Spectroscopic studies of Ln(III) complexes with polyoxometalates in solids, and aqueous and non-aqueous solutions

摘要

Chosen polyoxometalate (POM) anions and their lanthanide(III) complexes, LnPOM, havebeen synthesized and spectroscopically characterized in solid state, aqueous and non-aqueous solutions.POMs, such as Keggin's, Dawson's and Anderson's type,Na9EuW10O36, compositions that function as inorganic cryptands ([(Na)P5W30O110]14?-Preyssler anion, and [(Na)As4W40O140]27?), containing inorganic(Na+,K+,NH4+)or organic (tetrabutylammonium,NBu4+) counter cations were obtained and their Ln(III) complexes(sandwiched and encapsulated) studied. The synthesized compounds were identified using elementaland thermogravimetric analysis, UV-Vis spectrophotometry and FTIR spectroscopy. The complexation studieswere carried out with the use Nd(III) and Er(III) optical absorption and Eu(III) luminescence spectroscopy.Luminescence characterization, including results of intensity, quantum yields and luminescence lifetimes ofEuPOM complexes in aqueous, non-aqueous solutions (DMF, DMSO, acetonitryle) and solid are discussed.Based on luminescence lifetime measurements of the Eu(III) ion the hydration numbers of its sandwiched(efficient emitters) and encrypted complexes have been determined and quenching effect discussed. TheEu(III) complexes entrapped in a xerogel matrix have been studied as luminescent materials. Luminescenceintensity, lifetime and quantum yield of the EuPOM materials and their photochemical stability, during continuousUV irradiation, were tested.