Electrochemical Exploration of Active Cu-Based Atom Transfer Radical Polymerization Catalysis through Ligand Modification

The intersection between Cu-catalyzed atom transfer radical polymerization (ATRP) and organometallic mediated radical polymerization (OMRP) has been recently shown to be a result of competition between the CuI and CuII complexes of polyamine ligands for the same organic free radical. The tetradentate ligands N,N'-bis-2'-pyridylmethyl-ethane-1,2-diamine (L-1) and N,N'-dimethyl-N,N'-bis-2'-pyridylmethyl-ethane-1,2-diamine (L-2) form stable Cu complexes which, depending on their oxidation state, can either liberate or complex organic radicals. Herein, we show that this process may be affected by subtle changes to the ligand system. Switching from a tertiary amine (L-2) to a secondary amine (L-1) retains ATRP and OMRP activity through a series of cyclic voltammetry measurements in the presence of the initiator bromoacetonitrile.

Automated summary

The competition between CuI and CuII complexes of polyamine ligands for the same organic free radical is shown to be the intersection between Cu-catalyzed ATRP and OMRP. The stability of the Cu complexes depends on their oxidation state, and subtle changes to the ligand system may affect this process.