Name: controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes
Uploaded: 2017-11-21T15:00:00.000+00:00
Duration: 5 min 48 s
Description: Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

这项工作得到了弗吉尼亚理工学院和州立大学开办资金的支持。Q.F. 承认中国国家自然科学基金 (21504047)、江苏省自然科学基金 (BK20150834)、南京邮电大学科学基金 NUPTSF (NY214179) 的支持。

警告: 使用前请查阅所有相关材料安全数据表 (MSDS)。合成中使用的许多化学物质具有剧毒和致癌性。在执行反应时, 请使用所有适当的安全做法, 包括使用工程控制 (油烟罩和手套) 和个人防护用品 (安全眼镜、手套、实验室大衣、全长长裤、闭脚趾鞋、蓝光屏蔽安全护目镜)。以下程序涉及在手套箱中的标准无处理技术。所有的解决方案都是用吸管转移的。
1. 催化剂和引发剂的制备
注: 整个过程是在一个带有冷阱的手套箱中进行的。所有化学物质在进入盒子前都要经过干燥或纯化。13所有瓶子和玻璃器皿都在烤箱里烘干和加热, 然后再搬进盒子里。
<ol><li>
(bpy) 镍 (COD) 溶液的制备 注: (bpy) Ni (COD) 应在原位就地进行准备。它应存放在手套箱冷冻机 (-35 ° c), 并在一个星期内使用。所有其他催化剂和引发剂的解决方案都可以储存在1月以上的手套箱冰柜中。<ol>
<li>称 Ni (COD)2 (3.5 毫克, 12.7 µmol, 1.0 eq) 变成7毫升的闪烁瓶。</li>
		<li>称 2,2-吡啶 (5.9 毫克, 37.8 µmol) 为7毫升的闪烁小瓶。</li>
		<li>在1毫升无水四氢呋喃 (呋喃) 中溶解 2,2-吡啶。</li>
		<li>将产生的 2,2-吡啶溶液 (337 µL) 添加到含有 Ni (COD)2的小瓶中。</li>
		<li>稀释1毫升无水呋喃的混合物。</li>
		<li>瓶盖的瓶子和地方的反应混合物在室温下2小时。 注: ni (cod)2不可溶于呋喃, 而 (bpy) ni (cod) 可溶于呋喃。2小时后紫色溶液中不应有沉淀。</li>
		<li>将 (bpy) 镍 (COD) 储存在-35 ° c 的冰箱中。</li>
	</ol>
</li>
	<li>
锌 (HMDS)2溶液的制备
	<ol>
<li>添加锌 (HMDS)2 (3.3 毫克, 4 µL, 8.5 µmol) 到7毫升闪烁瓶。</li>
		<li>在1毫升无水呋喃中溶解锌 (HMDS)2 。</li>
		<li>存储锌 (HMDS)2解决方案在-35 ° c 的冰箱。</li>
	</ol>
</li>
	<li>
BnOH 溶液的制备
	<ol>
<li>添加 BnOH (4.0 毫克, 4 µL, 37.0 µmol) 到7毫升闪烁瓶。</li>
		<li>在4毫升无水呋喃中溶解 BnOH。</li>
		<li>在-35 ° c 冰箱中存储 BnOH 溶液。</li>
	</ol>
</li>
	<li>
Ir-1 溶液的制备
	<ol>
<li>关闭手套箱灯。 注意: 在聚合之前, 必须关闭手套盒灯以避免Ir-1的失活。</li>
		<li>将Ir-1 (2.9 毫克, 2.6 µmol) 添加到7毫升闪烁瓶中。</li>
		<li>在3毫升无水呋喃中溶解Ir-1 。</li>
		<li>将Ir-1解决方案存储在-35 ° c 的冰箱中。</li>
	</ol>
</li>
</ol>2. l-1 的 Photoredox 环开聚合
注: 整个过程是在一个带有冷阱的手套箱中进行的。在使用前, 所有的亚奥亚单体都是在手套箱中再结晶。13在这里, 我们给出的例子聚合在 DP=500 ([l -1]/[(bpy) 镍 (COD)]/[锌 (HMDS)2]/[BnOH]/[Ir-1] = 500/1/1/1/0.1)。聚合物在不同的 DPs 也可以通过相应的调整单体质量。
<ol><li>
聚合 l-1 溶液的制备
	<ol>
<li>将 l-1 (72.2 毫克, 375.7 µmol) 添加到7毫升闪烁瓶中。</li>
		<li>在722µL 的无水呋喃中溶解 l-1 。</li>
		<li>将 l-1解决方案中的200µL 添加到另一个 7 mL 闪烁小瓶中, 并装有搅拌棒。</li>
		<li>在7毫升的闪烁瓶中加入100µL 无水呋喃。</li>
		<li>盖上瓶子, 并将 l-1解决方案置于冷阱中。</li>
		<li>关闭手套箱灯。 注意: 在聚合之前, 必须关闭手套盒灯以避免Ir-1的失活。</li>
	</ol>
</li>
	<li>
冷却冷阱
	<ol>
<li>在盒子里, 把温度计放进冰冷的陷阱里。</li>
		<li>在盒子外面, 将约500毫升的乙醇加入杜瓦瓶。</li>
		<li>在杜瓦瓶中加入液氮。</li>
		<li>将团体杜瓦瓶装入冷阱。</li>
		<li>将冷阱冷却到-50 ° c。</li>
		<li>在冷阱下放置一个搅拌板 (参见图 1)。</li>
	</ol>
</li>
	<li>
进行 photoredox 环开聚合 注: 在开始聚合前, 放置安全护目镜, 阻挡蓝光。所有的催化剂系统解决方案立即从冷冻库中取出, 并先后添加到7毫升闪烁瓶包含20毫克的 l-1没有暂停或中断三十年代。<ol>
<li>添加 (bpy) Ni (COD) 溶液 (16.4 µL, 0.208 µmol) 到包含 l-1的 7 mL 闪烁小瓶中 (在2.1 中准备)。</li>
		<li>将锌 (HMDS)2溶液 (24.4 µL、0.208 µmol) 添加到小瓶中。</li>
		<li>将 BnOH 溶液 (22.5 µL, 0.208 µmol) 加入瓶中。</li>
		<li>将 Ir-1 溶液 (24.2 µL, 0.0208 µmol) 放入小瓶中, 然后盖上瓶子。</li>
		<li>戴安全护目镜阻挡蓝色 LED 灯。 注意: 当使用相对高强度的蓝色 LED 灯时, 在整个过程中佩戴安全护目镜。</li>
		<li>打开蓝色 led 灯 (34 W) 和风扇, 以驱散由 led 灯产生的热量。在寒冷的陷阱里把光引向瓶子。(图 1)</li>
		<li>打开搅拌器。</li>
		<li>用铝箔盖住冷阱。</li>
		<li>将反应温度保持在-15 ±5° c, 每15-20 分钟加液氮。 注: 反应温度的维持是聚合和兆瓦控制的重要因素。</li>
	</ol>
</li>
</ol>3. 用傅里叶变换红外光谱监测单体转换
注: 傅立叶变换红外光谱 (FTIR) 记录在红外光谱仪上, 装有金刚石 ATR 和透射采样附件。
<ol><li>在特定时间点, 添加一个小分聚合物溶液 (20 µL) 成一个7毫升的闪烁瓶, 并加盖。</li>
	<li>从手套箱里取出瓶子。</li>
	<li>立即将溶液 (3 µL) 放到 FTIR-ATR 金刚石取样器上。解答在十年代之内形成影片为光谱测量。</li>
	<li>测量样品的 FTIR 光谱。 注: 单体转换是由1760厘米-1和 1805s cm-1的强度比决定的: conversion% = I1760/(I1760 + i1805) (代表结果在图 2)。一般情况下, 从200到1000的 DP 范围, 聚合大约需要 1-8 h (详细的动力学在参考13中讨论)。</li>
</ol>4. 凝胶-渗透色谱法测定聚合物分子量
注: 凝胶渗透色谱 (GPC) 实验是在装有气、多激光光散射 (加工) 探测器 (GaAs 30 mW 激光 at λ = 690 nm) 和差分折射率 (直接还原铁) 探测器的系统上进行的。有 690 nm 的光源使用串行连接的大小排除列 (100 Å、500Å、103 Å和 104 Å列、5µm、300 x 4.6 mm) 在35° c 使用呋喃作为流动相, 以0.35 毫升/分钟的流速执行分色。聚合物分子量 (兆瓦) 和分子量分布 (-) 是用 Zimm 模型拟合的加工-直接还原铁数据确定的.聚合物中金属络合物的存在并不影响 GPC 的测量结果。
<ol><li>从手套箱中取出一小分聚合物溶液 (50 µL)。</li>
	<li>将100µL 的呋喃加入瓶中。</li>
	<li>将样品注入 GPC 取样器。</li>
	<li>在 GPC 运行完成后分析结果。 注: 聚合物应分散与狭窄的Đ (代表结果在图 3)。该聚合物 (20 毫克) 可由1毫升乙醚 (含1% 霍阿克和1毫升甲醇) 进行干燥和洗涤, 可去除87% 的镍和50% 的锌配合物, 由电感耦合等离子体质谱 (ICP) 测定。</li>
</ol>

<ol>
	<li>Rezwan, K., Chen, Q. Z., Blaker, J. J., Boccaccini, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+and+bioactive+porous+polymer/inorganic+composite+scaffolds+for+bone+tissue+engineering.">Biodegradable and bioactive porous polymer/inorganic composite scaffolds for bone tissue engineering.</a> Biomaterials. 27, 3413-3431 (2006).</li><li>Kataoka, K., Harada, A., Nagasaki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Block+copolymer+micelles+for+drug+delivery:+design,+characterization+and+biological+significance.">Block copolymer micelles for drug delivery: design, characterization and biological significance.</a> Adv. Drug Deliv. Rev. 47, 113-131 (2001).</li><li>Nagahata, R., Sano, D., Suzuki, H., Takeuchi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microwave-assisted+single-step+synthesis+of+poly+(lactic+acid)+by+direct+polycondensation+of+lactic+acid.">Microwave-assisted single-step synthesis of poly (lactic acid) by direct polycondensation of lactic acid.</a> Macromol. Rapid Commun. 28, 437-442 (2007).</li><li>Albertsson, A. -. C., Varma, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+in+ring+opening+polymerization+of+lactones+for+biomedical+applications.">Recent developments in ring opening polymerization of lactones for biomedical applications.</a> Biomacromolecules. 4, 1466-1486 (2003).</li><li>Vert, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aliphatic+polyesters:+great+degradable+polymers+that+cannot+do+everything.">Aliphatic polyesters: great degradable polymers that cannot do everything.</a> Biomacromolecules. 6, 538-546 (2005).</li><li>Thillayedu Boullay, O., Marchal, E., Martin-Vaca, B., Coss&#237;o, F. P., Bourissou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+activated+equivalent+of+lactide+toward+organocatalytic+ring-opening+polymerization.">An activated equivalent of lactide toward organocatalytic ring-opening polymerization.</a> J. Am. Chem. Soc. 128, 16442-16443 (2006).</li><li>Thillayedu Boullay, O., Bonduelle, C., Martin-Vaca, B., Bourissou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalized+polyesters+from+organocatalyzed+ROP+of+gluOCA,+the+O-carboxyanhydride+derived+from+glutamic+acid.">Functionalized polyesters from organocatalyzed ROP of gluOCA, the O-carboxyanhydride derived from glutamic acid.</a> Chem. Commun. , 1786-1788 (2008).</li><li>Pounder, R. J., Fox, D. J., Barker, I. A., Bennison, M. J., Dove, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ring-opening+polymerization+of+an+O-carboxyanhydride+monomer+derived+from+L-malic+acid.">Ring-opening polymerization of an O-carboxyanhydride monomer derived from L-malic acid.</a> Polym. Chem. 2, 2204-2212 (2011).</li><li>Zhang, Z., 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=Facile+functionalization+of+polyesters+through+thiol-yne+chemistry+for+the+design+of+degradable,+cell-penetrating+and+gene+delivery+dual-functional+agents.">Facile functionalization of polyesters through thiol-yne chemistry for the design of degradable, cell-penetrating and gene delivery dual-functional agents.</a> Biomacromolecules. 13, 3456-3462 (2012).</li><li>Lu, Y., 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=Synthesis+of+water-soluble+poly(&#945;-hydroxy+acids)+from+living+ring-opening+polymerization+of+O-benzyl-l-serine+carboxyanhydrides.">Synthesis of water-soluble poly(&#945;-hydroxy acids) from living ring-opening polymerization of O-benzyl-l-serine carboxyanhydrides.</a> ACS Macro Lett. 1, 441-444 (2012).</li><li>Chen, X., 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+bio-renewable+polyester+with+rich+side+amino+groups+from+L-lysine+via+controlled+ring-opening+polymerization.">New bio-renewable polyester with rich side amino groups from L-lysine via controlled ring-opening polymerization.</a> Polym. Chem. 5, 6495-6502 (2014).</li><li>Wang, R., 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=Controlled+ring-opening+polymerization+of+O-carboxyanhydrides+Using+a+&#946;-Diiminate+Zinc+Catalyst.">Controlled ring-opening polymerization of O-carboxyanhydrides Using a &#946;-Diiminate Zinc Catalyst.</a> Angew. Chem. Int. Ed. , 13010-13014 (2016).</li><li>Feng, Q., Tong, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+photoredox+ring-opening+polymerization+of+O-carboxyanhydrides.">Controlled photoredox ring-opening polymerization of O-carboxyanhydrides.</a> J. Am. Chem. Soc. 139, 6177-6182 (2017).</li><li>Martin Vaca, B., Bourissou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=O-Carboxyanhydrides:+useful+tools+for+the+preparation+of+Well-defined+functionalized+polyesters.">O-Carboxyanhydrides: useful tools for the preparation of Well-defined functionalized polyesters.</a> ACS Macro Lett. 4, 792-798 (2015).</li><li>Yin, Q., Yin, L., Wang, H., Cheng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+biomedical+applications+of+functional+poly(alpha-hydroxy+acids)+via+ring-opening+polymerization+of+O-carboxyanhydrides.">Synthesis and biomedical applications of functional poly(alpha-hydroxy acids) via ring-opening polymerization of O-carboxyanhydrides.</a> Acc. Chem. Res. 48, 1777-1787 (2015).</li><li>Xia, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-heterocyclic+carbenes+as+organocatalysts+in+controlled/living+ring-opening+polymerization+of+O-carboxyanhydrides+derived+from+l-lactic+acid+and+l-mandelic+acid.">N-heterocyclic carbenes as organocatalysts in controlled/living ring-opening polymerization of O-carboxyanhydrides derived from l-lactic acid and l-mandelic acid.</a> J. Polym. Sci., Part A: Polym. Chem. 52, 2306-2315 (2014).</li><li>Buchard, 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=Preparation+of+stereoregular+isotactic+poly(mandelic+acid)+through+organocatalytic+ring-opening+polymerization+of+a+cyclic+O-carboxyanhydride.">Preparation of stereoregular isotactic poly(mandelic acid) through organocatalytic ring-opening polymerization of a cyclic O-carboxyanhydride.</a> Angew. Chem. Int. Ed. 53, 13858-13861 (2014).</li><li>Zhuang, X. -. l., 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=Polymerization+of+lactic+O-carboxylic+anhydride+using+organometallic+catalysts.">Polymerization of lactic O-carboxylic anhydride using organometallic catalysts.</a> Chin. J. Polym. Sci. 29, 197-202 (2010).</li><li>He, Z., Jiang, L., Chuan, Y., Li, H., Yuan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ring-opening+polymerization+of+L-lactic+acid+O-carboxyanhydrides+initiated+by+alkoxy+rare+earth+compounds.">Ring-opening polymerization of L-lactic acid O-carboxyanhydrides initiated by alkoxy rare earth compounds.</a> Molecules. 18, 12768-12776 (2013).</li><li>Jia, F., 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=One-pot+atom-efficient+synthesis+of+bio-renewable+polyesters+and+cyclic+carbonates+through+tandem+catalysis.">One-pot atom-efficient synthesis of bio-renewable polyesters and cyclic carbonates through tandem catalysis.</a> Chem. Commun. 51, 8504-8507 (2015).</li><li>Tong, R., Cheng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug-initiated,+controlled+ring-opening+polymerization+for+the+synthesis+of+polymer-drug+conjugates.">Drug-initiated, controlled ring-opening polymerization for the synthesis of polymer-drug conjugates.</a> Macromolecules. 45, 2225-2232 (2012).</li><li>Bonduelle, C., Martin-Vaca, B., Bourissou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipase-catalyzed+ring-opening+polymerization+of+the+O-carboxylic+anhydride+derived+from+lactic+acid.">Lipase-catalyzed ring-opening polymerization of the O-carboxylic anhydride derived from lactic acid.</a> Biomacromolecules. 10, 3069-3073 (2009).</li><li>Yamamoto, T., Igarashi, K., Komiya, S., Yamamoto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+properties+of+phosphine+complexes+of+nickel-containing+cyclic+amides+and+esters+[(PR3)nNiCH2CH(R1)COZ+(Z+=+NR2,+O)].">Preparation and properties of phosphine complexes of nickel-containing cyclic amides and esters [(PR3)nNiCH2CH(R1)COZ (Z = NR2, O)].</a> J. Am. Chem. Soc. 102, 7448-7456 (1980).</li><li>Deming, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amino+acid+derived+nickelacycles:+intermediates+in+nickel-mediated+polypeptide+synthesis.">Amino acid derived nickelacycles: intermediates in nickel-mediated polypeptide synthesis.</a> J. Am. Chem. Soc. 120, 4240-4241 (1998).</li><li>Lee, D. -. Y., Hartwig, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zinc+trimethylsilylamide+as+a+mild+ammonia+equivalent+and+base+for+the+amination+of+aryl+halides+and+triflates.">Zinc trimethylsilylamide as a mild ammonia equivalent and base for the amination of aryl halides and triflates.</a> Org. Lett. 7, 1169-1172 (2005).</li><li>Yin, Q., 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=Drug-initiated+ring-opening+polymerization+of+O-carboxyanhydrides+for+the+preparation+of+anticancer+drug-poly(O-carboxyanhydride)+nanoconjugates.">Drug-initiated ring-opening polymerization of O-carboxyanhydrides for the preparation of anticancer drug-poly(O-carboxyanhydride) nanoconjugates.</a> Biomacromolecules. 14, 920-929 (2013).</li></ol>

作者声明没有竞争的金融利益。本论文提出了一项临时专利 (美国专利申请号:62/414016)。

协议中的关键步骤是保持反应温度在-15 ±5° c。在聚合之前, 所有的催化剂溶液和亚奥基单体都必须在-35 ° c 的手套箱冷冻库中储存。在寒冷的陷阱中, 反应瓶必须预。在反应过程中, 由于 LED 灯散热, 必须每 15-20 分钟监测反应。一旦温度上升到-10 ° c, 液态氮应加入到杜瓦瓶冷却陷阱。低温的原因是室温下镍 (CO) 络合物的形成, 这对受控的 photoredox 聚合是不利的, 并影响到兆瓦和Đ。<sup class="xr...

聚 (α-羟基酸) (PAHA) 是一类重要的生物降解和生物相容性高分子材料, 其应用范围广泛, 从医用设备到包装原料。1,2虽然 PAHAs 可以通过α-羟基酸的缩聚直接制备, 但产生的 PAHAs 的分子量 (MWs) 普遍较低。3酯 (如丙交酯和乙) 的开环聚合 (ROP) 是一种替代合成方法, 可以更好地控制 MWs 和分子量分布 (Đ), 而不是缩聚。然而, PAHAs 和酯的侧链功能的缺乏限制了物理和化学性质及其应用的多样性。4,5自2006年以来, 13--1,3--24-diones, so-called O-carboxyanhydrides (oca), 可以用丰富多样的侧链功能编写,6,7,8,9,10,11,12,13已成为聚酯聚合中一种高活性单体的替代类。14,15
oca 的催化系统可分为有机、8、12、16、17有机金属催化剂12、18、19 ,20,21和催化剂。22一般情况下, 由有机促进的 oca 的 ROP 以或多或少不受控制的方式进行, 例如异构化 (即缺少 stereoregularity), 用于 oca 轴承电子提取组,8,17不可预知的 MWs, 或慢聚合动力学。13为了解决这些问题, 研制了一种活性锌-醇络合物, 用于 oca 的 ROP。12井控保护在低聚合 (DP) 的情况下, 没有异构化。然而, 这种锌-醇催化剂不能有效地产生高聚合度的聚合物 (DP ≥ 300)。13
我们最近报告了一种有希望的方法, 大大提高了 PAHA 合成的可和效率 (图 1)。13将 photoredox 镍/Ir 催化剂与锌醇脱, 以调节环开聚合 oca。低温 (-15 ° c) 和 photoredox 镍/Ir 催化的使用, 协同加速了脱链的传播, 同时避免了不受欢迎的副反应, 如镍羰基的形成。23,24在转移与 Ni 复合体的活性锌-醇位于链终点链传播。13
在本协议中, 我们添加新鲜准备 (bpy) Ni (COD) (bpy = 22 '-吡啶, COD = 15-1,5-), Zn (HMDS)2 (HMDS = 烷),25苄醇 (BnOH) 和 Ir [dF (CF3) 吡]2(dtbbpy) PF6 (Ir-1, dF (CF3) 吡 = 2-(24-氟)-5-三氟甲基吡啶, dtbbpy = 44 "-di-叔-butyl-2,2'-bipyridine) 到单体 l-1解决方案26在一个带有冷陷阱的手套箱中, 在一个蓝色 LED 灯 (400-500 nm) 和风扇以保持温度 (图 1)。在聚合过程中, 温度保持在-15 ° c ±5° c。采用傅里叶变换红外光谱法对亚奥氏转化率进行了监测。由此产生的聚合物 MWs 和Đs 的特点是凝胶渗透色谱 (GPC)。homodecoupling 的1H 核磁共振研究确定所得到的聚合物是否是规的。由于大多数化学品对湿气高度敏感, 详细的视频协议旨在帮助新的从业者避免与 oca photoredox ROP 相关的陷阱。

<table><tbody><tr><td>Ni(COD)&lt;sub&gt;2&lt;/sub&gt;</td><td>Strem</td><td>28-0010</td><td>Stored in the glove box freezer.</td></tr><tr><td>2,2&amp;prime;-bipyridine</td><td>Strem</td><td>07-0290</td><td>Stored in the glove box freezer.</td></tr><tr><td>Zn(HMDS)&lt;sub&gt;2&lt;/sub&gt;</td><td>N/A</td><td>N/A</td><td>Synthesized following reported procedures.&lt;sup class=&quot;xref&quot;&gt;25&lt;/sup&gt; Stored in the glove box freezer.</td></tr><tr><td>Benzyl alcohol</td><td>Sigma-Aldrich</td><td>402834</td><td>Stored with 4&amp;Aring; molecular sieve</td></tr><tr><td>Ir[dF(CF&lt;sub&gt;3&lt;/sub&gt;)ppy]&lt;sub&gt;2&lt;/sub&gt;(dtbbpy)PF&lt;sub&gt;6&lt;/sub&gt;</td><td>Strem</td><td>77-0425</td><td>Stored in the glove box freezer.</td></tr><tr><td>THF</td><td>Sigma-Aldrich</td><td>34865</td><td>Dried by alumina columns and stored with 4&amp;Aring; molecular sieve in the dark bottle in the glove box.</td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>793175</td><td></td></tr><tr><td>GPC with an isocratic pump</td><td>Agilent</td><td>Agilent 1260 series</td><td></td></tr><tr><td>Dawn Heleos II Light Scatterer</td><td>Wyatt</td><td></td><td></td></tr><tr><td>Optilab rEX differential refractive index detector</td><td>Wyatt</td><td></td><td></td></tr><tr><td>Size exclusion columns</td><td>Phenomenex</td><td></td><td></td></tr><tr><td>Glass Scintillation Vials - 7 ml</td><td>VWR</td><td></td><td></td></tr><tr><td>FTIR spectrometer</td><td>Agilent</td><td></td><td></td></tr><tr><td>Stir bars</td><td>VWR</td><td>58948-091</td><td></td></tr><tr><td>Balance</td><td></td><td></td><td></td></tr><tr><td>Glove box</td><td>Mbraun</td><td>Labstar Pro</td><td></td></tr></tbody></table>

controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes

在这里, 我们描述一个有效的协议, 结合 photoredox 镍/Ir 催化与使用锌醇的有效开环聚合, 允许合成的规聚 (α-羟基酸) 与预期的分子量 (> 140kDa) 和窄分子量分布 (Mw/mn < 1.1)。这种环开聚合由 Ni 和锌配合物在乙醇引发剂和 photoredox 红外催化剂的存在下进行介导, 由蓝色 LED (400-500 nm) 照射。在低温 (-15 ° c) 下进行聚合以避免不受欢迎的副反应。完整的单体消耗可以在 4-8 小时内完成, 为聚合物提供接近分子量的分子量分布。结果数字平均分子量显示一个线性相关与聚合程度1000。homodecoupling 的1H 核磁共振研究证实, 所获得的聚合物是规没有异构化。本文所报告的聚合提供了一种实现快速、受控的O-carboxyanhydrides 聚合的策略, 以制备 stereoregular 聚 (α-羟基酸) 及其承载各种功能侧链基团的共聚物。

通过傅里叶变换红外光谱对亚奥的转换进行监测, 如图 2所示。在 1805 cm-1的峰值被分配为在亚奥理事会中的酸酐粘结拉伸;峰值在 1760 cm-1对应于聚合物中酯键的形成。一旦单体的峰值在1805厘米-1完全消失, 聚合完成。
所产生的聚合物的兆瓦和Đ以凝胶渗透色谱为特征。<strong c...

Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

介绍了由 Ni/锌配合物介导的受控 photoredox 环开放聚合的O-carboxyanhydrides 的协议。

镍/锌配合物介导的O-Carboxyanhydrides 的控制 Photoredox 环开聚合

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

controlled-photoredox-ring-opening-polymerization-o-carboxyanhydrides

Research

JoVE Journal

Chemistry

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

8.0K 次观看.  Nanjing University of Posts and Telecommunications. 介绍了由 Ni/锌配合物介导的受控 photoredox 环开放聚合的O-carboxyanhydrides 的协议。

视频: Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

乙烯聚合中使用并联电抗器的压力和链转移聚合的动力学分析

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

科研

化学

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

使用苝作为可见光光催化功能化的乙烯基单体原子转移自由基聚合

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

[4.4] 刺环氧基的固相合成

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes and determine the corresponding photochemical mechanism. Then, we describe a protocol to perform ring-opening metathesis polymerization (ROMP) in solution and in miniemulsion using this NHC-photogenerating system. To photogenerate IMes, a system comprising 2-isopropylthioxanthone (ITX) as the sensitizer and 1,3-dimesitylimidazolium tetraphenylborate (IMesH+BPh4-) as the protected form of NHC is employed. IMesH+BPh4- can be obtained in a single step by anion exchange between 1,3-dimesitylimidazolium chloride and sodium tetraphenylborate. A real-time steady-state photolysis setup is described, which hints that the photochemical reaction proceeds in two consecutive steps: 1) ITX triplet is photo-reduced by the borate anion and 2) subsequent proton transfer takes place from the imidazolium cation to produce the expected NHC IMes. Two separate characterization protocols are implemented. Firstly, CS2 is added to the reaction media to evidence the photogeneration of NHC through formation of the IMes-CS2 adduct. Secondly, the amount of NHC released in situ is quantified using acid-base titration. The use of this NHC photo-generating system for the ROMP of norbornene is also discussed. In solution, a photopolymerization experiment is conducted by mixing ITX, IMesH+BPh4-, [RuCl2(p-cymene)]2 and norbornene in CH2Cl2, then irradiating the solution in a UV reactor. In a dispersed medium, a monomer miniemulsion is first formed then irradiated inside an annular reactor to produce a stable poly(norbornene) latex.

We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.

n-杂环卡本的光生成在光致环开环转移聚合中的应用

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes ...

[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Our group recently reported the use of [(DPEPhos)(bcp)Cu]PF6 as a general copper-based photoredox catalyst which proved efficient to promote the activation of a broad variety of organic halides, including unactivated ones. These can then participate in various radical transformations such as reduction and cyclization reactions, as well as in the direct arylation of several (hetero)arenes. These transformations provide a straightforward access to a range of small molecules of interest in synthetic chemistry, as well as to biologically active natural products. Altogether, [(DPEPhos)(bcp)Cu]PF6 acts as a convenient photoredox catalyst which appears to be an attractive, cheap and complementary alternative to the state-of-the-art iridium- and ruthenium-based photoredox catalysts. Here, we report a detailed protocol for the synthesis of [(DPEPhos)(bcp)Cu]PF6, as well as NMR and spectroscopic characterizations, and we illustrate its use in synthetic chemistry for the direct arylation of (hetero)arenes and radical cyclization of organic halides. In particular, the direct arylation of N-methylpyrrole with 4-iodobenzonitrile to afford&#160;4-(1-methyl-1H-pyrrol-2-yl)benzonitrile and the radical cyclization of N-benzoyl-N-[(2-iodoquinolin-3-yl)methyl]cyanamide to afford natural product luotonin A are detailed. The scope and limitations of this copper-based photoredox catalyst are also briefly discussed.

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Detailed and general protocols are presented for the synthesis of [(DPEPhos)(bcp)Cu]PF6, a general copper-based photoredox catalyst, and for its use in synthetic chemistry for the direct arylation of C-H bonds in (hetero)arenes and radical cyclization of organic halides.

[(Dpepphos) (bcp) Cu]PF6: 一种通用的、广泛适用的铜基光氧催化剂

Our group recently reported the use of [(DPEPhos)(bcp)Cu]PF6 as a general copper-based photoredox catalyst which proved efficient to promote the ...

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. Traditionally, they were synthesized through thermal cycloaddition reactions, whereas today, photocatalysis is preferred due to the mild and efficient conditions. With this focus, a new photocatalytic method for the synthesis of nitrogen-containing heterocycles is highly desired. Here, we report a protocol for the biosynthesis of cercosporin, which could function as a metal-free photocatalyst. We then illustrate cercosporin-photocatalyzed protocols for the synthesis of nitrogen-containing heterocycles 1,2,3-thiadiazoles through annulation of azoalkenes with KSCN, and synthesis of 1,4,5,6-tetrahydropyridazines [4+2] through cyclodimerization of azoalkenes under mild conditions, respectively. As a result, there is a new bridge between the microbial fermentation method and organic synthesis in a mild, cost-effective, environmentally friendly and sustainable manner.

New routes for the synthesis of nitrogen-containing heterocycles utilizing cercosporin as a metal-free photocatalyst were developed.

神经素-光催化 [4]1]- 和 [4]2]- 在轻度条件下对阿佐尔克内斯的无效

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. ...

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. ...

Photochemical Initiation Of Radical Polymerization Reactions

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will carry out the photochemically initiated polymerization of styrene to generate polystyrene, which is an important commodity plastic. We will learn the fundamentals of photochemistry and use simple photochemistry to initiate radical polymerization reactions. Specifically, in this module we will examine the photochemistry of benzoyl peroxide and its role as a photo-initiator of styrene polymerization reactions. In the described experiments, we will investigate the role of wavelength, photon absorption, and excited state structure on the efficiency (measured as quantum yield) of photochemical reactions.

自由基聚合反应的光化学引发

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will carry out the photochemically initiated polymerization of styrene to ...

教育

JoVE Science Education

无机化学

Acid-Catalyzed Ring-Opening of Epoxides

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The reaction follows the SN2 mechanism, and the protonated oxygen, unlike other leaving groups, does not detach from the molecule. The regiochemistry of the products formed is governed by either steric or electronic effects. In the case of an asymmetrical epoxide bearing a primary and a secondary carbon, the steric effect dominates and favors the nucleophilic attack at a less-hindered carbon. However, in epoxides where one of the carbons is tertiary, the electronic effect comes into play and favors the attack at a more-hindered carbon. The stereochemistry of the products is similar to an SN2 reaction, where the nucleophile attacks anti to the leaving group. Notably, the anti-attack at a chiral carbon causes an inversion of configuration.

环氧化物的酸催化开环

Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the ...

JoVE Core

有机化学

Unit 1

醚类、环氧化物、硫化物

关键术语与概念

Base-Catalyzed Ring-Opening of Epoxides

Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile or a base. A variety of nucleophiles like sodium hydroxide, sodium alkoxide, sodium hydrosulfide, sodium cyanide, lithium aluminum hydride, and Grignard reagent can open the epoxide ring. The nucleophilic attack on the epoxide ring proceeds via an SN2 mechanism and involves an alkoxide intermediate. The product formed in base-catalyzed reactions shows SN2-like stereoselectivity and regioselectivity. The nucleophile attacks at the less-hindered carbon and anti to the leaving group, leading to the inversion of configuration at a chiral center. In contrast to epoxides, acyclic ethers do not undergo direct nucleophilic substitutions, as the reaction is thermodynamically unfavorable.

环氧化物的碱催化开环

Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of ...