Synthesis, Catalysis of Rare Earth Complexes with Aliphatic Noncyclic Polyether-Amino Acid Schiff Base

Eleven new rare earth complexes with aliphatic Schiff base, condensed from diglycol aldehyde and bis-arginine, were synthesized and characterized. They are confirmed as Ln（H2DAAR）（NO3）3·7H2O （Ln=La, Pr, Nd, Gd）, Ln3（H2DAAR）2（NO3）9·5H2O （Ln=Dy, Y） and Ln2（H2DAAR）（NO3）6·3H2O （Ln=La, Nd, Sm, Gd）, Ln3（DAAR）（NO3）7·4H2O （Ln=Dy, Yb, Y） respectively under different molar ratios of metal to ligand （DAAR=diglycol aldehyde bis-arginine）. The present paper deals with a synthetic method and catalytic properties of obtained complexes. The result shows that proper pH value is important for synthesis of the complexes and compositions of the lighter and the heavier rare earth complexes are different under the same reaction condition. Some new complexes obtained have proved their catalytic activity and 80% conversion with the viscosity-average molecular weight 230,000 for the polymerization of methyl methacrylate （MMA） without addition of any cocatalyst.