The authors wish to acknowledge the competitive faculty-initiated collaboration (FIC) grant from KAUST.

1.准备镨掺杂的SrTiO 3粉<ol><li>为了制备将10克锶0.95镨0.05的TiO 3粉末，权衡的SrCO 3粉末（7.53407克）的TiO 2纳米粉末（4.28983克），和Pr的化学计量的量2 O 3的烧结的块状（0.44299克）反应后对于 x = 0.05： </li></ol><img alt="式（1）" fo:content-width="5in" src="/files/ftp_upload/52869/52869eq1.JPG" width="550" /><ol start="2"><li>研磨称重镨2 O 3的烧结团块用玛瑙研钵和研杵微粒。 </li><li>将称取的SrCO 3粉末和TiO 2纳米粉末添加到镨2 O 3和继续研磨并用玛瑙研钵和研杵直到目视均匀的粉末达到混合。 </li><li>加载研磨粉末成玻璃罐混合使用湍流器进行30分钟至均匀第Ë混合物。 </li><li>加载所得混合粉放入一个精心清洗和抛光不锈钢模具（直径为1英寸）并夹持其两个不锈钢柱塞之间。 </li><li>冷压机使用约1吨载荷下按粉末。 </li><li>通过将管芯上的中空不锈钢圆筒，并用推入杆从顶部推柱塞和沉淀出弹出冷压球团。一旦从模具中冷压球团（生坯）的喷射，通过轻轻覆盖用小一块透明胶带的颗粒和通过翻录磁带除去一薄层清洗上的粒料的圆周表面上的任何污染。 </li><li>将沉淀垂直氧化铝舟填充商购的SrTiO 3粉末作为氧化铝舟和冷压球团之间的屏障。 </li><li>将船的管式炉，升温至1300℃，在3小时，并保持在该温度下15小时。允许粒料冷却至室温炉内当煅烧结束。这个步骤被称为“煅烧过程”之后。 </li><li>使用玛瑙研钵和杵研磨颗粒和负载所得粉末成玻璃瓶用于使用​​湍流器进一步混合。 </li><li>加载粉末放入不锈钢管芯和冷负荷下的约3吨挤压。 </li><li>在3小时重复步骤1.9一次在1400℃，并保持在该温度20小时。 </li><li>磨用玛瑙研钵和杵沉淀。 </li><li>重复步骤1.11，1.12，和1.13一次为固态反应达到完全。 </li></ol> 2.制备多晶硅散货镨掺杂的SrTiO 3陶瓷<ol><li>权衡1.6克所制备粉末（为一个盘2毫米厚和12.7毫米直径）。 </li><li>制备圆形graphoil件，以覆盖顶部和底部INTErface在石墨模具的夹持粉末和石墨柱塞。另外，制备另一矩形graphoil片以覆盖石墨模具的内壁。 </li><li>加载所制备粉末放入石墨模具（12.7毫米内径）和夹持相同大小的两个石墨柱塞之间的粉末。钻一个2毫米孔中的石墨模具的长度的中间，并且从模具的外表面，以约2mm的内表面的温度读数。 注意：调节模外其余的石墨柱塞的长度和定位夹持粉末汽缸，其中所述孔被放置以获得精确的温度读数的中心。石墨柱塞的表面需要对工件的加工过程中被精心整平。任何未对准可导致在烧结粒料的期间放电等离子烧结的开裂。 </li><li>冷压使用压在安装前的火花粉末轻轻（负载&lt;200千克）等离子体烧结板的腔室内部。使用顶部和底部的柱塞和新闻界级之间平面抛光不锈钢支撑板，以避免损坏石墨柱塞。 </li><li>裹一块石墨毡模具周围的绝缘和石墨丝固定。设计上感到通过切割一矩形片在温度读数孔被放置在模具中的毡的石墨的窗口。 </li><li>放置在放电等离子烧结室中的装载石墨模具和柱塞。移动阶段到最终位置。 </li><li>聚焦和对准上冲模的温度读取孔的高温计目标圆。确保高温计的发射率设置被设置为石墨。 </li><li>关闭室，并把7.7千牛负荷（约60兆帕）的样品。真空和吹扫该室用Ar三次和离开腔室6帕的动态真空下。 </li><li>通过增加电流（手动或使用增加温度程序）。使用一个250分钟-1（相当于约300-400℃，分-1），优化样本。这是该放电等离子烧结过程中最重要的步骤。 </li><li>通过手动调节电流或使用程序将温度保持在1500℃下进行5分钟。在5分钟保持期结束时，关断电流并快速松开7.7千牛顿负荷，以避免在冷却开裂的样品。让样品冷却至室温的室内。 </li><li>轻轻模具采用冷新闻稿散装颗粒从石墨。这是通过把石墨模具上的空心钢筒和喷射颗粒和使用的钢从顶部推入杆的石墨柱塞完成。 </li><li>除去对粒料用一把锋利的剃刀片顶面和底面以及所述圆周表面上的graphoil。 </li><li>使用粗糙的砂纸（400格）下来0.3-0.5毫米每边以保证擦亮样本彻底清除graphoil的。清洁用丙酮样品。 </li></ol>散装陶瓷3.电子表征及热传输特性<ol><li>确定所述陶瓷盘，ρ的密度，采用阿基米德法。 </li><li>测量样品的重量，W 干 ，然后将样品浸没在水中，的重量W 湿 ，在一个稳定的密度测量系统，并从计算阿基米德密度</li></ol><img alt="公式（2）" fo:content-width="2.1in" src="/files/ftp_upload/52869/52869eq2.JPG" width="260" />其中ρ 水是水在测量温度下的密度（ 例如，等于1克厘米-3，在300°K）。14 <ol start="2"><li>测量样品，D的热扩散率，使用下一个75毫升分钟-1流量的Ar的瞬时激光闪光技术。测量厚度样本，L的，准确首先使用数字微米。 注意：具有不同尺寸和形状（ 例如，圆盘12.7毫米直径或正方形10×10 平方毫米磁盘）和厚度平行面的样品毫米之间在0.5和5可以很容易地测量。 <ol><li>在激光闪光热扩散技术中，照射一个面样品的由短（约1毫秒）的激光脉冲和记录由红外线检测器的温度上升的相反面。然后从样品的厚度，并使用帕克方程式15的温度上升-时间分布计算热扩散通过激光闪光接口软件</li></ol></li></ol><img alt="公式3" fo:content-width="1.9in" src="/files/ftp_upload/52869/52869eq3.JPG" width="220" />其中L是磁盘和叔1/2的厚度的其他S的最大温升的一半时间IDE样品。 注意：帕克模型15假定绝热样品和瞬时脉冲加热，其他模型已被提出，多年来，占在测量各种损失，如热损失，有限脉冲持续时间，非均匀脉冲加热和非均质的理想条件结构。我们已经使用了考恩模型16与脉冲校正是最先进的方法之一。应当指出的是，为了最大化从正面发射的热能的量和以最大化由IR检测器观察到的信号中，样品表面必须高度发光。通常这需要一个薄的石墨涂层到样品表面上的应用程序。的2％-5％的热扩散率的测定不确 ​​定度的存在，从尺寸的确定而产生。17 <ol start="3"><li>用金刚石锯成矩形棒切盘沉淀，2×2×10毫米3，导电性和塞贝克系数的测量以及一个正方形盘，4×4×1.5 mm 3的高温比热和一个薄的矩形片，8×5×1毫米3对霍尔测量。 </li><li>测量的比热的样品，C 磷 ，在平坦和镜面抛光方片（4×4×1.5 立方毫米）使用差示扫描量热法（DSC）在氩气流下18 <ol><li>使用的5 K.分钟-1向上的加热速率40℃下等温保持10分钟，以使样品达到热平衡之后20K的分钟-1的加热速率高达500℃，用一个精确的冷却速度它紧随其后。氩气气流下进行测量（50毫升分钟-1建议）。 </li></ol></li></ol>注意：由于用于分析的方法的灵敏度，进行三次测量，以确定热容量<html>包括（1）的基线测量中减去背景，（2）测定用标准物质的比热（如蓝宝石）与已知的中c p，和样品的比热（3）的测量。保证样品是平的，镜面抛光，以使与测量坩埚底部的理想接触（铂/铑锅与Al在这项工作中使用2 O 3坩埚）。在DSC阶段的确切结构详情的DSC技术给他人，并用于测量样品的确切说明的比较可以在各种来源中找到。19 <ol start="5"><li>计算出的高温热传导从热扩散率，d时，比热，C P，以及密度的测量值的样本，κ，ρ用 20 </li></ol>/52869/52869eq4.JPG“WIDTH =”200“/&gt; <ol start="6"><li>金板的2×2×10mm的3片切来自样品的探针接触点（4接触），以减轻的接触电阻的问题。 <ol><li>为了溅射金仅在所需的接触区域，环绕的2×2×10mm的3样品一个苏格兰胶带作为模版来使用。离开2×2mm的2面未覆盖。用剃刀刀片，切出2非常小的孔（大约1毫米直径）中的2×10 平方毫米面沿着由探针距离分开的线的中间。 </li><li>使用台式黄金溅射装置溅射一〜200纳米厚的金膜。21 </li></ol></li><li>测量样品的电输送特性，即导电性和塞贝克系数）随温度22,23的功能。 <ol><li>使用四端子法测量电导率。衡量对SAM塞贝克系数E设定使用的温度和电压的测量通过两个中间热电偶“探针”。测量使用数字显微镜这两个探针之间的距离。上电输运测量的更多细节可以在其他地方被发现。22,23 </li></ol></li><li>测量霍尔载流子浓度作为温度上使用物理性质测量系统的8×5×1毫米3的样品的功能。24 </li></ol>

<ol>
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Jpn. 114, 102 (2006).</li><li>Wang, N., He, H., Ba, Y., Wan, C., Koumoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoelectric+Properties+of+Nb-doped+SrTiO3+Ceramics+Enhanced+by+Potassium+Titanate+Nanowires+Addition.">Thermoelectric Properties of Nb-doped SrTiO3 Ceramics Enhanced by Potassium Titanate Nanowires Addition.</a> J. Ceram. Soc. Jpn. 118, 1098 (2010).</li><li>Ohta, S., 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=Large+Thermoelectric+Performance+of+Heavily+Nb-doped+SrTiO3+Epitaxial+Film+at+High+Temperature.">Large Thermoelectric Performance of Heavily Nb-doped SrTiO3 Epitaxial Film at High Temperature.</a> Appl. Phys. Lett. 87, 092108 (2005).</li><li>Kovalevsky, A., Yaremchenko, A., Populoh, S., Weidenkaff, A., Frade, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+Thermoelectric+Performance+in+Strontium+Titanate+by+Praseodymium+Substitution.">Enhancement of Thermoelectric Performance in Strontium Titanate by Praseodymium Substitution.</a> J. Appl. Phys. 113, 053704 (2013).</li><li>Kovalevsky, A. V., 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=Towards+a+High+Thermoelectric+Performance+in+Rare-Earth+Substituted+SrTiO3:+Effects+Provided+by+Strongly-Reducing+Sintering+Conditions.">Towards a High Thermoelectric Performance in Rare-Earth Substituted SrTiO3: Effects Provided by Strongly-Reducing Sintering Conditions.</a> Phys. Chem. 16, 26946 (2014).</li><li>Dawson, J. A., Tanaka, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+Structure+and+Energetics+of+Pr-+and+La-Doped+SrTiO3+Grain+Boundaries+and+the+Influence+on+Core–Shell+Structure+Formation.">Local Structure and Energetics of Pr- and La-Doped SrTiO3 Grain Boundaries and the Influence on Core–Shell Structure Formation.</a> J. Phys. Chem. C. 118, 25765-25778 (2014).</li><li>Mehdizadeh Dehkordi, A., 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=New+Insights+on+the+Synthesis+and+Electronic+Transport+in+Bulk+Polycrystalline+Pr-doped+SrTiO3&#8722;&#948;.">New Insights on the Synthesis and Electronic Transport in Bulk Polycrystalline Pr-doped SrTiO3&#8722;&#948;.</a> Appl. Phys. Lett. 117, 055102 (2015).</li></ol>

The authors have nothing to disclose.

在这个协议中，我们已经提出，为了成功地批量制备多晶硅镨掺杂的SrTiO 3陶瓷具有改进的电子和热电性能的综合战略的步骤。该协议的主要步骤包括：（i）固态合成掺杂的SrTiO 3粉末在空气中在常压下与放电等离子体烧结法的能力（ⅱ）利用致密所制备的粉末成高密度散装陶瓷，并在同一时间，以进一步掺杂有镨的样品的晶界。据证实，通过施加高的SPS加热速度（300-400℃，分...

氧化物热电被证明是有前途的候选高温热电应用，从稳定性和成本的观点，以电子输运性质。之间的n型氧化物热电，高度掺杂的钛酸锶（STO）已经引起了人们的注意，因为它有趣的电子特性。然而，大的总热导率（κ〜12瓦米-1 K -1，在300°K的单结晶）1和低载流子迁移率（μ〜6cm 2的V -1秒-1，在300°K的单结晶） 1不利地影响热电性能是由优点的一个无量纲的数字计算，ZT =α2σT/κ，其中α是塞贝克系数，σ电导率，T为绝对温度以开尔文，以及κ的总热导率。这里我们定义的分子作为功率因数，PF =α263;吨。为了使该氧化物热电材料与其他高温热电（例如SiGe合金）进行竞争，在功率因数和/或减少晶格热导率更明显的增加是必需的。 为了提高STO的热电性能的大多数实验研究主要集中在热导率通过应变场和声子的质量波动散射的降低。这些尝试包括：（i）单或双掺杂锶2+和/或Ti 4+的网站，如相对于主要的努力这个方向，自然超晶格Ruddlesden -波普尔结构的2,3（二）合成为了通过加入纳米第二相绝缘的SrO层，4和（iii）复合工程进一步降低热导率不过5，直到最近，无增强策略已报道substantially增加这些氧化物热电功率因数。散装单和多晶的STO所报告的最大功率因数（PF）的值被限制于PF &lt;1.0 W M -1 K -1的上限。 各种合成方法和处理技术已经被用于实现上述尝试的想法。粉末合成途径包括传统的固态反应，6溶胶-凝胶，水热7，图8和燃烧合成，9而常规烧结，6热压10和最近放电等离子体烧结12顷之间用于将粉末压实成普通技术散装陶瓷。然而，对于一个类似的掺杂剂（ 例如，La）的和掺杂浓度，将得到的块状陶瓷表现出范围的电子和热传输性能。这在很大程度上是由于钛酸锶&lt;的强烈过程相关的缺陷化学子&gt; 3，这导致合成依赖特性。只有少数报告的优化合成和加工参数，以造福热电运输。值得一提的是，由于非常小的声子平均中的SrTiO 3自由程（升pH值 〜2在300K纳米），11纳米结构是不是一个可行的选择的散装STO陶瓷在TE性能主要是通过减少的改善的晶格热导率。 最近，我们报导优点在非均匀掺Pr的SrTiO 3陶瓷从同时提高热电功率因数始发热电数字超过30％的改善，并降低热导率。12,13在此详细的视频协议中，我们提出与讨论我们的综合战略，这些编制的步骤镨掺杂STO陶瓷具有改进的电子和热电性能。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>SrCO3 Powder, 99.9%</td>
			<td>Sigma Aldrich</td>
			<td>472018</td>
			<td></td>
		</tr>
		<tr>
			<td>TiO2 Nanopowder, 99.5%</td>
			<td>Sigma Aldrich</td>
			<td>718467</td>
			<td></td>
		</tr>
		<tr>
			<td>Pr2O3 Sintered Lumps, 99.9%</td>
			<td>Alfa Aesar</td>
			<td>35663&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name of&#160; Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spark Plasma Sintering&#160;</td>
			<td>Dr. Sinter Lab</td>
			<td>SPS-515S</td>
			<td></td>
		</tr>
		<tr>
			<td>Resistivity/Seebeck Coefficient Measurement System</td>
			<td>Ulvac-Riko</td>
			<td>ZEM-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Flash Thermal Diffusivity Measurement System</td>
			<td>Netzsch</td>
			<td>LFA-457 Microflash</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential Scanning Calorimetry (DSC) System</td>
			<td>Netzsch</td>
			<td>404C Pegasus</td>
			<td></td>
		</tr>
		<tr>
			<td>Physical Property Measurement system (PPMS)</td>
			<td>Quantum Design</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Field Emission Scanning Electron Microscope (FE-SEM)</td>
			<td>Hitachi</td>
			<td>SU-6600</td>
			<td></td>
		</tr>
		<tr>
			<td>Energyy-dispersive X-ray Spectroscopy (EDS)</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>X-ray Diffractometer</td>
			<td>Rigaku</td>
			<td>Ultima IV</td>
			<td></td>
		</tr>
		<tr>
			<td>Bench-top Sputter Coater</td>
			<td>Denton Vacuum</td>
			<td>Desk II</td>
			<td></td>
		</tr>
		<tr>
			<td>Diamond&#160; Wheel Saw</td>
			<td>South Bay Technology</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of non-uniformly pr-doped srtio3 ceramics and their thermoelectric properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

为了研究上的SrTiO镨掺杂的效果3晶格，镨的溶解度的SrTiO共收集所制备的粉末和相应散装陶瓷作为镨含量的函数（ 图1）的X射线衍射图案3和次要相（多个）的形成。模式确认的SrTiO 3相的所有所制备的粉末，其中所述的反射可以被索引到一个立方晶格，空间群（ 图1A）的形成。从一个= 3.906对于x = 0（未掺杂）随着Pr含量中索引晶格参数的单调变化证...

Watch this Scientific Journal Video about Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties at JoVE.com

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

非均匀掺Pr的SrTiO的合成<sub&gt; 3</sub&gt;陶瓷及其热电性能

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

synthesis-non-uniformly-pr-doped-srtio3-ceramics-their-thermoelectric

Research

JoVE Journal

Chemistry

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

9.7K 次观看.  Clemson University. A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

视频: Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand.

This protocol describes the use of amide coupling reactions of isonicotinic acid and diaminoalkanes to form bridging ligands suitable for use in the synthesis of multinuclear platinum complexes, which combine aspects of the anticancer drugs BBR3464 and picoplatin.

酰胺偶联反应为双吡啶基配体及其络合合成，以白金为双核抗癌药物

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. ...

科研

化学

Synthesis and Characterization of Supramolecular Colloids

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

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

超分子胶体的合成与表征

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

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

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

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

环状聚合物的合成及其在熔融状态扩散运动的表征在单分子水平

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

Synthesis and Characterization of Fe-doped Aluminosilicate Nanotubes with Enhanced Electron Conductive Properties

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe aims at lowering the band gap of imogolite, an insulator with the chemical formula (OH)3Al2O3SiOH, and at modifying its adsorption properties towards azo-dyes, an important class of organic pollutants of both wastewater and groundwater.
Fe-doped nanotubes are obtained in two ways: by direct synthesis, where FeCl3 is added to an aqueous mixture of the Si and Al precursors, and by post-synthesis loading, where preformed nanotubes are put in contact with a FeCl3&#8226;6H2O aqueous solution. In both synthesis methods, isomorphic substitution of Al3+ by Fe3+ occurs, preserving the nanotube structure. Isomorphic substitution is indeed limited to a mass fraction of ~1.0% Fe, since at a higher Fe content (i.e., a mass fraction of 1.4% Fe), Fe2O3 clusters form, especially when the loading procedure is adopted. The physicochemical properties of the materials are studied by means of X-ray powder diffraction (XRD), N2 sorption isotherms at -196 &#176;C, high resolution transmission electron microscopy (HRTEM), diffuse reflectance (DR) UV-Vis spectroscopy, and &#950;-potential measurements. The most relevant result is the possibility to replace Al3+ ions (located on the outer surface of the nanotubes) by post-synthesis loading on preformed imogolite without perturbing the delicate hydrolysis equilibria occurring during nanotube formation. During the loading procedure, an anionic exchange occurs, where Al3+ ions on the outer surface of the nanotubes are replaced by Fe3+ ions. In Fe-doped aluminosilicate nanotubes, isomorphic substitution of Al3+ by Fe3+ is found to affect the band gap of doped imogolite. Nonetheless, Fe3+ sites on the outer surface of nanotubes are able to coordinate organic moieties, like the azo-dye Acid Orange 7, through a ligand-displacement mechanism occurring in an aqueous solution.

Here, we present a protocol to synthesize and characterize Fe-doped aluminosilicate nanotubes. The materials are obtained by either sol-gel synthesis upon addition of FeCl3&#8226;6H2O to the mixture containing the Si and Al precursors or by post-synthesis ionic exchange of preformed aluminosilicate nanotubes.

以增强电子导电性能的合成与表征Fe掺杂碳纳米管硅铝的

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

形状-各向异性胶体镉硫纳米结构的 Facet-to-facet 连接

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

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.

稳定笼 Aziridinium 离子的制备及其开环 Azaheterocycles 的合成

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

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

通过活性表面生长机制合成基片束缚金纳米线

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

解析高强共聚物芳纶纤维使其力学性能的测定

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

37p20 (o2cr)51聚类中的合成及其转化为 inp 量子点

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...

Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds

Caged compounds enable the photo-mediated manipulation of the cell physiology with high spatiotemporal resolution. However, the limited structural diversity of currently available caging groups and the difficulties in synthetic modification without sacrificing their photolysis efficiencies are obstacles to expanding the repertoire of caged compounds for live cell applications. As the chemical modification of coumarin-type photo-caging groups is a promising approach for the preparation of caged compounds with diverse physical and chemical properties, we report a method for the synthesis of clickable caged compounds that can be modified easily with various functional units via the copper(I)-catalyzed Huisgen cyclization. The modular platform molecule contains a (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) group as a photo-caging group, which exhibits a high photolysis efficiency compared to those of the conventional 2-nitrobenzyls. General procedures for the preparation of clickable caged compounds containing amines, alcohols, and carboxylates are presented. Additional properties such as the water solubility and cell targeting ability can be readily incorporated into clickable caged compounds. Furthermore, the physical and photochemical properties, including the photolysis quantum yield, were measured and were found to be superior to those of the corresponding Bhc caged compounds. The described protocol could therefore be considered a potential solution for the lack of structural diversity in the available caged compounds.

A protocol for the synthesis and measurement of the photochemical properties of modular caged compounds with clickable moieties is presented.