Agradecemos el apoyo financiero nacional clave de investigación y desarrollo programa de Ministerio de ciencia y tecnología de China (2016YFB0600305), Fundación Nacional de Ciencias naturales de China (núms. 21573031 y 21373038), programa Excelente talento en ciudad de Dalian (2016RD09) y la educación tecnológica y superior Instituto de Hong Kong (sus SG1617105 y sus SG1617127).

PRECAUCIÓN: Para el manejo adecuado de métodos, propiedades y toxicidad de los productos químicos que se describe en este artículo, consulte las hojas de datos de seguridad material (MSDS). Algunos de los productos químicos utilizados son tóxicos y cancerígenos y especiales cuidados deben tomarse. Nanomateriales potencialmente pueden plantear riesgos de seguridad y salud. Debe evitarse el contacto de inhalación y piel. Debe tenerse precaución de seguridad, como la síntesis del catalizador en la humos campana y catalizador de evaluación del desempeño con los reactores de autoclave. Debe usarse equipo de protección personal.
1. preparación de Ni0.97Nota0.03O catalizadores donde relaciones molares de Nb:(Ni+Nb) igualan a 0.03
<ol><li>0,161 g de hidrato de oxalato de niobio (V) se combinan con 2,821 g de nitrato de níquel en 100 mL de agua desionizada en un matraz de fondo redondo cuello tres 250 mL equipado con una barra de agitación.</li>
	<li>Agitar la solución a 50 rpm y 70 ° C para disolver los compuestos hasta la desaparición del precipitado con un agitador magnético calefacción.</li>
	<li>Elevar la temperatura rápidamente hasta 80 ° C a una velocidad de 2 ° C por minuto.</li>
	<li>Añadir una solución básica mixta [hidróxido de amonio acuoso (50 mL, 1,0 M) e hidróxido de sodio (50 mL, 0,2 M)] en la mezcla de reacción, gota a gota hasta que el pH de la solución Ni/Nb llegue a 9.0.</li>
	<li>Agitando la mezcla de reacción, aumentar la temperatura a 120 ° C a 2 ° C por minuto.</li>
	<li>Revuelva la mezcla de reacción durante la noche a 50 rpm a 120 ° C hasta la completa desaparición del color verde de la solución.</li>
	<li>De emisión óptica de plasma acoplado inductivamente espectrometría (ICP-OES) análisis de la solución evaluar la concentración de Nb5 + iones en la solución restante Ni2 + y y asegurar la precipitación completa de níquel restantes nitrato.</li>
	<li>Recoger el sólido por filtración utilizando el frasco de Büchner. Lave el sólido mediante la adición de agua de 2 L desionizada repetidamente dentro de 20 minutos para quitar el catión Na+ residual.</li>
	<li>Recoger el sólido en un vidrio de reloj. Secar el sólido a 110 ° C por 12 h en horno seco.</li>
	<li>Calcinar por los sólidos en aire sintético (20 mL/min O2 y 80 mL/min N2) a 450 ° C durante 5 h en el horno de tubo de la calefacción. Compruebe toda la cristalería por defecto antes de usar la temperatura alta de reacción.</li>
	<li>Después de la calcinación, obtener 1 g de Ni0.97catalizador de0.03O Nb. Utilizar equipos de protección apropiados como gafas, guantes, bata de laboratorio, de humos y campana para llevar a cabo la reacción de nanocrystal debido a peligros de seguridad potenciales y efectos sobre la salud de los nanomateriales.</li>
</ol>2. preparación de Ni0,92Nb0.08O catalizadores que relaciones molares de Nb:(Ni+Nb) igualan a 0,08
<ol><li>Este procedimiento es similar a la de 1 excepto los dos primeros pasos:<ol>
<li>Disolver 0,43 g de hidrato de oxalato de niobio (V) en 100 mL de agua desionizada.</li>
		<li>Por separado, disolver 2,675 g de nitrato de níquel en 100 mL de agua desionizada.</li>
	</ol>
</li>
</ol>3. preparación de Ni0.85Nota0.15O catalizadores donde relaciones molares de Nb:(Ni+Nb) igualan a 0.15
<ol><li>El procedimiento es similar a la de 1 excepto los dos primeros pasos:<ol>
<li>Disolver 0,807 g de hidrato de oxalato de niobio (V) en 100 mL de agua desionizada.</li>
		<li>Por separado, disolver 2,472 g de nitrato de níquel en 100 mL de agua desionizada.</li>
	</ol>
</li>
</ol>4. preparación de Ni0.80Nb0.20O catalizadores donde relaciones molares de Nb:(Ni+Nb) igualan a 0.20
<ol><li>El procedimiento es similar a la de 1 excepto los dos primeros pasos:<ol>
<li>Disolver 1,076 g de hidrato de oxalato de niobio (V) en 100 mL de agua desionizada.</li>
		<li>Por separado, disolver 2,326 g de nitrato de níquel en 100 mL de agua desionizada.</li>
	</ol>
</li>
</ol>5. preparación de Nb2O5 utilizando el método de precipitación química
<ol><li>Calcinar el ácido niobic (Nb2O5·nH2O) en aire sintético de 5 horas a 450 ° C para obtener puro Nb2partículas de O5 . Nota: Confirme la finalización de la reacción usando análisis de difracción (DRX) polvo de rayos x, donde Nota2O5·nH2O es amorfo y cristalino Nb2O5 . Según el análisis, la calcinación de 5 horas a 450 ° C fue suficiente para completar la reacción.</li>
</ol>6. síntesis de compuesto modelo de lignina del β-O-4, 2-(2-methoxyphenoxy)-1-phenylethan-1-one
<ol><li>Disolver Bromoacetofenona (9,0 g, 45 mmol) y 2-Metoxifenol (6,6 g, 53 mmol) en 200 mL de dimetilformamida (DMF) en un erlenmeyer de 500 mL con un agitador magnético. Utilice adecuada protección equipo y humo de la capilla para realizar la reacción con los reactivos y sustancias químicas corrosivas y cancerígenas.</li>
	<li>La anterior solución DMF se mezclan con hidróxido de potasio (3.0 g, 53 mmol) y removemos la mezcla durante la noche a 50 rpm a temperatura ambiente utilizando agitadores magnéticos.</li>
	<li>Extraer el producto con la solución de mezcla de 200 mL de H2O y 600 mL de dietil éter (1:3, v/v) usando embudo de separación. Obtener la capa superior de éter dietílico de la solución.</li>
	<li>Añadir MgSO4 (10 g) para absorber la humedad de la solución de éter dietílico. Filtro de MgSO4 para obtener la solución de éter dietílico utilizando papel de filtro y embudo.</li>
	<li>Después de la eliminación de la solución de éter dietílico bajo presión reducida a 0.08 MPa con evaporador rotatorio, disolver el residuo en 5 mL de etanol.</li>
	<li>Lentamente se evapora el solvente etanol para recristalizan el producto en un vaso de precipitados de 10 mL. Obtener el producto (11,5 g) como polvo amarillento y el rendimiento del producto es 90% basado en Bromoacetofenona. 1análisis de RMN de H, 1H RMN (DMSO): δ 3.78 (s, 3 H, y3), 5,54 (s, H 2, CH2) 6,82-8.01 (m, H 9, aromáticos) ppm. 17
</li>
</ol>7. Hydrodeoxygenation de éter aromático lignina derivado
Nota: El éter aromático lignina derivado solicitado es anisole en este experimento y el catalizador es Ni0,92Nb0.08equipamiento de protección apropiado o uso y campana para llevar a cabo la reacción reactivos carcinogénicos.
<ol><li>Equipar un reactor autoclave de acero inoxidable de 50 mL con un calentador y un agitador magnético.</li>
	<li>Reducir el Ni0,92catalizador de0,08O Nb (1 g) obtenida en el paso 2 en el reactor autoclave en atmósfera de H2 a 400 ° C por 2 h y entonces apaciguar el catalizador bajo argón (50 mL/min) durante la noche.</li>
	<li>Anisole (1,1712 g, 8% en peso) se disuelven en n-decano (20 mL) con el uso de n-dodecano (0,2928 g, 2% en peso) como estándar interno para el análisis cuantitativo cromatografía de gases (GC).</li>
	<li>Introducir los catalizadores reducidos (0.1 g) en el reactor autoclave rápidamente para evitar el tiempo de exposición largo con aire (< 5 minutos).</li>
	<li>Sellar el reactor autoclave, purgación con H2 varias veces (3 veces, en 3 de MPa de presión) para eliminar el aire y luego la mezcla de reacción a presión ambiente.</li>
	<li>Establecer la velocidad de agitación a 700 rpm.</li>
	<li>Después de calentar a la temperatura deseada a 160-210 ° C a 2 ° C/min, presurice el reactor autoclave a 3 MPa y establecer el punto del tiempo cero (t = 0). Nota: El rango de temperatura de 160-210 ° C es apropiado en este informe.</li>
	<li>Posteriormente, enfriar la mezcla a la temperatura a 10 ° C/min inmediatamente y analizar los productos desoxigenados mediante cromatografía de gases con detector selectivo de masa. 17
</li>
	<li>Determinar la conversión del modelo de lignina compuesto según la siguiente ecuación: <img alt="Equation 1" src="/files/ftp_upload/56987/56987eq1.jpg">
</li>
	<li>Determinar la selectividad del producto según la siguiente ecuación: <img alt="Equation 2" src="/files/ftp_upload/56987/56987eq2.jpg">
</li>
</ol>

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No tenemos nada que revelar.

Uno de los métodos comunes para preparar las nanopartículas de óxido de niobio níquel dopados a granel es el método de la evaporación rotatoria. 9 mediante el empleo de diversas condiciones de presión y temperatura durante el proceso de evaporación rotatoria, la precipitación del comercio de partículas Ni-Nb-O con la eliminación lenta del solvente. En contraste con el método de evaporación rotatoria, el método de precipitación química reportado en este estudio ha recibido una atenc...

La preparación de nanocompuestos ha recibido creciente atención debido a su aplicación crucial en varios campo. Para preparar nanopartículas de óxido de Ni-Nb-O mixta,1,2,3,4,5,6 diferentes métodos se han desarrollado como método de mezcla seca,7, método de la evaporación de 8 ,9,10,11,12,13 sol gel método, método de descomposición térmica de14 ,15 y auto combustión. 16 en un método de evaporación típico9, soluciones acuosas que contengan la cantidad adecuada de precursores metálicos, nitrato de níquel hexahidratado y amonio oxalato de niobio se calienta a 70 ° C. Después de la remoción de solvente y posterior secado y calcinación, se obtuvo la mezcla de óxidos. Estos catalizadores de óxido exhiben excelente actividad catalítica y la selectividad hacia la deshidrogenación oxidativa (ODH) del etano, que se relaciona con el cambio electrónico y estructural inducido por la incorporación de cationes de niobio en el enrejado de NiO . 11 la inserción de la nota disminuye drásticamente la especie electrófila oxígeno, que es responsable de las reacciones de oxidación de etano12. Como resultado, las extensiones de este método se han realizado en la preparación de diferentes tipos de óxidos de Ni-Me-O mixtas, donde Me = Li, Mg, Al, Ga, Ti y Ta. 13 se encuentra que la variación de los dopantes de metal podría alterar a los radicales de oxígeno inespecíficos y electrofílico del NiO, así ajustar sistemáticamente la actividad de la ODH y selectividad hacia etano. Sin embargo, generalmente la superficie de estos óxidos es relativamente pequeño (< 100 m2/g), debido a la segregación de fase extendida y la formación de cristalitos grandes en nota2O5 y por lo tanto su uso en otros catalítico aplicaciones.
Mezcla el método, también conocido como el estado sólido pulido, seco es otro método utilizado para preparar los catalizadores de óxido mixto. Puesto que los materiales catalíticos se obtienen de una manera libre de solventes, este método proporciona una alternativa promisoria de verde y sostenible a la preparación de óxido mixto. La mayor superficie obtenida por este método es de 172 m2/g Ni80Nb20 a temperatura de calcinación de 250 ° C. 8 sin embargo, este método de estado sólido no es confiable como reactivos no se mezclan bien en la escala atómica. Por lo tanto, para un mejor control de homogeneidad química y granulometría específicas y morfología, otros métodos adecuados para preparar Ni-Nb-O mezclan óxido de nanopartículas todavía están siendo buscadas. 7
Entre diversas estrategias en el desarrollo de nanopartículas, precipitación química sirve como uno de los métodos prometedores para desarrollar nanocatalizadores, ya que permite la completa precipitación de los iones del metal. También, nanopartículas de superficies más comúnmente se preparan mediante este método. Para mejorar las propiedades catalíticas de las nanopartículas de Ni-Nb-O, Adjunto divulgamos el protocolo para la síntesis de una serie de catalizadores de óxido Ni-Nb-O mezclado con alta área superficial por el método de precipitación química. Hemos demostrado que la fracción molar de Nb:Ni es un factor crucial en la determinación de la actividad catalítica de los óxidos hacia la hydrodeoxygenation de compuestos orgánicos derivados de lignina. Con relación de alto Nb:Ni encima de 0.087, inactivo NiNb2O6 las especies se formaron. Ni0,92Nb0.08O, que tenía el área superficial más grande (173 m2/g), exhibe doblar-como nanosheets estructuras y mostró la mejor actividad y selectividad hacia el hydrodeoxygenation de anisole a ciclohexano.

<table>
	<tbody>
		<tr>
			<td>Niobium(V) oxalate hydrate, 98%</td>
			<td>Alfa</td>
			<td>L04481902</td>
			<td></td>
		</tr>
		<tr>
			<td>Nickel nitrate hexahydrate, 99%</td>
			<td>Aladdin</td>
			<td>N108891</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide, 98%</td>
			<td>Aladdin</td>
			<td>S111501</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide, 23-25%</td>
			<td>Aladdin</td>
			<td>A112077</td>
			<td></td>
		</tr>
		<tr>
			<td>Anisole, 99%</td>
			<td>Sinopharm</td>
			<td>81001728</td>
			<td></td>
		</tr>
		<tr>
			<td>Diphenyl ether, 98%</td>
			<td>Aladdin</td>
			<td>D110644</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenol, 98%</td>
			<td>Sinopharm</td>
			<td>100153008</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Methoxyphenol, 98%</td>
			<td>Sinopharm</td>
			<td>30114526</td>
			<td></td>
		</tr>
		<tr>
			<td>Vanillin, 99.5%</td>
			<td>Sinopharm</td>
			<td>69024316</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium hydroxide, AR</td>
			<td>Aladdin</td>
			<td>P112284</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-Dimethylformamide, 99.5%</td>
			<td>Sinopharm</td>
			<td>40016462</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Bromoacetophenone,98%</td>
			<td>Aladdin</td>
			<td>B103328</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl ether,99.5%</td>
			<td>Sinopharm</td>
			<td>10009318</td>
			<td></td>
		</tr>
		<tr>
			<td>Decane,98%</td>
			<td>Aladdin</td>
			<td>D105231</td>
			<td></td>
		</tr>
		<tr>
			<td>Dodecane,99%</td>
			<td>Aladdin</td>
			<td>D119697</td>
			<td></td>
		</tr>
		<tr>
			<td>Niobic acid</td>
			<td>CBMM</td>
			<td>1313968</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating and Drying Oven</td>
			<td></td>
			<td></td>
			<td>DHG Series (shanghai jinghong laboratory instrument co. ltd)</td>
		</tr>
		<tr>
			<td>Autoclave Reactor</td>
			<td></td>
			<td></td>
			<td>CJF-0.05&#8212;0.1L (Dalian Tongda Equipment Technology Development Co., Ltd)</td>
		</tr>
		<tr>
			<td>Tube&#160;furnace</td>
			<td></td>
			<td></td>
			<td>SK2-1-10/12 (Luoyang Huaxulier Electric Stove Co., Ltd)</td>
		</tr>
		<tr>
			<td>Heating magnetic stirrer</td>
			<td></td>
			<td></td>
			<td>DF-101 (Yu Hua Instrument Co. Ltd.)</td>
		</tr>
		<tr>
			<td>Rotary evaporator</td>
			<td></td>
			<td></td>
			<td>RE-3000A (Shanghai Yarong Biochemical Instrument Factory)</td>
		</tr>
		<tr>
			<td>Synthetic air</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen gas</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Argon gas</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

chemical precipitation method for the synthesis of nb2o5 modified bulk nickel catalysts with high specific surface area

Demostrar un método para la síntesis de catalizadores de1 xO NixNb con nanoestructuras esponjoso como una doblez. Variando la proporción de Nb:Ni, una serie de NixNbx 1O nanopartículas con diferentes composiciones atómicos (x = 0.03, 0.08, 0.15 y 0.20) han sido preparadas por precipitación química. Estos catalizadores de NixNbx 1O se caracterizan por difracción de rayos x, espectroscopía de fotoelectrones de rayos x y microscopía electrónica. El estudio reveló el aspecto esponjoso como una doblez de Ni0.97Nota0.03O y Ni0,92Nb0.08O en la superficie del NiO y la mayor superficie de estos catalizadores NixNbx 1O, en comparación con la mayor parte NiO. Máxima superficie de 173 m2/g puede obtenerse para los catalizadores de O de Ni0,92Nb0.08. Además, se han investigado la hydroconversion catalítica de compuestos derivados de lignina utilizando los síntesis Ni0,92Nb0.08O catalizadores.

Patrones de difracción de rayos x (DRX) (figura 1 y figura 2), apuesta superficies, reducción de temperatura programada de hidrógeno con hidrógeno (H2- TPR), microscopía electrónica de barrido (SEM) equipado con una energía dispersiva por rayos x (EDX ) analizador, espectroscopía de fotoelectrones de rayos x (XPS) fueron recogidos por las nanopartículas de NiO, Ni-Nb-O y Nb2O5 óxidos<sup...

Watch this Scientific Journal Video about Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area at JoVE.com

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

Se presenta un protocolo para la síntesis de esponjoso como una doblez Ni1 xNbxO nanopartículas por precipitación química.

Método de precipitación química para la síntesis de Nb2O5 modificado a granel catalizadores de níquel con alta superficie específica

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

chemical-precipitation-method-for-synthesis-nb2o5-modified-bulk

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Research

JoVE Journal

Chemistry

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

11.7K vistas.  Dalian University of Technology. Se presenta un protocolo para la síntesis de esponjoso como una doblez Ni1 xNbxO nanopartículas por precipitación química.

Video: Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Gyroid Níquel Nanoestructuras de copolímero de dibloques supramoléculas

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

Investigación

Química

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

Un método para manipular tensión superficial de un metal líquido a través de la oxidación de la superficie y Reducción

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

Protocolo para la Síntesis de<em&gt; Ortho</em&gt; derivados de anilina -trifluoromethoxylated

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

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 ...

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are demonstrated here. The catalyst forms a substitutional solid solution structure, with a small and uniform particle size around 2 nm. This is realized by careful control over the impregnation, calcination, and reduction steps during catalyst preparation and is identified by advanced in situ synchrotron techniques. The catalyst propane dehydrogenation performance continuously improves with increasing Cu:Pt atomic ratio.

A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.

Síntesis y Prueba de Catalizadores de Nanopartículas de Solución Sólida Pt-Cu Soportadas para la Deshidrogenación de Propano

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are ...

Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen reduction reaction. Spontaneous galvanic displacement was used to deposit Pt layers onto Ni nanowire substrates. The synthesis approach produced catalysts with high specific activities and high Pt surface areas. Hydrogen annealing improved Pt and Ni mixing and specific activity. Acid leaching was used to preferentially remove Ni near the nanowire surface, and oxygen annealing was used to stabilize near-surface Ni, improving durability and minimizing Ni dissolution. These protocols detail the optimization of each post-synthesis processing step, including hydrogen annealing to 250 &#176;C, exposure to 0.1 M nitric acid, and oxygen annealing to 175 &#176;C. Through these steps, Pt-Ni nanowires produced increased activities more than an order of magnitude than Pt nanoparticles, while offering significant durability improvements. The presented protocols are based on Pt-Ni systems in the development of fuel cell catalysts. These techniques have also been used for a variety of metal combinations, and can be applied to develop catalysts for a number of electrochemical processes.

&#160; The protocol describes the synthesis and electrochemical testing of platinum-nickel nanowires. Nanowires were synthesized by the galvanic displacement of a nickel nanowire template. Post-synthesis processing, including hydrogen annealing, acid leaching, and oxygen annealing were used to optimize nanowire performance and durability in the oxygen reduction reaction.

Síntesis de nanocables de platino y níquel y optimización de rendimiento de reducción de oxígeno

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen ...

Synthesis of a Thiol Building Block for the Crystallization of a Semiconducting Gyroidal Metal-sulfur Framework

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and porous metal-dithiolene network in the highly ordered single crystalline state. Unlike the highly reactive free-standing thiols, which tend to decompose and complicate the crystallization of metal-thiolate open frameworks, the thioester reacts in situ to provide the thiol species, serving to mitigate the reaction between the mercaptan units and the metal centers, and to improve crystallization consequently. Specifically, the thioester was synthesized in a one-pot procedure: an aromatic bromide (hexabromotriphenylene) reacted with excess sodium thiomethoxide under vigorous conditions to first form the thioether intermediate product. The thioether was then demethylated by the excess thiomethoxide to provide the thiolate anion that was acylated to form the thioester product. The thioester was conveniently purified by standard column chromatography, and then used directly in the framework synthesis, wherein NaOH and ethylenediamine serve to revert in situ the thioester to the thiol linker for assembling the single-crystalline Pb(II)-dithiolene network. Compared with other methods for thiol synthesis (e.g., by cleaving alkyl thioether using sodium metal and liquid ammonia), the thioester synthesis here uses simple conditions and economical reagents. Moreover, the thioester product is stable and can be conveniently handled and stored. More importantly, in contrast to the generic difficulty in accessing crystalline metal-thiolate open frameworks, we demonstrate that using the thioester for in situ formation of the thiol linker greatly improves the crystallinity of the solid-state product. We intend to encourage broader research efforts on the technologically important metal-sulfur frameworks by disclosing the synthetic protocol for the thioester as well as the crystalline framework solid.

Here, we present a one-pot, transition-metal-free synthesis of thiols and thioesters from aromatic halides and sodium thiomethoxide, followed by the preparation of single crystals of a metal-dithiolene network using thiol species generated in situ from the more stable and tractable thioester.

Síntesis de un componente tiol para la cristalización de un semiconductor marco Gyroidal Metal-azufre

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Síntesis de nanocables de Au sustrato enlazado mediante un mecanismo activo crecimiento superficial

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting self-assembled supramolecular structures. The synthetic route takes advantage of solid-phase peptide synthesis with the on-resin coupling of the dithiolane precursor molecule, 3-(acetylthio)-2-(acetylthiomethyl)propanoic acid, and the microwave-assisted thioacetate deprotection of the peptide N-terminus before final cleavage from the resin to yield the 1,2-dithiolane modified peptide. After the high-performance liquid chromatography (HPLC) purification of the 1,2-dithiolane peptide, derived from the nucleating core of the A&#946; peptide associated with Alzheimer&#39;s disease, the peptide is shown to self-assemble into cross-&#946; amyloid fibers. Protocols to characterize the amyloid fibers by Fourier-transform infrared spectroscopy (FT-IR), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM) are presented. The methods of N-terminal modification with a 1,2-dithiolane moiety to well-characterized self-assembling peptides can now be explored as model systems to develop post-assembly modification strategies and explore dynamic covalent chemistry on supramolecular peptide nanofiber surfaces.

A protocol for the synthesis of a 1,2-dithiolane modified peptide and the characterization of the supramolecular structures resulting from the peptide self-assembly.

Síntesis y caracterización de 1, 2-Dithiolane modifican uno mismo-montaje de péptidos

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting ...

Synthesis and Bioconjugation of Thiol-Reactive Reagents for the Creation of Site-Selectively Modified Immunoconjugates

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. Yet maleimide-based conjugates display limited stability in vivo because the succinimidyl thioether linkage can undergo a retro-Michael reaction. This, of course, can lead to the release of the radioactive payload or its exchange with thiol-bearing biomolecules in circulation. Both of these processes can produce elevated activity concentrations in healthy organs as well as decreased activity concentrations in target tissues, resulting in reduced imaging contrast and lower therapeutic ratios. In 2018, we reported the creation of a modular, stable, and easily accessible phenyloxadiazolyl methyl sulfone reagent &#8212; dubbed &#8216;PODS&#8217; &#8212; as a platform for thiol-based bioconjugations. We have clearly demonstrated that PODS-based site-selective bioconjugations reproducibly and robustly create homogenous, well-defined, highly immunoreactive, and highly stable radioimmunoconjugates. Furthermore, preclinical experiments in murine models of colorectal cancer have shown that these site-selectively labeled radioimmunoconjugates exhibit far superior in vivo performance compared to radiolabeled antibodies synthesized via maleimide-based conjugations. In this protocol, we will describe the four-step synthesis of PODS, the creation of a bifunctional PODS-bearing variant of the ubiquitous chelator DOTA (PODS-DOTA), and the conjugation of PODS-DOTA to the HER2-targeting antibody trastuzumab.

In this protocol, we will describe the synthesis of PODS, a phenyoxadiazolyl methyl sulfone-based reagent for the site-selective attachment of cargos to the thiols of biomolecules, particularly antibodies. In addition, we will describe the synthesis and characterization of a PODS-bearing bifunctional chelator and its conjugation to a model antibody.

Síntesis y Bioconjugation de tioles reactivos reactivos para la creación de sitio selectivamente modificados Immunoconjugates

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. ...

Método de precipitación química para la síntesis de Nb₂O₅ modificado a granel catalizadores de níquel con alta superficie específica

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