Study on macromolecular metal complexes: Synthesis, characterization, and fluorescence properties of stoichiometric complexes for rare earth coordinated with poly(acrylic acid)

Poly acrylic acid (PAA) and its stoichiometric complexes with trivalent rare earth (RE) have been synthesized and well characterized by means of elemental analysis, IR, TG-DTA, fluorescence spectra, etc. Chemical analysis indicated that the molar ratio of -COO- and RE(3+)in the complex was closely dependent on the pH and the molar ratio of PAA and RE in the feed. The stoichiometric complexes in which the molar ratio of -COO- and RE3+ is 3:1 can be formed under the conditions of pH 6.0 and PAA:RE = 3:1 (molar ratio in the feed). Spectroscopic studies suggested that the carboxylate bonded to the central metal ions was in the form of bidentate and these stoichiometric complexes possessed high-temperature resistance. Due to efficient energy transfer from polymer to central metal ions, the emission intensity of Eu3+ and Tb3+ complexes was stronger than that of simple compounds. Therefore, these complexes can be promising as potential fluorescent probes and photoluminous materials. (C) 2006 Wiley Periodicals, Inc. J Appl Polyrn Sci 103: 351-357, 2007