Click Heterogenization of Complex Phosphines in MOFs

• Applicant: Dr. Constanze Neumann
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573646171

The optimization of the activity and selectivity of homogeneous transition-metal catalysts is often very efficient due to the availability of huge libraries of privileged ligands such as phosphines. For heterogeneous catalysts, however, unambiguous structural characterization and structural tuning of the catalytic centers is challenging and time-consuming. For catalytic processes exceeding laboratory scale and the production of products such as drugs that cannot contain transition metal residues, however, there are strong economic and sustainability incentives to employ recyclable heterogeneous catalysts. A rapid and general approach for heterogenizing highly efficient and selective molecular catalyst without changing their catalytic performance could lay the foundation for an efficient delivery pipeline of high-performance heterogeneous catalysts. But the heterogenization, confinement or immobilization of molecular catalysts commonly leads to a change in the catalytic performance compared to the soluble analogue. We propose to develop a click-heterogenization strategy of phosphine ligands in metal-organic frameworks (MOFs) that furnishes heterogeneous, recyclable ligands, which faithfully reproduce the catalytic performance of the original phosphine in catalysis. A key focus of our work will rest in ensuring that heterogenization is synthetically facile and readily applicable to a wide range of structurally distinct phosphines. Via ionic tethering of phosphines to the pore wall of the MOF, we aim to ensure that the heterogeneous ligands have a substantial degree of mobility within the pores of the MOF, but do not leach from the MOF support. To test whether click heterogenized phosphines can reproduce homogeneous catalytic results, we propose to investigate cobalt-catalyzed hydroformylation, for which a range of different coordination environments and oxidation states of cobalt would have to be effectively accommodated by the heterogenized ligand set. Industrial hydroformylation remains reliant on homogeneous catalysis, and in the case of cobalt-catalyzed processes, the recycling of the homogeneous catalyst is cumbersome and associated with the creation of copious amounts of corrosive waste, rendering catalyst heterogenization highly desirable. In addition, we propose to develop heterogenized variants of a range of state-of-the art phosphine ligands and test the heterogeneous phosphine ligands in Suzuki-Miyaura reactions. The formation of C-C bonds via Pd-mediated cross-coupling holds a privileged position for the synthesis of complex molecules in medicinal chemistry, where the need to prevent Pd residues in drug substances renders catalyst heterogenization extremely attractive.

• DFG Programme: Research Grants