Invoking Side-Chain Functionality for the Mediation of Regioselectivity during Ring-Opening Polymerization of Glucose Carbonates
- 23 September 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 142 (40), 16974-16981
- https://doi.org/10.1021/jacs.0c05610
Abstract
The extent of participation of side-chain functionalities during the 1,5,7-triazabicyclo[5.4.0]dec-5-ene (TBD) organobase-catalyzed ring-opening polymerizations (ROP) of six-membered cyclic d-glucose-based carbonates was found to result in significantly different regiochemical outcomes. High regioselectivity was observed for naturally derived poly(4,6-d-glucose carbonate)s (PGCs) containing carbonate side chain substituents in the 2- and 3-positions, whereas regioirregularity was found for analogous PGCs with ether side-chain substituents. The backbone connectivities and structural details of these PGCs were examined through a combination of comprehensive 1D and 2D NMR studies on unimers and dimers, verifying the ring-opening preferences and indicating the contribution of side-chain functionalities in regioselective ROP processes. A molecular understanding of the curious role of side-chain functionalities was demonstrated via density functional theory calculations, revealing stabilization effects of intermolecular hydrogen bonding between the side-chain functionalities and TBD in the transition states. Overall, this work provides fundamental insights into the organocatalytic ROP of these specific six-membered asymmetric cyclic glucose carbonates. More importantly, these findings serve as a foundation for future design strategies that incorporate adjacent functionalities within monomers to act as directing groups and impart molecular interactions that define regiochemical ring-opening.Funding Information
- Division of Chemistry (CHE-1610311, CHE-1664866, CHE-2003771)
- Welch Foundation (A-0001, A-0648)
- Division of Materials Research (DMR-1905818, DMREF-1629094)
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