We are grateful to the National Science Foundation (CHE-1300508) and Mount St. Mary's University (Startup and Summer Faculty Development) for generous support of this work. Ben Rupert (University of Delaware, Mass Spectrometry Facility) is acknowledged for LIFDI mass spectral analyses.

1. Synthesis of an Isomeric Mixture of 3,4,5-Trimethyl-2,5-heptadien-4-ols
<ol>
	<li>Fill an oven dried, 500 mL beaker with 200 mL of hexanes and cover with an oven dried watch glass.
	<ol>
		<li>In an empty hood, use clean scissors to cut half inch pieces of lithium wire. Wipe each lithium piece on a paper towel to remove excess mineral oil, until all oil appears to be removed from the metal&#39;s surface, and place in the beaker containing hexanes.</li>
		<li>Fill an oven dried, 250 mL beaker with 100 mL of hexanes and cover with an oven dried watch glass. Tare this setup on a balance.</li>
		<li>Using oven dried tongs, remove the lithium wire from the first beaker, wipe quickly on a clean paper towel to remove any residual oil or hexanes, and transfer to the tared beaker. Repeat this process until 14.0 g (2.03 mol) of lithium wire have been added to the beaker.</li>
	</ol>
	</li>
	<li>Attach an oven-dried, 1 L three-neck flask equipped with a stir bar to a Schlenk line under a flow of argon in a fume hood. Heat gun the flask for a few minutes and allow it to cool under argon. 
	Caution: It is important to use argon to prevent a potential reaction between lithium and dinitrogen to form lithium nitride.
	<ol>
		<li>Once cooled, use tongs to quickly wipe the lithium pieces on a paper towel and then transfer the lithium into the flask under an argon counter flow.</li>
		<li>Submerge any excess lithium strips in mineral oil for storage. Rinse the tongs and scissors with copious amounts of water in an empty sink. Dry each with a paper towel and submerge the towels in water in the sink. 
		NOTE: No solvent bottles or paper towels should be near the sink.
		<ol>
			<li>Immerse any paper towels or gloves that have been used to cut lithium in a half-filled bowl of water and place in an empty sink. In an empty hood, slowly pour the hexanes from the beakers in 1.1-1.1.3 into a bowl containing water. Add water carefully into the empty beakers to quench any residual lithium.</li>
			<li>Rinse and wipe down the hood where the lithium was cut with water before continuing with the rest of the procedure. Submerge these paper towels in water in the sink before continuing.</li>
		</ol>
		</li>
		<li>Add approximately 500 mL of diethyl ether, collected directly from a solvent purification system, to the reaction flask via cannula transfer.</li>
		<li>Attach an oven dried reflux condenser, an addition funnel equipped with an inert gas sidearm, and a glass stopper to the three neck flask. Place a plastic bowl underneath the reaction setup in case of flask rupture.</li>
		<li>Add 2-bromo-2-butene (29.0 g, 0.218 mol), which has been dried over 4 &#197; molecular sieves overnight, to the addition funnel via syringe.</li>
		<li>Add approximately 3-4 mL of the 2-bromo-2-butene dropwise over the course of 5 minutes to initiate the reaction, whereupon reflux occurs and the solution becomes cloudy. If gentle reflux does not occur on its own after 10-15 minutes of stirring, then warm the flask gently with a heat gun for two-three minutes until reflux is achieved. This is usually adequate to initiate the reaction. 
		Caution: Even if the reaction does not initiate immediately, controlled addition of 2-bromo-2-butene is critical to keep the reaction under control.</li>
		<li>Add the remainder of the 2-bromo-2-butene in the addition funnel dropwise over the course of 90 minutes at a rate that maintains moderate reflux throughout the time period. The reaction mixture will turn a light green color.</li>
		<li>Syringe a mixture of ethyl acetate (40.0 g, 0.454 mol), which has been dried over 4 &#197; molecular sieves overnight, and 2-bromo-2-butene (103.85 g, 0.782 mol) into the addition funnel. Add this mixture to the reaction at a sufficient rate to maintain a controlled but vigorous reflux over the course of four hours.</li>
		<li>After addition is complete, syringe a small amount of ethyl acetate (2.71 g, 0.0308 mol) into the addition funnel and add dropwise to the reaction over 5 minutes. The mixture will be a cloudy orange/yellow color by the end of these additions. Allow the reaction to stir overnight at ambient temperature.</li>
	</ol>
	</li>
	<li>The next day, replace the addition funnel with a rubber septum.
	<ol>
		<li>Under an argon counter flow, remove the septum and use dry tongs to grab a piece of the unreacted lithium. To recover as much product as possible, rinse the lithium wire quickly with diethyl ether from a wash bottle and allow the solution to drip back into the reaction vessel. Then add the lithium piece to a 500 mL beaker filled with 250 mL of water. 
		Caution: The lithium pieces should be added individually to the beaker and the strip should be allowed to fully react before another is added. This minimizes the risk of fire given the significant amount of H2 generated during the quenching process. 
		NOTE: Other methods to quench the excess lithium, such as careful addition to isopropanol, also work but require significantly longer times to fully consume the excess lithium.</li>
		<li>Repeat 1.3.1 until all large pieces of lithium are quenched, which should require 60-90 minutes on the given scale.</li>
		<li>While still under argon, add a saturated ammonium chloride solution (250 mL) slowly dropwise to the stirring reaction mixture over the course of an hour, quenching the reaction mixture and any small pieces of unreacted lithium. The reaction may reflux gently during the process and become more difficult to stir based on solid formation. Continue addition until the layer of sediment completely dissolves at the bottom of the flask, forming a defined aqueous layer.</li>
		<li>Allow the reaction to cool for 30 min after addition of the solution is complete.</li>
		<li>Pour the contents of the flask into a 1 L separatory funnel and isolate the diethyl ether layer.</li>
		<li>Extract the aqueous layers with three 150 mL portions of diethyl ether.</li>
		<li>Combine all four diethyl ether layers and rotavap to a volume of approximately 75-100 mL.</li>
	</ol>
	</li>
</ol>
2. Synthesis of 1,2,3,4,5-Pentamethylcyclopentadiene (Cp*H)
<ol>
	<li>Attach an oven dried 500 mL three neck round bottom flask, equipped with a reflux condenser and stir bar, to a Schlenk line under a flow of inert gas.
	<ol>
		<li>Charge the flask with p-toluene sulfonic acid monohydrate (8.70 g, 0.0457 mol).</li>
		<li>Cannula approximately 50 mL of diethyl ether onto the solid.</li>
		<li>Under inert gas counter flow, attach an oven dried addition funnel to the reaction setup.</li>
		<li>Charge the funnel with the 3,4,5-trimethyl-2,5-heptadien-4-ols/diethyl ether concentrate from Step 1.</li>
		<li>Add the concentrate dropwise to the stirring slurry, maintaining a gentle reflux, over the course of 1 h. Allow the reaction to stir for an additional 1 h after the addition is complete.</li>
		<li>Pour the reaction mixture into 300 mL of a saturated sodium bicarbonate solution containing 4.59&#160;g (0.0433 mol) of sodium carbonate.</li>
		<li>Transfer the contents of the flask into a 1 L separatory funnel and isolate the diethyl ether layer. Extract the aqueous layer with three, 100 mL portions of diethyl ether.</li>
		<li>Combine the four diethyl ether layers and dry over magnesium sulfate for two hours.</li>
		<li>Filter the mixture and rotavap down the liquid until ~75-100 mL of material remains. At this stage, the concentrate can be stored in a refrigerator overnight prior to purification the following day.</li>
	</ol>
	</li>
	<li>Transfer the concentrate to an oven dried, round bottom flask equipped with a stir bar. Connect this flask to an oven dried transfer manifold equipped with another 100 mL round bottom flask.
	<ol>
		<li>Cool the receiving flask in ice while submerging the concentrate in an ambient temperature water bath.</li>
		<li>Apply dynamic vacuum to the setup, while stirring the concentrate, for 30-60 min to remove any residual diethyl ether.</li>
		<li>Seal the transfer setup and switch the bath for the receiving flask to a dry ice/acetone slurry while submerging the concentrate in a warm water bath. Allow the trap-to-trap distillation to continue while stirring over the course of 2-3 h, being careful to refresh the vacuum periodically (every 15-20 min) while the baths are also monitored over the same time period. 
		NOTE: After transfer, 39.0 g (0.286 moles, 58% based on 2-bromo-2-butene) of Cp*H can be isolated as a pale yellow oil.</li>
	</ol>
	</li>
</ol>
3. Synthesis of [Cp*RuCl2]229
<ol>
	<li>Charge 1.00 g (3.95 mmol) of ruthenium(III) chloride trihydrate in an oven dried 100 mL Schlenk flask equipped with a stir bar under a flow of inert gas on a Schlenk line.
	<ol>
		<li>Cannula transfer 50 mL of methanol, dried over Mg and distilled prior to use, onto the solid and stir for 30 min.</li>
		<li>Filter the solution under inert gas through an oven dried air free filter funnel, filled with an inch of oven dried Celite, into another 100 mL Schlenk flask equipped with a stir bar.</li>
		<li>Remove the air-free filter funnel and replace with a septum.</li>
		<li>Add Cp*H (1.20 g, 8.81 mmol) by syringe, attach an oven dried reflux condenser equipped with an inert gas sidearm adapter under a flow of inert gas.</li>
		<li>Seal the sidearm on the Schlenk flask and reflux for 4 h under a flow of inert gas.</li>
	</ol>
	</li>
	<li>Allow the reaction to cool and replace the reflux condenser with a glass stopper under a flow of inert gas.
	<ol>
		<li>Remove the solvent in vacuo and dry on a Schlenk line for three hours. Transfer the flask to a glovebox.</li>
		<li>Inside the glovebox, rinse the solid with pentane and scrape the solid from the sides of the flask. Filter the black solid onto a medium porosity frit, rinse with 50 mL of pentane, and dry for an additional hour in vacuo. 
		Note: [Cp*RuCl2]2 (1.53 g, 63% based on Ru) is isolated as a dark solid. Characterization matches literature reports.29</li>
	</ol>
	</li>
</ol>
4. Synthesis of [Cp*IrCl2]230
<ol>
	<li>Charge 1.00 g (2.60 mmol) of iridium(III) chloride hydrate in an oven dried 100 mL Schlenk flask equipped with a stir bar under a flow of inert gas on a Schlenk line.
	<ol>
		<li>Cannula transfer 50 mL of methanol onto the solid.</li>
		<li>Add Cp*H (0.50 g, 3.67 mmol) by syringe, attach an oven dried reflux condenser equipped with an inert gas sidearm adapter under a flow of inert gas.</li>
		<li>Seal the sidearm on the Schlenk flask and reflux for 48 h under inert gas flow.</li>
	</ol>
	</li>
	<li>Allow the reaction to cool and replace the reflux condenser with a septum under a flow of inert gas.
	<ol>
		<li>Cool the flask in an ice bath for 30 min.</li>
		<li>Filter the reaction in air through a 15 mL medium porosity frit.</li>
		<li>Rinse with 50 mL of diethyl ether and dry the solid in vacuo for two hours. 
		NOTE: [Cp*IrCl2]2 (1.23 g, 59% based on Ir) is isolated as an orange/red solid. Characterization matches literature reports.30</li>
	</ol>
	</li>
</ol>

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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=1,2,3,4,5-pentamethylcyclopentadiene.">1,2,3,4,5-pentamethylcyclopentadiene.</a> Org. Synth. 65, (1987).</li><li>Koelle, U., Kossakowski, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Di-&#181;-chloro-bis[(&#951;5-pentachlororuthenium(III)],+[Cp*RuCl2]2+and+Di-&#181;-methoxo-bis(&#951;5-pentamethylcyclomethylcyclopentadienyl)+diruthenium(II),+[Cp*RuOMe]2.">Di-&#181;-chloro-bis[(&#951;5-pentachlororuthenium(III)], [Cp*RuCl2]2 and Di-&#181;-methoxo-bis(&#951;5-pentamethylcyclomethylcyclopentadienyl) diruthenium(II), [Cp*RuOMe]2.</a> Inorg. Synth. 29, 225-228 (1992).</li><li>White, C., Yates, A., Maitlis, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#951;5-pentamethylcyclopentadienyl)rhodium+and+-iridium+compounds.">&#951;5-pentamethylcyclopentadienyl)rhodium and -iridium compounds.</a> Inorg. Synth. 29, 228-234 (1992).</li><li>Andersen, R. A., Blom, R., Boncella, J. M., Burns, C. J., Volden, H. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+thermal+average+molecular+structures+of+bis(pentamethylcyclopentadienyl)magnesium(II),+-calcium(II),+and+-ytterbium(II)+in+the+gas+phase.">The thermal average molecular structures of bis(pentamethylcyclopentadienyl)magnesium(II), -calcium(II), and -ytterbium(II) in the gas phase.</a> Acta Chem. Scand. 41A, 24-35 (1987).</li><li>Gross, J. H., 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=Liquid+injection+field+desorption/ionization+of+reactive+transition+metal+complexes.">Liquid injection field desorption/ionization of reactive transition metal complexes.</a> Anal. Bioanal. Chem. 386 (1), 52-58 (2006).</li></ol>

The authors have nothing to disclose.

During preparation of the heptadienol mixture, it is important to clean the lithium prior to initiating the reaction with the 2-bromo-2-butene. This is accomplished by wiping off residual mineral oil used for storage on paper towels, to the point that the oil appears fully removed from the surface, and by dissolving any remaining oil in the beaker of hexanes. The hexanes were used as received and not further dried before use in the procedure. Because of both the large scale of the reaction and an excess of lithium used, the weighing by difference method to determine the lithium mass is adequate. It is important to quench all materials in a hood immediately after cutting and weighing the lithium to minimize the risk of a fire secondary to the reaction vessel, including any residual lithium found on the tongs and scissors. Given the small amount of lithium remaining from the weighing process, we have found it safest to quench quickly with water rather than utilizing other milder routes.
Our group has primarily used lithium purchased commercially (see Materials) for the procedure, but similar diameter wire purchased from other vendors still provided isolation of Cp*H in comparable yields. Lithium wire is consistently used because it is simpler to cut into pieces easy to add to the reaction vessel, using only scissors. Regardless of the commercial source of the 2-bromo-2-butene, the lithium/halogen exchange has initiated on its own more than half the time our group has performed the reaction. Use of a heat gun has always provided successful initiation in all other instances. It is critical to allow adequate time for the reaction to initiate prior to the addition of large quantities of 2-bromo-2-butene to the mixture to ensure the reaction remains under control. See Figure 5a for a representative image of how the reaction mixture looks upon initiation. Isolation of the heptadienols relies on a modified workup procedure, to ensure safer and more controlled lithium quenching. Again, fast reaction of lithium with water has been preferable to other methods, so long as the lithium pieces are allowed to react individually over an adequate period of time. Our research group has never had a fire utilizing this method under controlled conditions. Alternatively, other quenching methods, such as use of isopropanol, work but require significantly longer times for complete consumption of the lithium. This quenching of the excess lithium outside the reaction vessel makes workup of the reaction much simpler, as all large pieces of Li metal have already been reacted prior to the addition of the ammonium chloride solution. It should be noted that a strong stirrer is recommended for this step (1.3.3), as the reaction mixture can become difficult to stir due to sediment formation until enough of the ammonium chloride solution is added to form a defined aqueous layer. See Figure 5b and 5c for images detailing the typical stages of the reaction quench.
<img alt="Figure 5" src="/files/ftp_upload/55366/55366fig5.jpg" /> 
Figure 5: (a) Initiation of the lithium halogen exchange with 2-bromo-2-butene. (b) Quenching of the heptadienol synthesis after 50 mL of a saturated ammonium chloride solution has been added. (c) Quenching of the heptadienol synthesis after 250 mL of a saturated ammonium chloride solution has been added. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
During the acid mediated cyclization to form Cp*H (Preparation 2, Figure 6), the heptadienols synthesized directly from Preparation 1 or diethyl ether solutions dried using magnesium sulfate prior to performing the reaction have been used, without any impact on the yield of the subsequent reaction. This indicates the exclusion of water in the heptadienol mixture is unnecessary for the cyclization step. Furthermore, the outlined purification (Figure 6b) for the Cp*H avoids a fractional distillation. However, the crude material remaining from the trap-to-trap distillation can be combined with material preserved from other Cp*H syntheses and fractionally distilled to provide additional purified ligand.
<img alt="Figure 6" src="/files/ftp_upload/55366/55366fig6.jpg" /> 
Figure 6: (a) Initial reaction setup for dienol cyclization to form Cp*H. (b) Trap-to-trap distillation setup for Cp*H purification. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Preparation of Cp*H with this method is usually performed over the course of four days, with the second and third days being the most intensive. The first day involves diethyl ether collection from a solvent purification system as well as drying of the 2-bromo-2-butene and ethyl acetate starting materials. Day 2 involves generation of the butenyl lithium and subsequent reaction with ethyl acetate to prepare the heptadienols. Day 3 encompasses the heptadienol reaction workup along with the acid mediated cyclization. The final day involves purification of Cp*H by the trap-to-trap distillation.
Synthesis of the [Cp*MCl2]2 complexes (Figure 7) described above demonstrate facile access to transition metal complexes using the Cp*H ligand from our protocol in moderate to good yields. Spectral data on the compounds match literature reports and demonstrate our procedure provides Cp*H of adequate purity for subsequent metallations. Though these reactions were performed on an intermediate scale, synthesis of these complexes should be amenable to larger scale preparation as necessary.
<img alt="Figure 7" src="/files/ftp_upload/55366/55366fig7.jpg" /> 
Figure 7: (a) Filter assembly setup for isolation of a RuCl3 solution (Step 3.1.2). (b) Initial reaction setup for preparation of [Cp*RuCl2]2 (Step 3.1.5). <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig7large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
A revised procedure is presented here for access to Cp*H on an intermediate scale which simplifies reaction workups and quenching of excess lithium while providing a streamlined purification for immediate use of the ligand in the preparation of transition metal Cp* complexes. The yields of all reactions are comparable to known literature procedures. This protocol demonstrates value to researchers requiring access to Cp*H on sizable quantities who wish to avoid the use of specialized glassware or laboratory equipment, providing a modified entry point into the chemistry of pentamethylcyclopentadienide metal complexes.

1950&#39;lerde Ferrocenenin keşif ve yapısal aydınlatılması yana, 1, 2, 3, 4 siklopentadienil (Cp) ikame ligandlar organometalik kimya gelişiminde hayati bir rol oynamıştır. Bu ligandlar, sıra dışı ve yapının çalışmaları, 5, 6, 7 aktivasyonu ve küçük moleküllerin işlevselleştirilmesi, 8, 9, 10, 11, 12, 13 ve kataliz yol metallerin bir dizi için çok yönlü bir yardımcı destek olarak hizmet etmiş olefin polimerizasyon dahil olmak üzere. 14, 15 1,2, 3,4,5-pentametilsiklopentadienil (Cp *) anyon metil grupları daha sterik koruma kazandırabileceği gibi, geçiş ve ana grubu metal kimya özellikle değerli ligand olduğu kanıtlanmıştır anyonik ligand tarafından elektron bağış artmış ve potansiyel aktivasyonunu bloke etti siklopentadienil halkasının. 16 anyon son zamanlarda Ir H / D değişimi desteklemek için kullanılmıştır olarak, 17 Cp * ligand, bugün bile ilgili kalır (III), Ti aracılık Rh, 19 ve eşlenik aminleşmeler tarafından 18 hidrür transferi (III). 20 Cp *, ligand ilgi alanımız küçük molekül aktivasyonunda kullanılmak için kobalt (I) &#39;in reaktif kaynaklarına erişmek için arzu kaynaklanmaktadır. 21 Bu çalışmalar, hem Cp * Co I ve Cp elde edilmesiyle sonuçlanmıştır * CO I L (L = N-heterosiklik karben) sp3 kullanım için benzerleri vesp 2 CH bağ oksidatif eklenmesi. Başlangıç malzemeleri 1,2,3,4,5-pentamethylcyclopentadiene belirgin miktarlarda gerektiren eden Cp * Co (II) erişim gibi 22, 23, 24, biz, büyük bir ticari maliyeti göz önüne alındığında cP multigram sentezi * H istenilen ligand. İki büyük yöntemler şu içsel teknik zorluklar ortaya her biri Cp * H, büyük çapta üretimi için mevcuttur. Marks ve arkadaşları tarafından geliştirilen bir prosedür metil lityum kullanarak nihai metil grubu yüklenmesi ve ardından 2,3,4,5-tetramethylcyclopent-2-enon bir iki aşamalı sentezi içerir. 25 sentezi de dört gün boyunca, 0 ° C de soğutulduktan sürekli düşük sıcaklık gerektirirken, 12 L&#39;lik tepkime kabı ve mekanik bir karıştırıcı kullanarak, büyük bir ölçekte açıklanmaktadır. Alternatif bir prosedür aslında geliştirilenBercaw ve çalışma arkadaşları tarafından 26, daha sonra 27 3,4,5-trimetil-2,5-heptadien-4-ol&#39;lerin izomerik karışım elde etmek üzere etil asetat nükleofılik saldırının bir alkenil lityum in situ üretimi kullanmaktadır, Marks adapte Cp *, H sağlamak için asit aracılı siklizasyon takip etmektedir. Bu yöntemin ilk raporlar büyük (3-5 L) ölçekte gerçekleştirilir ve mekanik karıştırma gerekli oldu. Buna ek olarak, bir lityum metal önemli bir fazlası, söndürme ve ara heptadienols arasında Takip eden işlem, karmaşık hale kullanılmıştır. Prosedürün bir sonraki revizyon reaksiyonu ve lityum, 28 miktarını ancak reaksiyon karışımının güvenli su verme bir sorun olmaya devam aşağı ölçekler. nedeniyle 2-bromo-2-büten reaktan lityum kaynağı ve saflık ve kuruyana farklılıklara alkenil lityum, başlatılmasında tekrarlanabilirliği daha endişeleri not edilir. Beton inşaat yaygın olarak kullanılan prosedürlere bu konuları göz önüne alındığındang Cp * H, biz, özel laboratuvar cam ve ekipman kullanımını engelleyecek reaksiyon tekrarlanabilirliği ve güvenliği artırmak ve tetkik ve ligand saflaştırma basitleştirmek olur bir ara ölçekte (30-40 g) ligand daha iyi erişim geliştirmek için baktım. Burada Bercaw ve arkadaşları tarafından geliştirilen mevcut prosedürün değişiklikler dayalı, 1,2,3,4,5-pentamethylcyclopentadiene o sentezini rapor. ligandın yeniden sentezi ve saflaştırılması iyi bir verimle (% 58) &#39;de Cp * H önemli miktarda (39 g) erişime izin veren ise esas amacı, yukarıda belirtilen gerçekleştirir. Prosedür, ara heptadienols üretimi sırasında fazla lityum daha kontrollü söndürme ve geçiş metalleri ile bir sonraki metalleşmeye yeterli saflıkta Cp * H basitleştirilmiş bir izolasyon dahil olmak üzere, diğer ek avantajlar sunmaktadır. Hazırlanan ligandın kullanılmasını göstermek için iki [Cp * MCI 2] 2 (M sentez için kullanılan= Ir, Ru) kompleksleri. aşağıda belirtilen yeniden protokolü mevcut prosedürler tamamlar ve organometalik kimyada her yerde bulunan bir yardımcı ligant destek kimyası daha basit ve daha kolay erişilebilir giriş noktasını sağlar.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Materials</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Lithium wire (in mineral oil)</td>
			<td style="width:71px;">Aldrich</td>
			<td>278327-100G</td>
			<td style="width:167px;">&#62;98%</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">2-bromo-2-butene (mixture of cis/trans isomers)</td>
			<td style="width:71px;">Acros</td>
			<td>200016-364&#160;&#160;</td>
			<td style="width:167px;">98%, dried over molecular sieves from an oven overnight before use</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hexanes</td>
			<td style="width:71px;">Millipore</td>
			<td style="width:119px;">HX0299-3</td>
			<td style="width:167px;">GR ACS, used as received</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Ethyl actetate</td>
			<td style="width:71px;">Millipore</td>
			<td style="width:119px;">EX0240-3</td>
			<td style="width:167px;">GR ACS, dried over molecular sieves from an oven overnight before use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ammonium chloride</td>
			<td style="width:71px;">Aldrich</td>
			<td style="width:119px;">213330-2.5kg</td>
			<td style="width:167px;">ACS Reagent</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Diethyl ether</td>
			<td style="width:71px;">Millipore</td>
			<td style="width:119px;">EX0190-5</td>
			<td style="width:167px;">GR ACS, collected from a solvent purification system before use</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Magnesium sulfate</td>
			<td style="width:71px;">Aldrich</td>
			<td style="width:119px;">793612-500g</td>
			<td style="width:167px;">Anhydrous, reagent grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">p-toluene sulfonic acid monohydrate</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">A320-500</td>
			<td style="width:167px;">ACS Certified</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium bicarbonate</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">5233-500</td>
			<td style="width:167px;">ACS Certified</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium carbonate</td>
			<td style="width:71px;">Amresco</td>
			<td style="width:119px;">0585-500g</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ruthenium (III) chloride trihydrate</td>
			<td style="width:71px;">Pressure Chemical</td>
			<td style="width:119px;">4750</td>
			<td style="width:167px;">40% Metal</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Iridium (III) chloride hydrate</td>
			<td style="width:71px;">Pressure Chemical</td>
			<td style="width:119px;">5730</td>
			<td style="width:167px;">53% Metal</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Methanol</td>
			<td style="width:71px;">Avantor</td>
			<td style="width:119px;">3016-22</td>
			<td style="width:167px;">AR ACS, distilled from Mg before use</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Pentane</td>
			<td style="width:71px;">J. T. Baker</td>
			<td style="width:119px;">T007-09</td>
			<td style="width:167px;">&#62;98%, dried with a solvent purification system before use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chloroform-d</td>
			<td style="width:71px;">Aldrich</td>
			<td style="width:119px;">151823-150G</td>
			<td style="width:167px;">99.8 atom % D</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Molecular sieves 4&#197;&#160;</td>
			<td style="width:71px;">Aldrich</td>
			<td style="width:119px;">208590-1KG</td>
			<td style="width:167px;">dried in an oven at 140 &#176;C before use&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Celite 545</td>
			<td style="width:71px;">Acros</td>
			<td style="width:119px;">AC34967-0025</td>
			<td style="width:167px;">dried in an oven at 140 &#176;C before use&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Name</td>
			<td style="width:71px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Equipment</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Schlenk line, with vacuum and inert gas manifolds</td>
			<td style="width:71px;">Custom</td>
			<td style="width:119px;">NA</td>
			<td>Used in Preps 1-4</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Solvent transfer manifold</td>
			<td style="width:71px;">Chemglass</td>
			<td style="width:119px;">AF-0558-01</td>
			<td style="width:167px;">Used in 2.2</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Airfree filter funnel</td>
			<td style="width:71px;">Chemglass</td>
			<td style="width:119px;">AF-0542-22</td>
			<td style="width:167px;">Used in 3.1.3</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">Glovebox</td>
			<td style="width:71px;">Vacuum Atmospheres</td>
			<td style="width:119px;">OMNI</td>
			<td style="width:167px;">Used in 3.2.2</td>
		</tr>
	</tbody>
</table>

accessing valuable ligand supports for transition metals: a modified, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene

1,2,3,4,5-pentamethylcyclopentadiene (Cp * H) güvenilir bir ara ölçekte hazırlanışı asit aracılı dienol siklizasyonu ve ardından ilk olarak 2-bromo-2-büten lityasyonundan elde mevcut protokollerinde modifikasyonları göre sunulmuştur . yine de iyi bir verimle (% 58) &#39;de Cp * H önemli miktarlarda (39 gr) erişime izin veren, bağ revize sentezi ve saflaştırılması mekanik karıştırma kullanılmasını önler. Prosedür, ara heptadienols üretimi sırasında fazla lityum daha kontrollü söndürme ve geçiş metalleri ile metalleştirme için yeterli saflıkta Cp * H basitleştirilmiş bir izolasyon dahil olmak üzere, diğer ek avantajlar sunmaktadır. Ligand daha sonra Cp * H hazırlanarak metotla arıtıldı yararını göstermek için [Cp * MCL 2] iridyum ve rutenyum hem 2 kompleksleri sentezlemek için kullanıldı. Burada özetlenen prosedür her yerde yardımcı ligant sup önemli miktarda tanıyorböylece 1,2,3,4,5-pentamethylcyclopentadiene kimyasına içine daha basit ve daha erişilebilir giriş noktası sağlayan özel laboratuar ekipmanı ihtiyacını en aza indirerek liman organometalik kimyada kullanılan.

The protocol described above for Cp*H synthesis relies on modification of the three step procedure developed by Bercaw and coworkers and modified by Marks (Figure 1). The air sensitive alkenyl lithium is prepared in situ from a mixture of cis and trans-2-butene via a lithium/halogen exchange reaction and is subsequently quenched with ethyl acetate to prepare an isomeric mixture of heptadienols. The mixture can be used without further purification in the acid mediated cyclization to provide the single desired product, Cp*H.
<img alt="Figure 1" src="/files/ftp_upload/55366/55366fig1.jpg" /> 
Figure 1: Synthetic scheme for Cp*H synthesis utilized in the described protocol. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
With our procedure described above, Cp*H can be consistently isolated in good yields (50-60%) of sufficient purity for subsequent use in direct metallation reactions with mid- to late transition metals or in the preparation of main group pentamethylcyclopentadienide salts.31 Representative 1H and 13C NMR spectra, recorded in CDCl3, of the Cp*H purified by the trap-to-trap distillation outlined above are provided in Figure 2.
<img alt="Figure 2" src="/files/ftp_upload/55366/55366fig2.jpg" /> 
Figure 2: (a) 1H NMR spectrum of Cp*H recorded in CDCl3 at 25 &#176;C. (b) 13C NMR spectrum of Cp*H recorded in CDCl3 at 25 &#176;C. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
To demonstrate the utility of the Cp*H generated by the protocol, two transition metal complexes were prepared using the ligand. The bridging ruthenium(III) halide, [Cp*RuCl2]2, is synthesized in moderate yield (63%) by refluxing Cp*H with ruthenium(III) chloride trihydrate in methanol (Figure 3a). The air sensitive product was isolated in a glovebox and subsequently characterized under an inert atmosphere. The 1H NMR spectrum of the paramagnetic product matches that of literature reports (Figure 3b). The identity of the complex was further confirmed by high-resolution Liquid Injection Field Desorption Ionization (LIFDI)32 mass spectrometry in chloroform, indicating successful preparation of the desired dimer.
<img alt="Figure 3" src="/files/ftp_upload/55366/55366fig3.jpg" /> 
Figure 3: (a) Synthesis of [Cp*RuCl2]2 utilized in the described protocol. (b) 1H NMR spectrum of [Cp*RuCl2]2 recorded in CDCl3 at 25 &#176;C. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The bridging iridium(III) halide, [Cp*IrCl2]2, was also prepared in moderate yield (59%) by refluxing Cp*H with iridium(III) chloride hydrate (Figure 4a). The air stable product was isolated on the benchtop and subsequently characterized. The 1H and 13C NMR spectra of the diamagnetic product matches that of prior reports (Figures 4b and 4c). The nuclearity of the complex was further confirmed by high-resolution LIFDI mass spectrometry in chloroform, indicating preparation of the desired dimer.
<img alt="Figure 4" src="/files/ftp_upload/55366/55366fig4.jpg" /> 
Figure 4: (a) Synthesis of [Cp*IrCl2]2 utilized in the described protocol. (b) 1H NMR spectrum of [Cp*IrCl2]2 recorded in CDCl3 at 25 &#176;C. (c) 13C NMR spectrum of [Cp*IrCl2]2 recorded in CDCl3 at 25 &#176;C. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55366/55366fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene at JoVE.com

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented. The revised protocol for the synthesis and purification of the ligand minimizes the need for specialized laboratory equipment while simplifying reaction workups and product purification. Use of Cp*H in the synthesis of [Cp*MCl2]2 complexes (M = Ru, Ir) is also described.

Değerli Ligand Erişme Geçiş Metaller için altlıklar: 1,2,3,4,5-Pentamethylcyclopentadiene bir Modifiye, Ara Ölçeği Hazırlık

A reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented, based on modifications of existing protocols that ...

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Reactions of Alkenes

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10.3K Görüntüleme.  Mount St. Mary's University. Reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented. The revised protocol for the synthesis and purification of the ligand minimizes the need for specialized laboratory equipment while simplifying reaction workups and product purification. Use of Cp*H in the synthesis of [Cp*MCl2]2 complexes (M = Ru, Ir) is also described. 

Video: Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

Bir Toprak Kolonundaki Yüzey modifiye Karbon Nanotüpler taşınması

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

Kimya

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.

DNA Origami Analiz ve Deney için Mika ve Silikon Yüzeyler Hazırlanması

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

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

Bir Kükürt Kopolimer Matrix içinde ligand-serbest CdS Nanopartiküller Sentezi

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and &#946; liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.

A protocol for in situ aqueous synthesis of a bis(iminoguanidinium) ligand and its utilization in selective separation of sulfate is presented.

bir bis-iminoguanidinium ligand ile seçici kristalleştirme ile Sülfat Ayırma

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, ...

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.

Hazırlama ve Değerlendirilmesi<sup&gt; 99m</sup&gt; Bioorthogonal Kimya Kullanarak Öncesi hedeflemek için üç dişli Şelatlar Tc-etiketli

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

Deposition of Porous Sorbents on Fabric Supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

Kumaş destekler gözenekli Sorbentler birikimi

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity in aqueous CO2 reduction. Different from traditional metal nanocrystals, the synthesis of metal single atoms involves a matrix material that can confine those single atoms and prevent them from aggregation. We report an electrospinning and thermal annealing method to prepare Ni single atoms dispersed and coordinated in a graphene shell, as active centers for CO2 reduction to CO. During the synthesis, N dopants play a critical role in generating graphene vacancies to trap Ni atoms. Aberration-corrected scanning transmission electron microscopy and three-dimensional atom probe tomography were employed to identify the single Ni atomic sites in graphene vacancies. Detailed setup of electrochemical CO2 reduction apparatus coupled with an on-line gas chromatography is also demonstrated. Compared to metallic Ni, Ni single atom catalyst exhibit dramatically improved CO2 reduction and suppressed H2 evolution side reaction.

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

Here, we present a protocol for the synthesis and electrochemical testing of transition metal single atoms coordinated in graphene vacancies as active centers for selective carbon dioxide reduction to carbon monoxide in aqueous solutions.

Sentez ve elektrokimyasal CO2 azaltılması için geçiş metalleri tek Atom katalizör performans karakterizasyonu

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

Çekirdekleşme ligand-aracılı ve Paladyum Metal nano tanecikleri gelişmesi

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

Microfluidic Preparation of Liquid Crystalline Elastomer Actuators

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation usually consists in the formation of droplets containing low molar mass liquid crystals at elevated temperatures. Subsequently, these particle precursors are oriented in the flow field of the capillary and solidified by a crosslinking polymerization, which produces the final actuating particles. The optimization of the process is necessary to obtain the actuating particles and the proper variation of the process parameters (temperature and flow rate) and allows variations of size and shape (from oblate to strongly prolate morphologies) as well as the magnitude of actuation. In addition, it is possible to vary the type of actuation from elongation to contraction depending on the director profile induced to the droplets during the flow in the capillary, which again depends on the microfluidic process and its parameters. Furthermore, particles of more complex shapes, like core-shell structures or Janus particles, can be prepared by adjusting the setup. By the variation of the chemical structure and the mode of crosslinking (solidification) of the liquid crystalline elastomer, it is also possible to prepare actuating particles triggered by heat or UV-vis irradiation.

This article describes the microfluidic process and parameters to prepare actuating particles from liquid crystalline elastomers. This process allows the preparation of actuating particles and the variation of their size and shape (from oblate to strongly prolate, core-shell, and Janus morphologies) as well as the magnitude of actuation.

Sıvı kristal Elastomer aktüatörler mikrosıvısal hazırlanması

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation ...

Gold Nanoparticle Modified Carbon Fiber Microelectrodes for Enhanced Neurochemical Detection

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into glass capillaries, pulled to a fine taper, and then sealed using an epoxy to create electrode materials that are used for fast scan cyclic voltammetry testing. The use of bare CFMEs has several limitations, though. First and foremost, the carbon fiber contains mostly basal plane carbon, which has a relatively low surface area and yields lower sensitivities than other nanomaterials. Furthermore, the graphitic carbon is limited by its temporal resolution, and its relatively low conductivity. Lastly, neurochemicals and macromolecules have been known to foul at the surface of carbon electrodes where they form non-conductive polymers that block further neurotransmitter adsorption. For this study, we modify CFMEs with gold nanoparticles to enhance neurochemical testing with fast scan cyclic voltammetry. Au3+ was electrodeposited or dipcoated from a colloidal solution onto the surface of CFMEs. Since gold is a stable and relatively inert metal, it is an ideal electrode material for analytical measurements of neurochemicals. Gold nanoparticle modified (AuNP-CFMEs) had a stability to dopamine response for over 4 h. Moreover, AuNP-CFMEs exhibit an increased sensitivity (higher peak oxidative current of the cyclic voltammograms) and faster electron transfer kinetics (lower &#916;EP or peak separation) than bare unmodified CFMEs. The development of AuNP-CFMEs provides the creation of novel electrochemical sensors for detecting fast changes in dopamine concentration and other neurochemicals at lower limits of detection. This work has vast applications for the enhancement of neurochemical measurements. The generation of gold nanoparticle modified CFMEs will be vitally important for the development of novel electrode sensors to detect neurotransmitters in vivo in rodent and other models to study neurochemical effects of drug abuse, depression, stroke, ischemia, and other behavioral and disease states.

In this study, we modify carbon-fiber microelectrodes with gold nanoparticles to enhance the sensitivity of neurotransmitter detection.

Gelişmiş nörokimyasal algılama için altın Nanopmakale modifiye karbon fiber Mikroelektrotlar

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into ...