这项工作得到了中国国家自然科学基金 (21301104)、中央大学基础研究基金 (FRF-TP-16-019A3) 和国家重点化学工程实验室 (SKL-ChE-14A04) 的支持。

1. 单 (23-dimethylbutyl) 膦酸的合成 18 , 19 <ol> <li> 反应 <ol> <li> 重 31.80 g 磷酸钠次水合物, 16.00g 乙酸, 8.42 克 23-二甲基-1-丁烯, 0.73 g di- 叔 butylnperoxide (DTBP), 和25.00 克四氢呋喃 (呋喃) 成100毫升聚四氟乙烯内衬不锈钢高压釜, 把一个磁力搅拌器放入高压釜, 并密封它. </li>
		<li> 将高压釜置于垂直管式炉中, 其下是磁性 stirringapparatus。启动磁搅拌装置, 设置速度在 800 rpm. </li>
		<li> 设置连接到高压釜的温度控制器的加热程序: 室温到120和 #176; c 在90分钟内, 保持120和 #176; c 为8小时, 然后自然地冷却到室温。启动加热程序. </li>
	</ol> </li> <li> 后处理 <ol> <li> 将产品转换为250毫升的单颈圆底烧瓶, 用50毫升呋喃清洗聚四氟乙烯衬里, 并将其添加到同一烧瓶中, 以确保所有产品均已转移. </li>
		<li> 使用旋转式蒸发器去除呋喃和未烯烃. </li>
		<li> 将残渣转化为250毫升分离漏斗, 分别用80毫升乙醚和30毫升去离子水冲洗烧瓶, 并将其放入相同的分离漏斗中, 以确保所有产品都被转移. </li>
		<li> 在上述分离漏斗中加入50毫升4% 氢氧化钠溶液, 用力摇动, 并分离水相。用20毫升4% 氢氧化钠溶液萃取三次 (20 毫升和 #215 3) 的有机相, 以确保水相超过 pH 值 10. </li>
		<li> 在上述步骤中结合水溶液, 并将其转化为500毫升分离漏斗. </li>
		<li> 添加 90 ml 10% H 2 所以 4 溶液和50毫升乙醚, 用力摇动, 并分离有机相; 然后用30毫升乙醚提取水相三次 (30 毫升和 #215; 3)。
		<li> 将乙醚溶液在阶梯1.2.6 中结合, 并将其转移到另外500毫升分离漏斗中. </li>
		<li> 用100毫升饱和 NaCl 溶液洗涤四次 (100 毫升和 #215; 4). </li>
		<li> 添加4克无水 MgSO 4 去除任何水溶性水。过滤器, 以消除固体, 并收集液体在一个干净的250毫升单颈部圆底烧瓶. </li>
		<li> 用旋转蒸发器将乙醚取出以获得17.92 克的原油产品. </li>
	</ol> </li> </ol> 2。纯化单 (23-dimethylbutyl) 膦酸 <ol> <li> 制备金刚烷胺溶液 <ol> <li> 在 500 ml 烧杯中的100毫升去离子水中溶解22.28 克胺烷胺胺. </li>
		<li> 加入100毫升饱和氢氧化钠溶液, 搅拌5分钟. </li>
		<li> 加入150毫升乙醚, 并搅拌, 直到白色沉淀产生的步骤2.1.2 消失. </li>
		<li> 将解决方案转换为500毫升分离漏斗, 用乙醚洗涤烧杯三次 (50 毫升和 #215; 3), 并将它们组合成相同的分离漏斗. </li>
		<li> 分离水相, 用饱和 NaCl 溶液洗涤有机相中五次 (100 毫升和 #215; 5). </li>
		<li> 添加4克无水 MgSO 4 去除任何水溶性水。过滤器获得金刚烷胺乙醚溶液. </li>
	</ol> </li> <li> 制备金刚烷胺和 #8729; 单 (23-dimethylbutyl) 膦酸盐 <ol> <li> 将 drop-wise 的粗单 (23-dimethylbutyl) 膦酸产品添加到金刚烷胺溶液中。在滴加150毫升乙醚, 以确保它可以正常搅拌. </li>
		<li> 用50毫升乙醚清洗单颈圆底烧瓶, 其中含有 23-dimethylbutyl) 膦酸产品, 确保将所有产品转移到金刚烷胺溶液中。搅拌30分钟, 让它坐一夜. </li>
		<li> 在减压下过滤, 用200毫升乙醚清洗滤饼. </li>
	</ol> </li> <li> 释放单声道 (23-dimethylbutyl) 膦酸 <ol> <li> 将过滤后的蛋糕转换为500毫升的烧杯, 添加80毫升的 1 M HCl, 并搅拌5分钟. </li>
		<li> 添加70毫升乙酸乙酯, 然后再搅拌5分钟. </li>
		<li> 将解决方案转换为250毫升分离漏斗并分离水相. </li>
		<li> 再次提取40毫升乙酸乙酯的水相, 并结合乙酸乙酯溶液. </li>
		<li> 以30毫升1米 HCl (30 毫升和 #215; 2) 和饱和 NaCl 三次 (80 毫升和 #215; 3) 依次冲洗乙酸乙酯溶液. </li>
		<li> 添加4克无水 MgSO 4 去除任何水溶性水。在一个250毫升的单颈圆底烧瓶中过滤和收集液体. </li>
		<li> 使用旋转式蒸发器取出乙酸乙酯, 并获得12.45 克纯单 (23-dimethylbutyl) 膦酸 (产量: 82.9%). </li>
	</ol> </li> </ol> 3。合成 (23-dimethylbutyl) (24, 4 和 #39;-2,4,4-) 膦酸 <ol> <li> 反应 <ol> <li> 将所有纯单 (23-dimethylbutyl) 膦酸产品转换为100毫升聚四氟乙烯内衬不锈钢高压釜, 加入4.95 克乙酸, 25.39 克丁烯, 0.30 克 DTBP, 将磁力搅拌器放入高压釜, 密封. </li>
		<li> 将高压釜放在垂直管式炉中, 其中有磁性搅拌装置, 启动磁力搅拌装置. </li>
		<li> 设置温度控制器的加热程序: 室温到135和 #176; c 在90分钟内, 保持在135° c, 在8小时内, 然后自然冷却到室温。启动加热程序. </li>
		<li> 当反应系统冷却到室温时, 再加0.30 克 DTBP, 重新启动加热程序. </li>
		<li> 重复步骤3.1.4 一次. </li>
	</ol> </li> <li> 后处理 <ol> <li> 将产品与100毫升乙醚稀释, 然后转到250毫升分离漏斗。
		<li> 冲洗30毫升4% 氢氧化钠三次 (30 毫升和 #215; 3), 以确保水相超过 pH 10. </li>
		<li> 添加 70 mL 10% H 2 所以 4 解决方案以酸化该产品. </li>
		<li> 用饱和 NaCl 溶液冲洗几次 (每次80毫升), 直到水相 ph 值等于 ph 值 6-7. </li>
		<li> 添加4克无水 MgSO 4 去除任何水溶性水。过滤器, 以消除固体, 并收集液体在一个干净的250毫升单颈部圆底烧瓶. </li>
		<li> 使用旋转蒸发器将乙醚和未烯烃除去, 以获得15.10 克的原油产品. </li>
	</ol> </li> </ol> 4。纯化 (23-dimethylbutyl) (24、4和 #39;-2,4,4-) 膦酸 <ol> <li> 获得纯 co (23-dimethylbutyl) (24、4和 #39;-2,4,4-) 膦酸络合物 <ol> <li> 2.30 毫升中溶解40克氢氧化钠去离子水。在含有粗 (23-dimethylbutyl) (24、4和 #39;-2,4,4-) 膦酸产品的烧瓶中加入氢氧化钠溶液, 用力摇动5分钟. </li>
		<li> 添加 0.5 M CoCl 2 解决方案滴, 而在摇晃直到没有更多的蓝色沉淀产生, 并在瓶子里的解决方案是粉红色。>> <li> 过滤和洗涤蓝色沉淀与去离子水, 直到滤饼是无色的. </li>
		<li> 将滤饼放入一个250毫升的烧杯中, 加入100毫升丙酮, 用保鲜膜封住, 然后在4和 #176 冷藏; 一晚. </li>
		<li> 粉碎蓝色沉淀物以释放在散装中捕获的任何杂质. </li>
		<li> 过滤和清洗100毫升新鲜丙酮。在室温下烘干滤饼, 然后将其转化为250毫升分离漏斗. </li>
	</ol> </li> <li> 可再生 (23-dimethylbutyl) (24、4和 #39;-2,4,4-) 膦酸 <ol> <li> 添加120毫升乙醚和 80 ml 10% H 2 所以 4 , 然后用力摇动直到蓝色沉淀消失. </li>
		<li> 分离水相, 连续洗涤有机阶段以30毫升 10% H 2 所以 4 一次和饱和 NaCl 溶液多次 (80 毫升) 直到水相 ph 等于 ph 6-7. </li>
		<li> 添加4克无水 MgSO 4 去除任何水溶性水。过滤器, 以清除固体和收集液体在一个干净的250毫升单颈部圆底烧瓶. </li>
		<li> 使用旋转蒸发器除去乙醚, 并获得纯产品的11.46 克 (产量: 52.8%). </li>
	</ol>
	</li>
</ol>

<ol>
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作者没有什么可透露的。

协议中最关键的步骤是单 alkylphosphinic 酸合成 (图 1a)。在这个反应中, 较高的产量和较少的 dialkylphosphinic 酸 by-product 是更好的。增加 NaH2PO2/烯烃 A 的摩尔比将提高产量, 抑制 dialkylphosphinic 酸 by-product 的产生。但是, 大型 NaH2PO2用量也会增加成本并引起搅拌问题。NaH2PO2/烯烃 A 的首选摩尔比为3:1。作为溶剂, 呋喃是优?...

酸性有机磷萃取被广泛应用于传统的湿法冶金领域, 用于稀土离子的萃取和分离1,2, 有色金属 (如钴/镍3,4), 稀有金属 (如 Hf/锆5, V6,7), 锕8,等。近年来, 它们在二次资源回收和高级液体废物处理方面也引起了更多的关注9。二 (2-乙基己基) 磷酸 (D2EHPA 或 P204), 2-ethylhexylphosphoric 酸 mono-2-ethylhexyl 酯 (EHEHPA, PC 88A, 或 P507), 和 di (24, 4 '-2,4,4-)-膦酸 (Cyanex272), 是 dialkylphosphoric 酸的代表,alkylphosphoric 酸单烷基酯和 dialkylphosphinic 酸分别是最常用的萃取。它们的酸度按以下顺序递减: P204 和 #62; P507 和 #62; Cyanex 272。相应的萃取能力、萃取能力、剥离酸度均为 P204 和 #62; P507 和 #62; Cyanex 272, 分离性能则相反。在大多数情况下, 这三萃取是有效的。然而, 仍有一些条件, 它们不是如此有效: 在重稀土分离, 其中存在的主要问题是选择性差, 高剥离酸性 P204 和 P507, 低萃取能力, 和乳液的趋势在提取期间为 Cyanex 272。近年来, 小说萃取的发展引起了人们的广泛关注。
dialkylphosphinic 酸萃取被认为是开发新萃取的重要研究方向之一。最近的研究表明, dialkylphosphinic 酸的提取能力主要取决于烷基取代基的结构10,11。它的范围可能比 Cyanex 27212的 P507 要低得多。然而, 对新型 dialkylphosphinic 酸萃取的探索仅限于商用烯烃结构10、12、13、14、15, 16。虽然 dialkylphosphinic 酸萃取也可以通过氏反应的方法合成, 但反应条件是严格的12,17。
NSDAPA, 其中两个烷基是不同的, 打开一扇门, 探索新的萃取。它使 dialkylphosphinic 酸的结构更加多样化, 其提取和分离性能可以通过对它的烷基结构进行 fine-tuned。传统的 NSDAPA 合成方法采用 PH 值为3作为磷源, 具有毒性高、反应条件严格、不易纯化等诸多缺点。最近, 我们报告了一种新的合成 NSDAPA 的方法, 利用磷酸钠作为磷源 (参见图 1) 并成功合成了三 NSDAPAs18。这个详细的协议可以帮助新的实践者重复实验, 掌握 NSDAPA 萃取的合成方法。我们以 (23-dimethylbutyl) (24, 4 '-2,4,4-) 膦酸为例。在表 1中显示了烯烃 a、单 alkylphosphinic 酸中间体、烯烃 B 和相应的 NSDAPA 的名称和结构。

<table><tbody><tr><td>2,3-dimethyl-1-butene</td><td>Adamas Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;6&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;12&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99%&lt;/span&gt;</td></tr><tr><td>diisobutylene</td><td>Shanghai&amp;nbsp;Aladdin&amp;nbsp;Bio-Chem&amp;nbsp;Technology&amp;nbsp;Co.,&amp;nbsp;LTD</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;16&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity 97%&lt;/span&gt;</td></tr><tr><td>acetic acid</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>di-&lt;span class=&quot;font9&quot;&gt;tert&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;-butylnperoxide&lt;/span&gt;</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;18&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;97.0%&lt;/span&gt;</td></tr><tr><td>tetrahydrofuran</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity A.R.&lt;/span&gt;</td></tr><tr><td>ethyl ether</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;10&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity &amp;ge;99.7%&lt;/span&gt;</td></tr><tr><td>ethyl acetate</td><td>Xilong Chemical Co., Ltd.</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;8&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>acetone</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: C&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;H&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;6&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;O, purity &amp;ge;99.5%&lt;/span&gt;</td></tr><tr><td>sodium hydroxide</td><td>Xilong Chemical Co., Ltd.</td><td></td><td>Molecular formula: NaOH, purity &amp;ge;96.0%</td></tr><tr><td>concentrated sulfuric acid</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: H&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;SO&lt;/span&gt;&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity 95-98%&lt;/span&gt;</td></tr><tr><td>hydrochloric acid</td><td>Beijing Chemical Works</td><td></td><td>Molecular formula: HCl, purity 36-38%</td></tr><tr><td>sodium chloride</td><td>Sinopharm Chemical Reagent Co., Ltd.</td><td></td><td>Molecular formula: NaCl, purity &amp;ge;99.5%</td></tr><tr><td>anhydrous magnesium sulfate</td><td>Tianjin Jinke Institute of Fine Chemical Industry</td><td></td><td>Molecular formula: MgSO&lt;span class=&quot;font8&quot;&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span class=&quot;font7&quot;&gt;, purity &amp;ge;99.0%&lt;/span&gt;</td></tr></tbody></table>

synthesis of high purity nonsymmetric dialkylphosphinic acid extractants

本文以 (23-dimethylbutyl) (24、4-2,4,4-) 膦酸的合成为例, 说明了一种合成高纯度对称 dialkylphosphinic 酸萃取的方法。以低毒磷酸钠为磷源, 与烯烃 A (23-二甲基-1-丁烯) 发生反应, 生成 monoalkylphosphinic 酸中间体。采用金刚烷胺除去 dialkylphosphinic 酸副产品, 因为只有 monoalkylphosphinic 酸能与金刚烷胺反应形成 amantadine∙mono-alkylphosphinic 酸盐, 而 dialkylphosphinic 酸不能与金刚烷胺反应, 因为其巨大的空间位阻。纯化后的 monoalkylphosphinic 酸与烯烃 B (丁烯) 反应产生对称 dialkylphosphinic 酸 (NSDAPA)。未 monoalkylphosphinic 酸可以通过简单的碱酸后处理去除, 通过钴盐的沉淀可以分离出其他有机杂质。(23-dimethylbutyl) (24, 4 '-2,4,4-) 膦酸的结构由31P 核磁共振、 1H 核磁共振、ESI 质谱和 FT IR 证实。纯度由电位滴定法测定, 结果表明纯度可超过96%。

31用金刚烷胺法 (图 1a-b) 纯化前后的单 (23-dimethylbutyl) 膦酸的核磁共振谱。31P 核磁共振谱1H 核磁共振谱、MS 谱和 FT 红外光谱分别收集 (23-dimethylbutyl) (24、4-2,4,4-) 膦酸 (见图 3、图 4、图 5和图 6) 后用钴盐沉淀法提纯。(23-dimethy...

Watch this Scientific Journal Video about Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants at JoVE.com

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

高纯度对称 Dialkylphosphinic 酸萃取的合成

介绍了一种合成高纯度对称 dialkylphosphinic 酸萃取的协议, 以 (23-dimethylbutyl) (24, 4 '-2,4,4-) 膦酸为例。

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high ...

synthesis-high-purity-nonsymmetric-dialkylphosphinic-acid

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Chemistry

Acid-base and Solubility Equilibria

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7.4K 次观看.  University of Science and Technology Beijing. 介绍了一种合成高纯度对称 dialkylphosphinic 酸萃取的协议, 以 (23-dimethylbutyl) (24, 4 '-2,4,4-) 膦酸为例。

视频: Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

紧凑型量子点的单分子成像

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

科研

工程学

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. Diiodomethyllithium is prepared by the deprotonation of diiodomethane with LiHMDS, in a THF/diethyl ether mixture, at -78 &#176;C in the dark. These conditions are essential for the stability of the LiCHI2 reagent generated. The subsequent dropwise addition of N-Ts aldimines to the preformed diiodomethyllithium solution affords an amino-diiodide intermediate, which is not isolated. Rapid warming of the reaction mixture to 0 &#176;C promotes cyclization to afford iodoaziridines with exclusive cis-diastereoselectivity. The addition and cyclization stages of the reaction are mediated in one reaction flask by careful temperature control.
Due to the sensitivity of the iodoaziridines to purification, assessment of suitable methods of purification is required. A protocol to assess the stability of sensitive compounds to stationary phases for column chromatography is described. This method is suitable to apply to new iodoaziridines, or other potentially sensitive novel compounds. Consequently this method may find application in range of synthetic projects. The procedure involves firstly the assessment of the reaction yield, prior to purification, by 1H NMR spectroscopy with comparison to an internal standard. Portions of impure product mixture are then exposed to slurries of various stationary phases appropriate for chromatography, in a solvent system suitable as the eluent in flash chromatography. After stirring for 30 min to mimic chromatography, followed by filtering, the samples are analyzed by 1H NMR spectroscopy. Calculated yields for each stationary phase are then compared to that initially obtained from the crude reaction mixture. The results obtained provide a quantitative assessment of the stability of the compound to the different stationary phases; hence the optimal can be selected. The choice of basic alumina, modified to activity IV, as a suitable stationary phase has allowed isolation of certain iodoaziridines in excellent yield and purity.

A protocol for the diastereoselective one-pot preparation of cis-N-Ts-iodoaziridines is described. The generation of diiodomethyllithium, addition to N-Ts aldimines and cyclization of the amino gem-diiodide intermediate to iodoaziridines is demonstrated. Also included is a protocol to rapidly and quantitatively assess the most appropriate stationary phase for purification by chromatography.

合成和Iodoaziridines纯化涉及定量选择最优固定相的色谱

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. ...

化学

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

对磷酸增强富集制备高度多孔配位聚合物涂层的孔聚合物石柱的

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Extraction and Characterization of Surfactants from Atmospheric Aerosols

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth&#39;s atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth&#39;s ecosystems.
In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter &#60;1 &#956;m) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

Methods are presented for the targeted extraction of surfactants present in atmospheric aerosols and the determination of their absolute concentrations and surface tension curves in water, including their Critical Micelle Concentration (CMC).

提取和表面活性剂的特性，从大气气溶胶

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in ...

环境科学

Facile Protocol for the Synthesis of Self-assembling Polyamine-based Peptide Amphiphiles (PPAs) and Related Biomaterials

Polyamine-based Peptide Amphiphiles (PPAs) are a new class of self-assembling amphiphilic biomaterials-related to the peptide amphiphiles (PAs). Traditional PAs possess charged amino acids as solubilizing groups (lysine, arginine), which are directly connected to a lipid segment or can contain a linker region made of neutral amino acids. Tuning the peptide sequence of PAs can yield diverse morphologies. Similarly, PPAs possess a hydrophobic segment and neutral amino acids, but also contain polyamine molecules as water solubilizing (hydrophilic) groups. As is the case with PAs, PPAs can also self-assemble into diverse morphologies, including small rods, twisted nano-ribbons, and fused nano-sheets, when dissolved in water. However, the presence of both primary and secondary amines on a single polyamine molecule poses a significant challenge when synthesizing PPAs. In this paper, we show a simple protocol, based on literature precedents, to achieve a facile synthesis of PPAs using solid phase peptide synthesis (SPPS). This protocol can be extended to the synthesis of PAs and other similar systems. We also illustrate the steps that are needed for cleavage from the resin, identification, and purification.

Facile Protocol for the Synthesis of Self-assembling Polyamine-based Peptide Amphiphiles PPAs and Related Biomaterials

The synthesis of polyamine-based peptide amphiphiles (PPAs) is a significant challenge due to the presence of multiple amine nitrogens, which requires judicious use of protecting groups to mask these reactive functionalities. In this paper, we describe a facile method for the preparation of these new class of self-assembling molecules.

自组装多胺基多肽 Amphiphiles (PPAs) 及相关生物材料的简易合成协议

Polyamine-based Peptide Amphiphiles (PPAs) are a new class of self-assembling amphiphilic biomaterials-related to the peptide amphiphiles (PAs). ...

Synthesis of Esters Via a Greener Steglich Esterification in Acetonitrile

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the reaction is commonly performed using chlorinated or amide solvent systems, which are hazardous to human health and the environment. Our methodology utilizes acetonitrile as a greener and less hazardous solvent system. This protocol exhibits rates and yields that are comparable to traditional solvent systems and employs an extraction and wash sequence that eliminates the need for the purification of the ester product via column chromatography. This general method can be used to couple a variety of carboxylic acids with 1&#176; and 2&#176; aliphatic alcohols, benzylic and allylic alcohols, and phenols to obtain pure esters in high yields. The goal of the protocol detailed here is to provide a greener alternative to a common esterification reaction, which could serve useful for ester synthesis in both academic and industrial applications.

A modified Steglich esterification reaction was used to synthesize a small library of ester derivatives with primary and secondary alcohols. The methodology uses a non-halogenated and greener solvent, acetonitrile, and enables product isolation in high yields without the need for chromatographic purification.

乙腈绿色 Steglich 酯化合成酯的研究

The Steglich esterification is a widely-used reaction for the synthesis of esters from carboxylic acids and alcohols. While efficient and mild, the ...

Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltrimethoxysilane (APTMS) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTMS. The deposition of APTMS and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.

Preparation of Polypentafluorophenyl acrylate Functionalized SiO2 Beads for Protein Purification

A protocol for the preparation of poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads is presented. The poly(PFPA) functionalized surface is then immobilized with antibodies and used successfully for the protein separation through immunoprecipitation.

聚五氟丙烯酸酯 (五氟丙烯酸酯) 功能化 sio2 珠的蛋白质纯化

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent ...

Enzymatic Synthesis of Epoxidized Metabolites of Docosahexaenoic, Eicosapentaenoic, and Arachidonic Acids

The epoxidized metabolites of various polyunsaturated fatty acids (PUFAs), termed epoxy fatty acids, have a wide range of roles in human physiology. These metabolites are produced endogenously by the cytochrome P450 class of enzymes. Because of their diverse and potent biological effects, there is considerable interest in studying these metabolites. Determining the unique roles of these metabolites in the body is a difficult task, as the epoxy fatty acids must first be obtained in significant amounts and with high purity. Obtaining compounds from natural sources is often labor intensive, and soluble epoxide hydrolases (sEH) rapidly hydrolyze the metabolites. On the other hand, obtaining these metabolites via chemical reactions is very inefficient, due to the difficulty of obtaining pure regioisomers and enantiomers, low yields, and extensive (and expensive) purification. Here, we present an efficient enzymatic synthesis of 19(S),20(R)- and 16(S),17(R)-epoxydocosapentaenoic acids (EDPs) from DHA via epoxidation with BM3, a bacterial CYP450 enzyme isolated originally from Bacillus megaterium (that is readily expressed in Escherichia coli). Characterization and determination of purity is performed with nuclear magnetic resonance spectroscopy (NMR), high-performance liquid chromatography (HPLC), and mass spectrometry (MS). This procedure illustrates the benefits of enzymatic synthesis of PUFA epoxy metabolites, and is applicable to the epoxidation of other fatty acids, including arachidonic acid (AA) and eicosapentaenoic acid (EPA) to produce the analogous epoxyeicosatrienoic acids (EETs) and epoxyeicosatetraenoic acids (EEQs), respectively.

We present a method useful for large-scale enzymatic synthesis and purification of specific enantiomers and regioisomers of epoxides of arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) with the use of a bacterial cytochrome P450 enzyme (BM3).

多克沙六烯、环氧体和阿拉奇酮酸的环氧代谢物酶合成

The epoxidized metabolites of various polyunsaturated fatty acids (PUFAs), termed epoxy fatty acids, have a wide range of roles in human physiology. These ...

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Aziridines, a class of reactive organic molecules containing a three-membered ring, are important synthons for the synthesis of a large variety of functionalized nitrogen-containing target compounds through the regiocontrolled ring-opening of C-substituted aziridines. Despite the tremendous progress in aziridine synthesis over the past decade, accessing contiguous bisaziridines efficiently remains difficult. Therefore, we were interested in synthesizing contiguous bisaziridines bearing an electronically diverse set of N-substituents beyond the single aziridine backbone for regioselective ring-opening reactions with diverse nucleophiles. In this study, chiral contiguous bisaziridines were prepared by organocatalytic asymmetric aziridination of chiral (E)-3-((S)-1-((R)-1-phenylethyl)aziridin-2-yl)acrylaldehyde with N-Ts-O-tosyl or N-Boc-O-tosyl hydroxylamine as the nitrogen source in the presence of (2S)-[diphenyl(trimethylsilyloxy)methyl]pyrrolidine as a chiral organocatalyst. Also demonstrated here are representative examples of regioselective ring-opening reactions of contiguous bisaziridines with a variety of nucleophiles such as sulfur, nitrogen, carbon, and oxygen, and the application of contiguous bisaziridines to the synthesis of multi-substituted chiral pyrrolidines by Pd-catalyzed hydrogenation.

Contiguous bisaziridines containing non-activated and activated aziridines were synthesized by asymmetric organocatalytic aziridinations and then subjected to chemoselective ring-opening reactions under acidic or basic conditions. The non-activated aziridine ring opens with less reactive nucleophiles under acidic conditions, whereas the activated aziridine ring opens with more reactive nucleophiles under basic conditions.

用于区域选择性开环反应的连续双氮丙啶的制备

Aziridines, a class of reactive organic molecules containing a three-membered ring, are important synthons for the synthesis of a large variety of ...

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. Achieving a closed-loop polymer economy via chemical recycling to monomer (CRM) is one such promising route. Our group recently reported a new CRM system based on polymers prepared by ring-opening metathesis polymerization (ROMP) of trans-cyclobutane fused cyclooctene (tCBCO) monomers. This system offers several key advantages, including the ease of polymerization at ambient temperatures, quantitative depolymerization to monomers under mild conditions, and a broad range of functionalities and thermomechanical properties. Here, we outline detailed protocols for the preparation of tCBCO-based monomers and their corresponding polymers, including the preparation of elastic polymer networks and compression molding of linear thermoplastic polymers. We also outline the preparation of high ring strain E-alkene tCBCO monomers and their living polymerization. Finally, the procedures for the depolymerization of linear polymers and polymer networks are also demonstrated.

Here, we describe protocols for the preparation of trans-cyclobutane fused cyclooctenes (tCBCO),&#160;their polymerization to prepare depolymerizable olefinic polymers, and the depolymerization of these polymers under mild conditions. Additionally, protocols for the preparation of depolymerizable networks and compression molding of rigid linear plastics based on this system are described.

基于熔环环辛烯单体的可解聚烯烃聚合物

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. ...