Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and D,L-lactide
Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and D,L-lactide
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DOI：
10.1016/j.poly.2013.11.011
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发表时间：
2014-02-17
期刊：
影响因子：
2.6
通讯作者：
Darkwa, James
中科院分区：
文献类型：
--
作者：
Appavoo, Divambal;Omondi, Bernard;Darkwa, James
3,5-二甲基吡唑(L)与[Cu(OAc)(2)]或[Zn(OAc)(2)]反应；,要么C6H5COOH 4-OH-C6H5COOH 3、5-NO2-C6H5COOH或2-Cl-C6H5COOH负担相应的金属配合物:[铜(C6H5COO) (2) (L)(2)(1),(铜(2-Cl-C6H4COO) (2) (L)(2)(2),(铜(3 5-NO2-C6H3COO) (2) (L)(2)(3),(铜(4-OH-C6H4COO) (2) (L)(2)(4),(锌(C6H5COO) (2) (L)(2)(5)(锌(2-Cl-C6H4COO) (2) (L)(2)(6)(锌(3 5-NO2-C6H3COO) (2) (L)(2)(7)(锌(4-OH-C6H4COO) (2) (L)(2)(8)。通过红外光谱、核磁共振光谱和元素分析对锌配合物进行了表征；顺磁性铜配合物仅通过红外光谱、元素分析和单晶x射线衍射进一步表征。这8种配合物在高温、无溶剂和甲苯条件下分别是开环聚合和D， l -丙交酯的良好引发剂；生产中等分子量的聚己内酯（PCL）和聚D， l -丙交酯（PLA） （Ca 4757 Da, PLA 2484 Da）和较窄的多分散性指数（PCL 1.36, PLA 1.42）。C-13（H-1）核磁共振谱表明聚乳酸的立体化学是异规的。(C) 2013 Elsevier Ltd.版权所有。
3,5-Dimethylpyrazole (L), reacts with [Cu(OAc)(2)] or [Zn(OAc)(2)]; and either C6H5COOH, 4-OH-C6H5COOH, 3,5-NO2-C6H5COOH or 2-Cl-C6H5COOH to afford the corresponding metal complexes: [Cu(C6H5COO)(2)(L)(2)] (1), [Cu(2-Cl-C6H4COO)(2)(L)(2)] (2), [Cu(3,5-NO2-C6H3COO)(2)(L)(2)] (3), [Cu(4-OH-C6H4COO)(2)(L)(2)] (4), [Zn(C6H5COO)(2)(L)(2)] (5), [Zn(2-Cl-C6H4COO)(2)(L)(2)] (6), [Zn(3,5-NO2-C6H3COO)(2)(L)(2)] (7), [Zn(4-OH-C6H4COO)(2)(L)(2)] (8). The diamagnetic zinc complexes were characterized by IR, NMR spectroscopy and elemental analysis; while the paramagnetic copper complexes were only characterized by IR spectroscopy, elemental analysis and 1 and 2 were further characterized by single crystal X-ray diffraction studies. All eight complexes are very good initiators for the ring opening polymerization (ROP) of epsilon-caprolactone and D,L-lactide at elevated temperatures, under solvent-free conditions and in toluene respectively; producing polycaprolactone (PCL) and poly(D,L-lactide) (PLA) of moderate molecular weights (Ca 4757 Da for PCL and 2484 Da for PLA) and narrow polydispersity indices (1.36 for PCL and 1.42 for PLA). The C-13(H-1) NMR spectra indicate the stereochemistry of PLA is heterotactic. (C) 2013 Elsevier Ltd. All rights reserved.