Vitamin B12 Derivative Enables Cobalt-Catalyzed Atom Transfer Radical Polymerization

Sajjad Dadashi-Silab, Cristina Preston-Herrera, Erin E. Stache

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Advances in controlled radical polymerizations by cobalt complexes have primarily taken advantage of the reactivity of cobalt as a persistent radical to reversibly deactivate propagating chains by forming a carbon-cobalt bond. However, cobalt-mediated radical polymerizations require stoichiometric ratios of a cobalt complex, deterring its utility in synthesizing well-defined polymers. Here, we developed a strategy to use cobalt as a catalyst to control radical polymerizations via halogen atom transfer with alkyl halide initiators. Using a modified, hydrophobic analogue of vitamin B12 (heptamethyl ester cobyrinate) as a cobalt precatalyst, we controlled the polymerization of acrylate monomers. The polymerization efficiency of the cobalt catalyst was significantly improved by additional bromide anions, which enhanced the deactivation of propagating radicals yielding polymers with dispersity values <1.2 using catalyst concentrations as low as 5 mol %. We anticipate that the development of cobalt catalysis in atom transfer radical polymerization will enable new opportunities in designing catalytic systems for the controlled synthesis of polymers.

Original languageEnglish (US)
Pages (from-to)19387-19395
Number of pages9
JournalJournal of the American Chemical Society
Issue number35
StatePublished - Sep 6 2023
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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