Date of Original Version
Thiourea (TU)/amine base co-catalysts are commonly employed for well-controlled, highly active ‘living’ organocatalytic ring-opening polymerizations (ROPs) of cyclic esters and carbonates. In this work, several of the most active co-catalyst pairs are shown by 1H-NMR binding studies to be highly associated in solution, dominating all other known non-covalent catalyst/reagent interactions during ROP. One strongly-binding catalyst pair behaves kinetically as a unimolecular catalyst species. The high selectivity and activity exhibited by these ROP organocatalysts is attributed to the strong binding between the two co-catalysts, and the predictive utility of these binding parameters is applied for the discovery of a new, highly active co-catalyst pair.
Kazakov, O. I., Datta, P. P., Isajani, M., Kiesewetter, E. T., & Kiesewetter, M. K. (2014). Cooperative hydrogen-bond pairing in organocatalytic ring-opening polymerization. Macromolecules, 47(21), 7463-7468. http://dx.doi.org/10.1021/ma501847x