Luminescence Of Rare Earth Carboxylic Acid Complexes Synthesis And Characterization,

In recent years, the rational design and synthesis of novel metal-organic coordination polymers based on carboxylate ligand have attracted considerable attention. The supramolecular complexes have interesting topological structure as well as potential applications. Especially, the rare earth ions (Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺) complexes with carboxylate ligand exhibit good fluorescence and the ternary complexes base on aromatic carboxylic acids have better fluorescence. Making use of the special property, the complexes require sufficient attention of other researchers and have potential applications as analytic determination, molecular biology, clinical chemistry, materials and environment science.Four rare earth complexes have been synthesized. In these complexes, carboxylic acids as the first ligand and 1,10-phen(or 2,2' -bipy) as the second ligand. The crystal structures were determined by X-ray diffraction and the properties are characterized by IR, UV, DTA-TG analysis and fluorescence spectra.The thesis consists of the following five parts:1. The mixed-ligands complexes of rare earth ions (Sm³⁺, Dy³⁺) with fumaric acid and 2,2'-bipyIn this paper, the Sm³⁺ ternary complex and Dy³⁺ ternary complex [Ln₂(C₄H₂O₄)₃(2,2'-bipy)₂(H₂O)₂]_n (Ln = Sm (1), Dy (2); C₄H₂O₄^2- = Fumarate; 2,2'-bipy = 2,2'-bipyridine) have been synthesized with fumaric acid and 2,2'-bipy under hydrothermal conditions and the structure of complexes have been introduced. The dimeric unit Sm₂(C₄H₂O₄)₃(2,2'-bipy)₂(H₂O)₂may be viewed as the building blocks with distance Sm...Sm ions of 0.4374(4) nm. Lanthanide ions bridged by the fumarate groups in tridentate and tetradentate coordination modes form 2-D layer structure like quadrilateral channel sheet. The 2,2'-bipy ligands coordinate to Sm³⁺ ions in chelating mode and are in the quadrilateral channel. Hydrogen bonds and Ï€-Ï€ stracking interaction between 2-D layer result in 3-D supramolecular structure. Their thermal stability and luminescence were researched and compared by the element analysis, IR, TGA-TG and fluorescence spectra.2. The complex of rare earth ion (Eu³⁺) with 3-iodobenzoic acid and 2,2' -bipyThe illuminant rare earth ion (Eu³⁺) mixed-ligands complex was synthesized from 3-iodobenzoic acid and 2, 2'-bipyridine. It is composed of centrosymmetric binuclear molecule in which the two Eu(III) ions are connected by four bidentate bridging carboxylate groups. TheEu(III) ions are eight-coordinated and the coordination polyhedron can be described as a distorted square antiprism. The solid sample of the complex emits intense red light when excited by ultraviolet light. In the emission spectrum, there are five main peaks, 580 run, 590 nm, 612 ran, 684 nm and 699 nm, respectively, corresponding to ⁵D₀→⁷F₀, ⁵D₀→7F₁, ⁵D₀→⁷F₂, ⁵D₀→⁷F₃ and ⁵D₀→⁷F₄ transitions of the Eu(III) ion. The intensity of ⁵D₀→⁷F₂ is much stronger than that of ⁵D₀→⁷F₁, that is the electric dipole transition probability is larger than the magnetic dipole transition probability, which indicates that the Eu(III) ions are not in an inversion center. 3. The complex of rare earth ion (Sm³⁺) with 2, 4-dimethylbenzoic acid and 1,10-phenThe new complex of Sm³⁺ ion with 2, 4-dimethylbenzoate and phen (Sm₂)(C₉H₉O₂)₆(C₁₂H₈N₂)₂ has been synthesized and been characterized in the article. Thecomplex exist as binuclear molecule, and crystallize in monoclinic, space group C2/c. The Sm³⁺ ions are bridged by four groups, and the coordination number of Sm³⁺ ion is eight. In the emission spectrum of the solid-state, there are three main peaks, 561 nm, 595 nm and 642 nm, respectively, corresponding to ⁴G_5/2→ ⁶F_5/2, ⁴G_5/2 → ⁶F_7/2 and ⁴G_5/2 → ⁶F_9/2 transitions of the Sm(III) ion.