SPECTROSCOPIC STUDY OF ION-BINDING IN SYNTHETIC POLYELECTROLYTES USING LANTHANIDE IONS

Spectroscopic properties of Ln(III) bound to six polyacrylic acids of molecular weights ranging from 2000 to 4 000 000 daltons are described . These complexes were characterized using Nd(III) absorption of the h ypersensitive band at similar to 575 nm and stopped-flow spectroscopy, as well as Eu(III) luminescence lifetime and D-5(0) <-- F-7(0) select ive excitation spectra. The luminescence lifetimes of Eu(III), the cha nges in the absorption of Nd(III) and passage through columns of catio n exchange resin gave a predominance of rapid, strong, binding of Eu(I II) with about 3% more weakly bound. The variation of intensity of the Eu(III) D-5(0) <-- F-7(0) selective excitation spectra indicates a mo lar ratio of 1:3 for Eu(III):[COO-] with three residual waters of hydr ation in the inner coordination sphere of the bound Ln(III). No signif icant changes in either the hydration number or the excitation spectra have been observed among the Eu/PAA complexes for varying PAA.