Redox-switchable polymerization has drawn increasing attention,in particular for the ring-opening polymerization(ROP)of biomass-derived monomers.However,an understanding of how the switch determines the observed chang...Redox-switchable polymerization has drawn increasing attention,in particular for the ring-opening polymerization(ROP)of biomass-derived monomers.However,an understanding of how the switch determines the observed changes is still limited.In this study,DFT calculations were employed to understand the redox-switchable ROP mechanism ofε-caprolactone catalyzed by group 4 metal complexes bearing[OSSO]-type ferrocene ligands.Our results suggest that two oxidized forms show higher reactivity because of the higher Lewis acidity of their catalytic metal centers in comparison with that of the corresponding reduced states.In one case,however,a lower activity of the oxidized species was observed that is likely due to the increased stability of the substrate-catalyst intermediate leading to a high activation barrier.In addition,other analogous metal complexes were computationally modelled by changing the metal center or modifying the ancillary ligand with different bridging-heteroatoms,and the results provide useful information on the development of new redox-switchable polymerization catalysts.展开更多
基金supported by the NSFC(21674014,U1862115)Y.L.and G.L.thank the Fundamental Research Funds for the Central Universities(DUT18GJ201,DUT18RC(3)002)+1 种基金PLD thanks the National Science Foundation for grant CHE-1809116The authors also thank RICC(RIKEN Integrated Cluster of Clusters)and the Network and Information Center of Dalian University of Technology for part of computational resources.
文摘Redox-switchable polymerization has drawn increasing attention,in particular for the ring-opening polymerization(ROP)of biomass-derived monomers.However,an understanding of how the switch determines the observed changes is still limited.In this study,DFT calculations were employed to understand the redox-switchable ROP mechanism ofε-caprolactone catalyzed by group 4 metal complexes bearing[OSSO]-type ferrocene ligands.Our results suggest that two oxidized forms show higher reactivity because of the higher Lewis acidity of their catalytic metal centers in comparison with that of the corresponding reduced states.In one case,however,a lower activity of the oxidized species was observed that is likely due to the increased stability of the substrate-catalyst intermediate leading to a high activation barrier.In addition,other analogous metal complexes were computationally modelled by changing the metal center or modifying the ancillary ligand with different bridging-heteroatoms,and the results provide useful information on the development of new redox-switchable polymerization catalysts.
