Synthesis,Characterization And Fluorescence Properties Of Rare Earth Perchlorate With Bis(Benzoylmethyl) Sulfoxide

Twelve solid complexes of rare earth perchlorate with bis(benzoylmethyl) sulfoxide (L) and twelve-different proportional mixed complexes (Tb³⁺ mixed by Tm³⁺, Eu³⁺ mixed by Pr³⁺) of rare earth perchlorate with the ligand (L) have been synthesized and characterized. By elemental analysis, coordination titration and TGA-DSC studies, the composition of the complexes were suggested as REL₅(ClO₄)₃·3H₂O(RE=Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb; L=C₆H₅CO CH₂SOCH₂COC₆H₅) and (Tb_xTm_y)L₅(ClO₄)₃·3H₂O (x:y=0.999:0.001, 0.995:0.005, 0.990:0.010, 0.950:0.050, 0.900:0.100, 0.800:0.200, 0.700:0.300; L=C₆H₅COCH₂SO CH₂COC₆H₅) and (Eu_xPr_y) L₅ (ClO₄)₃·3H₂O(x:y=0.999:0.001, 0.995:0.005, 0.990: 0.010, 0.950:0.050, 0.900:0.100, 0.800:0.200; L=C₆H₅COCH₂SOCH₂COC₆H₅). IR spectra and ¹HNMR spectra studies indicated that bis(benzoylmethyl) sulfoxide (L) bonded with RE³⁺ ions by the oxygen atom in sulfinyl group while the oxygen atom in carbonyl group did not. The molar conductivities in acetone solution indicated that two of three inorganic anions ClO₄^-are coordinated with RE³⁺. The change of melting points and decomposition points of complexes with the atomic number is serrated. All the complexes have good thermal stability. The fluorescence spectra illustrate that all of the Eu³⁺, Tb³⁺ and Dy³⁺ complexes display characteristic metal-centered fluorescence in solid state. Phosphorescent spectrum of ligand and fluorescent decay curve of complexes showed that the triplet state of ligand is higher than ⁵D₀ excited state of europium ion and ⁵D₄ excited state of terbium ion. So the ligand can transfer energy to them. At the same time, after rare earth complexes being generated, the configuration of 4f-4f transition forbiddance are released, consequently the rare earth ions not only have increased fluorescence intensity, but also have long fluorescence lifetime. Comparing the fluorescent spectrum of the simple complexes with those of mixed coordination compounds, one can find that the thulium ions and praseodymium ions have a sensitization effect to the fluorescence of Tb³⁺ and Eu³⁺ complexes. And sensitization effect is the strongest when the ratio of Tb³⁺:Tm³⁺=0.950:0.050 and Eu³⁺:Pr³⁺=0.995:0.005, the fluorescence intensity can be increased to 208% and 110%.