Financial support from the DFG (Heisenberg scholarship to M.K., KL 2221/4-1; KL 2221/3-1) and the Max-Planck-Institut fuer Kohlenforschung is gratefully acknowledged.

1. Síntesis de tetrahidrocarbazol hidroperóxidos <ol><li> La formación del hidroperóxido se ralentiza si el tetrahidrocarbazol está muy coloreado. En este caso, purificarlo por recristalización usando tolueno / pentano o por cromatografía en columna para obtener un material de partida incoloro. Para la purificación por cromatografía en columna, el paquete de una columna con una capa inferior de gel de sílice y una capa superior de la alúmina. Ponga la tetrahidrocarbazol en la parte superior de la columna y se eluye con tolueno. Todos los subproductos de color amarillo y negro no deseados son adsorbidos en la columna y se eluye tetrahidrocarbazol incoloro. Inmediatamente se evapora el disolvente y almacenar el producto blanco purificada bajo una atmósfera de argón en la oscuridad. </li><li> Pesar 1 g de tetrahidrocarbazol o de un tetrahidrocarbazol sustituido (1, sintetizado de acuerdo con métodos reportados 16) en un matraz de 250 ml. Añadir 100 ml de tolueno a este matraz. </li><li> Pesar Rosa de Bengala (2mg) y añadirlo a la mezcla de reacción anterior. </li><li> Añadir una barra de agitación y cubrir el recipiente con tabiques. </li><li> Añadir un balón de oxígeno a través del tabique; esto mantiene una presión positiva de atmósfera de oxígeno en la reacción. </li><li> Irradiar la mezcla de reacción con una lámpara de 23 vatios. </li><li> Comprobar el progreso de la reacción por cromatografía en capa fina (TLC, usando una mezcla de hexano / acetato de etilo 70:30 en relación; el valor de Rf de los hidroperóxidos descritos en el presente documento es entre 0,2 y 0,3) o por 1 H RMN de un muestra tomada (se evapora el disolvente en un evaporador rotatorio y el residuo se disuelve en DMSO-d6). Los tiempos de reacción pueden variar dependiendo de la fuente de luz y la pureza del material de partida, como se menciona en la parte 1.1. En general, la conversión total de tetrahidrocarbazoles 1 toma 3 horas. </li><li> Se filtra el sólido precipitado después de la conversión completa del material de partida. Lavado del sólido se puede hacer con pentano con el fin de eliminar la mayor parte deel tolueno, pero no es necesario para la purificación. </li><li> Secar el sólido aislado a presión reducida. </li></ol> PRECAUCIÓN: A pesar de que nunca he experimentado ningún problema en trabajar con o manipulación de los compuestos descritos en este trabajo, se deben tomar precauciones cuando se trabaja con peróxidos. En particular, debe evitarse en la medida de lo posible para exponer peróxidos aseados para calentar o para mezclarlos con metales o sales metálicas. Se recomienda llevar a cabo tales reacciones detrás de un escudo de la explosión. . 2 Reacción de acoplamiento - Método A Uso de 10% en moles de ácido trifluoroacético en metanol <ol><li> Pesar el hidroperóxido de (0,49 mmol, 1,0 equiv. Desde el paso 1) y el nucleófilo deseado anilina (0,49 mmoles, 1,0 equiv.) En un vial de 12 ml o un matraz de fondo redondo adecuado. </li><li> Añadir 10 ml de MeOH y, posteriormente, 3,74 l de ácido trifluoroacético (TFA, 0,049 mmoles, 0,1 equiv.) Al vial o matraz de fondo redondo. </li><li> Cerrar el recipiente con un tapón yse agita la mezcla de reacción a temperatura ambiente durante 4 h. El tratamiento variante A1 (para productos que precipitan en el transcurso de la reacción): </li><li> Se filtra el sólido precipitado para obtener el producto deseado. Se lava el producto con metanol (3 x 0,5 ml). </li><li> Para obtener una segunda fracción de producto, se evapora el metanol del filtrado. Disolver el producto bruto en 5 ml de acetato de etilo a 40 ° C, luego se enfría hasta temperatura ambiente y añadir 3-5 ml de pentano El producto puro precipita. </li><li> Combinar las diferentes fracciones de producto y secar bajo alto vacío. El tratamiento variante A2 (para productos que no precipitan): </li><li> Evaporar el disolvente directamente después de la reacción mediante el uso de un evaporador rotatorio y purificar el residuo por cromatografía en columna como se especifica (gel de sílice, hexano / acetato de etilo / trietilamina) para obtener el producto deseado. </li></ol> 3 reacción de acoplamiento -. Método BUsando ácido acético <ol><li> Pesar el hidroperóxido de (0,49 mmol, 1,0 equiv. Desde el paso 1) y el nucleófilo deseado anilina (0,49 mmoles, 1,0 equiv.) En un vial de 12 ml o un matraz de fondo redondo adecuado. </li><li> Añadir 10 ml de ácido acético (AcOH) a la que el vial o matraz de fondo redondo. </li><li> Cierre el recipiente con una tapa y se agita la mezcla de reacción a temperatura ambiente durante 4 h. El tratamiento variante B1 (para productos que precipitan en el transcurso de la reacción): </li><li> Se filtra el sólido precipitado para obtener el producto deseado. Se lava el producto con AcOH (3 x 0,5 ml). </li><li> Para obtener una segunda fracción de producto, se evapora el ácido acético a partir del filtrado. Disolver el producto bruto en 5 ml de acetato de etilo a 40 ° C, luego se enfría hasta temperatura ambiente y añadir 3-5 ml de pentano El producto puro precipita. </li><li> Combinar las diferentes fracciones de producto y secar bajo alto vacío. Variante Workup B2 </strong&gt; (para productos que no se precipitan): </li><li> Evaporar el disolvente directamente después de la reacción mediante el uso de un evaporador rotatorio y purificar el residuo por cromatografía en columna como se especifica (gel de sílice, hexano / acetato de etilo / trietilamina) para obtener el producto deseado. </li></ol>

<ol>
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Los autores no tienen nada que revelar.

En resumen, hemos podido demostrar que un enlace CH en tetrahidrocarbazoles puede ser convenientemente funcionalizado para generar productos CN-acoplamiento en un procedimiento de dos pasos. El primer paso es una oxidación fotocatalizada bien conocido de tetrahidrocarbazol (1) o sus derivados con oxígeno elemental 17,19, dando un hidroperóxido 2. Si se realiza en tolueno, los productos de hidroperóxido precipitan y pueden ser convenientemente ...

La funcionalización directa de enlaces CH es un importante y una meta permanente en química orgánica 1. Tales transformaciones pueden ser muy poderosos a fin de racionalizar la síntesis por el ahorro de pasos, el tiempo y el material en comparación con los métodos convencionales que requieren la introducción y extracción de la activación o dirigir grupos. Por lo tanto, la funcionalización de enlaces CH también es atractivo para la química verde 2. En condiciones oxidativas, dos enlaces CH o uno CH y un enlace heteroátomo-H puede ser transformado a enlaces CC y C-heteroátomo, respectivamente (Figura 1) 3-9. A menudo, estas reacciones de acoplamiento oxidativo requieren oxidantes sintéticos, catalizadores caros o altas temperaturas. Por lo tanto, se hicieron muchos intentos para desarrollar métodos que utilizan catalizadores baratos, las condiciones benignas y oxígeno o aire como oxidante terminal de 10. <img alt="Figura 1" fo:content-wUR A = &quot;5in&quot; src = &quot;/ files/ftp_upload/51504/51504fig1highres.jpg&quot; width = &quot;500&quot; /&gt; Figura 1. Reacciones de acoplamiento oxidativo. <a href="https://www.jove.com/files/ftp_upload/51504/51504fig1highres.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> Muchos compuestos orgánicos reaccionan lentamente con el oxígeno del aire en las reacciones de autooxidación que puede funcionalizar enlaces CH mediante la inserción eficaz de O 2, formando un resto hidroperóxido de 11,12. Procesos de autooxidación se utilizan a escala industrial a los compuestos oxigenados generados a partir de materias primas de hidrocarburos, pero auto-oxidación es también un proceso no deseado si conduce a la descomposición de compuestos o materiales valiosos. En algunos casos, por ejemplo éter dietílico, hidroperóxidos formados en el aire pueden también ser explosivo. Recientemente, hemos descubierto una reacción que utiliza un auto-oxidación para formar un nuevo enlace CC de enlaces CH y sin necesidad de un catalizador redox-activo 13,14 </sup&gt;. Simplemente agitar los sustratos de bajo oxígeno en presencia de un catalizador ácido conduce a la formación de los nuevos productos. Clave para la reacción es la formación fácil de hidroperóxidos intermedios, que están sustituidos con el segundo sustrato por catálisis ácida 15. La reacción, sin embargo, está restringida a xanteno y unos pocos compuestos relacionados que se oxidan fácilmente bajo una atmósfera de oxígeno y los productos tienen aplicaciones que hasta ahora no se han encontrado. No obstante inspirado por este descubrimiento, hemos desarrollado un método de acoplamiento oxidativo relacionado que utiliza el principio de CH funcionalización a través de intermedios peróxidos (chips) para sintetizar derivados de indol farmacéuticamente activas 16. Los indoles, especialmente tetrahidrocarbazoles 1, puede ser fácilmente oxidado a hidroperóxidos 2 en presencia de oxígeno singlete 17-19, que puede ser generada usando un sensibilizador y la luz visible 20. A hydrfracción operoxide puede, en principio, actúan como un grupo saliente si son activados mediante catálisis ácida y permite la introducción de un nucleófilo 21,22. Los hidroperóxidos son también conocidos a someterse a reacciones de transposición catalizada por ácido como se utiliza en la síntesis industrial de fenol a partir de cumeno, el procedimiento de Hock 23. Por los estudios de optimización cuidadosos, podríamos encontrar las condiciones para favorecer la reacción de sustitución deseada con N-nucleófilos como anilinas 3 más de las vías de descomposición indeseadas por reordenamiento 16. Aquí se describe este procedimiento CHIPS de dos pasos en detalle, usando sólo la luz visible, un sensibilizador, oxígeno y ácido. Entre los productos seleccionados son derivados de indol 4, que muestran una alta actividad antiviral o inhiben el factor de crecimiento endotelial vascular (VGF), que puede ser importante para la terapia de tumores 24-26.

<table border="0" cellpadding="0" cellspacing="0" width="797">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1,2,3,4-Tetrahydrocarbazole</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td style="width:151px;">T12408</td>
			<td style="width:291px;">If coloured, purification may be necessary. See Protocol 1.1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Methanol</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>322415</td>
			<td>99.8% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4-Nitroaniline</td>
			<td style="width:139px;">Acros Organics</td>
			<td>128371000</td>
			<td>99% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trifluoroacetic acid</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>T6508</td>
			<td>99% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Acetic acid</td>
			<td style="width:139px;">J. T. Baker</td>
			<td style="width:151px;">JTB RS 426960101</td>
			<td>99-100% purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aniline</td>
			<td style="width:139px;">Merck</td>
			<td>8222560100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">4-Aminobenzonitrile</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td>147753</td>
			<td>98% purity</td>
		</tr>
	</tbody>
</table>

synthesis of antiviral tetrahydrocarbazole derivatives by photochemical and acid-catalyzed c-h functionalization via intermediate peroxides (chips)

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order to streamline synthesis by saving steps, time and material compared to conventional methods that require the introduction and removal of activating or directing groups. Therefore, the functionalization of C-H bonds is also attractive for green chemistry. Under oxidative conditions, two C-H bonds or one C-H and one heteroatom-H bond can be transformed to C-C and C-heteroatom bonds, respectively. Often these oxidative coupling reactions require synthetic oxidants, expensive catalysts or high temperatures. Here, we describe a two-step procedure to functionalize indole derivatives, more specifically tetrahydrocarbazoles, by C-H amination using only elemental oxygen as oxidant. The reaction uses the principle of C-H functionalization via Intermediate PeroxideS (CHIPS). In the first step, a hydroperoxide is generated oxidatively using visible light, a photosensitizer and elemental oxygen. In the second step, the N-nucleophile, an aniline, is introduced by Br&#248;nsted-acid catalyzed activation of the hydroperoxide leaving group. The products of the first and second step often precipitate and can be conveniently filtered off. The synthesis of a biologically active compound is shown.

Síntesis de 1 - (5-nitroindolin-1-il) 2,3,4,9-tetrahidro-1H-carbazol (4a): Sintetizado de acuerdo con el Método A, Rf = 0,63 (hexano / acetato de etilo 70:30). Purificación: Purificar el producto mediante el uso de Método A, variante estudio diagnóstico A1 (pasos 2.4, 2.5, 2.6). Naranja sólido, Rendimiento: 95%. 1 H RMN (500 MHz, DMSO-d6): ...

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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

A two-step procedure for the synthesis of pharmaceutically active indole-derivatives by C-H functionalization with anilines is described, using photo- and Br&#248;nsted acid catalysis.

Síntesis de derivados Antiviral tetrahidrocarbazol por fotoquímica y catalizada por ácido CH funcionalización a través de intermedios peróxidos (CHIPS)

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order ...

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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Unit 1

Acids and Bases

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13.8K vistas.  Max-Planck-Institut fuer Kohlenforschung. A two-step procedure for the synthesis of pharmaceutically active indole-derivatives by C-H functionalization with anilines is described, using photo- and Brønsted acid catalysis.

Video: Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; therefore their preparation should be conducted under an inert atmosphere. Evaluation of the anticancer activity of these complexes can be achieved by the MTT assay.
The MTT assay is a colorimetric viability assay based on enzymatic reduction of the MTT molecule to formazan when it is exposed to viable cells. The outcome of the reduction is a color change of the MTT molecule. Absorbance measurements relative to a control determine the percentage of remaining viable cancer cells following their treatment with varying concentrations of a tested compound, which is translated to the compound anticancer activity and its IC50 values. The MTT assay is widely common in cytotoxicity studies due to its accuracy, rapidity, and relative simplicity.
Herein we present a detailed protocol for the synthesis of air sensitive metal based drugs and cell viability measurements, including preparation of the cell plates, incubation of the compounds with the cells, viability measurements using the MTT assay, and determination of IC50 values.

A method for synthesis of air-sensitive titanium and vanadium anticancer agents is described, along with the evaluation of their cytotoxic activity towards human cancer cell line by the MTT Assay.

Anticancerosos complejos metálicos: Síntesis y Evaluación de la citotoxicidad por el ensayo MTT

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; ...

Investigación

Química

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

Síntesis de capa por capa y Transferencia de Independientes conjugados microporosas de polímero nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Síntesis, caracterización y funcionalización de híbridos Au / CdS y Au / ZnS Core / Shell nanopartículas

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

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 ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

Funcionalización de pared simple nanotubos de carbono con Thermo-reversibles copolímeros de bloque y Caracterización de ángulo pequeño dispersión de neutrones

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

Síntesis de Proteínas bioconjugados<em&gt; vía</em&gt; Química cisteína-maleimida

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

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 ...

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. Recently, we have developed a two-step strategy for ketone enolate umpolung that has enabled the development of methods for chlorination, azidation, and amination using azoles. In addition, we have developed C-C bond&#8211;forming arylation and allylation reactions. At the heart of these methods is the preparation of the intermediate and highly reactive enolonium species prior to addition of a reactive nucleophile. This strategy is thus reminiscent of the preparation and use of metal enolates in classical synthetic chemistry. This strategy allows the use of nucleophiles that would otherwise be incompatible with the strongly oxidizing hypervalent iodine reagents. In this paper we present a detailed protocol for chlorination, azidation, N-heteroarylation, arylation, and allylation. The products include motifs prevalent in medicinally active products. This article will greatly assist others in using these methods.

A two step one-pot protocol for the umpolung of ketone enolates to enolonium species and addition of a nucleophile to the &#945;-position is described. Nucleophiles include chloride, azide, azoles, allyl-silanes, and aromatic compounds.

Un protocolo de dos etapas para funcionalización de Umpolung de cetonas vía Enolonium especies

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. ...

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4&#160;paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science &#38; Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of CuII ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.

Robust functional catechol coatings were produced in one step by direct reaction of the material known as HKUST with synthetic catechols under anaerobic conditions. The formation of homogeneous coatings surrounding the entire crystal is ascribed to the biomimetic catalytic activity of Cu(II) dimers on the external surface of the crystals.

Funcionalización de superficies de Metal-Organic Frameworks para resistencia a la humedad mejorada

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. ...

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the reaction is commonly performed using chlorinated or amide solvent systems, which are hazardous to human health and the environment. Our methodology utilizes acetonitrile as a greener and less hazardous solvent system. This protocol exhibits rates and yields that are comparable to traditional solvent systems and employs an extraction and wash sequence that eliminates the need for the purification of the ester product via column chromatography. This general method can be used to couple a variety of carboxylic acids with 1&#176; and 2&#176; aliphatic alcohols, benzylic and allylic alcohols, and phenols to obtain pure esters in high yields. The goal of the protocol detailed here is to provide a greener alternative to a common esterification reaction, which could serve useful for ester synthesis in both academic and industrial applications.

A modified Steglich esterification reaction was used to synthesize a small library of ester derivatives with primary and secondary alcohols. The methodology uses a non-halogenated and greener solvent, acetonitrile, and enables product isolation in high yields without the need for chromatographic purification.

Síntesis de ésteres mediante una esterificación Steglich más verde en acetonitrilo

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the ...

Síntesis de derivados Antiviral tetrahidrocarbazol por fotoquímica y catalizada por ácido CH funcionalización a través de intermedios peróxidos (CHIPS)

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