Stopper Ayellet, Rosen Tomer, Venditto Vincenzo, Goldberg Israel, Kol Moshe
School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv, 69978, Israel.
Dipartimento di Chimica e Biologia, Universitàdegli Studi di Salerno, Via Giovanni Paolo II 132, 84084, Fisciano, Salerno, Italy.
Chemistry. 2017 Aug 25;23(48):11540-11548. doi: 10.1002/chem.201701007. Epub 2017 Jul 3.
Phenylene-salalens-sequential tetradentate dianionic {ONNO}-type ligands that include an ortho-phenylene group bridging between an imine and amine internal donors bound to phenol arms with a broad variety of substitution patterns are described. Zirconium and hafnium complexes of the type [{ONNO}M(O-tBu) ] were formed as single diastereomers, which, according to crystallographic structures, featured the fac(around the amine)-mer(around the imine) wrapping mode. The reactivity and stereoselectivity in rac-lactide (rac-LA) polymerizations were found to depend on the substitution pattern: complexes featuring small groups on the imine-side phenol and bulky groups on the amine-side phenol exhibited the favorable combination of high activity and high isoselectivity (P ≤0.91). Isotactic stereoblock copolymers of high molecular weights were prepared. The polymers crystallized in the stereocomplex phase according to thermal (differential scanning calorimetry) and crystallographic analysis.
描述了亚苯基-水杨醛缩邻氨基酚序列四齿双阴离子{ONNO}型配体，其包括一个邻亚苯基基团，该基团桥接在与具有多种取代模式的酚臂相连的亚胺和胺内给体之间。[{ONNO}M(O-tBu)]型的锆和铪配合物以单一非对映体形式形成，根据晶体结构，其具有面式（围绕胺）-反式（围绕亚胺）包裹模式。发现外消旋丙交酯（rac-LA）聚合反应中的反应性和立体选择性取决于取代模式：在亚胺侧酚上具有小基团且在胺侧酚上具有大基团的配合物表现出高活性和高异规选择性（P≤0.91）的良好组合。制备了高分子量的全同立构规整嵌段共聚物。根据热分析（差示扫描量热法）和晶体学分析，聚合物在立体复合相中结晶。
