A Cation-Dependent Dual Activation Motif for Anionic Ring-Opening Polymerization of Cyclic Esters
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Updated: Sep 24, 2025

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
Caleb N Jadrich1, Vince E Pane1, Binhong Lin1
1Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States.
Abstract:
A new organocatalyst for the ring-opening polymerization of lactones has been identified. Under the tested conditions, the anions of 2,2'-bisindole promote fast, living polymerizations (as short as 10 ms) which are selective for chain elongation over transesterification (Đ ≤ 1.1). While structurally related to (thio)urea anion catalysts, anions of 2,2'-bisindole activate the monomer via the counterion rather than through hydrogen bonding. This new activation motif enables modulation of the polymerization rate by 2 orders of magnitude by changing the counterion.
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