Metal complexes of poly(2-acetamidoacrylic acid)

Abstract

Complexation constants of divalent and trivalent metal ions with 2-acetamidoacrylic acid (4A) and its polymer (P4A) were determined by the modified Bjerrum method. P4A has carboxyl and acetamido (acetyl) groups. Although an additive effect of two functional groups was expected in complexing with metal ions, the complexation constants of P4A were essentially the same as those for poly(acrylic acid), while P4A has greater complexing ability than 4A. The interactions of P4A and 4A with Cu(II) and Mn(II) ions were studied using 13C n.m.r. The addition of Cu(II) ion to P4A and 4A solutions selectively broadens the α-carbon and carboxyl carbon signals, and the addition of Mn(II) ion broadens the acetyl and carboxyl carbonyl carbon signals. This finding suggests that Cu(II) and Mn(II) ions form five-membered and seven-membered chelate rings, respectively.