Two Are Better Than One: Bimetallic Catalysts for the Conversion of Lignin-Derived Aryl-Ethers

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Aromatic building blocks are essential for the production of pharmaceuticals, cosmetics and plastics but are mainly produced from finite fossil resources. Lignin, a complex biopolymer that is rich in aromatic rings, can serve as a renewable source for aromatic base chemicals. Significant advances towards the depolymerization of lignin now give access to a plethora of small aromatic compounds with a variety of valuable functional groups. However, current catalyst systems are unable to convert these compounds into aromatic building blocks without loss of these desirable functional groups. Hence, there is a need for the development of new catalysts that are capable of handling these oxygen-rich materials that are derived from biomass. The objective of the proposed research is to develop novel bimetallic base metal catalysts for the conversion of lignin-derived compounds into aromatic building blocks. These bimetallic catalysts will be designed to specifically target the robust aromatic C-O ether bonds that are present in lignin-derived compounds. I will synthesize new ligand frameworks that can host two low-valent base metals, which strongly bind and activate aromatics. In contrast to conventional homogeneous catalysts, the envisioned catalysts will have active sites in close proximity to each other, enabling cooperative making and breaking of chemical bonds by multiple metal centers. The tunable nature of these ligands will enable obtaining detailed understanding on how to facilitate the bottleneck oxidative addition of aryl-ethers. The development of new catalytic methodologies that allow valorization of highly oxygenated biomass-derived compounds is essential to decrease our dependence on fossil resources. This research will fundamentally advance understanding of how multiple metals can activate strong chemical bonds, which will be employed to develop catalysts that use lignin-derived compounds for the synthesis of valuable aromatic building blocks.