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: Eseguire tutte le sintesi in una cappa aspirante, e solo dopo che i problemi di sicurezza del caso sono stati identificati e le misure adottate per la protezione contro di loro. Dispositivi di protezione individuale comprende un camice da laboratorio, guanti e occhiali di sicurezza e devono essere indossati in ogni momento. 1. Sintesi di N, N, N tris (diphenylphosphinomethylene) ammina, N (CH 2 PPh 2) 3 (N -triphos Ph) (1) <ol><li> Per ml asciugato in forno a 200 Vetreria Schlenk aggiungere difenil cloruro (idrossimetilene) fosfonio 11 (6,99 g, 24,7 mmol) e posto sotto azoto con tre cicli di vuoto-azoto sequenziali su una linea Schlenk dual-collettore. </li><li> Aggiungere metanolo degasato (30 ml) e trietilammina (9,5 ml, 68,1 mmol) e agitare a temperatura ambiente per 1 ora per assicurare la conversione del sale di fosfonio cloruro al fosfina hydroxymethene. Successivamente, aggiungere la soluzione di ammoniaca degasata in metanolo (2 M, 4,1 ml, 8,2 mmol). </li><li> Riscaldare la miscela di reazione per 2 ore a riflusso, Durante il quale il ligando si precipita come solido bianco. </li><li> Sebbene la N -triphos Ph ligando è stabile all&#39;ossidazione in aria su brevi periodi di tempo, per la purezza ottimale, rimuovere il solvente mediante cannula filtrazione 26 sotto azoto, e risciacquare con metanolo degasato (3 x 10 ml) per ottenere un prodotto analiticamente puro , e conservare sotto atmosfera di azoto. </li></ol> 2. Sintesi di [Ru (CO) 2 {N (CH 2 PPh 2) 3} 3 -κ P] (2) <ol><li> Per un pallone Schlenk 200 ml a forno, aggiungere N -Triphos Ph (1,0 g, 1.63 mmol) e [Ru 3 (CO) 12] (347 mg, 0,54 mmol), e posto sotto azoto con tre cicli di vuoto-azoto sequenziali su una linea a doppio collettore Schlenk. </li><li> Aggiungere 30 ml di secca, toluene da gas e portare il composto a riflusso per 12 ore. </li><li> Dopo questo 12 hr reflusso, filtrare la soluzione attraverso una cannula ad un secondo pallone a Schlenkrimuovere piccole quantità di rutenio metallico che si formano durante il corso della reazione. </li><li> Ridurre il volume di solvente a circa 10 ml sotto vuoto utilizzando una linea a doppio collettore Schlenk munito di azoto liquido trappola raffreddata, per indurre la precipitazione del complesso. </li><li> Ricristallizzare il precipitato con blando riscaldamento (80-90 ° C) in bagno d&#39;olio, fino alla completa ridissoluzione, e successivo raffreddamento lento a RT rimuovendo il calore dal bagno d&#39;olio, ma consentendo il pallone Schlenk di rimanere sommerso. Lascia O / N di dare una cristallina arancione solido. </li><li> Isolare i cristalli arancioni adatti per diffrazione di raggi X mediante cannula filtrazione del supernatante in un altro forno essiccati pallone Schlenk. Successivamente, lavare i cristalli con toluene anidro e degasato (2 x 5 ml) ed essiccare sotto vuoto O / N. Salvare il surnatante e lavaggi combinati in un pallone Schlenk separato. </li><li> Ottenere un secondo lotto di cristalli dal supernatante combinato e la soluzione di risciacquos mediante un processo simile a ricristallizzazione passi 2.5 e 2.6 per migliorare la resa complessiva di reazione. </li><li> Conservare il complesso sotto azoto come esposizione all&#39;aria porta alla lenta conversione al complesso carbonato ossidato (vedi sotto). </li></ol> 3. Sintesi di [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (3) <ol><li> Per un pallone da 200 ml Schlenk, aggiungere 2 (280 mg, 0,364 mmol) e 5 ml di toluene per generare una sospensione arancia parzialmente disciolto. </li><li> Inserire un ago attaccato ad un palloncino di ossigeno nella sospensione e bolle di ossigeno ad una velocità di 2-3 bolle al secondo attraverso la miscela di reazione per 10 min. </li><li> Come un precipitato arancione, raccoglierlo per filtrazione in aria e lavato con toluene (2 x 5 ml) e dietil etere (2 x 5 ml) e secco sotto vuoto per dare un arancio polvere scorrevole che era stabile in aria. </li><li> Per crescere cristalli adatti per X-ray diffrazione, sciolgono 100 mg di 3 in 3 ml di diclorometano in una fiala e lo strato 3 ml toluene sopra lentamente permettendo questo solvente a correre lungo il lato del flaconcino. <ol><li> Lasciare questo O / N per ottenere cristalli. Isolare i cristalli per decantazione del surnatante, e lavare il toluene (2 x 3 ml) e dietil etere (2 x 3 ml). Secco sotto vuoto su una linea Schlenk dual-collettore. </li></ol></li></ol> 4. Sintesi di [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (4) <ol><li> Preparare una soluzione di 3 (763 mg, 0,953 mmol) in 20 ml di asciutto, degassato THF e iniettare in un reattore da 100 ml ad alta pressione del tecnico Autoclave sotto una pressione positiva (0,2 bar) di azoto. </li><li> Cambiare il gas spazio di testa del reattore a 100% di idrogeno e pressurizzare a 15 bar a RT, allora il calore a 100 ° C con agitazione per 2 ore. Attenzione Garantire tutte le procedure di sicurezza sono state rispettate quando si utilizza altasistemi a pressione! </li><li> Dopo raffreddamento a RT, sfiatare accuratamente il gas idrogeno in eccesso nello spazio di testa del reattore e cambiare azoto. </li><li> Trasferire la soluzione di reazione ad un pallone da 100 ml Schlenk sotto azoto e, dopo aver ricollegato ad una linea a doppio collettore Schlenk, filtro mediante cannula e diluire con 20 ml di secca, degassato metanolo. </li><li> Rimuovere il solvente sotto vuoto utilizzando una linea a doppio collettore Schlenk munito di azoto liquido raffreddato trappola per dare una polvere arancione. Lavare la polvere arancione con secca, metanolo degasato (3 x 5 ml) e secco, degassato etere etilico (3 x 5 ml) e secco sotto vuoto. </li><li> Grow cristalli adatti per l&#39;analisi di diffrazione ai raggi X O / N da una soluzione toluenica saturo secco e degasata di 4 strati con una quantità Equivolume secco, degassato metanolo. </li><li> Conservare il complesso sotto azoto. </li></ol> 5. La reazione di [Ruh 2 (CO) {N (CH 2 PPh 2) 3} -κ 3 P] (4) con NH 4 PF 6 e Acid levulinico <ol><li> Preparare una soluzione di 4 (48,4 mg, 65,2 mmol) in 2 ml secco, degassata toluene in un forno essiccato beuta Schlenk, e aggiungere tramite siringa ad una soluzione agitata di NH 4 PF 6 (10,6 mg, 65,0 mmol) in acetonitrile (2 ml) in un forno separato essiccato pallone Schlenk. </li><li> Mescolare la miscela di reazione a temperatura ambiente per 2 ore. Dopo, rimuovere il solvente sotto vuoto con una linea a doppio collettore Schlenk munito di azoto liquido raffreddato trappola per dare l&#39;intermedio complesso [ruh (CO) (MeCN) {N (CH 2 PPh 2) 3} 3 -κ P] ( 5). </li><li> Lavare con secca, degassato esano (3 x 3 ml) e secco sotto vuoto per isolare complessi 5 come polvere marrone. </li><li> Ad una soluzione di 5 a 0,5 ml di acetone degassato-d 6, aggiungere l&#39;acido levulinico (10,8 mg, 93,0 mmol, 1,43 equiv.) In 0,5 ml di acetone degasato-d 6. Mescolare la miscela di reazione per 2 min usandoun agitatore vortex. </li><li> Record 1 H e 30 P {1} H NMR della reazione ogni ora per 16 ore per osservare la reazione. 27 </li></ol>

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The authors have nothing to disclose.

Qui abbiamo descritto procedure sintetiche efficienti per la sintesi di un legante tridentato fosfina ed una serie di complessi di rutenio. Il N -triphos Ph ligando (1) può essere facilmente preparato in alto rendimento con una procedura di work-up minimalista. Questa reazione Mannich base di fosforo utilizzato per sintetizzare questi tipi di leganti è del tutto generale e può essere utilizzato per altri derivati ​​ligando con R-gruppi differenti sul P-atomi. 10-12,15-18<...

Complessi basati Rutenio fosfina sono alcuni dei catalizzatori molecolari più studiati e chimicamente versatili. 1-9 Tipicamente, tali catalizzatori di rutenio contengono ligandi sia mono o bi-dentate che dettano dell&#39;elettronica, sterics, la geometria e la solubilità del complesso, e che impatto profondo sulle attività catalitica. Sistemi fosfina multidentati sono state meno ampiamente studiato per la catalisi, come sono noti per conferire maggiore stabilità sul centro metallico a causa del maggiore effetto chelato di donatori multipli fosforo sul centro metallico. Tale stabilizzazione può essere indesiderabile per catalisi, tuttavia, in condizioni severe di reazione (alte temperature e pressioni) le proprietà stabilizzanti complessi di tali ligandi può essere vantaggioso per garantire l&#39;integrità catalizzatore. Uno di questi sistemi ligando fosfina multidentati che abbiamo 10-12 e 13-18 gli altri hanno indagato per impartire stabilità del complesso e coor faccialegeometrie coordina- è la cosiddetta serie ligando N -triphos dove tre bracci fosfina sono attaccati ad un atomo di azoto apicale bridging formando un ligando potenzialmente tridentato. Una delle caratteristiche fondamentali di questi ligandi particolari è il modo facile che essi possono essere sintetizzati mediante una reazione di Mannich base di fosforo e di facile reperibilità fosfine secondarie (Figura 1), quindi fosfine con una varietà di gruppi R possono essere preparati solito in rese elevate e con il minimo work-up. L&#39;obiettivo generale di questa metodologia è quello di presentare un percorso facile attraverso il quale rutenio complessi diidruro dotate N -triphos ligandi si può accedere per le successive applicazioni catalitiche. Recentemente, complessi basati Ru-triphos hanno attirato l&#39;attenzione come catalizzatori per le reazioni di idrogenazione di biomassa prodotti derivati, come l&#39;acido levulinico, 19,20 bio-esteri 11,21 e anidride carbonica 22 a sostanze chimiche di maggior valore. Sarebbe vantaggiosodi ampliare la portata dei derivati ​​Ru-triphos che sono o come, o più attivi dei sistemi già riferito, specialmente se sono sinteticamente più facile accesso, come la N -triphos ligando. L&#39;analogo carbonio centrata più studiato soffre tipicamente da basso sintesi cedevole e coinvolge reagenti fosfuro metallo altamente aria-sensibili, a differenza della N -triphos ligando, che è più flessibile e più facile da preparare. 10-18 N -triphos ligandi rimangono relativamente sotto-indagato, con solo molibdeno, tungsteno, rutenio, rodio e oro complessi essendo stati segnalati da nove pubblicazioni. Questo è in netto contrasto con gli analoghi bóron- carbonio e centrata, per i quali vi sono circa 50 e 900 articoli, rispettivamente, con un gran numero di composti unici. Applicazione Tuttavia, -triphos N contenenti complessi hanno trovato nella idrogenazione catalitica asimmetrica di olefine pro-chirali 23 come noill cyclohydroamination come asimmetrica di N antideflagrante sulfamidici γ-allenyl. 24 Inoltre, un complesso di rutenio coordinato da ligando un ingombrante N -triphos con phospholane coordinamento frazioni è stato trovato per attivare silani, un passo fondamentale nello sviluppo della organosilicio chimica. 25 Come parte del programma di ricerca in corso nella catalisi, abbiamo cercato di preparare una serie di rutenio N -triphos precatalysts Ph e di indagare le loro reazioni stechiometrico e potenzialità catalitica. Nonostante complessi molibdeno di N -triphos Ph essendo stato segnalato più di 25 anni fa, la loro applicazione, catalitica o altrimenti non è stata studiata. Questo lavoro dimostra l&#39;applicabilità della N -triphos impalcatura, che pur essendo generalmente poco sviluppato, possiede molte caratteristiche desiderabili come stabilità del complesso. Qui riportiamo la via di sintesi e caratterizzazione di auna serie di rutenio N -triphos complessi Ph che possono trovare applicazione in reazioni di idrogenazione catalitica.

<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

Qui riportiamo la sintesi di un legante tridentato fosfina N (CH 2 PPh 2) 3 (N -triphos Ph) (1) tramite una base di fosforo reazione Mannich del precursore hydroxylmethylene fosfina con ammoniaca in metanolo sotto atmosfera di azoto. La N -triphos Ph ligando precipita dalla soluzione dopo circa 1 ora di reflusso e può essere isolato analiticamente puro mediante semplice procedura di filtrazione cannula sotto azoto. Reazione del N -triphos Ph ligando con [Ru 3 (CO) 12] a ricadere offre una soluzione rosso profondo che mostrano l&#39;evoluzione di gas CO il ligando complessazione. Cristalli arancioni del complesso [Ru (CO) 2 {N (CH 2 PPh 2) 3} 3 -κ P] (2) sono stati isolati per raffreddamento a RT. Lo spettro NMR 31 P {1 H} mostrato una caratteristica singolo picco a frequenza più bassarispetto al legante libero. Reazione di una soluzione toluenica di complesso 2 con l&#39;ossigeno portato alla precipitazione istantanea del carbonato complesso [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (3) come stabile dell&#39;aria arancione solido. Idrogenazione successiva di 3 con 15 bar di idrogeno in un reattore ad alta pressione ha dato il complesso diidruro [RUH 2 (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (4), che è stato pienamente caratterizzato da X cristallografia a raggi e spettroscopia NMR. Complessi 3 e 4 sono potenzialmente precursori di catalizzatori utili per una serie di reazioni di idrogenazione, compresi i prodotti derivati ​​da biomassa come l&#39;acido levulinico (LA). Complesso 4 è stato trovato reagire in modo pulito con LA in presenza dell&#39;additivo fonte protoni NH 4 PF 6 per dare [Ru (CO) {N (CH 2 PPh 2) 3} 3 -κ P {CH 3 CO (CH 2) 2 CO 2 H} -κ 2 O] (PF 6) (6).

La N -triphos Ph ligando (1) e la serie complesso di rutenio: Ru (CO) 2 {N (CH 2 PPh 2) 3} 3 -κ P] (2), [Ru (CO 3) (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (3) e [Ru (H) 2 (CO) {N (CH 2 PPh 2) 3} 3 -κ P] (4) sono state caratterizzate tramite 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

Complessi di Rutenio fosfina sono ampiamente utilizzati per le reazioni catalitiche omogenee quali idrogenazioni. È riportata la sintesi di una serie di nuovi complessi di rutenio tridentate recanti il N -triphos ligando N (CH 2 PPh 2) 3. Inoltre, la reazione stechiometrica di un complesso diidruro RU N -triphos con acido levulinico è descritto.

La sintesi, caratterizzazione e reattività di una serie di rutenio<em&gt; N</em&gt; -triphos<sup&gt; Ph</sup&gt; Complessi

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 Views.  Imperial College London.  Complessi di Rutenio fosfina sono ampiamente utilizzati per le reazioni catalitiche omogenee quali idrogenazioni. È riportata la sintesi di una serie di nuovi complessi di rutenio tridentate recanti il N -triphos ligando N (CH 2 PPh 2) 3. Inoltre, la reazione stechiometrica di un complesso diidruro RU N -triphos con acido levulinico è descritto. 

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.

Produzione di disolfuro-stabilizzati peptide transmembrana per gli studi strutturali

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

Ricerca

Chimica

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 Caratterizzazione chimica del lipide A da batteri Gram-negativi

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.

Antitumorali metallo Complessi: Sintesi e citotossicità valutazione da parte del saggio 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-e-pool Sintesi e caratterizzazione di peptidi Terziario Ammide 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.

Nucleosidi trifosfati - Dalla sintesi di biochimica Caratterizzazione

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.

Sintesi e caratterizzazione di funzionalizzato metallo-organici quadri

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.

Sintesi e caratterizzazione di supramolecolari colloidi

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.

Sintesi di ciclici polimeri e caratterizzazione di loro moto diffusivo allo stato fuso alla molecola Piano unico

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 combinazione a stato solido e tecniche di soluzione a base di: Sintesi e reattività di 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.

Palladio<em&gt; N</em&gt; Complessi di Carbene eterocicliche: Sintesi dei sali di benzimidazolium e attività catalitica in reazioni di formazione di legame di carbonio-carbonio

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