Anwendung neuartiger Metalsiloxid-Katalysatoren für die ringöffnende Polymerisation zyklischer Monomeren zu bioabbaubaren und biokompatiblen Polymeren

本项目的目标是合成和利用新型金属化合物作为催化剂，从容易获得的，廉价的可再生资源中生产可生物降解和生物相容性聚合物。具有医疗应用潜力的高性能材料（多氧酸盐、聚酰胺）将通过环状单体如丙交酯、环氧化物和吗啉的金属辅助开环聚合来制备。在这方面，将设计、合成和研究通式[（R3 SiO）-M]-OR的新型催化剂，其将无毒的硅烷醇配体与廉价且生物相容的金属如Zn、Mg、Ca（或毒性较小的Y、La、Al）组合。尽管这些化合物中的烷氧基（OR）是开环的引发剂，但吸电子硅氧配体（R3 SiO）显著增加了金属的亲电性。我们认为，与相关系统相比，这将导致增强的活动和选择性。为了获得足够稳定性的活性金属锂化物，将通过用氯硅烷（R2 SiCl 2）处理供体官能化的有机锂试剂并随后水解来制备具有可与催化活性金属中心配位的侧供体基团的新型空间位阻的硅烷醇。最后，将通过用反应性金属酰胺或醇盐处理所获得的硅烷醇来合成催化剂。

The objective of this project is to synthesize and utilize novel metal siloxides as catalysts for the production of biodegradable and biocompatible polymers from readily available, inexpensive renewable resources. Materials of high performance having a potential for medical application (polyoxogenates, polyamides) will be made by metal assisted ring opening polymerization of cyclic monomers such as lactides, epoxides and morpholines. In this regard, novel catalysts of the general formula [(R3SiO)"M]-OR, which combine non-toxic silanol ligands with inexpensive and biological compatible metals such as Zn, Mg, Ca (or less toxic Y, La, Al) will be designed, synthesized and studied. Whereas the alkoxide group (OR) in these compounds is an initiator for the ring opening, the electron withdrawing siloxide ligand (R3SiO) significantly increases the electrophilicity of the metal. We believe this should result in enhanced activities and selectivities in comparison to related systems. To obtain active metal siloxides of sufficient stability, novel sterically encumbered silanols with pendant donor groups that can coordinate to the catalytically active metal center will be prepared by treatment of donor functionalized organolithium reagents with chlorosilanes (R2SiC12) and subsequent hydrolysis. Finally, the catalysts will be synthesized by treatment of the obtained silanols with reactive metal amides or alkoxides.