Spectroscopic studies of Eu(III) and Nd(III) complexes with several polyoxometalates

The results of studies related to synthesis and spectroscopic properties of polyoxometalates (POM) and their europium(III) and neodymium(III) complexe s (Ln/POM) are presented. A series of lanthanide(III) sandwiched Ln(POM)(2) , Ln(2)POM or encapsulated within the cavity of the POM complexes, synthesi zed for these studies, were verified based on the results of thermogravimet ric analysis and infrared spectroscopy. Absorption of Nd(III) and luminesce nce (excitation and emission) spectra of Eu(III) as well as results of Eu(I II) ion lifetime measurements were used for characterization of the complex es. The Eu(III) luminescence lifetimes, measured both for solid and aqueous solutions, indicate that the sandwiched complexes Eu(POM)(2) have no water of hydration, whereas the complexes Eu(POM)(2) have four or six water mole cules, and europium-encrypted derivatives three or four H2Os in the Eu(III) inner coordination sphere. (C) 2000 Elsevier Science S.A. All rights reser ved.