Luminescence Spectral Properties of Europium(III) and Terbium(III) Complexes with Cinnamic Acid

Europium and terbium mixed-ligand complexes with cinnamic acid of composition Ln(Cin)₃· nD · xH₂O, where Ln = Eu³⁺or Tb³⁺, Cin is a cinnamate ion (C₆H₅CH=CHCOO^–), D = 1,10-phenantroline, 2,2"-dipyridyl, benzotriazole (n= 2, x= 0), triphenylphosphine oxide (n= 1, x= 2), or H₂O (n= 0 or 1, x= 0), were synthesized. The compounds were characterized by elemental analysis, IR and luminescence spectroscopy. The Stark structure of the ⁵ D ₀–⁷ F _j(j= 0, 1, 2) electronic transitions in the low-temperature luminescence spectra of europium complexes was analyzed. IR study has revealed a bidentate coordination of the cinnamate ion in the compounds.     

Synthesis and Luminescent Properties of Terbium(III) and Europium(III) Fluoride Nanoparticles Modified with Aromatic Carboxylic Acids

Europium(III) and terbium(III) fluoride nanoparticles modified with citric, anthranilic, benzoic, salicylic, and acetylsalicylic acids have been obtained by means of sorption from solution and modification in statu nascendi. The shape and size of the particles have been determined by scanning electron microscopy. The luminescence of the samples was studied and it has been established that terbium fluoride nanoparticles modified with acetylsalicylic acid exhibits the highest luminescence intensity.     

Antimony(III) Complexes with Quaternary Ammonium Bases: Synthesis, Spectral, and Luminescent Properties

Complexes of antimony(III) halides with quaternary ammonium bases of different composition were synthesized and characterized by elemental and X-ray diffraction analyses and IR and luminescence spectroscopy. For complexes [R"₃R"N]SbHal₄ (Hal = Cl^–, Br^–, R" = R" = CH₃, C₂H₅, C₄H₉), the maximum of the emission band and fluorescence intensity was found to depend on the nature of the halide ion and the alkyl radical length.     

Luminescent Properties of Europium(III) Complexes with Quinaldic Acid and Sulfur–Containing Neutral Ligands

The luminescent heteroligand complexes of europium(III) with quinaldic acid and sulfur-containing neutral ligands Eu(Quin)3∙D∙3H2O (Quin–quinaldic acid, D–dimethyl sulfoxide or dihexyl sulfoxide) and Eu(Quin)3∙3H2O have been obtained. Their composition and structure have been determined. The thermal and spectral-luminescent properties of the heteroligand europium(III) complexes have been studied. The quinaldate ion has been found to coordinate to the europium(III) ion as a bidentate ligand. The Stark structure of 5D0–7Fj (j = 0, 1, 2) transitions in the low-temperature luminescence spectra of the europium(III) complexes has been analyzed     

Lanthanide-Containing Monomers Produced from Unsaturated Acids: Synthesis,Polymerization, and Spectral and Luminescent Properties. Crystal Structure of Europium(III) Methacrylate

Synthesis of lanthanide-containing (Ln = Eu, Tb, Nd, Gd) monomers based on unsaturated acids is described, namely, of LnL¹ ₃ · nH₂O (L¹ are anions of acrylic and methacrylic acids) and Ln₂L² ₃ · nH₂O (L² are anions of maleic and fumaric acids); n = 0–3, 6. The compounds were characterized by elemental analysis, thermogravimetry, and IR and luminescence spectroscopy. Europium methacrylate Eu(Macr)₃ was studied using X-ray diffraction analysis: rhombic system, a = 14.831(3) Å, b = 12.964(2) Å, c = 7.761(1) Å, space group Cmc2₁, V = 1483.5(4) ų, (calcd) = 1.823 g/cm³. Infinite chains of Eu(Macr)₃ molecules are directed along crystallographic axis c and are bound by van der Waals interactions. Radical polymerization of Eu(III) and Tb(III) acrylates and Eu(III) methacrylate yields lanthanide-containing polymers with a high content of Ln (40–50 mass %). Their spectral and luminescent properties are studied.     

Luminescent Europium(III) Coordination Zippers Linked with Thiophene‐Based Bridges

Novel Eu^III coordination polymers [Eu(hfa)₃(dpt)]_n (dpt: 2,5‐bis(diphenylphosphoryl)thiophene) and [Eu(hfa)₃(dpedot)]_n (dpedot: 2,5‐bis(diphenylphosphoryl)ethylenedioxythiophene) with hydrogen‐bonded zipper structures are reported. The coordination polymers are composed of Eu^III ions, hexafluoroacetylacetonato ligands, and thiophene‐based phosphine oxide bridges. The zig‐zag orientation of single polymer chains induced the formation of densely packed coordination structures with multiple intermolecular interactions, resulting in thermal stability above 300 °C. They exhibit a high intrinsic emission quantum yield (ca. 80 %) due to their asymmetrical and low‐vibrational coordination structures around Eu^III ions. Furthermore, the characteristic alternative orientation of substituents also contributes to the dramatically high ligand‐to‐metal energy transfer efficiencies of up to 80 % in the solid state.     

Minocycline‐Based Europium(III) Chelate Complexes: Synthesis,Luminescent Properties,and Labeling to Streptavidin

Two chelate ligands for europium(III) having minocycline (=(4S,4aS,5aR,12aS)‐4,7‐bis(dimethylamino)‐1,4,4a,5,5a,6,11,12a‐octahydro‐3,10,12,12a‐tetrahydroxy‐1,11‐dioxonaphthacene‐2‐carboxamide; 5 ) as a VIS‐light‐absorbing group were synthesized as possible VIS‐light‐excitable stable Eu³⁺ complexes for protein labeling. The 9‐amino derivative 7 of minocycline was treated with H₆TTHA (=triethylenetetraminehexaacetic acid=3,6,9,12‐tetrakis(carboxymethyl)‐3,6,9,12‐tetraazatetradecanedioic acid) or H₅DTPA (=diethylenetriaminepentaacetic acid=N,N‐bis{2‐[bis(carboxymethyl)amino]ethyl}glycine) to link the polycarboxylic acids to minocycline. One of the Eu³⁺ chelates, [Eu³⁺(minocycline‐TTHA)] ( 13 ), is moderately luminescent in H₂O by excitation at 395 nm, whereas [Eu³⁺(minocycline‐DTPA)] ( 9 ) was not luminescent by excitation at the same wavelength. The luminescence and the excitation spectra of [Eu³⁺(minocycline‐TTHA)] ( 13 ) showed that, different from other luminescent Eu^III chelate complexes, the emission at 615 nm is caused via direct excitation of the Eu³⁺ ion, and the chelate ligand is not involved in the excitation of Eu³⁺. However, the ligand seems to act for the prevention of quenching of the Eu³⁺ emission by H₂O. The fact that the excitation spectrum of [Eu³⁺(minocycline‐TTHA)] is almost identical with the absorption spectrum of Eu³⁺ aqua ion supports such an excitation mechanism. The high stability of the complexes of [Eu³⁺(minocycline‐DTPA)] ( 9 ) and [Eu³⁺(minocycline‐TTHA)] ( 13 ) was confirmed by UV‐absorption semi‐quantitative titrations of H₄(minocycline‐DTPA) ( 8 ) and H₅(minocycline‐TTHA) ( 12 ) with Eu³⁺. The titrations suggested also that an 1 : 1 ligand Eu³⁺ complex is formed from 12 , whereas an 1 : 2 complex was formed from 8 minocycline‐DTPA. The H₅(minocycline‐TTHA) ( 12 ) was successfully conjugated to streptavidin (SA) (Scheme 5), and thus the applicability of the corresponding Eu³⁺ complex to label a protein was established.     

Variable Dimensionality of Europium(III) and Terbium(III) Coordination Compounds with a Flexible Hexacarboxylate Ligand

A reaction between 4,4′,4″-(benzene-1,3,5-triyltris(oxy))triphthalic acid (H₆L) and lanthanide(III) nitrates (Ln = Eu³⁺, Tb³⁺) in water under the same conditions gave a molecular coordination compound [Tb(H_4.5L)₂(H₂O)₅]∙6H₂O in the case of terbium(III) and a one-dimensional linear coordination polymer {[Eu₂(H₃L)₂(H₂O)₆]∙8H₂O}_n in the case of europium(III). The crystal structures of both compounds were established by single-crystal X-ray diffraction, and they were further characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. The compounds demonstrated characteristic lanthanide-centered photoluminescence. The lanthanide-dependent dimensionality of the synthesized compounds, which are the first examples of the coordination compounds of hexacarboxylic acid H₆L demonstrates its potential as a linker for new coordination polymers.     

Heterometallic Europium(III)–Lutetium(III) Terephthalates as Bright Luminescent Antenna MOFs

A new series of luminescent heterometallic europium(III)–lutetium(III) terephthalate metal–organic frameworks, namely (Eu_xLu_1−x)₂bdc₃·nH₂O, was synthesized using a direct reaction in a water solution. At the Eu³⁺ concentration of 1–40 at %, the MOFs were formed as a binary mixture of the (Eu_xLu_1−x)₂bdc₃ and (Eu_xLu_1−x)₂bdc₃·4H₂O crystalline phases, where the Ln₂bdc₃·4H₂O crystalline phase was enriched by europium(III) ions. At an Eu³⁺ concentration of more than 40 at %, only one crystalline phase was formed: (Eu_xLu_1−x)₂bdc₃·4H₂O. All MOFs containing Eu³⁺ exhibited sensitization of bright Eu³⁺-centered luminescence upon the 280 nm excitation into a ¹ππ* excited state of the terephthalate ion. The fine structure of the emission spectra of Eu^{3+ 5}D₀-⁷F_J (J = 0–4) significantly depended on the Eu³⁺ concentration. The luminescence quantum yield of Eu³⁺ was significantly larger for Eu-Lu terephthalates containing a low concentration of Eu³⁺ due to the absence of Eu-Eu energy migration and the presence of the Ln₂bdc₃ crystalline phase with a significantly smaller nonradiative decay rate compared to the Ln₂bdc₃·4H₂O.     

Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions

New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu (III) complexes, Eu(PEP)₂Cl₃ and Eu(PEP)₂(NO₃)₃, are synthesized and characterized. The synthetic procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single crystals obtained. The compounds [Eu(PEP)₂Cl₃]·2CH₃CN and [Eu(PEP)₂(NO₃)₃]∙2CH₃CN crystalize in monoclinic space group P2_1/n and P2_1/c, respectively, with two acetonitrile solvent molecules. Intra- and inter-ligand π-π stacking interactions are present in solid stat and are realized between the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as antenna for sensitization of Eu (III) emission. The newly designed complexes differ in counter ions in the inner coordination sphere, which allows exploring their influence on the stability, molecular and supramolecular structure, fluorescent properties and symmetry of the Eu (III) ion. In addition, molecular simulations are performed in order to explain the observed experimental behavior of the complexes. The discovered structure-properties relationships give insight on the role of the counter ions in the molecular design of new Eu (III) based luminescent materials.     

Sensing Uranyl(VI) Ions by Coordination and Energy Transfer to a Luminescent Europium(III) Complex

The release of uranyl(VI) is a hazardous environmental issue, with limited ways to monitor accumulation in situ. Here, we present a method for the detection of uranyl(VI) ions through the utilization of a unique fluorescence energy transfer process to europium(III). Our system displays the first example of a “turn‐on” europium(III) emission process with a small, water‐soluble lanthanide complex triggered by uranyl(VI) ions.     

铕(III)三元配合物荧光性质的研究

According to fluorescent spectra of a series of Eu(III) ternary complexes in the three solvents EtOH, DMF and CH3CN, the fluorescence is stronger in the solvent CH3CN than in the solvents EtOH and DMF, and fluorescent intensity is contrary to the affinity of three solvents with rare earth ions. Center ions emit fluorescence mainly by an intramolecular energy transfer from the broad absorbing β-diketonate TTA, BTA or BA to the chelated rare earth ions.     

稀土Eu(Ⅲ)双酞菁衍生物LB膜的荧光性

合成了八－４－（四氢糠氧基）酞菁铕（Ⅲ）,通过元素分析、红外光谱、质谱和紫外－可见光谱加以确认。测定了配合物的ＩＩ－Ａ曲线,证明它有很好的成膜性,Ｚ型沉积形成的ＬＢ膜材料有很强的荧光响应,随着ＬＢ膜厚度的增加,荧光性增强。掺杂邻菲咯啉形成的混合ＬＢ膜,其荧光性比纯膜强。但不是邻菲咯啉加入的量越多荧光性越强。配合物：邻菲咯啉＝１：１０时（摩尔比）,有最好的荧光行为。用电子光谱对ＬＢ膜的结构进行了表征     

Dy(III) - and Yb(III) -Curcuminoid Compounds: Original Fluorescent Single-Ion Magnet and Magnetic Near-IR Luminescent Species

The multifunctional behavior of two mononuclear lanthanide compounds attached to a curcuminoid called 9?Accm has been investigated. The results show that [Dy(9?Accm)(2) (NO(3) )(dmf)(2) ] Yb(9?Accm)(3) (py)] behaves as a single-ion magnet and that both compounds display luminescent responses and exhibit affinity for graphite surfaces.     

Synthesis and Spectral Properties of Terbium(III) and Gadolinium(III) Complexes with Hydroxybenzoic Acids

Russian Journal of General Chemistry - Coordination compounds of terbium(III) and gadolinium(III) with some hydroxybenzoic acids were electrochemically synthesized. Structure and spectral...     

Terbium(III) Complexes with Pyrazolones-5 on Zirconium Phosphate: Synthesis and Luminescent Properties

Sorption of Tb³⁺ ions by zirconium phosphate (ZrP), their complexation with some pyrazolones-5, and composition of compounds formed on a solid matrix are studied. Unlike solutions with the ratio Tb : pyrazolone = 1 : 3, compounds formed on ZrP have the ratio Tb : L = 1 : 3, 1 : 2, and 1 : 1, depending on the availability and size of a substituent at the reaction site. The luminescence intensity of the adsorbed Tb pyrazolonates was found to correlate with a sum of the Hammet induction -constants of substituents in the ligand molecule. The luminescence intensity of the studied complexes on ZrP is two times and more higher than that in solutions, which makes it possible to use ZrP as a solid substrate.     

New 2,2′-Bipyridine Derivatives and Their Luminescence Properties with Europium(III) and Terbium(III) Ions

Twenty differently substituted 2,2′,2″,2? -[(2,2′-bipyridine-6,6′-diyl)bis(methylenenitrilo)]tetrakis(acetc acids) 75–94 were synthesized with the purpose of developing new markers to be used in bioaffinity assays based on the unique luminescence properties of Eu^III and Tb^III ions. The relative luminescence yields, excitation maxima, and emission decay constants were determined for the corresponding Eu^III and Tb^III chelates. The substituents at the bipyridine moiety had a significant effect on the luminescence properties: the best relative luminescence yields R were obtained for ligands with electron-donating substituents (e.g. Me, Ph), electron-withdrawing substituents (e.g. NO₂, COOH) had a reverse effect. However, no clear correlation between the relative luminescence yields and the substituent parameters was found.     

吡啶基双苯并咪唑的合成及其荧光性能

以多聚磷酸(PPA)为催化剂和溶剂,氮气保护下,吡啶基芳香二酸与邻苯二胺经缩合反应合成了三个新的吡啶基双苯并咪唑化合物(2a~2c),其结构经¹H NMR, ¹³C NMR, FT-IR和元素分析表征。2a~2c的固体荧光发射波长分别为473 nm, 427 nm和453 nm。     

Europium(III) Acrylatodibenzoylmethanate: Synthesis,Spectroscopy (IR,Luminescence), and Polymerization Properties

Eu(III) acrylatodibenzoylmethanate was synthesized with the aim of obtaining luminescent macromolecular Ln(III) complexes with chromophores. It was homo- and copolymerized with methyl methacrylate. The compounds formed were characterized by elemental analysis, luminescence, and IR spectroscopy. The luminescence intensity of the macromolecular Eu(III) complexes containing dibenzoylmethanate ions was shown to exceed the intensity of the monomeric complex by several times. The increase in the luminescence intensity when going from the monomer to copolymers is explained by the weakening of the quenching effect of the low state of the metal–ligand charge transfer.     

Unique Spectral Overlap and Resonant Energy Transfer between Europium(II) and Ytterbium(III) Cations: No Quantum Cutting

Samples of the Ca₃Sc₂Si₃O₁₂ (CSS) host singly doped with Eu²⁺ or Yb³⁺, doubly doped with Eu²⁺ and Yb³⁺, and triply doped with Ce³⁺, Eu²⁺ and Yb³⁺ were synthesized by a sol–gel combustion process under reducing conditions. Unlike previous reports of Eu²⁺→Yb³⁺ energy transfer in other systems, the energy transfer is resonant in the CSS host and the transfer efficiency reaches 100 % for lightly doped samples. The transfer mechanism is multipolar rather than electron transfer for the sample compositions employed herein. The emission intensity of Yb³⁺ is further enhanced by co‐doping with Ce³⁺ in addition to Eu²⁺. The quantum efficiencies of the doped materials range between 9 % and 93 %.