New publication in ChemSusChem online

Effective Ligand Design: Zinc Complexes with Guanidine Hydroquinoline Ligands for Fast Lactide Polymerization and Chemical Recycling

In the group of Prof. Dr. Herres-Pawlis a variety of robust and biocompatible zinc or iron guanidine complexes for the polymerization of lactide have been developed in recent years. The aim in designing these complexes is to produce catalysts that are as efficient as possible and can replace the industrially toxic tin catalyst. In this publication, it is shown that an enormous increase in activity in lactide polymerization can be achieved by the targeted modification of the ligand backbone for zinc guanidine complexes. This increased polymerization activity results from the newly developed hydroquinoline ligand backbone, which is partially saturated compared to the literature known aromatic ligand backbone. By combining the new hydroquinoline ligand with weakly coordinating triflate counterions, zinc guanidine complexes with a high Lewis acidity can thus be synthesized.

For a future sustainable circular economy, however, not only the production of bioplastics with biocompatible catalysts is important, but also the recycling of these materials. The zinc guanidine complexes presented here also show excellent capabilities in the depolymerization of polylactide to methyl lactate under mild conditions.

The findings from this study can therefore be used in the future for the targeted design of highly active zinc catalysts for polymerization and recycling processes. The full article can be viewed on the publisher's website.