Control of Stereoselectivity in Heterogeneous Catalysis by Functionalization of Pt Nanoparticles with Proline and Proline-derivatives

• Applicant: Professor Dr. Marcus Bäumer, since 9/2018
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 289757887

Chiral compounds in their enantiomeric pure form are of great importance e.g. as pharmaceutical ingredients. The demand for enantiomeric pure substances is continuously growing and as a result the need for sustainable preparation routes. Due to its ability to address this issue asymmetric catalysis is one of the most important research fields in chemistry and of great ecologic and economic relevance. It is a well-established topic in bio and metal-organic catalysis research. However, besides some few approaches asymmetric catalysis still remains a fundamental challenge for heterogeneous catalysis that requires new conceptional ideas and knowledge from basic research. Recently, the applicant demonstrated a proof of concept for a novel approach within the field of asymmetric, heterogeneous catalysis. Colloidal nanoparticles Pt were functionalized with hydrophilic ligands by coordinative or covalent binding, then supported and applied as heterogeneous catalysts. The potential of this concept was demonstrated and stereoselectivties were obtained already in the first investigations. So far, only little is known about what determines the catalytic properties of these materials. This is however prerequisite for developing novel stereoselective, active and stable catalysts based on ligand-functionalized nanoparticles. Recently, we were able to show that by functionalizing Pt nanoparticles with amine ligands the activity can be enhanced beyond the limit of ligand-free particles. Furthermore, the use of proline as ligands enabled us for achieving an enantiomeric excess of 34 % for the hydrogenation of a beta-ketoester (ethylacetoacetate). Based on these promising results the aim of the proposed project is to study the hydrogenation of beta-ketoesters over Pt nanoparticles functionalized with proline and proline derivatives. In order to tackle this challenge in a systematic manner we established a synthesis strategy that enables for the independent control of all catalytically relevant material properties (particle, ligand, and support). The influence of each of these as well as the reaction parameters on the stereoselectivity, activity, and stability shall now be investigated systematically. As ligand-functionalized nanoparticles exhibit characteristics of homogeneous metalorganic (ligand) as well as heterogeneous catalysts (particle, support) the guidelines for the studies are based on established knowledge of both fields. Thereby not merely the influence of the material characteristics on the catalytic properties will be investigated but furthermore to what extend concepts of the two catalysis areas are applicable to support ligand-functionalized nanoparticles.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Sebastian Kunz, until 8/2018