Synthesis and magnetic properties of the Ho(BA)2AA complex monomer and its copolymer with MMA

A new Ho(III) ternary complex was synthesized by the reaction of holmium isopropoxide with benzoylacetone (BA) and acrylic acid (AA) and its copolymer with methyl methacrylate (MMA) was prepared through free radical initiation polymerization. The complex monomer and the corresponding copolymer were characterized by elemental analysis, FT-IR, UV–VIS spectroscopy and thermal gravimmetric analysis (TGA). The dependence of magnetic susceptibility of the monomer and polymer on the temperature (4–300 K) was measured. The effective magnetic moment of both monomer Ho(BA)2AA and copolymer MMA-co-AAHo(BA)2 decreased with the temperature descending in 4–200 K and the values of χM were found to obey the Curie–Weiss law. These results indicate the existence of weak antiferromagnetic interaction between Ho(III) ions in the copolymer, which may be ascribed to a superexchange interaction between the Ho(III) ions through coordination atoms.