这项工作是由能源合同号DE-AC36-08GO28308美国能源部与美国国家可再生能源实验室的支持。通过能源效率的美国能源部办公室和可再生能源生物能源技术办公室提供资金。美国政府保留和发布，通过接受的文章发表，承认美国政府保留了非排他性的，缴足，不可撤销的，全球性的许可发布或转载本文的发表形式，或允许其他人这样做，对于美国政府的目的。

注意:请阅读开始之前所有相关的材料安全数据表（MSDS）。酒精是易燃品。所有相关化学品处理程序应遵循，以及所有适用的废一次性和处理程序。 1.试剂解决方案<ol><li>制备羟胺盐酸盐溶液（溶液A）:添加7.7克羟胺盐酸盐和50毫升去离子水至250毫升容量瓶中。当所有固体溶解，稀释用乙醇来标记。这导致在80％（体积/体积）乙醇中的0.55微米盐酸羟胺溶液。 </li><li>制备三乙醇胺溶液（溶液B）:加入17.4毫升的三乙醇胺到250毫升容量瓶中。添加10mL水，然后稀释到用乙醇标志。如果水的加入被跳过也可以使用95％的乙醇。这导致了0.48三乙醇胺的溶液在96％（体积/体积）乙醇</li><li>制备盐酸解。无论是购买0.1N的溶液或用10毫升浓准备HCl和1升的水。 </li></ol> 2.生物油采样和处理<ol><li>确保油样中抽取样品之前在室温下。 （通过剧烈振荡至少1分钟的混合，并目视检查样品以确保它是均匀的，有些生物油可能需要更长的振荡时间）充分均匀化生物油，得到有代表性的样品。 </li><li>为生物油样品中，使用生物油为100至150毫克。 </li><li>尽量减少暴露到氧气和热量，以防止在分析前样品降解。 </li></ol> 3.分析程序<ol><li> 碱溶液的标准化 <ol><li>干燥的 Na 2 CO 3中在105℃的烘箱主标准过夜以确保一干燥样品。允许的 Na 2 CO 3称重前冷却到室温。 </li><li>称重100至150毫克碳酸钠滴定容器，记录实际重量，加入搅拌棒和补充足够的水分，以覆盖pH电极灯泡和结。 </li><li>将样品转移至滴定容器中，用乙醇和水分别洗涤反应瓶多次比例使乙醇/水的最终的80％溶液。使用自动滴定到终点的酸溶液滴定。记录端点。端点被定义为滴定曲线上的拐点。 </li><li>重复该过程两次获得三分。 </li><li>使用该平均值作为该酸溶液的正常性。 </li></ol></li><li> 滴定空白的制备 <ol><li>对于空白答:加入0.5毫升二甲基亚砜（DMSO），以5毫升小瓶旋转叶片。 </li><li>加入2毫升盐酸羟胺溶液（溶液A）。 </li><li>加入2毫升三乙醇胺溶液（溶液B）。 </li><li>盖紧瓶盖，置于预热（80℃）热器块或水浴，搅拌2小时。 </li><li>使用自动滴定到终点记录端点酸溶液中，并滴定。 </li><li>为空白B:如果无机酸被怀疑存在于样本中，添加0.5mL的DMSO中，5毫升小瓶使用旋叶片。 </li><li>加入2毫升三乙醇胺溶液（溶液B）。 </li><li>帽密封和搅拌在80℃进行2小时。 </li><li>将样品转移至滴定容器中，用乙醇和水分别洗涤反应瓶多次比例使乙醇/水的最终的80％溶液。使用自动滴定到终点的酸溶液滴定。记录端点。 </li><li>重复过程三次以获得三点。 </li></ol></li><li> 使用公知的羰基的方法的验证 <ol><li>称取约100毫克4-（苄氧基）苯甲醛（4-BBA）到5毫升的小瓶，记录实际重量，增加一个旋转叶片。 </li><li>添加0.5毫升DMSO中。 </li><li>溶解在2mL盐酸羟胺溶液（溶液A）的样品。 </li><li>加入2毫升三乙醇胺溶液（溶液B）。 </li><li>关闭盖紧锅盖，搅拌在80℃2小时。 </li><li>将样品转移至滴定容器中，用乙醇和水分别洗涤反应瓶多次比例使乙醇/水的最终的80％溶液。使用自动滴定到终点的酸溶液滴定。记录端点。 </li><li>重复该过程三次，得到三点。 </li></ol></li><li> 生物油的分析使用方法 <ol><li>权衡接近100毫克生物油至5ml小瓶中，记录实际重量并添加旋叶片。 </li><li>添加0.5毫升DMSO中。 </li><li>溶解在2mL盐酸羟胺溶液（溶液A）的样品。 </li><li>加入2毫升三乙醇胺溶液（溶液B）。 </li><li>关闭盖紧锅盖，搅拌在80℃2小时。 </li><li>转让日Ë样品滴定容器中，在比例用乙醇和水分别洗涤反应小瓶几次，使乙醇/水的最终的80％溶液。使用自动滴定到终点的酸溶液滴定。记录端点。 </li><li>重复该过程三次，得到三点。 </li><li>坯料C:如果无机酸被怀疑存在于样本，称量接近100毫克生物油的成5毫升小瓶中，记录重量和添加旋叶片。 </li><li>添加0.5毫升DMSO中。 </li><li>加入2毫升三乙醇胺溶液（溶液B）。 </li><li>帽密封和搅拌在80℃进行2小时。 </li><li>将样品转移至滴定容器中，用乙醇和水分别洗涤反应瓶多次比例使乙醇/水的最终的80％溶液。使用自动滴定到终点的酸溶液滴定。记录端点。 </li><li>重复过程三次以获得三点。 </li></ol></li></ol> 4.计算<ol><li> 碱溶液的标准化 <ol><li>计算使用下面的公式的酸溶液（摩尔/升）的浓度。干碳酸钠以克的重量为w 1，纯度被写入为分数（ 即 ，99％是0.99），和端点处于毫升。 <img alt="式（1）" src="/files/ftp_upload/55165/55165eq1.jpg" /></li></ol></li><li> 使用公知的羰基的方法的验证 <ol><li>使用下列公式计算4BBA（摩尔/升）的样品中的浓度。该4BBA的以克的重量W 2，该4BBA纯度被写入为分数（ 即 ，99％是0.99），酸溶液（摩尔/升）的浓度为[酸]，三乙醇胺/羟胺•盐酸空白端点EP BA（三坯的平均值，以mL），并且端点是EP（以mL）。&lt;BR /&gt; <img alt="公式（2）" src="/files/ftp_upload/55165/55165eq2.jpg" /></li></ol></li><li> 生物油的分析 <ol><li>计算使用以下等式在生物油羰[CO]（毫摩尔/克生物油）的浓度。生物油的以克的重量为w 3，所述酸溶液（摩尔/升）的浓度为[酸]，三乙醇胺/羟胺•盐酸空白端点EP BA（三个坯料以mL的平均值） ，和端点是EP（以毫升）。 <img alt="公式3" src="/files/ftp_upload/55165/55165eq3.jpg" /></li></ol></li><li> 纠正酸 注:无机酸或有机酸与pKa值&lt;2的存在会引起人为的低羰基值由于与三乙醇胺的酸的反应。 <ol><li>如对此有怀疑，执行的部分3.2.6和3.4.8中详述的空白。生物油的样品中以克的重量是W 3，EP是样品的端点和EP，BA是三乙醇胺/羟胺空。 EP BB是空白B的终点，EP BC是空白C中使用的油空白C和重量（克）终点为W BC: <img alt="公式4" src="/files/ftp_upload/55165/55165eq4.jpg" /> 为主要包含乙酸生物油的样品，这是不必要的步骤。 </li></ol></li></ol>

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	<li>Oasmaa, A., Kuoppala, E., Solantausta, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+pyrolysis+of+forestry+residue.+2.+physicochemical+composition+of+product+liquid.">Fast pyrolysis of forestry residue. 2. physicochemical composition of product liquid.</a> Energy Fuels. 17 (2), 433-443 (2003).</li><li>Olarte, 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=Stabilization+of+Softwood-Derived+Pyrolysis+Oils+for+Continuous+Bio-oil+Hydroprocessing.">Stabilization of Softwood-Derived Pyrolysis Oils for Continuous Bio-oil Hydroprocessing.</a> Top. Catal. 59 (1), 55-64 (2016).</li><li>Nicolaides, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The chemical characterization of pyrolytic oils. , (1984).</li><li>Oasmaa, A., Korhonen, J., Kuoppala, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+approach+for+stability+measurement+of+wood-based+fast+pyrolysis+bio-oils.">An approach for stability measurement of wood-based fast pyrolysis bio-oils.</a> Energy Fuels. 25 (7), 3307-3313 (2011).</li><li>Chen, C. L., Lin, S. Y., Dence, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Methods in Lignin Chemistry. , 446-457 (1992).</li><li>Scholze, B., Hanser, C., Meier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+water-insoluble+fraction+from+fast+pyrolysis+liquids+(pyrolytic+lignin)+Part+II.+GPC,+carbonyl+groups,+and+13C-NMR.">Characterization of the water-insoluble fraction from fast pyrolysis liquids (pyrolytic lignin) Part II. GPC, carbonyl groups, and 13C-NMR.</a> J. Anal. Appl. Pyrolysis. 58-59, 387-400 (2001).</li><li>Bayerbach, R., Meier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+water-insoluble+fraction+from+fast+pyrolysis+liquids+(pyrolytic+lignin).+Part+IV:+Structure+elucidation+of+oligomeric+molecules.">Characterization of the water-insoluble fraction from fast pyrolysis liquids (pyrolytic lignin). Part IV: Structure elucidation of oligomeric molecules.</a> J. Anal. Appl. Pyrolysis. 85 (1-2), 98-107 (2009).</li><li>Faix, O., Andersons, B., Zakis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+Carbonyl+Groups+of+Six+Round+Robin+Lignins.">Determination of Carbonyl Groups of Six Round Robin Lignins.</a> Holzforschung. 52, 268-272 (1998).</li><li>Black, S., Ferrell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+Carbonyl+Groups+in+Pyrolysis+Bio-oils+Using+Potentiometric+Titration:+Review+and+Comparison+of+Methods.">Determination of Carbonyl Groups in Pyrolysis Bio-oils Using Potentiometric Titration: Review and Comparison of Methods.</a> Energy Fuels. 30 (2), 1071-1077 (2016).</li><li>Ferrell, J., 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=Standardization+of+Chemical+Analytical+Techniques+for+Pyrolysis+Bio-oil:+History,+Challenges,+and+Current+Status+of+Methods.">Standardization of Chemical Analytical Techniques for Pyrolysis Bio-oil: History, Challenges, and Current Status of Methods.</a> Biofuels, Bioprod. Biorefin. 10, 496-507 (2016).</li></ol>

作者什么都没有透露。

代表滴定曲线示于图2。一个空白滴定，以及用于热解油样品滴定，被示出。此外，该滴定曲线（DPH / DV）的一次导数中示出，这允许容易识别滴定终点。关于图2中的插图表显示为热解油和空白滴定式三份的数据，以平均值和标准偏差。 （以mL）中所示的端点值在第4节用于计算所述热解油样中的总羰基含量（毫摩尔/克）。对于图2中所示的热解油滴定，生物油样品质量为0.1148克，酸的浓度为0.07032摩尔/升，坯终点是13.041毫升，并热解油终点是4.891毫升。这导致4.992毫摩尔/克生物油的羰基含量。 在方法开发过程，不干扰被视为对醋酸乙酯或cetic酸。我们已发现，加入的醇的引起干扰，但是它是依赖于链长度。这是因为，尚未确定，但与溶剂的醇的性质可以是相关的。值得一提的是，单糖都采用这种方法进行测定。该方法的选择性通过使用1-丁醇，1-戊醇，叔丁醇，2-丙醇，乙酸乙酯，乙酸，木糖和葡萄糖作为模型化合物，代表醇，酯，羧酸和碳水化合物的生物测试油。此方法已被用来可靠地分析至少20生热解生物油，新鲜和在80℃老化高达120小时。此外，一些加氢裂解生物油已被成功地分析。此方法以各种各样的生物油样品，具有高水平的准确性和可靠性的结合的适用性，可借此方法在以后的其他应用。例如，羰基含量可以使用在一个生物来代替粘度油老化测试。 在原来的方法，Faix 等。 8混合三乙醇胺和盐酸羟胺溶液，使原液。这导致三乙醇胺的形成•盐酸，这将导致测量误差。在该方法中，样品的滴定应立即以下肟化（搅拌2小时后）完成。如果滴定延迟下列肟化，三乙醇胺可以形成三乙醇胺•盐酸，这将导致在测量中的误差。 乙醇80％的溶液是没有必要的样品滴定容器的转移;仅需要80％的乙醇的最终体积。作为模型化合物，4-（苄氧基）苯甲醛（4-BBA）具有足够高的分子量约为使用相同量（约100毫克），为生物油样品。虽然我们建议使用4- BBA作为羰模型化合物，可以使用的其它化合物代替4- BBA的。最后，坯料B和C是不必要的，如果只有机酸存在于生物油样本。 如在引言中所讨论的，这里介绍的Faix方法比传统的羰基滴定法（尼古拉德斯方法）的许多优点。最近，尼古拉德斯和Faix滴定方法的比较表明，尼古拉德斯方法显著低估生物油9的羰基含量。此外，在2015年的实验室间研究的原始热解生物油进行，而这项研究既包括Faix和尼古拉德斯滴定法10。结果发现，这里介绍的Faix羰基法，尤其是可靠的，与所有参与实验室间的&lt;5％，相对标准偏差（RSD）变异。相比较而言，尼古拉德斯方法表明〜10％的RSD的实验室间的变异性。最后，虽然这种方法用于分析Ø开发˚F生热解生物油，它也被成功地用于在升级热解生物油羰定量。

而热解生物油是由大量的各种化合物和化学官能团，羰基的定量是特别重要的。羰基是公知的两个存储器1和处理2期间负责生物油的不稳定性。这里介绍的滴定法是一种简单的技术，它能够可靠地量化生物油的总羰基含量。只有醛和酮官能团使用这种方法量化;羧酸和内酯基团没有定量。 为生物油的分析，通过滴定羰基的量化历来使用尼古拉德斯3的方法来实现的。这种方法已在生物油文献4，5，6，7被广泛使用。这是一个简单的过程，其中羰基被转化为相应的肟（ 见图1）。释出的盐酸用吡啶到平衡强行完成反应。吡啶的共轭酸滴定用NaOH（碱滴定剂）的已知量。使用氢氧化钠的当量数是按化学计量当量存在于生物油羰的摩尔数。 所述尼古拉德斯方法，但是，有一些限制。它可以要求反应时间超过48小时，达到完成。这严重限制了样品通量。它利用吡啶，其是有毒的。的1〜2克样品重量是必需的。使用样品重量是依赖于羟胺盐酸的存在量和样品的羰基含量。如果所使用的样品重量的初始估计是不正确的，滴定必须重复。 Faix 等。 8开发已被修改h的方法ERE解决方法尼古拉德斯的问题。该反应在80℃进行2小时，从而增加样品通量。吡啶已被替换为三乙醇胺，它是一种毒性较小的化学物质。样本大小可以减小到100至150毫克。三乙醇胺消耗释放的盐酸，驱动反应完成和未消耗的三乙醇胺是直接滴定。羟胺的第二个滴定是不必要的。这些滴定方法的比较表明，尼古拉德斯方法显著低估生物油9的羰基含量。 此处所描述的方法已经从原来的方法8修改成更适用于热解生物油的分析。这种方法对原材料热解生物油的分析开发的，但它已被成功地应用到其它类型的生物衍生的油，包括加氢处理的生物油。阿迪tionally，这种方法已被用于同时监测老化和升级过程中羰基含量的变化。

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		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dimethyl sulfoxide</td>
			<td style="width:131px;"></td>
			<td style="width:119px;"></td>
			<td>CAS # 67-68-5</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">5 mL glass Reacti-vials with solid lid and teflon spinvane</td>
			<td style="width:131px;">Thermoscientific</td>
			<td style="width:119px;">TS-13223</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">200 mL volumetric flask</td>
			<td style="width:131px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Volumetric or mechanical pipettes</td>
			<td style="width:131px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

determination of carbonyl functional groups in bio-oils by potentiometric titration: the faix method

是已知的存在于生物油的羰基化合物是负责在贮存和升级过程中生物油属性更改。具体地，羰基引起粘度生物油的储存期间的增加（通常被称为"老化"）。因此，羰基含量以前已用作跟踪生物油的老化和缩合反应具有比粘度测量的变异较少的方法。此外，羰基还负责在生物油升级进程积炭。鉴于生物油羰基的重要性，它们的量化精确的分析方法可用于生物油社区非常重要的。长期以来被用于羰基含量在热解生物油的确定基于羰基肟化电位滴定方法。这里，我们提出的，其导致较少的反应时间的传统羰肟化的方法的改进，更小的样本大小，更高的精度，并且更ACC尿酸测定羰基。而传统的羰基肟化方法发生在室温下，这里提出的Faix方法时发生在升高的温度为80℃。

<html>一个典型的滴定曲线由一个单一端点的， 如图2。为原料的生物油样品，和一个空白滴定典型滴定，被示出。作为终点在于在滴定曲线的拐点;端点可以通过绘制滴定曲线的一阶导数（在右侧轴上，DPH / DV所示，在图2中）容易地识别。许多自动滴定系统具有计算滴定曲线，它有时被称为端点识别条件（ERC）的衍生物的软件。 <img alt="图1" src="/files/ftp_upload/55165/55165fig1.jpg" /> 图1:肟化反应。反应示意图表示的羰基化合物为相应的肟的转化。 尔斯/ ftp_upload / 55165 / 55165fig2.jpg"/&gt; 图2: 样品和空白滴定曲线。为原料的热解生物油代表滴定曲线，并一空白滴定。滴定曲线，DPH / DV的第一衍生物，还示出。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55165/55165fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method at JoVE.com

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.

该Faix方法:生物油羰基官能团通过电位滴定法测定

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls ...

determination-carbonyl-functional-groups-bio-oils-potentiometric

Nanyang Technological University

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Education

JoVE Journal

JoVE Core

Organic Chemistry

Analytical Chemistry

Chemistry

Unit 1

Aldehydes and Ketones

Complexometric Titration, Precipitation Titration, and Gravimetry

SCIENTISTS IN ACTION

11.0K 次观看.  National Renewable Energy Laboratory. Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.

视频: Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

Determination of the Gas-phase Acidities of Oligopeptides

Amino acid residues located at different positions in folded proteins often exhibit different degrees of acidities. For example, a cysteine residue located at or near the N-terminus of a helix is often more acidic than that at or near the C-terminus 1-6. Although extensive experimental studies on the acid-base properties of peptides have been carried out in the condensed phase, in particular in aqueous solutions 6-8, the results are often complicated by solvent effects 7. In fact, most of the active sites in proteins are located near the interior region where solvent effects have been minimized 9,10. In order to understand intrinsic acid-base properties of peptides and proteins, it is important to perform the studies in a solvent-free environment.
We present a method to measure the acidities of oligopeptides in the gas-phase. We use a cysteine-containing oligopeptide, Ala3CysNH2 (A3CH), as the model compound. The measurements are based on the well-established extended Cooks kinetic method (Figure 1) 11-16. The experiments are carried out using a triple-quadrupole mass spectrometer interfaced with an electrospray ionization (ESI) ion source (Figure 2). For each peptide sample, several reference acids are selected. The reference acids are structurally similar organic compounds with known gas-phase acidities. A solution of the mixture of the peptide and a reference acid is introduced into the mass spectrometer, and a gas-phase proton-bound anionic cluster of peptide-reference acid is formed. The proton-bound cluster is mass isolated and subsequently fragmented via collision-induced dissociation (CID) experiments. The resulting fragment ion abundances are analyzed using a relationship between the acidities and the cluster ion dissociation kinetics. The gas-phase acidity of the peptide is then obtained by linear regression of the thermo-kinetic plots 17,18.
The method can be applied to a variety of molecular systems, including organic compounds, amino acids and their derivatives, oligonucleotides, and oligopeptides. By comparing the gas-phase acidities measured experimentally with those values calculated for different conformers, conformational effects on the acidities can be evaluated.

The determination of the gas-phase acidities of cysteine-containing oligopeptides is described. The experiments are performed using a triple quadrupole mass spectrometer. The relative acidities of the peptides are measured using collision-induced dissociation experiments, and the quantitative acidities are determined using the extended Cooks kinetic method.

寡肽测定气相酸性

Amino acid residues located at different positions in folded proteins often exhibit different degrees of acidities. For example, a cysteine residue ...

科研

化学

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Copper (I) binding by metallochaperone transport proteins prevents copper oxidation and release of the toxic ions that may participate in harmful redox reactions. The Cu (I) complex of the peptide model of a Cu (I) binding metallochaperone protein, which includes the sequence MTCSGCSRPG (underlined is conserved), was determined in solution under inert conditions by NMR spectroscopy.
NMR is a widely accepted technique for the determination of solution structures of proteins and peptides. Due to difficulty in crystallization to provide single crystals suitable for X-ray crystallography, the NMR technique is extremely valuable, especially as it provides information on the solution state rather than the solid state. Herein we describe all steps that are required for full three-dimensional structure determinations by NMR. The protocol includes sample preparation in an NMR tube, 1D and 2D data collection and processing, peak assignment and integration, molecular mechanics calculations, and structure analysis. Importantly, the analysis was first conducted without any preset metal-ligand bonds, to assure a reliable structure determination in an unbiased manner.

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

The NMR-solution structure of a metallochaperone model peptide with Cu (I) was determined, and a detailed protocol from sample preparation and 1D and 2D data collection to a three-dimensional structure is described.

Copper (I) binding by metallochaperone transport proteins prevents copper oxidation and release of the toxic ions that may participate in harmful redox ...

Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures in multi-gram scale quantities. The goal of this manuscript is to clearly detail how to handle and prepare these unique carbenes such that a synthetic chemist of any skill level can work with them. The two carbenes described are a diamidocarbene (DAC, carbene 1) and a monoamidoaminocarbene (MAAC 2). These carbenes are highly electron-deficient and as such display reactivity profiles that are atypical of more traditional N-heterocyclic carbenes. Additionally, these two carbenes only differ in their electrophilic character and not their steric parameters, making them ideal for studying how carbene electronics influence reactivity. To demonstrate this phenomenon, we are also describing the activation of white phosphorus (P4) using these carbenes. Depending on the carbene used, two very different phosphorus-containing compounds can be isolated. When the DAC 1 is used, a tris(phosphaalkenyl)phosphane can be isolated as the exclusive product. Remarkably however, when MAAC 2 is added to P4 under identical reaction conditions, an unexpected carbene-supported P8&#160;allotrope of phosphorus is isolated exclusively. Mechanistic studies demonstrate that this carbene-supported P8allotrope forms via a [2+2] cycloaddition dimerization of a transient diphosphene which has been trapped by treatment with 2,3-dimethyl-1,3-butadiene.

Here, we present a protocol for the synthesis of two carbonyl-decorated carbenes. The protocol makes these interesting compounds readily available to chemists of all skill levels. In addition to the synthesis of these two carbenes, their use in the activation of white phosphorus is also described.

羰基饰卡宾的白色磷的活化制备方法和用途

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures ...

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

层 - 层的合成和独立式共轭微孔聚合物纳米薄膜的转移

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

蛋白质生物缀合物的合成<em&gt;通过</em&gt;半胱氨酸马来酰亚胺化学

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

用电动势技术测定碱土金属合金的热力学性质

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Preparation of Functional Silica Using a Bioinspired Method

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally purify the same by acid elution. By combining sodium silicate with a polyfunctional bioinspired additive, silica is rapidly formed at ambient conditions upon neutralization. 
The effect of neutralization rate and biomolecule addition point on silica yield are investigated, and biomolecule immobilization efficiency is reported for varying addition point. In contrast to other porous silica synthesis methods, it is shown that the mild conditions required for bioinspired silica synthesis are fully compatible with the encapsulation of delicate biomolecules. Additionally, mild conditions are used across all synthesis and modification steps, making bioinspired silica a promising target for the scale-up and commercialization as both a bare material and active support medium.
The synthesis is shown to be highly sensitive to conditions, i.e., the neutralization rate and final synthesis pH, however tight control over these parameters is demonstrated through the use of auto titration methods, leading to high reproducibility in reaction progression pathway and yield. 
Therefore, bioinspired silica is an excellent active material support choice, showing versatility towards many current applications, not limited to those demonstrated here, and potency in future applications.

Here, we present a protocol to synthesize bioinspired silica materials and immobilize enzymes therein. Silica is synthesized by combining sodium silicate and an amine &#39;additive&#39;, which neutralize at a controlled rate. Material properties and function can be altered either by in situ enzyme immobilization or post-synthetic acid elution of encapsulated additives.

用 Bioinspired 法制备功能性二氧化硅

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

由 F− 310 Nm 支队所示的阴离子光电子成像

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

一种用于水降解光催化过程的高效双氧化二碘微球合成方法

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

The single deuterium substitution in porphycene leads to an asymmetric molecular geometry, which may affect the double proton transfer process in the porphycene molecule. In this study, we applied an enhanced QM/MM method called SITS-QM/MM to investigate hydrogen/deuterium (H/D) isotope effects on the double proton transfer in porphycene. Distance changes in SITS-QM/MM molecular dynamics simulations suggested that the deuterium substituted porphycene adopted the stepwise double proton transfer mechanism. The structural analysis and the free energy shifts of double proton transfer process indicated that the asymmetric isotopic substitution subtly compressed the covalent hydrogen bonds and may alter the original transition state location.

A protocol that uses enhanced QM/MM method to investigate the isotopic effect on the double proton transfer process in porphycene is presented here.

增强QM/MM方法研究的植物双质子转移过程中的同位素效应

The single deuterium substitution in porphycene leads to an asymmetric molecular geometry, which may affect the double proton transfer process in the ...

该Faix方法:生物油羰基官能团通过电位滴定法测定

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