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: Executar todas as sínteses em um exaustor, e só depois de as questões de segurança apropriadas foram identificados e as medidas tomadas para proteger contra eles. Equipamento de proteção individual incluem um jaleco, luvas e óculos de segurança e deve ser usado em todos os momentos. 1. Síntese de N, N, N-tris (diphenylphosphinomethylene) amina, N (CH 2 PPh 2) 3 (N -triphos Ph) (1) <ol><li> Para um de 200 ml, seco em estufa balão de Schlenk adicionar cloreto de difenil (hidroximetileno) fosfónio 11 (6,99 g, 24,7 mmol) e coloca-se sob azoto, através de três ciclos de vácuo-azoto sequenciais numa linha de Schlenk dupla colector. </li><li> Adiciona-se metanol desgaseificado (30 ml) e trietilamina (9,5 ml, 68,1 mmol), e agitar temperatura ambiente durante 1 hora para assegurar a conversão do sal de fosfónio com a fosfina hydroxymethene. Em seguida, adicionar uma solução de amoníaco em metanol desgasif içado (2 M, 4,1 ml, 8,2 mmol). </li><li> Aquece-se a mistura de reacção durante 2 horas sob refluxo, Durante o qual o ligando irá precipitar como um sólido branco. </li><li> Embora a N -triphos Ph ligando é estável à oxidação em ar ao longo de curtos períodos de tempo, para um melhor grau de pureza, remover o solvente através de uma cânula de filtração 26 sob azoto, e enxagua-se com metanol desgaseificado (3 x 10 ml) para se obter um produto analiticamente puro , e armazenar sob uma atmosfera de azoto. </li></ol> 2. Síntese de [Ru (CO) 2 {N (CH 2 PPh 2) 3} -κ 3 P] (2) <ol><li> A um balão de Schlenk de 200 ml, seco em estufa, adicionar N -Triphos Ph (1,0 g, 1,63 mmol) e [Ru 3 (CO) 12] (347 mg, 0,54 mmol), e coloca-se sob azoto, através de três ciclos de vácuo-azoto sequenciais sobre uma linha dual-colector de Schlenk. </li><li> Adicionar 30 ml de seco, tolueno desgaseificado e levar a mistura ao refluxo durante 12 h. </li><li> Após este 12 h de refluxo, filtrar a solução através de uma cânula para um segundo balão de Schlenk deremover pequenas quantidades de ruténio metálico que se formam durante o decurso da reacção. </li><li> Reduzir o volume de solvente para cerca de 10 ml sob vácuo utilizando um colector de linha dupla de Schlenk equipado com uma armadilha de azoto líquido arrefecido, para induzir a precipitação do complexo. </li><li> Recristaliza-se o precipitado mediante aquecimento suave (80-90 ° C) em um banho de óleo até a redissolução completa ocorre, e subsequente arrefecimento lento até à temperatura ambiente, removendo o calor do banho de óleo, mas permitindo que o frasco de Schlenk a permanecer submerso. Deixar O / N para dar um sólido cristalino cor de laranja. </li><li> Isolar os cristais cor de laranja adequados para difracção de raios-X de uma cânula através de filtração do sobrenadante para outro forno balão de Schlenk seco. Em seguida, lavar os cristais com tolueno seco e desgaseificado (2 x 5 ml) e seco in vácuo O / N. Salve o sobrenadante e as lavagens num balão Schlenk separado. </li><li> Obter um segundo lote de cristais a partir do sobrenadante combinado e solução de enxaguamentos por um processo de recristalização semelhantes aos passos 2.5 e 2.6 para melhorar o rendimento global da reacção. </li><li> Armazenar o complexo sob azoto como a exposição ao ar leva à conversão lenta para o complexo de carbonato oxidado (ver abaixo). </li></ol> 3. Síntese de [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (3) <ol><li> A um balão de Schlenk de 200 ml, adicionar 2 (280 mg, 0,364 mmol) e 5 ml de tolueno para gerar uma suspensão cor de laranja parcialmente dissolvido. </li><li> Inserir uma agulha ligada a um balão de oxigénio na bolha de oxigénio e de suspensão a uma taxa de 2-3 bolhas por segundo através da mistura reaccional durante 10 min. </li><li> Como forma-se um precipitado cor de laranja, recolher por filtração ao ar e lavado com tolueno (2 x 5 ml) e éter dietílico (2 x 5 mL) e seco em vácuo para dar um pó cor de laranja de fluxo livre, que fosse estável em ar. </li><li> Para crescer os cristais adequados para diffr de raios-Xação, dissolver 100 mg de 3 em 3 ml de diclorometano em um frasco e camada 3 ml de tolueno em cima lentamente permitindo que este solvente para correr para o lado do frasco. <ol><li> Deixar este S / N para se obter cristais. Isolar os cristais por decantação do sobrenadante e lavar o tolueno (2 x 3 ml) e éter dietílico (2 x 3 ml). Seco no vácuo em uma linha Schlenk dual-manifold. </li></ol></li></ol> 4. Síntese de [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) <ol><li> Prepara-se uma solução de 3 (763 mg, 0,953 mmol) em 20 ml de seco, desgaseificado THF e injectar no reactor de 100 ml de alta pressão do engenheiro autoclave sob uma pressão positiva (0,2 bar) de azoto. </li><li> Mudar o gás do espaço de cabeça do reactor para 100% de hidrogénio e pressurizar a 15 bar à temperatura ambiente, em seguida aquecer a 100 ° C com agitação durante 2 horas. Atenção! Certifique-se de todos os procedimentos de segurança foram respeitados quando usando altasistemas de pressão! </li><li> Após arrefecimento até à TA, vent cuidadosamente o excesso de gás de hidrogénio no espaço de cabeça do reactor e para mudar de azoto. </li><li> Transferir a solução de reacção para um balão de Schlenk de 100 mL sob atmosfera de azoto e, depois de voltar a ligar a uma linha Schlenk dupla colector, filtrar através de uma cânula e dilui-se com 20 ml de seca, desgaseif içada de metanol. </li><li> Remover o solvente sob vácuo utilizando um colector de linha dupla de Schlenk equipado com uma armadilha de azoto líquido arrefecido para dar um pó cor de laranja. Lavar este pó cor de laranja com metanol seco, desgaseificado (3 x 5 ml) e seco, desgaseificado éter dietílico (3 x 5 ml) e seco in vácuo. </li><li> Crescer cristais adequados para análise de difracção de raios-X O / N a partir de uma solução saturada de tolueno seco e desgaseificado de 4 camadas com um volume equivalente de quantidade seca, desgaseif içada de metanol. </li><li> Guarde o complexo em azoto. </li></ol> 5. Reacção de [RuH 2 (CO) {N (CH 2 PPh 2) 3} 3 P -κ] (4) com NH 4 PF 6 e Ácido Levulínicos <ol><li> Prepara-se uma solução de 4 (48,4 mg, 65,2 pmol) em 2 mL seco, desgaseif içada de tolueno num balão de Schlenk, seco em estufa, e adicionar através de uma seringa a uma solução agitada de NH 4 PF 6 (10,6 mg, 65,0 nmol) em acetonitrilo (2 ml) em um forno separado balão de Schlenk seco. </li><li> Agita-se a mistura de reacção à temperatura ambiente durante 2 horas. Depois, remover o solvente em vácuo utilizando um colector de linha dupla de Schlenk equipado com uma armadilha de azoto líquido arrefecido para dar o intermediário complexo [RuH (CO) (MeCN) {N (CH 2 PPh 2) 3} -κ 3 P] ( 5). </li><li> Lava-se com a seco, desgaseificado hexano (3 x 3 ml) e seco em vácuo para isolar complexo 5 como um pó castanho. </li><li> A uma solução de 5 em 0,5 ml de acetona desgaseificada-d 6, adiciona-se ácido levulínico (10,8 mg, 93,0 umol, 1,43 equiv.) Em 0,5 ml de acetona desgaseificada-d 6. Agita-se a mistura de reacção durante 2 minutos usandoum agitador de vórtice. </li><li> Ficha de 1 H e 30 P {1 H} espectros de RMN da reacção a cada hora durante 16 horas para observar a reacção. 27 </li></ol>

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The authors have nothing to disclose.

Aqui descrevemos processos de síntese eficiente para a síntese de um ligando tridentado fosfina e uma série de complexos de ruténio. A N -triphos ligando Ph (1) pode ser facilmente preparado, com elevado rendimento com um procedimento de processamento minimalista. Esta reacção de Mannich com base de fósforo usada para sintetizar estes tipos de ligandos é muito geral e pode ser utilizado para outros derivados de ligandos com diferentes grupos R nos átomos de P. 10-12,15-...

Complexos de ruténio com base de fosfina são alguns dos catalisadores moleculares mais amplamente estudados e quimicamente versáteis. 1-9 Tipicamente, tais catalisadores de ruténio conter tanto ligandos mono- ou bi-dentadas que ditam a electrónica, sterics, geometria e a solubilidade do complexo, e que impactar profundamente na atividade catalítica. Sistemas de fosfina multidentados foram menos estudados para a catálise, como são conhecidos para conferir maior estabilidade no centro do metal devido ao maior efeito quelato de múltiplos doadores de fósforo no centro de metal. Tal estabilização pode ser indesejável para a catálise, no entanto, sob condições mais severas de reacção (temperaturas e pressões mais elevadas), as propriedades de estabilização de tais ligandos complexos pode ser vantajoso para assegurar a integridade do catalisador. Um tal sistema de ligando fosfina multidentado que 10-12 e 13-18 foram investigadas outras para conferir estabilidade do complexo e coor facialgeometrias coor- é o chamado série ligando N -triphos onde três braços de fosfina estão ligados a um átomo de azoto em ponte apical formando um ligando tridentado potencialmente. Uma das características chave para estes ligandos específicos é o caminho simplista de que eles podem ser sintetizados por meio de uma reacção de Mannich com base de fósforo a partir de fosfinas secundárias prontamente disponíveis (Figura 1), portanto, fosfinas com uma variedade de grupos R pode ser preparado geralmente em rendimentos elevados e com o mínimo de trabalho-up. O objetivo geral desta metodologia é o de apresentar uma rota fácil pelo qual rutênio complexos dihydride caracterizam ligantes N -triphos pode ser acessado por aplicações catalíticas subsequentes. Recentemente, os complexos à base de Ru-triphos têm atraído a atenção como catalisadores para as reacções de hidrogenação de produtos derivados da biomassa, tais como ácido levulínico, 19,20 bio-ésteres de 11,21 e 22 dióxido de carbono para os produtos químicos de alto valor. Seria vantajosopara expandir o escopo de derivados Ru-triphos que ou são tão ou mais ativo do que os sistemas já relatados, especialmente se eles são sinteticamente mais fácil acesso, tais como a N -triphos ligando. O análogo centrado no carbono mais estudado é tipicamente afectada de baixo rendimento e envolve a síntese de reagentes de fosforeto de metal altamente sensíveis ao ar, ao contrário do N -triphos ligando, que é mais flexível e mais fácil de preparar. 10-18 Ligantes N -triphos permanecem relativamente pouco investigado, com apenas molibdênio, tungstênio, rutênio, ródio e ouro complexos tendo sido relatada a partir de nove publicações. Isso está em contraste gritante com os análogos de boro e centrados em carbono, para o qual não estão em torno de 50 e 900 artigos, respectivamente, com um grande número de compostos únicos. Aplicação No entanto, -triphos N contendo complexos de ter encontrado na hidrogenação catalítica assimétrica de olefinas pró-quirais 23 como nósll cyclohydroamination como assimétrica de N-protegido sulfonamidas γ-alenil. 24 Adicionalmente, um complexo de ruténio coordenado por um ligando volumoso N -triphos caracteriza phospholane coordenação porções foi encontrado para activar silanos, um passo chave no desenvolvimento de organo-silício química. 25 Como parte do programa de investigação em curso em catálise, buscou-se preparar uma série de rutênio N -triphos precatalysts Ph e investigar suas reações estequiométricas e potencial catalítico. Apesar de complexos de molibdênio de N -triphos Ph tendo sido relatada pela primeira vez mais de 25 anos atrás, a sua aplicação, ou de outra forma catalítica não foi investigado. Este trabalho demonstra a aplicabilidade da N -triphos andaime, que apesar de ser em geral, subdesenvolvida, possuem muitas características desejáveis, tais como a estabilidade do complexo. Neste artigo descrevemos uma via de síntese e caracterização de auma série de complexos de ruténio N -triphos pH que podem encontrar aplicação em reacções de hidrogenação 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

Aqui relatamos a síntese de um ligando tridentado fosfina N (CH 2 PPh 2) 3 (N -triphos Ph) (1) através de uma reacção de Mannich com base de fósforo do precursor hidroxilmetileno fosfina com amónia em metanol, sob uma atmosfera de azoto. A N -triphos Ph ligando precipita a partir da solução após cerca de 1 hora de refluxo e pode ser isolado analiticamente puro através do procedimento de filtração simples cânula sob azoto. A reacção do N -triphos ligando Ph com [Ru 3 (CO) 12], sob refluxo, proporciona uma solução vermelho escuro que mostram evolução de gás de CO em complexação ligando. Cristais cor de laranja do complexo [Ru (CO) 2 {N (CH 2 PPh 2) 3} -κ 3 P] (2) foram isolados por arrefecimento até à temperatura ambiente. A 31 P {1 H} espectro de RMN mostrou um pico única característica com menor frequênciaem comparação com o ligando livre. A reacção de uma solução de tolueno do complexo 2 com oxigénio resultou na precipitação instantânea do carbonato de complexo [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (3) como um estável ar sólido cor de laranja. A subsequente hidrogenação de 3 sob 15 bar de hidrogénio num reactor de alta pressão deu o complexo dihydride [RuH 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4), a qual foi totalmente caracterizado por X cristalografia de raios- e espectroscopia de RMN. Complexos de 3 e 4 são potencialmente precursores de catalisadores úteis para uma série de reações de hidrogenação, incluindo produtos derivados da biomassa, como o ácido levulínico (LA). Complexo 4 foi encontrado para reagir de forma limpa com LA na presença do aditivo fonte de protões NH 4 PF 6 para se obter a [Ru (CO) {N (CH 2 PPh 2) 3} 3 P -κ {CH 3 CO (CH 2) 2 CO 2 H} -κ 2O] (PF 6) (6).

A N -triphos Ph ligando (1) e da série de complexo de ruténio: 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) e [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) foram caracterizados através de um H, 13 C {...

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

Complexos de rutênio de fosfina são amplamente utilizados para reações catalíticas homogêneas, como hidrogenação. A síntese de uma série de novos complexos de ruténio tridentado que ostentam o ligando -triphos N N (CH 2 PPh 2) 3 é relatado. Além disso, a reacção estequiométrica de um complexo dihydride Ru- N -triphos com ácido levulínico é descrito.

A Síntese, Caracterização e Reatividade de uma série de Rutênio<em&gt; N</em&gt; -triphos<sup&gt; Ph</sup&gt; Complexos

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

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Research

JoVE Journal

Chemistry

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

12.0K visualizações.  Imperial College London.  Complexos de rutênio de fosfina são amplamente utilizados para reações catalíticas homogêneas, como hidrogenação. A síntese de uma série de novos complexos de ruténio tridentado que ostentam o ligando -triphos N N (CH 2 PPh 2) 3 é relatado. Além disso, a reacção estequiométrica de um complexo dihydride Ru- N -triphos com ácido levulínico é descrito. 

Vídeo: 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.

Complexos de produção de transmembrana Disulfide-estabilizados Peptídicos para estudos estruturais

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

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.

Isolamento e Caracterização química do lípido A de bactérias 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.

Anticâncer metal Complexos: Síntese e Avaliação de citotoxicidade pelo ensaio 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.

Split-and-piscina Síntese e Caracterização de Peptídeos Terciário Amide 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.

Nucleosídeos Trisfosfatos - Da síntese à Caracterização 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.

Síntese e caracterização de funcionalizados metal-organic frameworks

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.

Síntese e Caracterização de Supramoleculares Colloids

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.

Síntese de polímeros cíclicos e Caracterização do seu movimento difusivo no estado fundido na molécula de nível único

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.

Combinando Solid-state e técnicas baseadas em Solução: Síntese e reatividade de Chalcogenidoplumbates (II ou 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.

Complexos de paládio N-heterocíclicos de carbeno: síntese a partir de sais de benzimidazólio e atividade catalítica em reações de formação de ligações carbono-carbono

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