Tripodal "click" ligands for copper-catalyzed ATRP

A series of tris(R-methyltriazolylmethyl)amines [R = C₆H ₅ (1), 4-FC₆H₄ (2), 4-MeOC₆H ₄ (3), Fc (4)] were prepared and used as ligands for catalytic ATRP of methyl methacrylate (MMA). Despite a lower activity, the CuBr/4 catalyst promoted relatively well controlled polymerization compared to CuBr/1, as evidenced by narrower polydispersity indices. Meanwhile, no polymerization activity was observed with CuBr/2 and CuBr/3 under the catalytic conditions investigated. The CV measurements of CuBr₂ complexes supported 1 and 4 in DMSO showed E_1/2 values of -0.206 and -0.224 V, respectively, confirming the more electron-rich nature of CuBr/4. Although both CuBr/1 and CuBr/4 catalysts were only partially soluble in several organic solvents used, kinetic studies revealed a pseudo first order linear plot of ln[M] ₀/[M]_t versus time. Addition of CuBr₂ into the polymerization systems led to a decrease in polymer polydispersities and the observed rate constants (k_obs). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013