Mononuclear salen-gallium complexes for iso-selective ring-opening polymerization (ROP) of rac-lactide,Dalton Transactions

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Mononuclear salen-gallium complexes for iso-selective ring-opening polymerization (ROP) of rac-lactide
Dalton Transactions ( IF 3.5 ) Pub Date : 2017-09-08 00:00:00 , DOI: 10.1039/c7dt02730c
David Specklin _{1,

2,

3,

4,

5} , Christophe Fliedel _{1,

2,

3,

4,

5} , Frédéric Hild _{1,

2,

3,

4,

5} , Samir Mameri _{1,

2,

3,

4,

5} , Lydia Karmazin _{2,

3,

4,

5,

6} , Corinne Bailly _{2,

3,

4,

5,

6} , Samuel Dagorne _{1,

2,

3,

4,

5}

Affiliation

A series of mononuclear salen-supported gallium amido/alkoxide derivatives were prepared and structurally characterized and subsequently used as initiators in rac-lactide ring-opening polymerisation (ROP). The reaction of variously substituted salen ligands (1a–1f) with 0.5 equiv. of Ga₂(NMe₂)₆ allowed the isolation of the corresponding (salen)Ga-NMe₂ chelates (2b–2d, 2f) via an amine elimination route, as poorly soluble compounds in common solvents. The (salen)Ga-OBn derivatives (3a–3e) may be readily accessed by an amine-elimination/alcoholysis sequence and the molecular structures of 3a, 3d and 3e were confirmed through X-ray crystallography diffraction analysis. The present (salen)Ga-X species may effectively mediate the iso-selective ROP of rac-LA in a controlled manner (P_m up to 0.77 using a 1/1 2f/BnOH mixture as ROP initiator), with a ROP activity greatly dependent upon steric hindrance and geometrical constraints imposed by the variously substituted salen ligands. Based on the present study, salen ligands with limited steric hindrance and a certain degree of flexibility appear best suited for iso-selective ROP by (salen)Ga chelates. The salen-gallium complex 3a is also effective for the controlled ROP of ε-caprolactone (CL) and the production of PCL-b-PLA copolymers.

中文翻译：

用于外消旋丙交酯的等选择性开环聚合（ROP）的单核salen-镓络合物

制备了一系列单核塞伦支持的镓酰胺基/烷氧基镓衍生物，并对其结构进行了表征，随后将其用作外消旋-丙交酯开环聚合（ROP）中的引发剂。各种取代的Salen配体（1a-1f）与0.5当量的反应。Ga ₂（NMe ₂）₆的分离允许通过胺消除途径分离相应的（salen）Ga-NMe ₂螯合物（2b-2d，2f），因为它们在一般溶剂中的溶解性较差。（salen）Ga-OBn衍生物（3a-3e）可以容易地通过胺消除/醇解序列获得，并且3a，3d和3e的分子结构通过X射线晶体衍射分析证实。当前的（salen）Ga-X物种可以以受控方式有效地介导rac -LA的等选择性ROP （使用1/2 2f的P _m高达0.77/ BnOH混合物作为ROP引发剂），其ROP活性很大程度上取决于各种取代的Salen配体所施加的位阻和几何约束。根据本研究，具有有限的位阻和一定程度的柔韧性的Salen配体似乎最适合（salen）Ga螯合物的等选择性ROP。塞伦-镓络合物3a对于ε-己内酯（CL）的受控ROP和PCL - b- PLA共聚物的生产也是有效的。

更新日期：2017-09-18

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