de aluminio. Cabe destacar que la solución de cloruro de aluminio debe utilizarse dentro de varios días de preparación porque con el tiempo, el ácido acuoso [Al (H2O) 6 ] 3+ se...

Los materiales hechos de hidróxido de aluminio son candidatos prometedores para una variedad de aplicaciones industriales, incluyendo catálisis, productos farmacéuticos, tratamiento de agua y cosméticos. 1 , 2 , 3 , 4 A temperaturas elevadas, el hidróxido de aluminio absorbe una cantidad sustancial de calor durante la descomposición para producir alúmina (Al2O3), haciéndolo un agente retardador de llama útil. 5 Los cuatro polimorfos conocidos del hidróxido de aluminio ( es decir , gibbsite, bayerita, nordstrandita y doyleita) han sido investigados usando técnicas computacionales y experimentales para mejorar nuestra comprensión de la formación y estructuras de los mismos 6 . La preparación de partículas de nanoescala es de particular interés debido a su potencial para exhibir efectos cuánticos y propiedades que difieren de las de losR contrapartes a granel. Las partículas de nanopartículas con dimensiones del orden de 100 nm se preparan fácilmente bajo diversas condiciones 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 . Superar los desafíos inherentes asociados con la reducción de los tamaños de partícula más es difícil; Por lo tanto, sólo existen unos pocos casos donde las partículas de nanogibbsite tienen dimensiones del orden de 50 nm. 14 , 15 , 16 , 17 Hasta donde sabemos, no ha habido informes de nanogibbsite partículas menores de 50 nm. En parte, esto se atribuye al hecho de que las nanopartículas tienden a aglomerarse debido a la inestabilidad electrostáticaY la alta probabilidad de formación de enlaces de hidrógeno entre las partículas coloidales, especialmente en disolventes próticos polares. Nuestro objetivo fue sintetizar pequeñas nanopartículas de Al (OH) 3 utilizando ingredientes y precursores exclusivamente seguros. En el presente trabajo, se inhibió la agregación de partículas acuosas incorporando un aminoácido ( es decir , L-arginina) como tampón y estabilizador. Además, se ha descrito que la arginina que contiene guanidinio impidió el crecimiento y la agregación de partıculas de hidróxido de aluminio para dar una suspensión coloidal acuosa con tama~nos medios de partıculas de 10-30 nm. Se propone aquí que las propiedades anfóteras y zwitteriónicas de la arginina mitiguen la carga superficial de las nanopartículas de hidróxido de aluminio durante la hidrólisis suave para desfavorecer el crecimiento de partículas más allá de 30 nm. Aunque la arginina no era capaz de reducir el tama~no de partıcula por debajo de 10 nm, tales partıculas se consiguieron aprovechando el efecto de confinamiento de &quot;jaula&quot;Hin los mesoporos de MCM-41. La caracterización del material compuesto Al-MCM-41 reveló nanopartículas de hidróxido de aluminio ultrafino dentro de la sílice mesoporosa, que tiene un tamaño medio de poro de 2,7 nm.

<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

Se sintetizó una suspensión acuosa de nanogibbsite mediante la titulación de ácido acuoso de aluminio [Al (H _ { 2 } O) _ { 6 } ] _ { 3+} con L - arginina a pH 4,6. Dado que se sabe que la hidrólisis de sales de aluminio acuosas produce una amplia gama de productos con una amplia gama de distribuciones de tamaños, una variedad de instrumentos de vanguardia ( es decir, 27 Al / 1H NMR, FTIR, ICP-OES , TEM-EDX, XPS, XRD y BET) para caracterizar los productos de síntesis e identificación de subproductos. El producto, que estaba compuesto de nanopartículas (10 - 30 nm), se aisló usando cromatografía de permeación de gel (GPC). La espectroscopia de infrarrojo por transformada de Fourier (FTIR) y la difracción de rayos X en polvo (PXRD) identificaron el material purificado como el polimorfo gibbsita del hidróxido de aluminio. La adición de sales inorgánicas ( por ejemplo , NaCl) indujo la desestabilización electrostática de la suspensión, aglomerando así las nanopartículas a yieLd Al (OH) 3 precipita con grandes tamaños de partícula. Utilizando el nuevo método de síntesis descrito aquí, Al (OH) 3 se cargó parcialmente dentro del marco mesoporoso altamente ordenado de MCM-41, con dimensiones de poro promedio de 2,7 nm, produciendo un material de aluminosilicato con Al (Oh / T $ _ { d } $ = 1,4). El contenido total de Al, medido usando espectrometría de rayos X de energía dispersiva (EDX), fue 11% p / p con una relación molar Si / Al de 2,9. Una comparación de EDX en masa con espectroscopía de superficie de espectroscopía de rayos X (XPS) análisis elemental proporcionó información sobre la distribución de Al dentro del material de aluminosilicato. Además, se observó una relación más alta de Si / Al en la superficie externa (3.6) en comparación con la masa (2.9). Las aproximaciones de las relaciones O / Al sugieren una mayor concentración de grupos Al (O) 3 y Al (O) 4 cerca del núcleo y la superficie externa, respectivamente. La recién desarrollada síntesis de Al-MCM-41 produce unaCon alto contenido de Al, manteniendo al mismo tiempo la integridad de la estructura de sílice ordenada y puede utilizarse para aplicaciones en las que las nanopartículas de Al2O3 hidratadas o anhidras son ventajosas.

Síntesis de Nanogibbsite El Nanogibbsite se preparó titulando AlCl $ ₃ $ 6H $ ₂ $ O (14% en peso) con L-arginina hasta una relación molar Arg / Al final de 2,75. La síntesis de partículas de nanogibbsite se controló mediante SEC, que es una técnica de análisis ampliamente utilizada para soluciones de cloruro de aluminio parcialmente hidrolizadas, capaces de discernir cinco dom...

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

Se preparó una suspensión de nanopartículas de hidróxido de aluminio ultrafino mediante la titulación controlada de [Al (H2O)] 3+ con L-arginina hasta pH 4.6 con y sin confinamiento de efecto jaula dentro de canales mesoporosos de MCM-41.

Facile Preparación de Partículas de Hidróxido de Aluminio Ultrafino con o sin Mesoporous MCM-41 en Ambientes Ambientales

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

Research

JoVE Journal

Chemistry

10.8K vistas.  Colgate-Palmolive Company.  Se preparó una suspensión de nanopartículas de hidróxido de aluminio ultrafino mediante la titulación controlada de [Al (H2O)] 3+ con L-arginina hasta pH 4.6 con y sin confinamiento de efecto jaula dentro de canales mesoporosos de MCM-41. 

Video: 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.

Partículas sin caja: Cepillo-primero Síntesis de fotodegradables PEG estrellas Polímeros bajo Condiciones Ambientales

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

Investigación

Química

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.

Activación de moléculas, iones y partículas sólidas con cavitación acústica

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.

Síntesis y rendimiento catalítico de Oro intercalados en las Murallas de sílice mesoporoso

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.

Preparación Facile y Eficiente de la glicopolímeros fluorescentes Tri-componentes a través de polimerización BALSA controlado

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.

Construcción y sistemática Estudios simétricas de una serie de clusters supramoleculares con Triphenylacetates amonio binarias o ternarias

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.

Preparación fácil del ensamblado autónomos Internamente Lípidos Las partículas estabilizadas por nanotubos de carbono

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.

Preparación Facile de derivados de quinazolina 4-sustituidos

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.

La visualización del ambiente Espectrometría de Masas con el uso de la fotografía Schlieren

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.

Síntesis Facile de micelas similares a gusanos de luz visible mediada por dispersión Polimerización con catalizador Photoredox

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.

Preparación Facile de (2<emZ</em&gt;, 4<emE</em&gt;) - Dienamidas por la olefinación de electrones deficientes Alkenes con acetato de alilo

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