Luminescence determination of DNA using terbium complexes with 2-oxo-4-hydroxyquinoline-3-carboxylic acid amides as probes

It was found that the presence of DNA significantly enhanced the 4f luminescence of terbium(III) in its complexes with a number of 2-oxo-4-hydroxyquinoline-3-carboxylic acid amide derivatives (L₁-L₆). For the high-sensitivity determination of DNA, L₁ and L₄ were chosen from two proposed groups, in complexes with which terbium ions exhibited the most intense luminescence. Under optimum conditions, the luminescence intensity of terbium was proportional to the concentration of DNA over the ranges 0.025–1.2 μg/mL (detection limit of 10 ng/mL) and 0.01–1.2 λg/mL (detection limit of 3 ng/mL) for L₁ and L₄, respectively. The mechanisms of the interaction of Tb-L complexes with DNA molecules were hypothesized.     

Luminescence determination of sodium and potassium using molecular sensors on the basis of terbium(III) complexes of 4-carboxybenzocrown ethers

The spectral luminescent properties of terbium(III) complexes of 4-carboxybenzo-15-crown-5 (L₁) and 4-carboxybenzo-18-crown-6 (L₂) are studied. The quenching of the luminescence of lanthanide by alkali metal ions is discovered, which is referred to as the formation of mixed Tb(III)-L₁-Na⁺ and Tb(III)-L₂-K⁺ complexes. The complexes are useful as molecular sensors for the luminescence determination of Na⁺ and K⁺ with the detection limits 1.5 and 25.0 μg/mL. Using the Tb(III)-L₁ complex, sodium can be determined in the presence of a 1000-fold excess of potassium. The developed procedures are utilized for the determination of KCl in the Kalipoz medication in tablet form and the total sodium salts (NaCl, NaHCO₃) in the Trisol solution for infusions.     

Synthesis and Spectroscopic Studies of Chosen Heteropolytungstates and Their Ln(III) Complexes

The heteropolytungstates [(Na)P₅W₃₀O₁₁₀]^4– (I), [(Na)Sb₉W₂₁O₈₆]^18– (II) and [(Na)As₄W₄₀O₁₄₀]^27– (III) and the monovacant Keggin structure of the general formula [XW_11–xMo_xO₃₉]^n– (X-Si, P; n = 7 for P and 8 for Si) (IV) as well as their europium(III) complexes were studied. The structures of I–IV as well as the europium(III) encrypted [(Eu)P₅W₃₀O₁₁₀]^12– (VI), [(Eu)Sb₉W₂₁O₈₆]^16– (VII), [(Eu)As₄W₄₀O₁₄₀]^25– (VIII) and sandwiched [Eu(XW_11–xMo_xO₃₉)₂]^n– (n =11 for P and n = 13 for Si) (V) complexes were synthesized and spectroscopically characterized. The complexes were studied using UV-Vis absorption and luminescence, as well as the laser-induced europium ion luminescence spectroscopy. Absorption spectra of Nd(III) were used to characterize the complexes formed. Excitation and emission spectra of Eu(III) were obtained for solid complexes and their solutions. The relative luminescence intensities of the Eu(III) ion, expressed as the ratio of the two strongest lines at 594 nm and 615 nm, = I₆₁₅/I₅₉₄, which is sensitive to the environment of the primary coordination sphere about the Eu(III) ion, was calculated. In the case of the sandwiched [Eu(XW_11–xMo_xO₃₉)₂]^n– complexes a linear dependence of the luminescence quantum yield of Eu(III) ion, , (calculated using [Ru(bpy)₃]Cl₂ as a standard) on the content of Mo (number of atoms, x) in the [Eu(XW_11–xMo_xO₃₉)₂]^n– structure was observed.     

Luminescent fluorinated chiral liquid crystalline oligomers containing Eu(III) complexes

Luminescent ?uorinated chiral liquid crystalline oligomers containing Eu(III) complexes (Eu-LCOs) with good liquid crystalline properties and obvious luminescence properties were prepared using Poly(methylhydrogeno)siloxane (PMHS), chiral liquid crystalline monomer (M₁), ?uorinated liquid crystalline monomer (M₂), ?uorinated Eu(III) complex (M₃). The chemical structures, liquid crystalline behaviours of Eu-LCOs were characterised by various experimental techniques. The introduction of small quantity of ?uorinated Eu(III) complexes endowed the oligomers with excellent luminescence properties. The Eu(III) complexes did not change the liquid crystalline textures of the oligomers. Fourier transform infrared imaging showed that Eu(III) complexes were evenly distributed in oligomers. In order to express the mutual effect and distribution of the components, a structural representation of Eu-LCOs was established. The Eu-LCOs displayed wide mesophase temperature ranges and reversible mesomorphic phase transitions. The Eu-LCOs can emit soft red light when being excited. Luminescence intensities of Eu-LCOs gradually increased with an increase of Eu(III) complexes from 0 to 1.0 mol%. However, the luminescence intensities of Eu-LCOs decreased monotonically with the increase of temperature in liquid crystalline phase.     

Novel Lanthanide (III) Complexes Derived from an Imidazole–Biphenyl–Carboxylate Ligand: Synthesis,Structure and Luminescence Properties

A series of neutral mononuclear lanthanide complexes [Ln(HL)₂(NO₃)₃] (Ln = La, Ce, Nd, Eu, Gd, Dy, Ho) with rigid bidentate ligand, HL (4′-(1H-imidazol-1-yl)biphenyl-4-carboxylic acid) were synthesized under solvothermal conditions. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. According to X-ray diffraction, all the complexes are a series of isostructural compounds crystallized in the P2/n monoclinic space group. Additionally, solid-state luminescence measurements of all complexes show that [Eu(HL)₂(NO₃)₃] complex displays the characteristic emission peaks of Eu(III) ion at 593, 597, 615, and 651 nm.     

The luminescence response of Eu(III)-thenoyltrifluoroacetonate complexes upon preresonant excitation with femtosecond laser pulses

The luminescence of thenoyltrifluoroacetonate (TTA) coordination complexes of trivalent europium ion (Eu(III)) in aqueous solutions and in solid-state polymeric films is probed upon single- and two-photon preresonant excitation with Ti:sapphire femtosecond laser. Particularly, diamine-liganded Eu(III)(TTA)₃ and poly(oxyethylene phosphate)tris(β-diketonate)Eu(III) complexes are examined aiming their possible applications as luminescent labels for sensing and imaging of biological molecules. Even at a pre-resonance, the excitation of these compounds with high-intensity, broadband light of frequency-doubled Ti:sapphire femtosecond laser centered around 400 nm results in a luminescence response suitable for fluorometric applications.     

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.     

Synthesis,characterization and luminescence properties of Eu(III) and Tb(III) complexes with novel pyrazole derivatives and 1,10-phenanthroline

Two novel pyrazole-derived ligands, 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinic acid (CDPA) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenylpicolinamide (CDPP) were prepared by 3,6-dichloropicolinic acid (DCPA). Their complexes with terbium(III) and europium(III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra, ¹H NMR and TG–DTG. Furthermore, the above complexes using 1,10-phenanthroline as a secondary ligand were also synthesized and characterized. The luminescence properties of these complexes in solid state were investigated. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes and the fluorescence of the complexes with 1,10-phenanthroline as a secondary ligand was prominently stronger than that of complexes without this ligand., and the three ligand (DCPA), (CDPP) and (CDPA) are excellent sensitizers to Eu(III) and Tb(III) ion.     

Determination of Methacycline and Glucose in Biological Fluids by Europium(III)-Sensitized Luminescence

Complexation in the Eu(III)–methacycline and Eu(III)–methacycline–hydrogen peroxide systems was studied by luminescence. It was proposed to use the studied complexes as analytical forms for the luminescence determination of methacycline in blood plasma (lower determination limit 2.5 g/mL) and urine (25 g/mL) and for the indirect determination of 0.025–0.7 mM glucose in blood plasma.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.     

Synthesis,Structures, and Luminescent Properties of Chloride and Nitrate LnIII Complexes Coordinated by tris(Pyrazolyl)methane

We report the synthesis of Ln³⁺ nitrate [Ln(Tpm)(NO₃)₃] ⋅ MeCN (Ln=Yb ( 1Yb ), Eu ( 1Eu )) and chloride [Yb(Tpm)Cl₃] ⋅ 2MeCN ( 2Yb ), [Eu(Tpm)Cl₂(μ-Cl)]₂ ( 2Eu ) complexes coordinated by neutral tripodal tris(3,5-dimethylpyrazolyl)methane (Tpm). The crystal structures of 1Ln and 2Ln were established by single crystal X-ray diffraction, while for 1Yb high resolution experiment was performed. Nitrate complexes 1Ln are isomorphous and both adopt mononuclear structure. Chloride 2Yb is monomeric, while Eu³⁺ analogue 2Eu adopts a binuclear structure due to two μ²-bridging chloride ligands. The typical lanthanide luminescence was observed for europium complexes ( 1Eu and 2Eu ) as well as for terbium and dysprosium analogues ([Ln(Tpm)(NO₃)₃] ⋅ MeCN, Ln=Tb ( 1Tb ), Dy ( 1Dy ); [Ln(Tpm)Cl₃] ⋅ 2MeCN, Ln=Tb ( 2Tb ), Dy ( 2Dy )).     

Synthesis,crystal structure,and properties of a new lanthanide tartrate coordination polymer

A new coordination polymer of terbium tartrate [Tb(H₂O)₃(C₄H₅O₆)(C₄H₄O₆)] has been synthesized and crystallizes in the polar space group P4₁ with cell constants a = 6.0415(9), b = 6.0415(9), c = 36.516(7) Å, V = 1332.8(4) ų, Z = 4. The terbium(III) ion of title complex is nine-coordinate through oxygen donors. Four different coordination modes of tartrate occur. This Tb(III) complex exhibits a characteristic luminescence in the visible region upon excitation at 353 nm. The temperature-dependent magnetic properties of the Tb(III) complex were investigated in the temperature range of 2–300 K. Title compound exhibits significant ferroelectric properties at room temperature (remnant polarization 2P _r = 0.160 μC cm^?2, coercive field 2E _c = 44.5 kV cm^?1, saturation of the spontaneous polarization P _s = 0.176 μC cm^?2).     

Beziehungen zwischen Lumineszenzspektrum und Struktur von Seltenerdkomplexen. III. Zur Existenz unterschiedlicher Polyedertypen bei Alkalitetrakis(dibenzoylmethanato)europat(III)-Komplexen

The luminescence spectra of alkali tetrakis(dibenzoylmethido)europate(III) complexes in the crystalline state at 77°K have been measured in the spectral region 510–640 nm. The spectra show the existence of different modifications of these compounds. The spectra of the β-forms are consistent with a site symmetry D₂ at the Eu(III) ion, the spectra of the corresponding α-forms with a site symmetry D₄. A conversion from the β-form into the α-form on heating is observed in some cases. The conversion involves a change from dodecahedral into antiprismatic coordination around the Eu(III) ion.     

Determination of fluoroquinolone antibiotics through the fluorescent response of Eu(III) based nanoparticles fabricated by layer-by-layer technique

The present work introduces the determination of fluoroquinolone antibiotics (FQs) in aqueous solutions through the fluorescent response of Eu(TTA)₃ and [Eu(TTA)₃1] (TTA⁻ and 1 are thenoyltrifluoroacetonate and phosphine oxide derivative) complexes encapsulated into the polyelectrolyte capsules fabricated through layer-by-layer deposition of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI). The variation of luminescent core, polyelectrolyte deposition and concentration conditions reveals two modes of fluorescent response on FQs of diverse structure namely the sensitization and quenching of Eu(III) centered luminescence. The obtained regularities reveal the ternary complex formation and the ligand exchange occurring at the interface of polyelectrolyte coated [Eu(TTA)₃1] based colloids as the reasons of the diverse fluorescent response of Eu(III) centered luminescence on FQs. The factors affecting the fluorescent response have been revealed, which are: the content of luminescent core, the mode of polyelectrolyte deposition, concentration and structure of FQs. The discrimination of moxifloxacin and lomefloxacin from levofloxacin, ofloxacin, difloxacin, perfloxacin through the quenching of Eu(III) luminescence in PSS-[Eu(TTA)₃1] colloids has been revealed.     

Synthesis,thermal, and photophysical properties of polymethylmethacryalte (PMMA) doped with ternary deuterated Eu(III) complexes

Two Eu(III) ternary luminescent complexes, Eu(tpb-H)₃(Tppo)₂ and Eu(tpb-H)₃(Topo)₂ (Tppo: triphenylphosphine oxide, Topo: trioctylphosphine oxide, tpb: 4,4,4-trifluoro-1-phenyl-1,3-butanedione) were synthesized using β-diketonates and phosphine oxides as ligands. Luminescent polymers were fabricated by incorporating the deuterated Eu(III) complexes in a PMMA matrix. Luminescent PMMA containing Eu(tpb-D)₃(Tppo)₂ exhibited relatively higher quantum yield, faster radiation rate, sharper red emission and larger stimulated emission cross-section and the results indicated prepared luminescent polymers including Eu(tpb-D)₃(Tppo)₂ showed promising results for applications in novel organic Eu(III) devices. Additionally, the Eu(III) complexes and luminescent PMMA showed good thermostabilization.     

Strongly photoluminescent Eu(III) tetrazolate ternary complexes with phosphine oxides as powerful sensitizers

The Eu(III) cation forms electrically neutral photoluminescent complex with 5-(2-pyridyl-1-oxide)tetrazolate (PTO) anion. Although the photoluminescence properties of such tertiary Eu(III) and Tb(III) complexes were not as high (13 and 31% photoluminescence quantum yield, respectively) as reported for other diketonate lanthanide complexes probably because of high number of nitrogen atoms involved in PTO which leads to attachment of water molecules, reducing the luminescence quantum yield with vibrational and rotational quenching. Here, we report the removal of quencher molecules from the coordination sphere of tris–europium tetrazolate oxide complex by replacing them with various phosphine oxides which leads to improved photoluminescence quantum yield for the complexes by acting as auxiliary co-ligands with that of the main antenna 5-(2-pyridyl-1-oxide)tetrazolate. The coordination sphere in these complexes can be complemented by aromatic phosphine oxides to provide highly photoluminescent Eu(III) complexes. The highest quantum yield was 38% in 3 [Eu(PTO)₃·DPEPO](H₂O)₅ containing bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) as compared to tris–europium complex with 5-(2-pyridyl-1-oxide)tetrazolate.     

Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing β‐Diketone and Schiff Bases

The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)₃]; Hpta=1,1,1‐trifluoro‐5,5‐dimethylhexane‐2,4‐dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H₂saltn), bis[5‐(tert‐butyl)salicylidene]trimethylenediamine (H₂(^tBu)saltn), or bis(salicylidene)cyclohexane‐1,2‐diyldiamine (H₂salchn), and the corresponding Zn^II complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)₃] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a ^tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)₃]. The luminescence spectrum of [ZnB] showed a band around 450 nm. The intensity decreased in the presence of [Eu(pta)₃], reflecting complexation between [Eu(pta)₃] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)₃Zn(saltn)], [Eu(pta)₃Zn{(^tBu)saltn}], and [Eu(pta)₃Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log , where =[[Eu(pta)₃ZnB]]([[Eu(pta)₃]][[ZnB]])^?1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)₃Zn(salchn)] revealed the strongest luminescence at 613 nm. The results of X‐ray diffraction analysis for [Eu(pta)₃Zn(saltn)] showed that Zn^II had a coordination number of five and was bridged with Eu^III by three donor O‐atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta.     

Complexation of Eu(Fod)3 in the ground and excited electronic states with the enantiomers of camphor in benzene: Chemiluminescence, kinetic luminescence, and polarimetric investigations

Complexation between europium(III) 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionate Eu(Fod)₃ in the ground and excited electronic states and D-(D) and L-camphor (L) in benzene was studied. The stability constants and thermodynamic parameters of formation of the complexes [Eu(Fod)₃(L)] and [Eu(Fod)₃(D)] were determined by chemiluminescent and polarimetric methods for the ground state and by kinetic luminescence spectroscopy for the excited state. The photoexcitation of Eu(Fod)₃ was found to enhance the stabilities of [Eu(Fod)₃(L)] and [Eu(Fod)₃(D)]. It was concluded that the photoexcitation of the f-f transitions in Eu(Fod)₃ increases the contribution from the 4f orbital to coordination bonding.     

1,2,4-Triazine method of bipyridine ligand synthesis for the preparation of new luminescent Eu(III) complexes

The ‘triazine’ methodology for the synthesis of functionalized bipyridine ligands proved to be a convenient method for the preparation of luminescent Eu(III) complexes. The approach allows flexible construction of chromophore and coordination sphere with control of photophysical properties. Europium(III) complexes [Eu1]-[Eu5] prepared in this way exhibit intense long-life metal-centered luminescence in aqueous media. The aromatic substituent in the position 5 of bipyridine has a significant influence on luminescence parameters and is used to introduce functionality for bioconjugation. The complexes [Eu4] and [Eu5] bearing primary amine groups are ready-to-go luminescent ‘tags’ for peptide labeling.