Synthesis And Characterization Of Complexes Of Rare Earth Perchlorate With Styryl P-Tolyl Sulfoxide And Studies On Fluorescence Of Complexes

Twelve solid complexes of rare earth perchlorate with styryl p-tolyl sulfoxide (L) andfive-different proportional mixed complexes (Eu³⁺ mixed by Tm³⁺) of rare earth perchlorate withthe ligand (L) have been synthesized and characterized. By elemental analysis, coordinationtitration and TGA-DSC studies, the composition of the complexes were suggested as RE(ClO₄)₃·L₇(RE=Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tin, Yb; L=CH₃C₆H₄SOCH=CHC₆H₅)and (Eu_xTm_y) (ClO₄)₃·L₇ (x:y=0.999: 0.001, 0.995: 0.005, 0.990: 0.010, 0.950: 0.050, 0.900:0.100) respectively. IR spectra and ¹HNMR spectra studies indicated that styryl p-tolyl sulfoxide(L) bonded with RE³⁺ ions by the oxygen atom in sulfmyl group while vinyl did not. The molarconductivities in acetone solution indicated that one of the three inorganic anions ClO₄^- iscoordinated with RE³⁺. The change of melting points of complexes with the atomic number is thethe "Z" mode from La to Eu, but the melting points of complexes increase along with increasedatomic number from Gd to Yb. The thermal stability of the complexes is very good and theirdecomposition points are above 200℃. Phosphorescent spectrum of ligand showed that matchingextent of triplet state of ligand with excited state of the rare earth ions was not good. The energy,which was absorbed by ligands, could not be transferred to rare earth ions effectively. But the fluorescence of europium ion and samarium ion was enhanced, owing to the influence of ligands.The medial triplet state of ligand is little higher than ⁵D₄ excited state of terbium ion and it is lowerthan ⁴F_9/2 excited state of dysprosium ion. So the ligand can not transfer energy to terbium ion anddysprosium ion. However, terbium ion and dysprosium ion can transfer energy to the ligand. Thus,the fluorescence of complexes of terbium and dysprosium comes from ligands. Fluorescencespectra of the europium complexes exhibit Eu³⁺ characteristic red emission, when excitation lightwas fixed at 393 nm. The fluorescent intensity of electric dipolar ⁵D₀→⁷F₂ transition is strongerthan that of the magnetic dipolar ⁵D₀→⁷F₁ transition. This phenomenon suggests the europium ion islocated at an asymmetry environment and the complex has not a center of symmetry. Comparing thefluorescent spectrum of the simple europium complex with those of mixed coordination compounds,one can fred that the thulium ions have a sensitization effect to the fluorescence of the europium ions.And sensitization effect is the strongest when the ratio of thulium ions and europium ions is0.001:0.999.