P‐Substituted Tris(2‐pyridylmethyl)amines as Ligands for Highly Active ATRP Catalysts: Facile Synthesis and Characterization. Issue 35 (17th June 2020)

• Record Type: Journal Article
• Authors: Enciso, Alan E.; Lorandi, Francesca; Mehmood, Arshad; Fantin, Marco; Szczepaniak, Grzegorz; Janesko, Benjamin G.; Matyjaszewski, Krzysztof
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 35(2020)
• Page Start: 14910
• Page End: 14920
• Publication Date: 2020-06-17
• Subjects: amine ligands -- ATRP -- catalysis -- copper -- polymer synthesis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202004724
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A facile and efficient two‐step synthesis of p ‐substituted tris(2‐pyridylmethyl)amine (TPMA) ligands to form Cu complexes with the highest activity to date in atom transfer radical polymerization (ATRP) is presented. In the divergent synthesis, p ‐Cl substituents in tris(4‐chloro‐2‐pyridylmethyl)amine (TPMA 3Cl ) were replaced in one step and high yield by electron‐donating cyclic amines (pyrrolidine (TPMA PYR ), piperidine (TPMA PIP ), and morpholine (TPMA MOR )) by nucleophilic aromatic substitution. The [Cu II (TPMA NR2 )Br] + complexes exhibited larger energy gaps between frontier molecular orbitals and >0.2 V more negative reduction potentials than [Cu II (TPMA)Br] +, indicating >3 orders of magnitude higher ATRP activity. [Cu I (TPMA PYR )] + exhibited the highest reported activity for Br‐capped acrylate chain ends in DMF, and moderate activity toward C−F bonds at room temperature. ATRP of n ‐butyl acrylate using only 10–25 part per million loadings of [Cu II (TPMA NR2 )Br] + exhibited excellent control. Abstract : Evolution of activity : A facile and high‐yield synthesis of para ‐substituted tris(2‐pyridylmethyl)amine‐based ligands is presented. Copper complexes with these ligands exhibit very high activity in atom transfer radical polymerization.