AP is grateful to Imperial College London for a PhD studentship via the Frankland Chair endowment. Johnson Matthey plc are also thanked for the loan of the precious metal salts used in this work.

Nota: Llevar a cabo todas las síntesis en una campana de extracción, y sólo después de los problemas de seguridad apropiadas han sido identificados y las medidas adoptadas para proteger en contra de ellos. Equipo de protección personal incluye una bata de laboratorio, guantes y gafas de seguridad y se debe usar en todo momento. 1. Síntesis de N, N, N tris (diphenylphosphinomethylene) amina, N (CH 2 PPh 2) 3 (Ph N -triphos) (1) <ol><li> A ml secado en estufa a 200 matraz Schlenk agregar difenil cloruro (hidroximetileno) fosfonio 11 (6,99 g, 24,7 mmol) y colocar en nitrógeno a través de tres ciclos de vacío con nitrógeno secuenciales en una línea de doble colector Schlenk. </li><li> Añadir metanol desgasificado (30 ml) y trietilamina (9,5 ml, 68,1 mmol), y se agita a RT durante 1 hora para asegurar la conversión de la sal de cloruro de fosfonio a la fosfina hydroxymethene. A continuación, añadir la solución de amoníaco en metanol desgasificado (2 M, 4,1 ml, 8,2 mmol). </li><li> Calentar la mezcla de reacción durante 2 horas a reflujo, Durante el cual el ligando se precipitar como un sólido blanco. </li><li> Aunque el N -triphos Ph ligando es estable a la oxidación en el aire durante períodos cortos de tiempo, para la pureza óptima, eliminar el disolvente mediante filtración cánula 26 en atmósfera de nitrógeno, y enjuague con metanol desgasificado (3 x 10 ml) para obtener un producto analíticamente puro y almacenar en una atmósfera de nitrógeno. </li></ol> 2. Síntesis de [Ru (CO) 2 {N (CH 2 PPh 2) 3} -κ 3 P] (2) <ol><li> A un matraz Schlenk secado al horno 200 ml, añadir N -Triphos Ph (1,0 g, 1,63 mmol) y [Ru 3 (CO) 12] (347 mg, 0,54 mmol), y el lugar en atmósfera de nitrógeno a través de tres ciclos de vacío con nitrógeno secuenciales en una línea Schlenk de doble colector. </li><li> Añadir 30 ml de seco, tolueno desgasificado y llevar la mezcla a reflujo durante 12 hr. </li><li> Después de esto 12 horas de reflujo, se filtra la solución a través de una cánula a un segundo matraz Schlenk aeliminar pequeñas cantidades de rutenio metálico que se forman durante el curso de la reacción. </li><li> Reducir el volumen de disolvente a aproximadamente 10 ml a vacío utilizando una línea Schlenk de doble colector equipado con una trampa de nitrógeno líquido refrigerado, para inducir la precipitación del complejo. </li><li> Se recristaliza el precipitado mediante calentamiento suave (80-90 ° C) en un baño de aceite hasta que se produce la redisolución completa, y posterior enfriamiento lento a RT por eliminar el calor del baño de aceite, pero permitiendo que el matraz Schlenk a permanecer sumergido. Deja O / N para dar un sólido cristalino naranja. </li><li> Aislar los cristales de color naranja adecuados para la difracción de rayos X a través de filtración cánula del sobrenadante en otro horno secaron matraz de Schlenk. A continuación, enjuagar los cristales con tolueno seco y desgasificado (2 x 5 ml) y se seca a vacío O / N. Guardar el sobrenadante y los lavados se combinaron en un matraz Schlenk separado. </li><li> Obtener un segundo lote de cristales a partir del sobrenadante combinado y la solución de enjuagues por un proceso de recristalización similar a los pasos 2.5 y 2.6 para mejorar el rendimiento global de la reacción. </li><li> Almacenar el complejo bajo nitrógeno como la exposición al aire conduce a la lenta conversión al complejo de carbonato oxidado (ver más abajo). </li></ol> 3. Síntesis de [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (3) <ol><li> A un matraz de Schlenk de 200 ml, añadir 2 (280 mg, 0,364 mmol) y 5 ml de tolueno para generar una suspensión de color naranja se disolvió parcialmente. </li><li> Inserte una aguja unida a un balón de oxígeno en la suspensión y la burbuja de oxígeno a un ritmo de 2-3 burbujas por segundo a través de la mezcla de reacción durante 10 min. </li><li> Como se forma un precipitado de color naranja, recoger por filtración en el aire y se lavó con tolueno (2 x 5 ml) y éter dietílico (2 x 5 ml) y se seca a vacío para dar un polvo de color naranja que fluye libremente que era estable en el aire. </li><li> Con el fin de hacer crecer cristales adecuados para diffr de rayos Xacción, se disuelven 100 mg de 3 en 3 ml de diclorometano en un vial y la capa 3 ml de tolueno en la parte superior permitiendo que este disolvente lentamente a correr por el lado del vial. <ol><li> Deje este O / N para obtener cristales. Aislar los cristales por decantación el sobrenadante, y el lavado del tolueno (2 x 3 ml) y éter dietílico (2 x 3 ml). Seco al vacío en una línea de doble colector Schlenk. </li></ol></li></ol> 4. Síntesis de [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) <ol><li> Preparar una solución de 3 (763 mg, 0,953 mmol) en 20 ml de seco, desgasificado THF y se inyecta en un reactor de 100 ml de alta presión del ingeniero autoclave bajo una presión positiva (0,2 bar) de nitrógeno. </li><li> Cambiar el espacio de gas cabeza del reactor a 100% de hidrógeno y presurizar a 15 bar a temperatura ambiente, luego se calienta a 100 ° C con agitación durante 2 hr. ¡Atención! Asegúrese de que todos los procedimientos de seguridad se hayan seguido utilizando altasistemas de presión! </li><li> Después de enfriar a RT, ventilar cuidadosamente el gas de hidrógeno en exceso en el espacio de cabeza del reactor y cambiar al nitrógeno. </li><li> Transferir la solución de reacción a un matraz Schlenk de 100 ml bajo nitrógeno y, después de volver a conectarse a una línea de Schlenk de doble colector, el filtro mediante una cánula y diluir con 20 ml de seco, desgasificado metanol. </li><li> Eliminar el disolvente en vacío utilizando una línea Schlenk de doble colector equipado con una trampa de nitrógeno líquido se enfrió para dar un polvo naranja. Lavar este polvo naranja con seca, metanol desgasificado (3 x 5 ml) y seco, desgasificado éter dietílico (3 x 5 ml) y se seca a vacío. </li><li> Grow cristales adecuados para el análisis de difracción de rayos X O / N a partir de una solución de tolueno saturado seco y desgasificado de 4 capas con una cantidad de equivolumen seco, desgasificado metanol. </li><li> Guarde el complejo bajo nitrógeno. </li></ol> 5. La reacción de [RuH _ 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) con NH 4 PF 6 y ácido levulínico <ol><li> Preparar una solución de 4 (48,4 mg, 65,2 mmol) en 2 ml seco, se desgasificó tolueno en un matraz de Schlenk secado en horno, y añadir medio de una jeringa a una solución agitada de NH 4 PF 6 (10,6 mg, 65,0 mmol) en acetonitrilo (2 ml) en un horno separado se secó matraz de Schlenk. </li><li> Se agita la mezcla de reacción a temperatura ambiente durante 2 hr. Después, eliminar el disolvente a vacío usando una línea Schlenk de doble colector equipado con un nitrógeno líquido enfriado trampa para dar el intermedio complejo [RuH _ (CO) (MeCN) {N (CH 2 PPh 2) 3} -κ 3 P] ( 5). </li><li> Lavar con seco, desgasificado hexano (3 x 3 ml) y se seca a vacío para aislar complejo 5 como un polvo marrón. </li><li> A una solución de 5 en 0,5 ml desgasificado acetona-d 6, se añade ácido levulínico (10,8 mg, 93,0 mmol, 1,43 equiv.) En 0,5 ml de desgasificado acetona-d 6. Se agita la mezcla de reacción durante 2 min usandoun agitador de vórtice. </li><li> Record 1 H y 30 P {1} H NMR espectros de la reacción cada hora durante 16 horas para observar la reacción. 27 </li></ol>

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The authors have nothing to disclose.

En este documento hemos descrito procedimientos sintéticos eficientes para la síntesis de un ligando de fosfina tridentado y una serie de complejos de rutenio. El N -triphos ligando Ph (1) se puede preparar fácilmente con un alto rendimiento con un procedimiento de tratamiento minimalista. Esta reacción de Mannich base de fósforo usado para sintetizar estos tipos de ligandos es muy general y puede ser utilizado para otros derivados de ligandos con diferentes grupos R en el P-át...

Complejos de fosfina basados ​​en rutenio son algunos de los catalizadores moleculares más ampliamente estudiados y químicamente versátiles. 1-9 Típicamente, tales catalizadores de rutenio contener ligandos mono- o bi-dentado que dictan la electrónica, sterics, la geometría y la solubilidad del complejo, y que tener un profundo impacto sobre la actividad catalítica. Sistemas de fosfina multidentados han sido menos ampliamente estudiado para la catálisis, como son conocidos para impartir una mayor estabilidad en el centro de metal debido a la mayor efecto quelato de múltiples donantes de fósforo en el centro metálico. Tal estabilización puede ser indeseable para la catálisis, sin embargo, en condiciones más severas de reacción (temperaturas más altas y presiones) las complejas propiedades estabilizadoras de dichos ligandos puede ser ventajoso en asegurar la integridad del catalizador. Uno de tales sistemas ligando de fosfina multidentado que 10-12 y 13-18 otros han investigado para impartir la estabilidad del complejo y COOR facialgeometrías de coor- es la llamada serie de ligando N -triphos donde tres brazos de fosfina están unidos a un átomo puente de nitrógeno apical formando un ligando tridentado potencialmente. Una de las características clave de estos ligandos en particular es la manera fácil de que se pueden sintetizar a través de un fósforo basado reacción de Mannich de fosfinas secundarias fácilmente disponibles (Figura 1), por lo tanto, fosfinas con una variedad de grupos R se pueden preparar por lo general en altos rendimientos y con un mínimo de trabajo en marcha. El objetivo general de esta metodología es presentar una ruta fácil por que rutenio complejos dihidruro ofrecen ligandos N -triphos se puede acceder para aplicaciones catalíticas posteriores. Recientemente, complejos basados ​​en Ru-triphos han atraído la atención como catalizadores para las reacciones de hidrogenación de la biomasa productos derivados, tales como ácido levulínico, 19,20 bio-ésteres 11,21 y dióxido de carbono 22 a los productos químicos de mayor valor. Sería ventajosopara ampliar el alcance de los derivados de Ru-triphos que son o bien como, o más activos que los sistemas ya reportados, especialmente si son sintéticamente más fácil acceso, como el ligando N -triphos. El análogo de carbono centrado más estudiado típicamente sufre de síntesis de bajo rendimiento e implica reactivos de fosfuro de metal altamente sensible al aire, a diferencia de la N -triphos ligando, que es más adaptable y más fáciles de preparar. 10-18 Ligandos N -triphos siguen siendo relativamente poco investigado, con complejos sólo de molibdeno, tungsteno, rutenio, rodio y oro de haber sido informado de nueve publicaciones. Esto está en marcado contraste con los análogos de boro-carbono y centrado, para los que hay alrededor de 50 y 900 artículos, respectivamente, con un gran número de compuestos únicos. Aplicación obstante, -triphos N contienen complejos han encontrado en la hidrogenación catalítica asimétrica de olefinas pro-quirales 23 como nosotrosll cyclohydroamination como asimétrica de N -Protegido sulfonamidas γ-alenilo. 24 Además, un complejo de rutenio coordinado por un ligando N voluminosos -triphos con fosfolano coordinar restos se encontró para activar silanos, un paso clave en el desarrollo de la química orgánico de silicio. 25 Como parte del programa de investigación en curso en la catálisis, hemos tratado de preparar una serie de rutenio N -triphos precatalizadores Ph e investigar sus reacciones estequiométricas y potencial catalítico. A pesar de los complejos de molibdeno de Ph N -triphos antes haber sido reportado hace más de 25 años, su aplicación, catalítica o de lo contrario no se ha investigado. Este trabajo demuestra la aplicabilidad del andamio del N -triphos, que a pesar de ser en general poco desarrollado, posee muchas características deseables, tales como la estabilidad del complejo. Aquí nos presenta la ruta de síntesis y caracterización de auna serie de complejos de rutenio Ph N -triphos que pueden encontrar aplicación en reacciones de hidrogenación catalítica.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Methanol</td>
			<td rowspan="5">&#8211;</td>
			<td rowspan="5">&#8211;</td>
			<td rowspan="5">Obtained from in-house solvent purification system: Innovative Technology, inc &#34;pure solv&#34; drying tower. Stored in ampules over activated molecular sieves under nitrogen.</td>
		</tr>
		<tr>
			<td>Toluene</td>
		</tr>
		<tr>
			<td>Diethyl Ether</td>
		</tr>
		<tr>
			<td>Tetrahydrofuran (THF)</td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
		</tr>
		<tr>
			<td>d6-Acetone</td>
			<td>VWR</td>
			<td>VWRC87152.0011</td>
			<td>Store in fridge</td>
		</tr>
		<tr>
			<td>Triethylamine</td>
			<td>Sigma-Aldrich</td>
			<td>TO886-1L</td>
			<td>Distilled and stored over activated molecular sieves under N2</td>
		</tr>
		<tr>
			<td>2M Ammonia solution in methanol</td>
			<td>Sigma-Aldrich</td>
			<td>341428-100ML</td>
			<td>Solution comes in a &#34;Sure-Seal&#34; bottle</td>
		</tr>
		<tr>
			<td>NH4PF6</td>
			<td>Sigma-Aldrich</td>
			<td>216593-5G</td>
			<td>Store in desiccator</td>
		</tr>
		<tr>
			<td>Levulinic Acid</td>
			<td>Acros Organics</td>
			<td>125142500</td>
			<td>Solid but melts close to room temperature</td>
		</tr>
		<tr>
			<td>3 &#197; Molecular sieves</td>
			<td>Alfa Aesar</td>
			<td>LO5359</td>
			<td>Activate by heating over night under vacuum</td>
		</tr>
		<tr>
			<td>Schlenk flasks</td>
			<td>GPE</td>
			<td>Custom design</td>
			<td>&#8211;</td>
		</tr>
		<tr>
			<td>Dual-manifold Schlenk line</td>
			<td>GPE</td>
			<td>Custom design</td>
			<td>Dual-manifold of i) N2 that has been passed through a silica drying column and ii) vacuum.</td>
		</tr>
		<tr>
			<td>Rotary vacuum pump</td>
			<td>Edwards</td>
			<td>RV3 A652-01-903</td>
			<td>&#8211;</td>
		</tr>
		<tr>
			<td>100 ml Autoclave Engineer&#39;s high pressure reactor</td>
			<td>Autoclave Engineer</td>
			<td>Custon design</td>
			<td>&#8211;</td>
		</tr>
		<tr>
			<td>Vortex Stirrer</td>
			<td>VWR</td>
			<td>444-1378</td>
			<td>&#8211;</td>
		</tr>
	</tbody>
</table>

the synthesis, characterization and reactivity of a series of ruthenium n-triphosph complexes

Aquí nos presenta la síntesis de un ligando de fosfina tridentado N (CH 2 PPh 2) 3 (Ph N -triphos) (1) a través de una reacción de Mannich de fósforo a base del precursor de fosfina hydroxylmethylene con amoniaco en metanol bajo una atmósfera de nitrógeno. El N -triphos Ph ligando precipita de la solución después de aproximadamente 1 h de reflujo y se puede aislar analíticamente puro a través de la cánula sencillo procedimiento de filtración en atmósfera de nitrógeno. La reacción de la N -triphos ligando Ph con [Ru 3 (CO) 12] a reflujo proporciona una solución de color rojo intenso que muestran la evolución de gas CO en la formación de complejos ligando. Cristales de color naranja del complejo [Ru (CO) 2 {N (CH 2 PPh 2) 3} -κ 3 P] (2) se aislaron en el enfriamiento a RT. El 31 P {1} H NMR mostró un pico sola característica en la frecuencia más bajaen comparación con el ligando libre. Reacción de una solución en tolueno del complejo 2 con oxígeno dio lugar a la precipitación instantánea de la carbonato de complejo [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (3) como un estable de aire sólido de color naranja. La subsiguiente hidrogenación de 3 bajo 15 bar de hidrógeno en un reactor de alta presión dio el complejo dihidruro de [RuH _ 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4), que fue totalmente caracterizado por X cristalografía de rayos y la espectroscopia de RMN. Complejos 3 y 4 son potencialmente precursores de catalizadores útiles para una amplia gama de reacciones de hidrogenación, incluyendo los productos derivados de la biomasa tales como el ácido levulínico (LA). Complejo 4 se encontró que reacciona limpiamente con LA en presencia del aditivo fuente de protones NH 4 PF 6 para dar [Ru (CO) {N (CH 2 PPh 2) 3} P {-κ 3 CH 3 CO (CH2) 2 CO 2 H} -κ 2 O] (PF 6) (6).

El N -triphos ligando Ph (1) y la serie de complejo de rutenio: Ru (CO) 2 {N (CH 2 PPh 2) 3} -κ 3 P] (2), [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (3) y [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) se caracterizaron mediante 1 H, 13 C {1} ...

Watch this Scientific Journal Video about The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes at JoVE.com

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Complejos de fosfina de rutenio se utilizan ampliamente para reacciones catalíticas homogéneas tales como hidrogenaciones. Se ha informado de la síntesis de una serie de complejos de rutenio tridentado novedosos que lleven la N -triphos ligando N (CH 2 PPh 2) 3. Además, se describe la reacción estequiométrica de un complejo dihidruro SRC N -triphos con ácido levulínico.

La síntesis, caracterización y reactividad de una serie de rutenio<em&gt; N</em&gt; -triphos<sup&gt; Ph</sup&gt; Complejos

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the ...

the-synthesis-characterization-reactivity-series-ruthenium-n

Research

JoVE Journal

Chemistry

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

12.0K vistas.  Imperial College London.  Complejos de fosfina de rutenio se utilizan ampliamente para reacciones catalíticas homogéneas tales como hidrogenaciones. Se ha informado de la síntesis de una serie de complejos de rutenio tridentado novedosos que lleven la N -triphos ligando N (CH 2 PPh 2) 3. Además, se describe la reacción estequiométrica de un complejo dihidruro SRC N -triphos con ácido levulínico. 

Video: The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Physical interactions among the lipid-embedded alpha-helical domains of membrane proteins play a crucial role in folding and assembly of membrane protein complexes and in dynamic processes such as transmembrane (TM) signaling and regulation of cell-surface protein levels. Understanding the structural features driving the association of particular sequences requires sophisticated biophysical and biochemical analyses of TM peptide complexes. However, the extreme hydrophobicity of TM domains makes them very difficult to manipulate using standard peptide chemistry techniques, and production of suitable study material often proves prohibitively challenging. Identifying conditions under which peptides can adopt stable helical conformations and form complexes spontaneously adds a further level of difficulty. Here we present a procedure for the production of homo- or hetero-dimeric TM peptide complexes from materials that are expressed in E. coli, thus allowing incorporation of stable isotope labels for nuclear magnetic resonance (NMR) or non-natural amino acids for other applications relatively inexpensively. The key innovation in this method is that TM complexes are produced and purified as covalently associated (disulfide-crosslinked) assemblies that can form stable, stoichiometric and homogeneous structures when reconstituted into detergent, lipid or other membrane-mimetic materials. We also present carefully optimized procedures for expression and purification that are equally applicable whether producing single TM domains or crosslinked complexes and provide advice for adapting these methods to new TM sequences.

Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.

La producción de disulfuro estabilizados complejos transmembrana de péptidos de Estudios Estructurales

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

Investigación

Química

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

Aislamiento y Caracterización química del lípido A de bacterias gram-negativas

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

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; ...

Split-and-pool Synthesis and Characterization of Peptide Tertiary Amide Library

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid phase by using combinatorial chemistry. One of the most well studied classes of peptidomimetics is peptoids. Peptoids are easy to synthesize and have been shown to be proteolysis-resistant and cell-permeable. Over the past decade, many useful protein ligands have been identified through screening of peptoid libraries. However, most of the ligands identified from peptoid libraries do not display high affinity, with rare exceptions. This may be due, in part, to the lack of chiral centers and conformational constraints in peptoid molecules. Recently, we described a new synthetic route to access peptide tertiary amides (PTAs). PTAs are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. With side chains on both &#945;-carbon and main chain nitrogen atoms, the conformation of these molecules are greatly constrained by sterical hindrance and allylic 1,3 strain. (Figure 1) Our study suggests that these PTA molecules are highly structured in solution and can be used to identify protein ligands. We believe that these molecules can be a future source of high-affinity protein ligands. Here we describe the synthetic method combining the power of both split-and-pool and sub-monomer strategies to synthesize a sample one-bead one-compound (OBOC) library of PTAs.

Peptide tertiary amides (PTAs) are a superfamily of peptidomimetics that include but are not limited to peptides, peptoids and N-methylated peptides. Here we describe a synthetic method which combines&#160;both split-and-pool and sub-monomer strategies to synthesize a one-bead one-compound library of PTAs.

Síntesis Split-y-piscina y caracterización del péptido Terciario Amida Biblioteca

Peptidomimetics are great sources of protein ligands. The oligomeric nature of these compounds enables us to access large synthetic libraries on solid ...

Nucleoside Triphosphates - From Synthesis to Biochemical Characterization

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

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

Nucleósidos Trifosfatos - De la síntesis a la Caracterización bioquímica

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

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Marcos de síntesis y caracterización de funcionalizado metal-orgánico

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Síntesis y caracterización de supramoleculares Coloides

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

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

Síntesis de polímeros cíclicos y caracterización de su movimiento difusivo en el estado fundido en la molécula de un solo nivel

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)

The phases of &#34;PbCh2&#34; (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica glass ampules). Reduction of such phases by elemental alkaline metals in amines affords crystalline chalcogenidoplumbate(II) salts comprised of [PbTe3]2- or [Pb2Ch3]2- anions, depending upon which sequestering agent for the cations is present: crown ethers, like 18-crown-6, or cryptands, like [2.2.2]crypt. Reactions of solutions of such anions with transition-metal compounds yield (poly-)chalcogenide anions or transition-metal chalcogenide clusters, including one with a &#181;-PbSe ligand (i.e., the heaviest-known CO homolog).
In contrast, the solid-state synthesis of a phase of the nominal composition &#34;K2PbSe2&#34; by successive reactions of the elements and by the subsequent solvothermal treatment in amines yields the first non-oxide/halide inorganic lead(IV) compound: a salt of the ortho-selenidoplumbate(IV) anion [PbSe4]4-. This was unexpected due to the redox potentials of Pb(IV) and Se(-II). Such methods can further be applied to other elemental combinations, leading to the formation of solutions with binary [HgTe2]2- or [BiSe3]3- anions, or to large-scale syntheses of K2Hg2Se3 or K3BiSe3 via the solid-state route.
All compounds are characterized by single-crystal X-ray diffraction and elemental analysis; solutions of plumbate salts can be investigated by 205Pb and 77Se or 127Te NMR techniques. Quantum chemical calculations using density functional theory methods enable energy comparisons. They further allow for insights into the electronic configuration and thus, the bonding situation. Molecular Rh-containing Chevrel-type compounds were found to exhibit delocalized mixed valence, whereas similar telluridopalladate anions are electron-precise; the cluster with the &#181;-PbSe ligand is energetically favored over a hypothetical CO analog, in line with the unsuccessful attempt at its synthesis. The stability of formal Pb(IV) within the [PbSe4]4- anion is mainly due to a suitable stabilization within the crystal lattice.

Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of ChalcogenidoplumbatesII or IV

The synthesis of chalcogenidoplumbates(II,IV) via the in situ reduction of nominal "PbCh2" (Ch = Chalcogen) and via a solid-state reaction and subsequent solvothermal reactions is presented. Additionally, reactivities of plumbate(II) solutions are portrayed, which yield the heaviest-known CO homolog known to date: the &#181;-PbSe ligand.

La combinación de estado sólido y técnicas basadas en Solución: Síntesis y reactividad de Chalcogenidoplumbates (II o IV)

The phases of &#34;PbCh2&#34; (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica ...

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. The complexes were tested for catalytic activity in arylation and Suzuki-Miyaura reactions. For each reaction investigated, at least one of the four complexes successfully catalyzed the reaction.

Paladio<em&gt; N</em&gt; -Heterocíclicos de los complejos de carburo: Síntesis a partir de sales de benzimidazolio y actividad catalítica en las reacciones de formación de enlaces carbono-carbono

Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from ...