The authors thank the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Canada Foundation for Innovation (CFI) for funding and scholarship support.

NOTA: Solventi deuterati sono stati essiccati in base alla procedura di letteratura quando necessario, e di tutti gli altri solventi sono stati essiccati su una serie di colonne Grubbs&#39; di tipo 12 e degasate prima dell&#39;uso. Potassio 1,2,4-tris (diphenylphosphino) ciclopentadiene [K] [(Ph 2 P) 3 C 5 H 2] e la N-eterociclico carbene 1,3,4,5-tetramethylimidazole-2-ilidene (Me Me NHC ) sono stati sintetizzati secondo le procedure letteratura e quest&#39;ultima è stata sublimata prima dell&#39;uso. 9,13 Cyclohexene viene anidrificata su CaH 2, distillata e degassata prima dell&#39;uso. Acetonitrile-d 3 (CD 3 CN) e diclorometano-d 2 (CD 2 Cl 2) sono stati essiccato su pentossido di fosforo e degassata prima dell&#39;uso. La terra di diatomee è stato essiccato in stufa a 150 ° C durante la notte prima dell&#39;uso. Tutti gli altri reagenti sono stati utilizzati come ricevuti. 1. Sintesi di [dppeP] [Br] <ol><li> Dissolve 1,00 g di 1,2-bis (difenilfosfino) etano (dppe) in circa 40 ml di anidra, degassata diclorometano (DCM) in un pallone da 250 ml Schlenk, sotto gas inerte, dotato di un setto di gomma. </li><li> Con siringa o cannula, aggiungere 2,53 ml di secca, degasato, cicloesene al pallone Schlenk contenente la soluzione di agitazione dppe. </li><li> A questa soluzione, aggiungere 0,26 ml di PBr 3 tramite siringa, goccia a goccia con agitazione vigorosa. La soluzione dovrebbe diventare immediatamente precipitato giallo, pallido e bianco dopo agitazione la soluzione per 20 minuti. Lasciare che la reazione a mescolare per diverse ore o durante la notte. </li><li> Dopo agitazione per alcune ore o durante la notte, filtrata la miscela di reazione attraverso un pallone sinterizzato sormontato da una presa di terra di diatomee spessore di un pollice per rimuovere il precipitato. </li><li> Raccogliere la soluzione risultante e rimuovere il DCM sotto vuoto su una linea Schlenk. </li><li> Per l&#39;olio risultante, aggiungere circa 75 ml di tetraidrofurano (THF), mentre stirring vigorosamente (o sonicazione) per precipitare il prodotto come solido bianco. </li><li> Subito dopo le forma un precipitato bianco, la raccolta tramite filtrazione con un pallone sinterizzato in atmosfera inerte. Raccogliere il solido immediatamente, e non lasciare la sospensione a mescolare per più di 30 min. </li><li> Una volta raccolte, sciogliere una piccola quantità di [dppeP] [Br] nel CD 2 Cl 2 o CDCl 3 per ottenere 31 P, 1 H e 13 C NMR per confermare la purezza. [dppeP] [Br] possono essere conservati a tempo indeterminato in atmosfera inerte, o per diverse settimane sul banco. 6 </li></ol> 2. Sintesi di [dppeP] [IPB 4] <ol><li> Sciogliere 0,5 g di [dppeP] sale [Br] in 5 ml di DCM, in un pallone Schlenk. Agitare la soluzione sotto azoto. Quindi, aggiungere 0,35 g di tetrafenilborato di sodio in 5 ml di THF. </li><li> Lasciare che la soluzione a mescolare per diverse ore o durante la notte, fino a quando una multa forma un precipitato. </li><li> Centrifugare le suspension per eliminare il precipitato (KBr) e rimuovere il solvente a pressione ridotta per dare [dppeP] [BPH 4] come una polvere bianca. </li></ol> 3. Sintesi di [Me NHC Me 2 P] [IPB 4] <ol><li> Caricare un pallone da 100 ml Schlenk con 0,200 g di Me NHC Io e un ancoretta in atmosfera inerte. </li><li> Caricare un pallone a fondo rotondo da 100 ml con 0.603 g di [dppeP] [4 IPB] in atmosfera inerte. </li><li> Cannula 20 ml di THF al pallone Schlenk contenente 0,200 g di Me Me NHC e iniziare agitazione magnetica. </li><li> Cannula 20 ml di THF ai 100 ml pallone a fondo tondo con 0,603 g di [dppeP] [4 IPB] e mescolare fino a scioglimento. </li><li> Cannula trasferire la soluzione di [dppeP] [IPB 4] in THF alla soluzione agitazione di Me Me NHC in THF e consentire la soluzione gialla a mescolare per 1 ora. </li><li> Concentrare le s gialloolution ad un terzo del volume originale (13 ml) sotto pressione ridotta. </li><li> Aggiungere dietiletere (Et 2 O) (40 ml) alla soluzione concentrata agitazione per avviare precipitazione del prodotto giallo e consentire la sospensione risultante a mescolare per 20 min. </li><li> Inserire una fritta sigillato montato collegato a un pallone da 100 ml Schlenk sulla linea Schlenk e creare un&#39;atmosfera inerte evacuando la beuta usando il vuoto e riempire il matraccio con azoto dalla linea Schleck. Evacuare per 5 minuti e riempire con azoto per 3 volte per assicurare un&#39;atmosfera inerte. </li><li> Cannula trasferire la sospensione Et 2 O nell&#39;apparecchio e filtrare il precipitato. </li><li> Lavare il precipitato con 10 ml di Et 2 O tre volte e lasciare il precipitato asciugare sotto pressione ridotta per 2 ore. </li><li> Opzionali) permettono il filtrato e lavaggi ad evaporare lentamente sotto azoto per ricristallizzare PDPE. Lavare i cristalli con una minima quantità di esano, secca, e raccogliere ilcristalli per il riutilizzo. </li></ol> 4. Sintesi di (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P <ol><li> Per un 150 ml pallone Schlenk contenente 0.484g [dppeP] [Br] in atmosfera inerte, aggiungere 40 ml di secca, degassato THF. </li><li> Posizionare il Schlenk in un bagno di ghiaccio secco / acetone per raffreddare la sospensione a -78 ° C. </li><li> Cannula trasferire una soluzione THF di 0.625g [K] [(Ph 2 P) 3 C 5 H 2] in un pallone a fondo tondo, al flash Schlenk contenente [dppeP] [Br]. </li><li> Quando l&#39;aggiunta è completa, rimuovere il pallone Schlenk dal bagno di acetone e lasciarla riscaldare a temperatura ambiente. Dopo agitazione per 2 ore, la soluzione sarà giallo chiaro con un precipitato bianco presente. </li><li> Trasferire la sospensione in un filtro poroso privo di aria dotato di un pallone da 150 ml Schlenk, per rimuovere il precipitato bianco (KBr). </li><li> Raccogliere la soluzione gialla e rimuovere il THF sotto vuoto. </li><li> Aggiungere un 80:20miscela di secco e degasato dietiletere: pentano l&#39;olio risultante e lasciare agitare per 20 min. </li><li> Raccogliere il prodotto (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P come un precipitato giallo pallido filtrando la sospensione attraverso una, pallone sinterizzato privo di aria. La soluzione rimanente etere / pentano contiene l&#39;impurità dppe e può essere scartata o il solvente può essere rimosso sotto vuoto ed il dppe raccolti per ulteriore uso. </li></ol>

<ol>
	<li>Macdonald, C. L. B., Ellis, B. D., Swidan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-Oxidation-State+Main+Group+Compounds.">Low-Oxidation-State Main Group Compounds.</a> Encyclopedia of Inorganic and Bioinorganic Chemistry. , (2011).</li><li>Coffer (n&#233;e Monks), P. K., Dillon, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+triphosphenium+ions+and+related+species.">Cyclic triphosphenium ions and related species.</a> Coord. Chem. Rev. 257 (5-6), 910-923 (2013).</li><li>Schmidpeter, A., Lochschmidt, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Products+from+PCl3,+P(NMe2)3,+and+AlCl3.">New Products from PCl3, P(NMe2)3, and AlCl3.</a> Angew. Chem. Internat. Ed. in Engl. 25 (3), 253-254 (1986).</li><li>Schmidpeter, A., Lochschmidt, S., Karaghiosoff, K., Sheldrickb, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Triphosphane-l,3-di-ium+Ions.">Triphosphane-l,3-di-ium Ions.</a> J. Chem. Soc. Chem. Commun. , 1447-1448 (1985).</li><li>Ellis, B. D., Carlesimo, M., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stabilised+phosphorus(I)+and+arsenic(I)+iodide:+readily-synthesised+reagents+for+low+oxidation+state+main+group+chemistry.">Stabilised phosphorus(I) and arsenic(I) iodide: readily-synthesised reagents for low oxidation state main group chemistry.</a> Chem. Commun. 15 (15), 1946-1947 (2003).</li><li>Norton, E. L., Szekely, K. L. S., Dube, J. W., Bomben, P. G., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+convenient+preparative+method+for+cyclic+triphosphenium+bromide+and+chloride+salts.">A convenient preparative method for cyclic triphosphenium bromide and chloride salts.</a> Inorg. Chem. 47 (3), 1196-1203 (2008).</li><li>Ellis, B. D., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphorus(I)+iodide:+a+versatile+metathesis+reagent+for+the+synthesis+of+low+oxidation+state+phosphorus+compounds.">Phosphorus(I) iodide: a versatile metathesis reagent for the synthesis of low oxidation state phosphorus compounds.</a> Inorg. Chem. 45 (17), 6864-6874 (2006).</li><li>Kosnik, S. C., Farrar, G. J., Norton, E. L., Cooper, B. F. T., Ellis, B. D., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-Valent+Chemistry:+An+Alternative+Approach+to+Phosphorus-+Containing+Oligomers.">Low-Valent Chemistry: An Alternative Approach to Phosphorus- Containing Oligomers.</a> Inorg. Chem. 11 (53), 13061-13069 (2014).</li><li>Kosnik, S. C., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+zwitterionic+triphosphenium+compound+as+a+tunable+multifunctional+donor.">A zwitterionic triphosphenium compound as a tunable multifunctional donor.</a> Dalton Trans. 45 (14), 6251-6258 (2016).</li><li>Binder, J. F., Swidan, A., Tang, M., Nguyen, J. H., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remarkably+stable+chelating+bis-N-heterocyclic+carbene+adducts+of+phosphorus(I)+cations.">Remarkably stable chelating bis-N-heterocyclic carbene adducts of phosphorus(I) cations.</a> Chem. Commun. 51 (36), 7741-7744 (2015).</li><li>Binder, J. F., Corrente, A. M., Macdonald, C. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+route+to+phosphamethine+cyanines+from+S,N-heterocyclic+carbenes.">A simple route to phosphamethine cyanines from S,N-heterocyclic carbenes.</a> Dalton Trans. 45 (5), 2138-2147 (2016).</li><li>Pangborn, A. B., Ma Giardello, ., Grubbs, R. H., Rosen, R. K., Timmers, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Safe+and+Convenient+Procedure+for+Solvent+Purification.">Safe and Convenient Procedure for Solvent Purification.</a> Organometallics. 15 (5), 1518-1520 (1996).</li><li>Smaliy, R. V., Beaup&#233;rin, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hexaphosphine:+A+multifaceted+ligand+for+transition+metal+coordination.">Hexaphosphine: A multifaceted ligand for transition metal coordination.</a> Eur. J. Inorg. Chem. (9), 1347-1352 (2012).</li><li>Klebach, T. C., Lourens, R., Bickelhaupt, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+mesityldiphenylmethylenephosphine:+a+stable+compound+with+a+localized+phosphorus:carbon+bond.">Synthesis of mesityldiphenylmethylenephosphine: a stable compound with a localized phosphorus:carbon bond.</a> J. Amer. Chem. Soc. 100 (15), 4886-4888 (1978).</li><li>Alcarazo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#945;-Cationic+Phosphines:+Synthesis+and+Applications.">&#945;-Cationic Phosphines: Synthesis and Applications.</a> Chem. Eur. J. 20 (26), 7868-7877 (2014).</li></ol>

Gli autori non hanno nulla da rivelare.

Strutture cristalline e NMR multi-nucleare (31 P, 1 H e 13 C) sono stati ottenuti per tutti i prodotti segnalati per confermare la connettività. Elettrospray ionizzazione spettrometria di massa è stata utilizzata per confermare la presenza di cationi e analisi elementare è stata utilizzata per confermare la purezza specifica dei campioni. E &#39;indispensabile che tutte le reazioni sono fatte in un ambiente asciutto e privo di aria per garantire che nessun imprevisto sottoprodotti o prodotti di decomposizione si formano. Utilizzando un leggero eccesso di dppe nonché un eccesso (10 equivalenti) di cicloesene è necessario, per garantire buone rese di [dppeP] [Br]. Non ci sono grandi limitazioni delle tecniche descritte nel presente documento. Le reazioni ligando di spostamento con [dppeP] [Br] sono limitate solo ai ligandi di capacità donatore sufficiente a spostare il PDPE dal [dppeP] [Br] molecola. Nonostante il significativo vantaggio di questo metodo è il controllerd uscita di &quot;P +&quot; senza la generazione di imprevisti sottoprodotti o l&#39;uso di reagenti aggressivi. Così, questo metodo può essere impiegato in futuro per generare nuove molecole contenenti frazioni P I.

La chimica degli elementi dei gruppi principali in insolitamente bassi di ossidazione o di valenza Uniti è stata una zona di notevole interesse nel corso degli ultimi due decenni. 1 A parte l&#39;interesse fondamentale derivante dal loro legame e la struttura unica, tali composti spesso mostrano reattività che sono molto diversi da quelli delle loro controparti più tipici stato di ossidazione. In questo senso, essi offrono un potenziale significativo come reagenti per la costruzione di altri principali gruppi elementi contenente materiali complessi. Una classe punto di riferimento di basso-valente fosforo contenenti molecole sono cationi &quot;triphosphenium&quot; che sono stati segnalati dai Schmidpeter nel 1980. 2 Questi ioni dispongono di un dicoordinate di fosforo (I) agli ioni di legatura da due sostituenti phosphonio, con le varianti più stabili costruiti da un . chelante quadro 3,4 il nostro gruppo ha ottimizzato le sintesi di sali di alogenuro triphosphenium 5-7 e hahanno dimostrato che questi composti stabili sono versatili trasferitori P + che sono utili per la sintesi controllata di fosforo (I) oligomeri -aventi, 8 zwitterione, 9 e coloranti cianinici phosphamethine. 10,11 Mentre le sintesi originali di tali composti comprendono spesso fosforo pericolose -contenente reagenti e / o altamente condizioni riducenti, il percorso controllato presentiamo è sicuro, P-atomo efficiente e conveniente. I risultati del metodo di materiali di alta purezza, che possono essere utilizzati come coloranti, leganti per complessi di metalli di transizione e precursori per più specie contenenti fosforo complesse.

<table border="0" cellpadding="0" cellspacing="0" width="968">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">bis(diphenyl)phosphino ethane (dppe)</td>
			<td style="width:99px;">Strem</td>
			<td style="width:119px;">1663-45-2</td>
			<td style="width:468px;">98% Stored in gloved box, used as is.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Anhydrous Dichloromethane (DCM)</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">270997</td>
			<td>Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Anhydrous Cyclohexene&#160;</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">29240</td>
			<td>Dried over calcium hydride and distilled.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Phosphorus Tribromide (PBr3)</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">157783</td>
			<td>99% Stored in glove box, used as is. Air sensitive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Anyhydrous Tetrahydrofuran (THF)</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">401757</td>
			<td>Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Methylene Chloride-D2 (CD2Cl2)</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td style="width:119px;">DLM-23-25</td>
			<td>Dried over phosphorus pentoxide, vacuum transferred or distilled</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Acetonitrile</td>
			<td style="width:99px;">Alfa Aesar</td>
			<td align="right" style="width:119px;">5/8/1975</td>
			<td>Stored in glove box, used as is</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Sodium Tetraphenylborate</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td style="width:119px;">T25402</td>
			<td>Stored in glove box, used as is</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Anyhydrous Diethyl Ether&#160;</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">673811</td>
			<td>Purified through solvent purification system, or standard methods</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Anhydrous Pentane</td>
			<td style="width:99px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">236705</td>
			<td>Purified through solvent purification system, or standard methods</td>
		</tr>
	</tbody>
</table>

preparation and reactivity of a triphosphenium bromide salt: a convenient and stable source of phosphorus(i)

Presentiamo qui la sintesi ottimizzata di un sale triphosphenium bromuro. Oltre ad essere un reagente di metatesi versatile, questo composto low-valente-contenente fosforo insolitamente stabile agisce come un utile agente di trasferimento P +. A differenza dei metodi tradizionali impiegati per accedere a bassa coordinate specie fosforo che di solito richiedono precursori piroforiche contenenti fosforo (fosforo bianco, Tris (trimetilsilil) fosfina, ecc), o agenti riducenti aggressivi (metalli alcalini, grafite potassio, ecc), la corrente approccio non comporta reagenti piroforici o esplosivi e può essere fatto su larga scala (&gt; 20 g) in ottime rese da studenti universitari con una formazione sintetico privo di aria di base. Lo ione contatore bromuro è facilmente scambiato con altri anioni quali tetrafenil borato (qui descritto) utilizzando reagenti tipici sale metatesi di ottenere materiali con proprietà e reattività desiderate. La versatilità di questo P + trasferimento diPPROCCIO è esemplificata dalle reazioni di questi precursori triphosphenium con un carbene N-eterociclico e un bisphosphine anionico, ciascuna delle quali facilmente spostare il bisphosphine neutro per dare un fosforo (I) catione NHC stabilizzato e fosforo (I) contenente zwitterion rispettivamente .

Un sale stabile ([dppeP] [Br]) contenente una sorgente a bassa valente fosforo (I) può essere sintetizzato facilmente con l&#39;aggiunta di PBr 3 a diphenylphosphinoethane (dppe) in presenza di un eccesso di cicloesene (Figura 1) 6. Al lavoro della reazione, 31 spettri P NMR mostrano la presenza di un segnale tripletta che è significativamente schermato a -220 ppm, e un segnale doppietto a 50 ppm. Forte accoppiamento tra i nuclei si osserva dell&#39;ordine di 500 Hz (Figura 2). Cristalli singoli possono essere coltivate da soluzioni acetonitrile o diclorometano concentrati e cristallo singolo a raggi X analisi di diffrazione rivela che [dppeP] [Br] ha una struttura di ioni separati con due unità formula presenti nell&#39;unità asimmetrica (Figura 4). Lo ione bromuro può essere scambiato per un anione meno reattivo, such come trifluorometano sulfonato (triflato, OTF) o tetrafenilborato (BPH 4). L&#39;NMR spettro 31 P di questo prodotto è quasi identica a quella del materiale di partenza [dppeP] [Br] (Figura 3). Aggiunta di [dppeP] [IPB 4] Ad una soluzione contenente due equivalenti dei carbenici Me NHC Me provoca lo spostamento del chelanti bis-fosfina dai più fortemente donatori ligandi NHC e genera giallo colorante phosphamethine cianina [Me NHC Me 2 P ] [BPH 4] (Figura 1). Poiché [Me NHC Me 2 P] [IPB 4] è solubile in THF ma insolubile in etere dietilico, il secondo è usato per rimuovere il sottoprodotto bisphosphine, che è altamente solubile in molti solventi. Una volta separato per filtrazione, lavato ed essiccato, [Me NHC Me 2 P] [IPB 4] è ottenuto comepolvere gialla analiticamente puro. L&#39;NMR spettro 31 P di questo materiale sciolto in acetonitrile-d 3 dispone di un segnale di singoletto a -113 ppm, che è schermato in modo significativo rispetto al phosphaalkenes tipici (cf. 31 P NMR δ P -mesityldiphenylmethylenephosphine = 233.06 ppm 14) che è coerente con l&#39;assegnazione di fosforo (I) (Figura 5). Analogamente, le lunghezze relativamente lunghi obbligazioni CP, l&#39;angolo acuto CPC e torsione degli eterocicli dal piano CPC osservata nella struttura cristallina di [Me NHC Me 2 P] [IPB 4] (figura 6) sono anche più coerente con fosforo (I) descrizione. Oltre alle sue potenziali applicazioni come un colorante, composti come [Me NHC Me 2 P] [IPB 4] hanno anche dimostrato di essere ligandi utili e reagenti per la preparazione di cafosfine tionic di un tipo che sono componenti utili in applicazioni catalitiche. 15 La reazione di potassio 1,2,4-tris (difenilfosfino) ciclopentadiene in un rapporto 1: 1 con stechiometrico [dppeP] [Br] rese (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P in resa quantitativa ( Figura 1) 9. Gli unici sottoprodotti di questa reazione, cioè KBr e dppe, possono essere rimossi filtrazioni in THF e dietiletere / pentano rispettivamente. Lo spettro NMR 31 P ottenuto da una soluzione concentrata di (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P in CD 2 Cl 2 (figura 7) rivela la presenza di un segnale tripletta a -174 ppm, attribuibili alla la dicoordinate fosforo (I) centrale, un segnale singoletto a -16,9 ppm per il frammento Ph 2 P sul backbone, ed un segnale doppietto imputabile ai due Ph &lt;gruppi di sub&gt; 2 P che chelato il centro di fosforo (I). Questa struttura di questa molecola ottenuta da un singolo cristallo di analisi a raggi X di diffrazione è mostrato in figura 8. Cristalli possono coltivare via lenta evaporazione di una soluzione concentrata di DCM, THF, o anche una soluzione diluita di dietiletere. La chimica ligando di (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P è di interesse perché la molecola dispone di tre diversi tipi di siti donatori con cui si può interagire con i metalli: è dotato di un sito fosfina, un phosphide- come sito, e un sito ciclopentadienuri. 9 <img alt="Figura 1" src="/files/ftp_upload/55021/55021fig1.jpg" /> Figura 1. Reazione di PDPE con PBr 3 e cicloesene, [dppeP] [IPB 4] con Me NHC Me, e dppeP] [Br] con [K] [(Ph 2 P)3 C 5 H 2]. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig1large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> <img alt="figura 2" src="/files/ftp_upload/55021/55021fig2.jpg" /> Figura 2. 31 P (A), 1 H (B), e 13 C (C) spettri NMR di [dppeP] [Br] raccolto nel CD 2 Cl 2 preparato come descritto nel protocollo. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig2large.jpg" target="_blank">Clicca qui per visualizzare un più grande versione di questa figura.</a> <img alt="Figura 3" src="/files/ftp_upload/55021/55021fig3.jpg" /> <sTrong&gt; Figura 3. 31 P (A), 1 H (B), 11 B (C), e 13 C (D) [dppeP] [IPB 4] raccolti in CD 2 Cl 2 preparato come descritto nel protocollo. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig3large.jpg" target="_blank">favore clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 4" src="/files/ftp_upload/55021/55021fig4.jpg" /> Figura 4. Struttura molecolare di [dppeP] [Br] (A) e [dppeP] [IPB 4] (B). <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig4large.jpg" target="_blank">Clicca qui per vedere una versione più grande di Th</a>è figura. <img alt="Figura 5" src="/files/ftp_upload/55021/55021fig5.jpg" /> Figura 5. 31 P (A), 1 H (B), 11 B (C) e 13 C (D) spettri NMR di [Me NHC Me 2 P] [IPB 4] raccolto in CD 3 CN preparato come descritto nel protocollo. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig5large.jpg" target="_blank">clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 6" src="/files/ftp_upload/55021/55021fig6.jpg" /> Figura 6.<html> Struttura molecolare di [Me NHC Me 2 P] [IPB 4]. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig6large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 7" src="/files/ftp_upload/55021/55021fig7.jpg" /> Figura 7. 31 P (A), 1 H (B), e 13 C (C) spettri NMR di (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P raccolte in CD 2 Cl 2 preparato come descritto il protocollo.//ecsource.jove.com/files/ftp_upload/55021/55021fig7large.jpg &quot;target =&quot; _ blank &quot;&gt; Clicca qui per vedere una versione più grande di questa figura. <img alt="Figura 8" src="/files/ftp_upload/55021/55021fig8.jpg" /> Figura 8. Struttura molecolare di (Ph 2 P) C 5 H 2 (Ph 2 P) 2 P. <a href="http://ecsource.jove.com/files/ftp_upload/55021/55021fig8large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a>

Watch this Scientific Journal Video about Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI at JoVE.com

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

Preparazione e reattività di un Triphosphenium Bromuro di sale: una fonte conveniente e stabile di fosforo (I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable ...

preparation-reactivity-triphosphenium-bromide-salt-convenient-stable

Nanyang Technological University

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JoVE Journal

Chemistry

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)

7.7K Views.  University of Windsor. The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

Video: Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

Preparation and Use of Samarium Diiodide (SmI2) in Organic Synthesis: The Mechanistic Role of HMPA and Ni(II) Salts in the Samarium Barbier Reaction

Although initially considered an esoteric reagent, SmI2 has become a common tool for synthetic organic chemists. SmI2 is generated through the addition of molecular iodine to samarium metal in THF.1,2-3 It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI2 can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds.2-12 One of the fascinating features of SmI-2-mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo- or stereoselectivity of reactions.13-14 Additives commonly utilized to fine tune the reactivity of SmI2 can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac)2, FeCl3, etc).3
Understanding the mechanism of SmI2 reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot.1,15 Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported,1,3,7,10,12 and have been utilized in key steps of the synthesis of large natural products.16,17 Previous studies on the effect of additives on SmI2 reactions have shown that HMPA enhances the reduction potential of SmI2 by coordinating to the samarium metal center, producing a more powerful,13-14,18 sterically encumbered reductant19-21 and in some cases playing an integral role in post electron-transfer steps facilitating subsequent bond-forming events.22 In the Sm-Barbier reaction, HMPA has been shown to additionally activate the alkyl halide by forming a complex in a pre-equilibrium step.23
Ni(II) salts are a catalytic additive used frequently in Sm-mediated transformations.24-27 Though critical for success, the mechanistic role of Ni(II) was not known in these reactions. Recently it has been shown that SmI2 reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry.28
These mechanistic studies highlight that although the same Barbier product is obtained, the use of different additives in the SmI2 reaction drastically alters the mechanistic pathway of the reaction. The protocol for running these SmI2-initiated reactions is described.

Preparation and Use of Samarium Diiodide SmI2 in Organic Synthesis: The Mechanistic Role of HMPA and NiII Salts in the Samarium Barbier Reaction

A straightforward procedure for the preparation of samarium diiodide (SmI2) in THF is described. The role of two main additives namely hexamethylphosphoramide (HMPA) and Ni(acac)2 in Sm mediated reactions is demonstrated in the Sm-Barbier reaction.

Preparazione ed uso di samario diioduro (SMI<sub&gt; 2</sub&gt;) Nella sintesi organica: il ruolo meccanicistico di HMPA e Ni (II) sali nella reazione Samario Barbier

Although initially considered an esoteric reagent, SmI2 has become a common tool for synthetic organic chemists. SmI2 is generated through the addition of ...

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Chimica

Preparing Adherent Cells for X-ray Fluorescence Imaging by Chemical Fixation

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over large or small sample areas. It has been applied in many areas of science, including materials science, geoscience, studying works of cultural heritage, and in chemical biology. In the case of chemical biology, for example, visualizing the metal distributions within cells allows us to study both naturally-occurring metal ions in the cells, as well as exogenously-introduced metals such as drugs and nanoparticles. Due to the fully hydrated nature of nearly all biological samples, cryo-fixation followed by imaging under cryogenic temperature represents the ideal imaging modality currently available. However, under the circumstances that such a combination is not easily accessible or practical, aldehyde based chemical fixation remains useful and sometimes inevitable. This article describes in as much detail as possible in the preparation of adherent mammalian cells by chemical fixation for X-ray fluorescent imaging.

Here, we present a protocol on how to determine the quantity and distribution of metals in a sample using synchrotron X-ray fluorescence. We focus on adherent cells, and describe the chemical fixation method to prepare this sample. We then describe how to mount and image the sample using synchrotron X-rays.

Preparazione cellule aderenti per X-ray Fluorescence Imaging da Chemical Fixation

X-ray fluorescence imaging allows us to non-destructively measure the spatial distribution and concentration of multiple elements simultaneously over ...

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

Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the hydroxylmethylene phosphine precursor with ammonia in methanol under a nitrogen atmosphere. The N-triphosPh ligand precipitates from the solution after approximately 1 hr of reflux and can be isolated analytically pure via simple cannula filtration procedure under nitrogen. Reaction of the N-triphosPh ligand with [Ru3(CO)12] under reflux affords a deep red solution that show evolution of CO gas on ligand complexation. Orange crystals of the complex [Ru(CO)2{N(CH2PPh2)3}-&#954;3P] (2) were isolated on cooling to RT. The 31P{1H} NMR spectrum showed a characteristic single peak at lower frequency compared to the free ligand. Reaction of a toluene solution of complex 2 with oxygen resulted in the instantaneous precipitation of the carbonate complex [Ru(CO3)(CO){N(CH2PPh2)3}-&#954;3P] (3) as an air stable orange solid. Subsequent hydrogenation of 3 under 15 bar of hydrogen in a high-pressure reactor gave the dihydride complex [RuH2(CO){N(CH2PPh2)3}-&#954;3P] (4), which was fully characterized by X-ray crystallography and NMR spectroscopy. Complexes 3 and 4 are potentially useful catalyst precursors for a range of hydrogenation reactions, including biomass-derived products such as levulinic acid (LA). Complex 4 was found to cleanly react with LA in the presence of the proton source additive NH4PF6 to give [Ru(CO){N(CH2PPh2)3}-&#954;3P{CH3CO(CH2)2CO2H}-&#954;2O](PF6) (6).

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

Ruthenium phosphine complexes are widely used for homogeneous catalytic reactions such as hydrogenations. The synthesis of a series of novel tridentate ruthenium complexes bearing the N-triphos ligand N(CH2PPh2)3 is reported. Additionally, the stoichiometric reaction of a dihydride Ru&#8211;N-triphos complex with levulinic acid is described.

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 ...

Preparation of Mica and Silicon Substrates for DNA Origami Analysis and Experimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of these applications require interaction with and adhesion of DNA nanostructures to a substrate. Due to its atomically flat and easily cleaned nature, mica has been the substrate of choice for DNA origami experiments. However, the practical applications of mica are relatively limited compared to those of semiconductor substrates. For this reason, a straightforward, stable, and repeatable process for DNA origami adhesion on derivatized silicon oxide is presented here. To promote the adhesion of DNA nanostructures to silicon oxide surface, a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) is deposited from an aqueous solution that is compatible with many photoresists. The substrate must be cleaned of all organic and metal contaminants using Radio Corporation of America (RCA) cleaning processes and the native oxide layer must be etched to ensure a flat, functionalizable surface. Cleanrooms are equipped with facilities for silicon cleaning, however many components of DNA origami buffers and solutions are often not allowed in them due to contamination concerns. This manuscript describes the set-up and protocol for in-lab, small-scale silicon cleaning for researchers who do not have access to a cleanroom or would like to incorporate processes that could cause contamination of a cleanroom CMOS clean bench. Additionally, variables for regulating coverage are discussed and how to recognize and avoid common sample preparation problems is described.

Reproducible cleaning processes for substrates used in DNA origami research are described, including bench-top RCA cleaning and derivatization of silicon oxide. Protocols for surface preparation, DNA origami deposition, drying parameters, and simple experimental set-ups are illustrated.

Preparazione di Mica e Silicon substrati per il DNA Origami Analisi e sperimentazione

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of ...

Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar concentration forming hydrophobic cores surrounded by hydrophilic shells in aqueous environments. The core of these micelles can be utilized to load hydrophobic, poorly water soluble drugs like docetaxel (DTX) and everolimus (EVR). Systematic characterization of the micelle structure and drug loading capabilities are important before in vitro and in vivo studies can be conducted. The goal of the protocol described herein is to provide the necessary characterization steps to achieve standardized micellar products. DTX and EVR have intrinsic solubilities of 1.9 and 9.6 &#181;g/ml respectively Preparation of these micelles can be achieved through solvent casting which increases the aqueous solubility of DTX and EVR to 1.86 and 1.85 mg/ml, respectively. Drug stability in micelles evaluated at room temperature over 48 hr indicates that 97% or more of the drugs are retained in solution. Micelle size was assessed using dynamic light scattering and indicated that the size of these micelles was below 50 nm and depended on the molecular weight of the polymer. Drug release from the micelles was assessed using dialysis under sink conditions at pH 7.4 at 37 oC over 48 hr. Curve fitting results indicate that drug release is driven by a first order process indicating that it is diffusion driven.

The goal of this protocol is to describe the preparation and characterization of physically entrapped, poorly water soluble drugs in micellar drug delivery systems composed of amphiphilic block copolymers.

Preparazione e caratterizzazione di individuale e Multi-droga Loaded Fisicamente intrappolate polimerici Micelle

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Un metodo semplice per la dimensione sintesi controllata di stabili oligomeriche Grappoli di oro nanoparticelle in condizioni ambientali

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

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 ...

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the inverse electron demand Diels-Alder (IEDDA) cycloaddition between a radiolabeled tetrazines and trans-cyclooctene (TCO) linked to a biomolecule has proven to be a highly effective bioorthogonal approach to imaging specific biological targets. Despite the fact that technetium-99m remains the most widely used isotope in diagnostic nuclear medicine, there is a scarcity of methods for preparing 99mTc-labeled tetrazines. Herein we report the preparation of a family of tridentate-chelate-tetrazine derivatives and their Tc(I) complexes. These hitherto unknown compounds were radiolabeled with 99mTc using a microwave-assisted method in 31% to 83% radiochemical yield. The products are stable in saline and PBS and react rapidly with TCO derivatives in vitro. Their in vivo pre-targeting abilities were demonstrated using a TCO-bisphosphonate (TCO-BP) derivative that localizes to regions of active bone metabolism or injury. In murine studies, the 99mTc-tetrazines showed high activity concentrations in knees and shoulder joints, which was not observed when experiments were performed in the absence of TCO-BP. The overall uptake in non-target organs and pharmacokinetics varied greatly depending on the nature of the linker and polarity of the chelate.

Preparation and Evaluation of 99mTc-labeled Tridentate Chelates for Pre-targeting Using Bioorthogonal Chemistry

Here, we describe a protocol for radiolabeling and in vivo testing of tridentate 99mTc(I) chelate-tetrazine derivatives for pre-targeting and bioorthogonal chemistry.

Preparazione e valutazione di<sup&gt; 99m</sup&gt; Tc marcato tridentate chelati di pre-targeting Utilizzando Bioorthogonal Chimica

Pre-targeting combined with bioorthogonal chemistry is emerging as an effective way to create new radiopharmaceuticals. Of the methods available, the ...

A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites

The extraction and analysis of catecholamine neurotransmitters in biological fluids is of great importance in assessing nervous system function and related diseases, but their precise measurement is still a challenge. Many protocols have been described for neurotransmitter measurement by a variety of instruments, including high-pressure liquid chromatography (HPLC). However, there are shortcomings, such as complicated operation or hard-to-detect multiple targets, which cannot be avoided, and presently, the dominant analysis technique is still HPLC coupled with sensitive electrochemical or fluorimetric detection, due to its high sensitivity and good selectivity. Here, a detailed protocol is described for the pretreatment and detection of catecholamines with high pressure liquid chromatography with electrochemical detection (HPLC-ECD) in real urine samples of infants, using electrospun composite nanofibers composed of polymeric crown ether with polystyrene as adsorbent, also known as the packed-fiber solid phase extraction (PFSPE) method. We show how urine samples can be easily precleaned by a nanofiber-packed solid phase column, and how the analytes in the sample can be rapidly enriched, desorbed, and detected on an ECD system. PFSPE greatly simplifies the pretreatment procedures for biological samples, allowing for decreased time, expense, and reduction of the loss of targets. 
Overall, this work illustrates a simple and convenient protocol for solid-phase extraction coupled to an HPLC-ECD system for simultaneous determination of three monoamine neurotransmitters (norepinephrine (NE), epinephrine (E), dopamine (DA)) and two of their metabolites (3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC)) in infants' urine. The established protocol was applied to assess the differences of urinary catecholamines and their metabolites between high-risk infants with perinatal brain damage and healthy controls. Comparative analysis revealed a significant difference in urinary MHPG between the two groups, indicating that the catecholamine metabolites may be an important candidate marker for early diagnosis of cases at risk for brain damage in infants.

We present a convenient solid-phase extraction coupled to high-pressure liquid chromatography (HPLC) with electrochemical detection (ECD) for simultaneous determination of three monoamine neurotransmitters and two of their metabolites in infants' urine. We also identify the metabolite MHPG as a potential biomarker for the early diagnosis of brain damage for infants.

Un metodo pratico per estrazione ed analisi con cromatografia liquida dei neurotrasmettitori della catecolamina e loro metaboliti

The extraction and analysis of catecholamine neurotransmitters in biological fluids is of great importance in assessing nervous system function and ...

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the aziridine ring. The utility of bicyclic aziridinium ions, specifically 1-azoniabicyclo[3.1.0]hexane and 1-azoniabicyclo[4.1.0]heptane tosylate highlighted in the aziridine ring openings by the nucleophile with the release of the ring strain to yield the corresponding ring-expanded azaheterocycles such as pyrrolidine, piperidine and azepane with diverse substituents on the ring in regio- and stereospecific manner. Herein, we report a simple and convenient method for the preparation of the stable 1-azabicyclo[4.1.0]heptane tosylate followed by selective ring opening via a nucleophilic attack either at the bridge or at the bridgehead carbon to yield piperidine and azepane rings, respectively. This synthetic strategy allowed us to prepare biologically active natural products containing piperidine and azepane motif including sedamine, allosedamine, fagomine and balanol in highly efficient manner.

Bicyclic aziridinium ions such as 1-azoniabicyclo[4.1.0]heptane tosylate were generated from 2-[4-tolenesulfonyloxybutyl]aziridine, which was utilized for the preparation of substituted piperidines and azepanes via regio- and stereospecific ring-expansion with various nucleophiles. This highly efficient protocol allowed us to prepare diverse azaheterocycles including natural products such as fagomine, febrifugine analogue and balanol.

Preparazione di stabile biciclico Aziridinium ioni e loro anello-apertura per la sintesi di Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the ...