Rare-earth (RE) amino-bisphenolates featuring a tethered donor ligand have emerged as a privileged class of catalyst for ring-opening polymerization (ROP). In our study, we have found that removal of the coordinated tether, coupled with addition of external neutral ligands to the Rare-earth amino-bisphenolate complexes promotes accelerated ROP of beta-butyrolactone (BBL) with high stereospecificity. The new catalysts not only identify an overlooked type of complex, but also provide access to the polymers with opposite selectivity to the well-known tethered donors. Our discovery challenges the perceived requirement of tethering a neutral donor to the supporting ligand to arrive at highly active and stereoselective catalysts for ROP, and provides an entry into new catalyst design strategies. Mechanistic study of these catalyst in ROP will be shared, and the role of additional ligands will be discussed.

Tethered donor not required: Approaches to stereoselective ring-opening polymerization of (<i>rac</i>)-beta butyrolactone by rare-earth catalysts

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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Tethered donor not required: Approaches to stereoselective ring-opening polymerization of (rac)-beta butyrolactone by rare-earth catalysts