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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 (Pm 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 26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-2d2f),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3a3d3e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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