Synthesis and Characterization of Self-Supported Coordination Polymer Catalysts.

点击翻译按钮获取中文摘要

Self-supported layered dirhodium coordination polymers exhibit an excellent catalytic performance, which strongly exceeds the performance of its immobilized counterparts. In the present proposal, we want to exploit this result and study, whether such a better performance is a general property of these coordination polymer catalysts. Accordingly, our objectives are the development of novel dirhodium coordination polymers, the evaluation of their catalytic performance in carbene transfer reactions, and their characterization by solid-state NMR (if necessary combined with DNP enhancement), SEM, TEM and AFM, and a correlation between catalytic efficiency and enantioselectivity of the catalyst, and structural and dynamic properties of the catalyst. In particular we will employ 13C CP MAS and 19F MAS NMR to characterize the structure of the bulk materials, DNP enhanced 19F-solid state NMR spectroscopy to study the number and structure of defect sites and variable temperature 2H solid state NMR (static and MAS line-shape analysis) to investigate the dynamic behavior of bridging linkers in the coordination polymers. For the synthesis of bulk dirhodium coordination polymers, ditopic ligands with different sizes and functionality will be employed. By adjusting the layer distance via ligand size, various bulk dirhodium coordination polymers are prepared via ligand exchange. The resulting coordination polymers will be evaluated with respect to their catalytic efficacy and selectivity, employing the cyclopropanation between styrene and ethyl diazoacetate as model reaction to establish the relationship between the structure of the catalyst and its catalytic efficiency. In the next step, dirhodium coordination polymers containing chiral dicarboxylic ligands will be synthesized and their catalytic efficiency and enantioselectivity in C-H insertion reactions will be evaluated. Finally, the catalytic properties of nano-flakes prepared by exfoliation from the layered bulk-coordination polymers will be investigated.