Rare earth complexes with 3,4-dimethylbenzoic acid and 2,2:6′,2″-terpyridine: Synthesis, crystal structures, luminescence and thermodynamic properties

Effects of Europium Complex on Thermal and Photoluminescence Properties of Polyurethane-Europium Materials

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments.

Eu3+- and Tb3+-Based Coordination Complexes of Poly(N-Isopropyl,N-methylacrylamide-stat-N,N-dimethylacrylamide) Copolymer: Synthesis, Characterization and Property

This contribution reports the syntheses, structural analyses and properties of europium (Eu³⁺)- and terbium (Tb³⁺)-based coordination complexes of poly(N-isopropyl,N-methylacrylamide-stat-N,N-dimethylacrylamide) (poly(iPMAm-stat-DMAm)) copolymer, named as poly-Eu(III) and poly-Tb(III), respectively. In greater detail, poly(iPMAm₈₅-stat-DMAm₁₅) is first prepared by random copolymerization of N-isopropyl,N-methylacrylamide (iPMAm) and N,N-dimethylacrylamide (DMAm) via group transfer polymerization (GTP). Next, poly(iPMAm₈₅-stat-DMAm₁₅) is used as the polymer matrix for chelating with Eu³⁺ and Tb³⁺ cations at its side amide groups, to produce poly-Eu(III) and poly-Tb(III). Their structural characterizations by FT-IR spectroscopy and XPS confirm the formation of polymeric complexes. The study on their fluorescence emission characteristics and luminescence lifetime demonstrates that Poly-Eu(III) shows four strong emission peaks at 578, 593, 622, and 651 nm, which are responsible for the electron transitions from the excited ⁵D₀ state to the multiplet ⁷F_J (J = 0, 1, 2, 3) states, respectively, and poly-Tb(III) also displays four emission peaks at 489, 545, 588, and 654 nm, mainly due to the electron transitions of ⁵D₄ → ⁷F_i (i = 6, 5, 4, 3). The luminescence lifetimes of poly-Eu(III) (τ_poly-Eu(III)) and poly-Tb(III) (τ_poly-Tb(III)) are determined to be 4.57 and 7.50 ms, respectively. In addition, in aqueous solutions, poly-Eu(III) and poly-Tb(III) are found to exhibit thermoresponsivity, with their cloud temperatures (T_cs) locating around 36.4 and 36.8 °C, respectively. Finally, the cytotoxicity study on the human colon carcinoma cells LoVo and DLD1 suggests that the luminescent Eu³⁺ and Tb³⁺ in the chelated state with poly(iPMAm-stat-DMAm) show much better biocompatibility and lower toxicity than their inorganic salts.

Five Dinuclear Lanthanide Complexes Based on 2,4-dimethylbenzoic Acid and 5,5'-dimethy-2,2'-bipyridine: Crystal Structures, Thermal Behaviour and Luminescent Property

A series of new complexes, [Ln (2,4-DMBA)3(5,5'-DM-2,2'-bipy)]2 (Ln = Sm(1), Eu (2)), [Pr (2,4-DMBA)3 (5,5'-DM-2,2'-bipy)]2·0.5(C2H5OH) (3), [Ln (2,4-DMBA)3 (5,5'-DM-2,2'-bipy)]2·0.5(2,4-DMBAH)·0.25(5,5'-DM-2,2'-bipy) (Ln = Tb (4), Dy (5)) (2,4-DMBA = 2,4-dimethylbenzoate, 5,5'-DM-2,2'-bipy = 5,5'-dimethy-2,2'-bipyridine) were synthesized via hydrothermal reaction conditions. The complexes were characterized through elemental analysis, Infrared spectra (IR), Raman (R) spectra, UV-Vis spectra, single X-ray diffraction. Single crystal data show that complexes 1-5 are binuclear complexes, but they can be divided into three different crystal structures. The thermal decomposition mechanism of complexes 1-5 were investigated by the technology of simultaneous TG/DSC-FTIR. What's more, the luminescent properties of complexes 1-2 and 4 were discussed, and the luminescence lifetime (τ) of complexes 2 and 4 were calculated.

Synthesis, crystal structure, and two-dimension correlation infrared spectroscopy on two novel Pr carboxylic acid coordination polymers

Two new coordination polymers [Pr(PCPA)₃(H₂O)]_n1 and [Pr₂(PCPA)₆(H₂O)₃]_n·nH₂O 2(PCPA = p-chlorophenoxyacetic acid) have been synthesized under similar conditions by the hydrothermal method and characterized by single-crystal X-ray diffraction, elemental analyses, powder X-ray diffraction (PXRD) analysis, IR spectroscopy, two-dimensional correlation infrared spectroscopy(2D-IR COS) and ultraviolet-visible diffuse reflection integral spectroscopy (UV-Vis DRIS). 1 displays a 1D infinite chain, which is further linked by O/CH⋯O hydrogen bonds to form a 3D supra-molecular architecture. 2 shows a 2D layer structure, which is extended by CH⋯Cl hydrogen bonds generating a 3D network. Noteworthy, we also studied 2D-IR COS under the thermal perturbation to contribute to the development of theory. The 2D-IR correlation spectroscopy analysis is consistent with the analysis of structure and it is superior to 1D IR spectroscopy especially in the coordinated carboxyl group.