Synthesis Characterization Research Of Fluorescence Properties And Discussion In Luminescence Mechanism Of Rare Earth Perchlorate With Bis(Benzoylmethyl) Sulfoxide And Different Second Ligands

Sixteen solid trinary complexes of rare earth perchlorate with bis(benzoylmethyl) sulfoxide (L) as the first ligand and O-Phenanthroline(L'), Benzoic Acid(L'), Salicylic Acid(L'), 2.2' -Dipyridyl(L') as the second ligands have been synthesized and characterized. By elemental analysis, coordination titration and TGA-DSC studies, the composition of the complexes were suggested as RE (L)₅ L'(ClO₄)₃·2H_O (RE=Sm,Eu,Tb,Dy;L'=O-Phenanthroline,2.2'-Dipyridyl);Sm(L)₅L'(ClO₄)₂·7H₂O(L'=C₆H₅COO^-,C₆H₄OHCOO^-);Eu(L)₅L'(ClO₄)₂·8H₂O(L'=C₆H₅COO^-);Eu(L)₅L'(ClO₄)₂·6H₂O(L'=C₆H₄OHCOO^-); Tb (L)₅ L'(ClO₄)₂·6H₂O (L'=C₆H₅COO^-,C₆H₄OHCOO^-); Dy (L)₅ L' (ClO₄)₂·8H₂O (L'=C₆H₅COO^-, C₆H₄OHCOO^-). 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 second ligands O-Phenanthroline and 2.2' -Dipyridyl bonded with RE³⁺ ions by the nitrogen atom respectively. The second ligand Benzoic Acid bonded with RE³⁺ ions by one oxygen atom in carbonyl group which coordinated as an unidentate group. But the second ligand Salicylic Acid not only bonded with RE³⁺ ions by one oxygen atom in carbonyl group which coordinated as an unidentate group but also bonded with RE³⁺ ions by one oxygen atom in the phenolic hydroxyl group. The molar conductivities in DMF solution indicated that all the inorganic anions ClO₄^- are not coordinated with RE³⁺. The fluorescence spectra illustrate that all of the Sm³⁺, Eu³⁺, Tb³⁺ and Dy³⁺ complexes display characteristic metal-centered fluorescence in solid state. As phosphorescent spectra of ligands show that the triplet state of second ligands have different energy level and different scope., the efficiency of the energy transfer is different. So compared with the binary complexes, some trinary complexes have stronger fluorescence but the others do not. The fluorescence decay curves illustrate that all the complexes have long fluorescence lifetime.