Influence of Ligand Design and Non‐Covalent Interactions on the Isoselective Ring‐Opening Polymerization of rac ‐β‐Butyrolactone Using Salan and Salalen Rare‐Earth Metal Catalysts
Year: 2025
Type: article
Abstract: We herein report the influence of the ligand framework on the isoselective ring‐opening polymerization (ROP) of rac ‐β‐butyrolactone using highly active in situ generated salan [ONNO] H2 and salalen [ONNO] H rare‐earth metal complexes. The stereochemistry was found to be highly dependent on the ortho ‐substituents, enabling the synthesis of either isotactic poly(3‐hydroxybutyrate) (PHB) (up to P m = 0.92) or syndiotactic PHB (up to P r = 0.91). To obtain further information on the mechanism of the isoselective ROP, which exhibits an enantiomorphic site control (ESC), a new hybrid Y[ONNO] H (N(SiHMe 2 ) 2 )(THF) complex was isolated and characterized via NMR, DFT, and mass‐spectrometry experiments. The impact of non‐covalent interactions (NCIs) was demonstrated by the addition of NCI inhibitors. Kinetic studies revealed a secondary kinetic isotope effect (SKIE) of 1.14, indicating that the pre‐coordination of the monomer plays a significant role in the mechanism. These findings provide a foundation for the future design of catalysts for isoselective ROP.
Institution: Technical University of Munich
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,510
OpenAlex ID: W4409047129