Overcoming aggregation in indium salen catalysts for isoselective lactide polymerization.
Overcoming aggregation in indium salen catalysts for isoselective lactide polymerization.
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DOI：
10.1039/c5sc01584g
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发表时间：
2015-09-01
期刊：
影响因子：
8.4
通讯作者：
Mehrkhodavandi P
中科院分区：
文献类型：
--
作者：
Aluthge DC;Ahn JM;Mehrkhodavandi P
报道了一种控制外消旋丙交酯开环聚合中高活性等选择性铟催化剂聚集的方法。报道了一种控制外消旋丙交酯开环聚合中高活性等选择性铟催化剂聚集的方法。合成了一系列带salen配体[(ONNOR)InOEt]2 （R = Br, Me, admantyl, cumyl, t-Bu）的外消旋和对映双核氧化铟配合物，并对其进行了表征。利用螯合2-吡啶甲氧基官能团控制聚集，合成了单核类似物（ONNOR）InOCH2Pyr （R = Br, t-Bu, SiPh3）。金属配合物的核性用PGSE核磁共振谱证实。详细的动力学研究表明，这些双核催化剂有明确的起始期，这是它们的单核类似物所缺乏的。类似的双核和单核化合物的聚合行为是相同的，并与单核繁殖物种一致。采用直接积分法和峰反褶积法对所得聚合物的等规性进行了研究，并对两者进行了比较。
A methodology for controlling aggregation in highly active and isoselective indium catalysts for the ring opening polymerization of racemic lactide is reported. A methodology for controlling aggregation in highly active and isoselective indium catalysts for the ring opening polymerization of racemic lactide is reported. A series of racemic and enantiopure dinuclear indium ethoxide complexes bearing salen ligands [(ONNOR)InOEt]2 (R = Br, Me, admantyl, cumyl, t-Bu) were synthesized and fully characterized. Mononuclear analogues (ONNOR)InOCH2Pyr (R = Br, t-Bu, SiPh3) were synthesized by controlling aggregation with the use of chelating 2-pyridinemethoxide functionality. The nuclearity of metal complexes was confirmed using PGSE NMR spectroscopy. Detailed kinetic studies show a clear initiation period for these dinuclear catalysts, which is lacking in their mononuclear analogues. The polymerization behavior of analogous dinuclear and mononuclear compounds is identical and consistent with a mononuclear propagating species. The isotacticity of the resulting polymers was investigated using direct integration and peak deconvolution methodologies and the two were compared.
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