Investigation on the synthesis and characterization of rare earth metal‐containing polymers. II. Fluorescence properties of Eu3+–polymer complexes containing β‐diketone ligand

Europium(III) chelates of dibenzoylmethane (DBM) (1) and β‐diketone‐containing polymers, i.e., poly(p‐benzoylacetylstyrene) (2) and poly(aryl β‐diketone) (3), were prepared. In the polymer 2 the β‐diketone moiety is attached to the phenyl ring, and for polymer 3 the β‐diketone group is incorporated in the linear chain. The chelate structures were confirmed by measuring IR spectra, TGA, and DTA. The fluorescence emission intensity was measured on fine powder samples. For the composite samples of Eu(DBM)4 in polystyrene, the fluorescence intensity was found to increase linearly with increasing Eu content. However, for Eu coordination polymers, the intensity reached a maximum at Eu3+ content as small as 1 wt % and remained constant on further increasing the Eu3+ content. When the fluorescence intensities of Eu complexes were compared under the same conditions, namely, 1 wt % Eu, at which Eu–2 and Eu–3 show nearly maximum intensity, the order was found to be Eu–1 > Eu–2 > Eu–3. These phenomena were accounted for by the differences in the coordination number of the Eu complexes.