Influence of the steric properties of pyridine ligands on the structure of complexes containing the {LnCd2(bzo)7} fragment

The reaction of Cd(NO₃)₂ · 4H₂O and Eu(NO₃)₃ · 6H₂O or Tb(NO₃)₃ · 6H₂O with potassium 3,5-di-tert-butylbenzoate (Kbzo) and N-donor ligands (1,10-phenanthroline (phen), 2,4-lutidine (2,4-lut), 3,4-lutidine (3,4-lut), phenanthridine (phtd), 2,3-cyclododecenopyridine (cdpy), acridine (acr)) afforded heterometallic LnCd₂ complexes: [EuCd₂(bzo)₇(EtOH)₂(phen)] (2), [LnCd₂(bzo)₇(2,4-lut)₄] (Ln = Eu (3), Tb (4)), [EuCd₂(bzo)₇(H₂O)₂(2,4-lut)₂] · MeCN (5), [EuCd₂(NO₃)(bzo)₆(EtOH)₂(2,4-lut)₂] (6), [EuCd₂(bzo)₇(H₂O)(EtOH)(3,4-lut)₂] · 5EtOH (7), 3[EuCd₂(bzo)₇(H₂O)₂(phtd)₂] · 4phtd (8), [EuCd₂(bzo)₇(EtOH)₃(cdpy)] (9), 2[EuCd₂-(bzo)₂(EtOH)₄] · acr (10). The structures of complexes 2, 3, and 5–10 were determined by single-crystal X-ray diffraction. The isostructurality of complexes 3 and 4 was confirmed by powder X-ray diffraction. The structure of the trinuclear {Ln₂Cd} metal core is stable and independent of the type of peripheral ligands coordinated to cadmium atoms. Photoluminescent properties of compounds 3 and 4 were studied.

     

Modified method for the synthesis of isomeric N-substituted (1<Emphasis Type="Italic">H</Emphasis>-pyrazolyl)propane-1,3-diones

The condensation reaction of isomeric N-substituted (1H-pyrazol-4-yl)ethanones with the ethyl esters of pyrazole carboxylic acids and fluoroacetic acids has been studied using NaH as the base. Under optimized conditions, it proved to be a convenient and preparative method for the synthesis of N-substituted (1H-pyrazolyl)propane-1,3-diones and (1H-pyrazolyl)-4-polyfluorobutane-1,3-diones.     

Luminescent Properties of a Composite of Acrylic Polymers Doped with Eu(III) Complex for Ink-Jet Printing Applications

We present a composite material based on polymer matrices doped with a new europium(III) complex exhibiting high quantum yield. The Eu(III) complex was introduced into two types of polymer matrices. We investigate the concentration influence of the complex embedded into polymers on luminescent properties of the composite material. This Eu(III) complex proved to be highly dispersible in polymers and compatible with ink-jet technology.     

Mono- and Mixed Metal Complexes of Eu3+, Gd3+, and Tb3+ with a Diketone,Bearing Pyrazole Moiety and CHF2-Group: Structure,Color Tuning,and Kinetics of Energy Transfer between Lanthanide Ions

Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL₃(H₂O)₂], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [Eu_xTb_1-xL₃(H₂O)₂] (Eu_xTb_1-xL₃), [EuxGd_1-xL₃(H₂O)₂] (Eu_xGd_1-xL₃), and [Gd_xTb_1-xL₃(H₂O)₂] (Gd_xTb_1-xL₃), were studied. The Eu_xTb_1-xL₃ complexes exhibit the simultaneous emission of both Eu³⁺ and Tb³⁺ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu³⁺. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb³⁺ and Eu³⁺ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation.     

Novel D-A-D Fluorescent Dyes Based on 9-(p-Tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole as a Donor Unit for Solution-Processed Organic Light-Emitting-Diodes

New fluorescent D-A-D dyes containing 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole as a donor unit and 2,1,3-benzochalcogenadiazoles as an electron-withdrawing group were synthesized. The photoluminescent and electroluminescent properties of novel dyes for fluorescent OLED application were investigated. It was demonstrated that the replacement of lightweight heteroatoms by heavier ones enables the fine tuning of the maximum emission without significantly reducing the luminescence quantum yield. The maximum quantum yield value of 62.6% for derivatives based on 2,1,3-benzoxadiazole (1a) in cyclohexane was achieved. Two devices with the architecture of glass/ITO/PEDOT-PSS/poly-TPD/EML/TPBi/LiF/Al (EML = emitting layer) were fabricated to check the suitability of the synthesized compounds as a single active emission layer in OLED. These OLEDs exhibited clear red electroluminescence of the dyes with the maximum current efficiency of 0.85 Cd/A.     

Luminescent Hybrid Materials Based on Polymers of Poly(Alpha-Fluoroacrylates) Doped with Tb(III) Complex

This study is devoted to the development of efficient luminescent hybrid materials excited by UV radiation and featuring narrow luminescence lines as well as light, humidity, and temperature resistance. As a luminescent material, a terbium ion coordination compound introduced into the matrix of an organofluorine polymer is used. It has been shown that efficient excitation transfer to electronic levels of the terbium ion can be achieved by proper ligand selection. The polymer matrix material does not affect the luminescence properties of the Tb(III) coordination compound.     

Comparison of Luminescent Properties of Nd3+ Complexes with Pyrazole-Substituted 1,3-Diketone in DMSO Solutions and in KBr Pellets

Bulletin of the Lebedev Physics Institute - Luminescence characteristics of Nd3+ coordination compounds with pyrazole-substituted 1,3-diketonate ligand environment in KBr micropellets are studied....     

Variable Luminescence and Chromaticity of Homoleptic Frameworks of the Lanthanides together with Pyridylpyrazolates

Homoleptic, 3D coordination polymers of the formula ³³_∞[Ln(3-PyPz)₃] and ³_∞[Ln(4-PyPz)₃], (3-PyPz)⁻=3-(3-pyridyl)pyrazolate anion, (4-PyPz)⁻=3-(4-pyridyl)pyrazolate anion, both C₈H₆N₃⁻, Ln=Sm, Eu, Gd, Tb, Dy, were obtained as highly luminescent frameworks by reaction of the lanthanide metals (Ln) with the aromatic heterocyclic amine ligands 3-PyPzH and 4-PyPzH. The compounds form two isotypic series of 3D coordination polymers and exhibit fair thermal stability up to 360 °C. The luminescence properties of all ten compounds were determined in the solid state, with an antenna effect through ligand–metal energy transfer leading to high efficiency of the luminescence displayed by good quantum yields of up to 74 %. The emission is mainly based on ion-specific lanthanide-dependent intra 4 f–4 f transitions for Tb³⁺: green, Dy³⁺: yellow, Sm³⁺: orange-red, Eu³⁺: red. For the Gd³⁺-containing compounds, the yellow emission of ligand triplet-based phosphorescence is observed at room temperature and 77 K. Co doping of the Gd-containing frameworks with Eu³⁺ and Tb³⁺ allow further shifting of the chromaticity towards white light emission.     

The complex Eu(phen)L3��5CH2Cl2 (HL is 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione): synthesis, crystal structure, and luminescent properties

A reaction of Eu(NO₃)₃·6H₂O with the novel heterocyclic ligand 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione and 1,10-phenanthroline in the presence of NaOH gave the complex Eu(phen)L₃·5CH₂Cl₂. The crystal structure of the complex was determined by single-crystal X-ray diffraction. The coordination polyhedron {EuO₆N₂} is a tetragonal antiprism. The complex shows bright orange-red luminescence in both the solid state and solution.     

Synthesis and crystal structure of [Na(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>][EuL<Subscript>4</Subscript>] · 0.775CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript> (HL = 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione)

[Na(H₂O)₄][EuL₄] · 0.775CH₂Cl₂ (I) has been synthesized by the reaction of Eu(NO₃)₃ · 6H₂O with 1,3-bis(1,3-dimethyl-1H-pyrasol-4-yl)-1,3-propanedione (HL) in the presence of NaOH. Its crystal structure has been solved by X-ray diffraction analysis. Crystals are tetragonal; a = 16.2401(5) Å, c = 11.9113(4) Å, V= 3141.50(17) ų, ρ_calcd = 1.427 g/cm³, μ(MoK _α) = 1.140 mm^?1, space group P4/n, Z = 2. The structural units forming a crystal of compound I are [EuL₄]^? complex anions, [Na(H₂O)₄]⁺ cations, and CH₂Cl₂ molecules. The coordination polyhedron of the Eu atom is an Archimedean antiprism formed by the O atoms of four bidentate chelate ligands L^?.