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.     

The luminescence of some lanthanide decatungstates

Luminescence of Na₉LnW₁₀O₃₆ · 18H₂O (Ln = Sm, Tb, Dy) and K₉EuW₁₀O₃₆ · 18H₂O is reported. Low efficiency of the Tb³⁺ compound is ascribed to non-radiative loss via a charge-transfer (Tb⁴⁺-W⁵⁺) state. The Sm³⁺ and Dy³⁺ compounds have only medium luminescence efficiency due to cross relaxation between lanthanide ions. The Eu³⁺ compound demonstrates again the sensitivity of Eu³⁺ luminescence to small changes.     

Coordination compounds of europium(III), terbium(III), dysprosium(III), samarium(III), and gadolinium(III) with 2-acetylbenzoic acid

LnAcbenz₃ · 3H₂O complexes of Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺, and Gd³⁺ with 2-acetylbenzoic acid (HAcbenz) have been synthesized. The complexes have been studied by thermogravimetry and infrared and luminescence spectroscopy. According to IR spectroscopy data, the complexation of Acbenz^? with lanthanide ions occurs due to the bidentate coordination of carboxyl groups. According to thermal analysis, the complexes are dehydrated at a temperature above 140°C, and their thermodestruction begins at a temperature above 250°C. From the luminescence spectra measured at 77 and 300 K, it has been established that the integral luminescence intensity of EuAcbenz₃ · 3H₂O and TbAcbenz₃ ° 3H₂O is, respectively, 10 and 19 times higher than for tris-benzoates of the same metals. TbAcbenz₃ ° 3H₂O, the most intensively luminescing complex, is recommended for use as a promising luminescent material.     

A Highly Stable Yttrium Organic Framework as a Host for Optical Thermometry and D2O Detection

The yttrium organic framework (Y_0.89Tb_0.10Eu_0.01)₆(BDC)₇(OH)₄(H₂O)₄ (BDC=benzene-1,4-dicarboxylate) is hydrothermally stable up to at least 513 K and thermally stable in air in excess of 673 K. The relative intensities of luminescence of Tb³⁺ and Eu³⁺ are governed by Tb³⁺-to-Eu³⁺ phonon-assisted energy transfer and Tb³⁺-to-ligand back transfer and are responsible for the differing temperature-dependent luminescence of the two ions. This provides a ratiometric luminescent thermometer in the 288–573 K temperature range, not previously seen for MOF materials, with a high sensitivity, 1.69±0.04 % K⁻¹ at 523 K. In aqueous conditions, loosely bound H₂O can be replaced by D₂O in the same material, which modifies decay lifetimes to yield a quantitative luminescent D₂O sensor with a useful sensitivity for practical application.     

多色发光层状稀土氢氧化物/聚甲基丙烯酸甲酯复合荧光薄膜的组装

本文通过水热法合成了含有3种不同稀土离子的层状稀土氢氧化物(Gd0.5Tb0.5-xEux)2(OH)5NO3.nH2O,并选择有机物水杨酸(HSA)作为敏化剂,通过在水热条件下的离子交换反应,成功将其以有机阴离子形式与层状稀土氢氧化物插层组装获得有机-无机杂化荧光材料(SA--LRHs∶xEu)。荧光性质测定表明,SA-通过有效的能量转移增强了Tb3+的特征绿色荧光发射,随着Eu3+含量的增加,Eu3+的特征红色荧光发射随之增强,而Tb3+的特征绿色荧光发射随之减弱。在此基础上,将发光颜色可调的有机-无机荧光材料与聚甲基丙烯酸甲酯(PMMA)复合组装出透明的荧光薄膜。     

Synthesis,crystal structures and luminescent properties of two new Ln(III)-dicarboxylate (Ln=Eu,Tb) complexes exhibiting three dimensional networks

Two new coordination polymers, {[Eu₂(L₁)₃(H₂O)₂]?·?H₂O} _n (1), (Cu(II)?···?Cu(II), [Tb(H₂O)]₂(L₂)₃?·?4H₂O (2) (H₂L₁?=?succinic acid, H₂L₂?=?glutaric acid) have been hydrothermally synthesized and characterized by elemental analysis, IR, luminescence spectra and single crystal X-ray diffraction. The complexes are constructed by dicarboxylates bridging chains of edge-sharing EuO₈(H₂O) and TbO₈(H₂O) polyhedra to form 3D network structures. Complexes 1 and 2 exhibit intense red and green photoluminescence upon UV excitation in the solid state at room temperature.     

多色发光层状稀土氢氧化物/聚甲基丙烯酸甲酯复合荧光薄膜的组装

本文通过水热法合成了含有3种不同稀土离子的层状稀土氢氧化物 (Gd_0.5Tb_0.5-xEu_x)₂(OH)₅NO₃·nH₂O, 并选择有机物水杨酸(HSA)作为敏化剂, 通过在水热条件下的离子交换反应, 成功将其以有机阴离子形式与层状稀土氢氧化物插层组装获得有机-无机杂化荧光材料(SA^--LRHs:xEu)。荧光性质测定表明, SA^-通过有效的能量转移增强了Tb³⁺的特征绿色荧光发射, 随着Eu³⁺含量的增加, Eu³⁺的特征红色荧光发射随之增强, 而Tb³⁺的特征绿色荧光发射随之减弱。在此基础上, 将发光颜色可调的有机-无机荧光材料与聚甲基丙烯酸甲酯(PMMA)复合组装出透明的荧光薄膜。     

Preparation,Characterization and Luminescence Study of Chitosan Membrane and Powder Forms with Eu3 + and Tb3 +

Chitosan membranes with trivalent lanthanide ion Eu^{3 +} were prepared at a ratio of 3:1 w/w (chitosan:lanthanide). There was no membrane formation at a ratio of 1:1 w/w (chitosan: Eu^{3 +} or Tb^{3 +}); in this case a white solid powder was obtained. Both chitosan compounds were characterized by elemental analysis (CHN), thermal analysis (TG/DTG), scanning electron microscopy (SEM) and luminescence spectroscopy. CHN analysis was performed only for chitosan compounds in powder form, suggesting that these compounds have the general formula QUILn.6H₂O, where QUI = Chitosan and Ln = Eu^{3 +} or Tb^{3 +}. The results of TG/DTG curves for chitosan membranes with Eu^{3 +} ion indicate that the introduction of this metal into the chitosan structure causes gradual degradation in residual carbons, showing lower weight loss in the Eu^{3 +} membranes compared to pure chitosan membrane. Analysis of luminescence demonstrated that chitosan membranes with Eu^{3 +} ion exhibit emission in the visible region, showing emission bands from chitosan and Eu^{3 +} moieties. For chitosan with Eu^{3 +} and Tb^{3 +} ions compounds, in powder form, the analysis of luminescence suggested that chitosan is not transferring energy to the lanthanide ion; however, the chemical region where the lanthanide ion is found breaks the selection rules and favors the emission of these ions.     

Lanthanide(<Emphasis Type="SmallCaps">III</Emphasis>) ion as a luminescent and catalytically active reaction center of aniline condensation with butyraldehyde

A new type of chemiluminescence catalytic conversion in which the lanthanide(III) ion is a luminescent and highly efficient catalytically active center was found. Chemiluminescence (CL) is generated in the condensation reaction of aniline with butyraldehyde in DMF to form 3-ethyl-2-propylquinoline. The reaction is catalyzed by LnCl₃·6H₂O (Ln = Eu, Tb, and Ho). When EuCl₃·6H₂O and TbCl₃·6H₂O salts are used as catalysts, the CL emitters are the Eu³⁺* and Tb³⁺* excited ions. In the case of HoCl₃·6H₂O, the emitter is 3-ethyl-2-propylquinoline in the triplet-excited state. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 429–431, March, 2007.     

Syntheses and structures of p-HOOCC6F4COOH · H2O (H2L · H2O) and luminescent coordination polymers [Tb2(H2O)4(L)3 · 2H2O] n and Tb2(Phen)2(L)3 · 2H2O

Compounds p-HOOCC₆F₄COOH · H₂O (H₂L · H₂O), [Tb₂(H₂O)₄(L)₃ · 2H₂O] _n (I), and Tb₂(Phen)₂(L)₃ · 2H₂O (II) are synthesized. According to the X-ray structure analysis data, the crystal structure of H₂L · H₂O is built of centrosymmetric molecules H₂L and molecules of water of crystallization. The crystal structure of compound I is built of layers of coordination 2D polymer [Tb₂(H₂O)₄(L)₃] _n and molecules of water of crystallization. The ligands are the L^2? anions performing both the tetradentate bridging and pentadentate bridging-chelating functions. The coordination polyhedron TbO₉ is a distorted three-capped trigonal prism. Acid H₂L manifests photoluminescence in the UV region (??_max = 368 nm). Compounds I and II have the green luminescence characteristic of the Tb³⁺ ions, and the band with ??_max = 545 nm (transition ⁵ D ₄?? ⁷ F ₅) is maximum in intensity. The photoluminescence intensity of compound II is higher than that for compound I.     

苯并咪唑衍生配体锌-铕(或铽)异金属双核配合物的合成、结构与光学性质

合成了四个锌-铕(或铽)异金属双核配合物[ZnLnL¹(NO₃)₃Py] (Ln=Eu (1), Tb (2); HL¹=1-H-2-(2-羟基-3-甲氧基苯基)苯并咪唑; Py=吡啶)和[ZnLnL²(NO₃)₃Py] (Ln=Eu (3), Tb (4); HL²=1-H-2-(2-羟基-3-甲氧基-5-溴苯基)苯并咪唑; Py=吡啶), 其中1、2、3是单晶态, 化合物4则为多晶样品; 通过单晶X射线衍射、元素分析、傅里叶变换红外光谱和电喷雾质谱对化合物进行了表征. 化合物的紫外-可见吸收光谱、荧光激发和发射光谱表明配体的激发态能量有效传递到配合物中的镧系金属离子中, 含有铽(III)离子的配合物发射出其特征发射光谱, 而含有铕(III)离子的配合物由于其它去活方式, 没有辐射出铕(III)离子的特征发射光谱.     

A new disordered langbeinite‐type compound,K2Tb1.5Ta0.5P3O12, and Eu3+‐doped multicolour light‐emitting properties

For the first time, a new langbeinite‐type phosphate, namely potassium terbium tantalum tris(phosphate), K₂Tb_1.5Ta_0.5(PO₄)₃, has been prepared successfully using a high‐temperature flux method and has been structurally characterized by single‐crystal X‐ray diffraction. The results show that its structure can be described as a three‐dimensional open framework of [Tb_1.5Ta_0.5(PO₄)₃]_∞ interconnected by K⁺ ions. The Tb^III and Ta^V cations in the structure are disordered and occupy the same crystallographic sites. The IR spectrum, the UV–Vis spectrum, the morphology and the Eu³⁺‐activated photoluminescence spectroscopic properties were studied. A series of Eu³⁺‐doped phosphors, i.e. K₂Tb_1.5–xTa_0.5(PO₄)₃:xEu³⁺ (x = 0.01, 0.03, 0.05, 0.07, 0.10), were prepared via a solid‐state reaction and the photoluminescence properties were studied. The results show that under near‐UV excitation, the luminescence colour can be tuned from green through yellow to red by simply adjusting the Eu³⁺ concentration from 0 to 0.1, because of the efficient Tb³⁺→Eu³⁺ energy‐transfer mechanism.     

A rht-Type Luminescent Zn (II)-MOF Constructed by Triazine Hexacarboxylate Ligand: Tunable Luminescent Performance and White-light Emission Regulation through doping Eu3+/Tb3+

White-light emitting materials have become a hot research field of luminescent MOF (Metal–Organic Framework) because of its high practical application value. Herein, we successfully synthesized and characterized a rht-type fluorescent MOF Zn-TDPAT [H₆TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine] with a topology of (3, 24) connected nodes. A series of MOFs materials x%Tb + y%Eu@Zn-TDPAT were prepared by incorporating different concentrations of green emission center Tb³⁺ and red emission center Eu³⁺ into the blue-emitting Zn-MOF. The luminescence properties of MOFs materials x%Tb + y%Eu@Zn-TDPAT can be effectively adjusted by incorporating different concentrations of Tb³⁺ and Eu³⁺ and can obtain multi-color luminescence properties from blue, blue-green, green, yellow green, yellow, blue-red, yellow-red and white. According to trichromatic mechanism, by reasonably matching the intensity of blue light, green light and red light emitted by x%Tb + y%Eu@Zn-TDPAT at 420, 543 and 616 nm, MOFs materials 0.75%Tb + 5%Eu@Zn-TDPAT, 0.65%Tb + 5.5%Eu@Zn-TDPAT and 0.5%Tb + 7.5%Eu@Zn-TDPAT with white-light emission are obtained. Their CIE coordinates are 0.3162, 0.3345 (0.3162, 0.3345), (0.3138, 0.3339) and (0.3329, 0.3222), respectively, which are very close to ideal white-light emission (0.3333,0.3333).     

Solvo-thermal Preparation and Characterization of Two CdII Coordination Polymers Constructed From 2,6-(1,2,4-Triazole-4-yl)pyridine and 5-R-Isophthalic Acid (R = Nitro,Sulfo)

Under the solvo-thermal conditions, two novel Cd^II mixed-ligand coordination materials with 2,6-(1,2,4-triazole-4-yl)pyridine(L₁) and aromatic poly-carboxylic acid co-ligands such as 5-R-isophthalic acid (R = nitro, sulfo), namely [Cd(L₁)(NO₂-BDC)(H₂O)₂] · 2H₂O ( 1 ) and [Cd(L₁)(HSIP)(H₂O)] · 4H₂O ( 2 ) (NO₂-H₂BDC = 5-nitroisophthalic acid, H₃SIP = 5-sulfobenzene -isophthalic acid) were successfully prepared. These Cd^II mixed-ligand coordination polymers 1 – 2 have been measured by crystal X-ray analysis, FT-IR spectra and powder X-ray diffraction analyses. In 1 , these seven-coordinate Cd^II atoms (Cd1) are inter-linked by didentate 5-nitroisophthalic acid ligands forming 1D chain structures. In 2 , these L₁ and partially de-pronated HSIP^2– are inter-linked by central Cd^II centers and are arranged into the unique 2D micro-porous metal-organic framework of 2 . Side view of 2 , it is noted that numerous oxygen atoms of un-coordinated carboxylate groups and coordinated SO₃ groups protrude out and decorate the 2D framework of 2 . PXRD patterns of 1 and 2 sample is tested, which is consistent with the simulated PXRD diffraction pattern. Photoluminescence studies show that 2 is highly selective and sensitive to trace elements of Eu³⁺ with excellent K_sv value (7.86 × 10⁴ m ^–1) and low detection limit (5.56 × 10^–2 mM), which also provides a convenient method and platform for real-time detection of Eu³⁺.     

Two binuclear lanthanide complexes with 4-quinoline carboxylic acid: crystal structures and luminescent properties

Two isomorphic lanthanide complexes [Eu₂(L)₆(H₂O)₄] · 2H₂O (1) and [Tb₂(L)₆(H₂O)₄] · 2H₂O (2), (HL = 4-quinoline carboxylic acid) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are binuclear and each metal center adopts nine-coordination with nine oxygens from two H₂O molecules and carboxylates of three ligands; L exhibits three different coordination modes. Luminescent properties of 1 and 2 at room temperature indicate that the triplet-state level of this ligand matches better with the lowest excited state level of Eu(III) than with Tb(III).     

Study of lanthanide aromatic acid complexes in silica gels by photoacoustic spectroscopy

Lanthanide complexes Ln(p-ABA)₃·H₂O (p-ABA: p-aminobenzoic acid; Ln³⁺:La³⁺, Tb³⁺ and Er³⁺) have been incorporated into silica gels via a sol–gel method. Upon heat treatment at 120 °C, photoacoustic (PA) intensity of the ligand increases for Tb³⁺, La³⁺ and Er³⁺ complexes in silica gels, respectively, while this difference cannot be observed for the samples without heat treatment. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The nephelauxetic parameters and PA branching vectors of Er³⁺ complex in silica gel have been calculated. Spectral results indicate that p-ABA does not coordinate with lanthanide ions in silica matrix without a suitable heat treatment. For the co-doped samples, it is shown that the emissions of Tb³⁺ are enhanced with addition of La(p-ABA)₃·H₂O and remarkably quenched with the addition of Er(p-ABA)₃·H₂O. The possible mechanisms for these phenomena are proposed.     

Mechanistic Insight into Energy-Transfer Dynamics and Color Tunability of Na4CaSi3O9:Tb3+,Eu3+ for Warm White LEDs

In this work, a latent energy-transfer process in traditional Eu³⁺,Tb³⁺-doped phosphors is proposed and a new class of Eu³⁺,Tb³⁺-doped Na₄CaSi₃O₉ (NCSO) phosphors is presented which is enabled by luminescence decay dynamics that optimize the electron-transfer energy process. Relative to other Eu³⁺,Tb³⁺-doped phosphors, the as-synthesized Eu³⁺,Tb³⁺-doped NCSO phosphors show improved large-scale tunable emission color from green to red upon UV excitation, controlled by the Tb³⁺/Eu³⁺ doping ratio. Detailed spectroscopic measurements in the vacuum ultraviolet (VUV)/UV/Vis region were used to determine the Eu³⁺–O²⁻ charge-transfer energy, 4f–5d transition energies, and the energies of 4f excited multiplets of Eu³⁺ and Tb³⁺ with different 4f^N electronic configurations. The Tb³⁺→Eu³⁺ energy-transfer pathway in the co-doped sample was systematically investigated, by employing luminescence decay dynamics analysis to elucidate the relevant energy-transfer mechanism in combination with the appropriate model simulation. To demonstrate their application potential, a prototype white-light-emitting diode (WLED) device was successfully fabricated by using the yellow luminescence NCSO:0.03Tb³⁺, 0.05Eu³⁺ phosphor with high thermal stability and a BaMgAl₁₀O₁₇:Eu²⁺ phosphor in combination with a near-UV chip. These findings open up a new avenue to realize and develop multifunctional high-performance phosphors by manipulating the energy-transfer process for practical applications.     

Supramolecular networks constructed from mono- and bi-nuclear lanthanide complexes with 1,2-phenylenedioxydiacetic acid

[Tb₂(1,2-pdoa)₃ · 6H₂O] · H₂O (1) and [La(1,2-pdoa)(1,2-H₂pdoa)(OH) · H₂O] · 5H₂O (2) (1,2-H₂pdoa = 1,2-phenylenedioxydiacetic acid) have been synthesized and structurally characterized by single crystal X-ray diffraction. Complex 1 is a binuclear molecule in which one 1,2-pdoa ligand is a tetradentate bridge linking two Tb³⁺ ions, the other two 1,2-pdoa ligands bond Tb1³⁺ and Tb1A³⁺ via tetradentate chelating coordination. Tb³⁺ is nine-coordinate by six oxygens of 1,2-pdoa and three waters. Complex 2 is mono-nuclear with La³⁺ ten-coordinate by eight oxygens of two 1,2-pdoa, one hydroxide and one water. 1,2-Pdoa is tetradentate chelating with La³⁺ ion. The packing diagrams of 1 and 2 show supramolecular networks via H-bonds. The fluorescence spectrum of 1 shows characteristic emission of Tb³⁺ with ⁵D₄ → ⁷F_j (j = 6–3) transitions.     

Synthesis, Characterization and Thermochemistry of 2MgO：B2O3：1.5H2O

Introduction　　 2MgO·B2 O3(Mg2 B2 O5)and 2MgO·B2 O3·H2 Omightbepreparedaswhiskermaterials .12MgO·B2 O3·H2 OnamedszaibelyiteisamagnesiumboratemineralwithastructuralformulaofMg2 [B2 O4 (OH) 2 ].2 Itisdifficulttosynthesizethiscompoundinthelaboratory .Recently ,weobtainedasimilarcompound 2MgO·B2 O3·1 5H2 Owhenwetriedtopreparewhiskerof 2MgO·B2 O3·H2 Obythephasetransformationof 2MgO·2B2 O3·MgCl2 ·14H2 OinH3BO3solutionunderhydrothermalcondition .Itishope fultopreparewh…     

Trigonal (-3) symmetry octahedral lanthanide(III) complexes of zwitterionic tripodal ligands: luminescence and magnetism

Sandwich coordination complexes, [Ln^III(H₃L)₂]X₃?solvents, of Tb(III), Eu(III), Dy(III), Ho(III) and Er(III) were prepared with two new zwitterionic ester-substituted tripodal amine ligands, tris((2-hydroxy-5-n-butyl benzoate)aminoethyl)-amine (H₃L¹) and tris((2-hydroxy-5-methyl benzoate)aminoethyl)-amine (H₃L²). These ligands were synthesised by condensation of the appropriately substituted salicylaldehyde with tris(2-aminoethyl)amine (tren) followed by in situ reduction of the tris-imine to tris-amine. Subsequent 2:1 reaction with lanthanide(III) ions yields [Ln^III(H₃L)₂]X₃?solvents (L = L¹, L²; X = Cl^?, NO₃^?; solvents = MeOH or H₂O). All complexes were characterised by microanalysis, infrared spectroscopy, high resolution mass spectrometry and solid-state photoluminescence measurements. The crystal structures of [Tb^III(H₃L¹)₂]Cl₃·6MeOH, [Dy(H₃L¹)₂]Cl₃·6MeOH, [Eu^III(H₃L¹)₂]Cl₃·6MeOH and [Tb^III(H₃L¹)₂](NO₃)₃ reveal high-crystallographic ?3 symmetry at the O₆-coordinated octahedral lanthanide(III) ions and that the tripodal ligands are bound in zwitterionic form: the protons from the phenolic oxygens have migrated to the amino nitrogens. Photoluminescence measurements indicate various degrees of energy transfer of the ligand chromophore to the lanthanide ions, as both ligand and lanthanide emission features are observed. Despite the high-crystallographic symmetry and the likely small transverse magnetic anisotropy of the complexes, no evidence of slow relaxation of the magnetisation, characteristic of a single-molecule magnet, was observed for [Tb^III(H₃L¹)₂]Cl₃·MeOH·3H₂O, [Dy^III(H₃L¹)₂]Cl₃·6H₂O, [Ho^III(H₃L¹)₂](NO₃)₃·2H₂O, [Er^III(H₃L¹)₂]·H₂O and [Tb^III(H₃L¹)₂](NO₃)₃ down to 2.0 K.