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Sample records for lanthanide btp complexes

  1. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Corneillie, Todd M; Xu, Jide

    2014-05-20

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  2. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N [Berkeley, CA; Corneillie, Todd M [Campbell, CA; Xu, Jide [Berkeley, CA

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  3. Aromatic triamide-lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Petoud, Stephane; Xu, Jide

    2013-10-08

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  4. New types of lanthanide complexes

    SciTech Connect

    Kahwa, I.A.K.

    1986-01-01

    Three new types of lanthanide (Ln) complexes, namely, the first examples of homodinuclear macrocyclic lanthanide complexes, novel binary and ternary gaseous polyatomic lanthanide oxides and new lanthanide oxalato complexes are described in chapters one, two and three respectively. The homodinuclear complexes are 2:2 condensation products of 2,6-diformyl-p-cresol and triethylenetetramine templated by Ln(NO/sub 3/)/sub 3/ and Ln(ClO/sub 4/)/sub 3/. The complexes are dimorphic, and are off-white (the more stable form) when they are obtained from dilute solutions and orange if they arise from more concentrated reactants. The complexes were characterized by elemental analysis, fast atom bombardment mass spectrometry (FAB MS), electronic absorption and IR spectroscopy, thermogravimetry along with preliminary spectroscopic studies using electron paramagnetic resonance, magnetic susceptibility and luminescence. The orange complexes exhibit more antiferromagnetic exchange interactions, low Ln/sup 3 +/magnetic moments and multi-exponential luminescence decay kinetics, whereas the off-white complexes show single exponential luminescence decay and free ion magnetic moments. At low temperatures and in presence of excess triethylenetetramine, solvated light lanthanide mononuclear complexes of a 1:1 acyclic Schiff base acetal were isolated and the structure of one of these was confirmed by single crystal x-ray diffraction crystallography.

  5. Lanthanide directed self-assembly of highly luminescent supramolecular "peptide" bundles from α-amino acid functionalized 2,6-bis(1,2,3-triazol-4-yl)pyridine (btp) ligands.

    PubMed

    Byrne, Joseph P; Kitchen, Jonathan A; O'Brien, John E; Peacock, Robert D; Gunnlaugsson, Thorfinnur

    2015-02-16

    Ligands containing the [2,6-bis(1,2,3-triazol-4-yl)pyridine] (btp) motif have recently shown promise in coordination chemistry. The motif is synthesized via the Cu(I)-catalyzed "click" reaction and can be conveniently functionalized when compared to other terdentate chelating motifs. Ligand 1 was synthesized and shown to sensitize Eu(III) and Tb(III) excited states effectively. The use of these ions to synthesize self-assembly structures in solution was investigated by carrying out both (1)H NMR and photophysical titrations. The latter were used to determine high binding constants from changes in the absorption, ligand emission (fluorescence), and lanthanide-centered emission. A small library of amino acid derivatives of 1, ligands 3, were prepared upon coupling reactions with Gly, Ala, Phe, and Trp methyl esters, with a view to introducing biologically relevant and chiral moieties into such ligands. All of these derivatives were shown to form stable, emissive Ln(III) self-assemblies, emitting in the millisecond time range, which were studied by means of probing their photophysical properties in organic solutions using lanthanide ion titrations. All the Tb(III) complexes, with the exception of Trp based derivatives, gave rise to highly luminescent and bright complexes, with quantum yields of Tb(III) emission of 46-70% in CH3CN solution. In contrast, the Eu(III) complexes gave rise to more modest quantum yields of 0.3-3%, reflecting better energy match for the Tb(III) complexes, and hence, more efficient sensitization, as demonstrated by using low temperature measurements to determine the triplet state of 1.

  6. Increasing the luminescence of lanthanide complexes.

    PubMed

    Leif, Robert C; Vallarino, Lidia M; Becker, Margie C; Yang, Sean

    2006-08-01

    This review compares the chemical and physical properties of lanthanide ion complexes and of other narrow-emitting species that can be used as labels for cytometry. A series of luminescent lanthanide ion macrocyclic complexes, Quantum Dyes, which do not release or exchange their central lanthanide ion, do accept energy transfer from ligands, and are capable of covalent binding to macromolecules, including proteins and nucleic acids, is described and their properties are discussed. Two methods are described for increasing the luminescence intensity of lanthanide ion complexes, which intrinsically is not as high as that of standard fluorophores or quantum dots. One method consists of adding a complex of a second lanthanide ion in a micellar solution (columinescence); the other method produces dry preparations by evaporation of a homogeneous solution containing an added complex of a second lanthanide ion or an excess of an unbound antenna ligand. Both methods involve the Resonance Energy Transfer Enhanced Luminescence, RETEL, effect as the mechanism for the luminescence enhancement.

  7. Chiroptical Probing of Lanthanide-Directed Self-Assembly Formation Using btp Ligands Formed in One-Pot Diazo-Transfer/Deprotection Click Reaction from Chiral Amines.

    PubMed

    Byrne, Joseph P; Martínez-Calvo, Miguel; Peacock, Robert D; Gunnlaugsson, Thorfinnur

    2016-01-11

    A series of enantiomeric 2,6-bis(1,2,3-triazol-4-yl)pyridines (btp)-containing ligands was synthesized by a one-pot two-step copper-catalyzed amine/alkyne click reaction. The Eu(III) - and Tb(III) -directed self-assembly formation of these ligands was studied in CH3 CN by monitoring their various photophysical properties, including their emerging circular dichroism and circularly polarized luminescence. The global analysis of the former enabled the determination of both the stoichiometry and the stability constants of the various chiral supramolecular species in solution.

  8. Hexaaza macrocyclic complexes of the lanthanides

    SciTech Connect

    De Cola, L.; Smailes, D.L.; Vallarino, L.M.

    1986-05-07

    The authors systematically investigate the conditions leading to the metal-templated macrocyclic synthesis and obtain by an appropriate combination of counterions and experimental conditions, two series of complexes of the macrocyclic ligand L = C/sub 22/H/sub 26/N/sub 6/, with every lanthanide(III) ion except radioactive Pm. Their synthesis, characterization, and properties are described here. 13 references, 2 figures.

  9. Calibration beads containing luminescent lanthanide ion complexes

    EPA Science Inventory

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  10. Calibration beads containing luminescent lanthanide ion complexes

    EPA Science Inventory

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  11. On the stoichiometry and stability of americium(III) complexes with a hydrophilic SO3-Ph-BTP ligand, studied by liquid-liquid extraction.

    PubMed

    Steczek, Łukasz; Rejnis, Magdalena; Narbutt, Jerzy; Charbonnel, Marie-Christine; Moisy, Philippe

    1:1 and 1:2 complexes of americium(III) with a hydrophilic anionic SO3-Ph-BTP(4-) ligand were detected in acidic aqueous nitrate solutions by a solvent extraction method. The determined conditional stability constants of these complexes, logβ1 = 4.35 ± 0.07 and logβ2 = 7.67 ± 0.06, related to 1 M aqueous solutions, are much lower than the literature values for the analogous curium species, determined by TRLFS in very dilute aqueous solutions. There is also no evidence for the existence of the 1:3 Am(3+) complex similar to the reported curium(III) complex. A hypothesis has been formulated to explain these discrepancies. It suggests the necessity to carefully check the equilibria in each phase of solvent extraction systems containing two competing ligands-lipophilic and hydrophilic.

  12. Luminescent lanthanide complexes for advanced photonic applications

    NASA Astrophysics Data System (ADS)

    Puntus, Lada N.; Sergeeva, Elena V.; Antonov, Dmitrii Y.; Lyssenko, Konstantin A.; Kajzar, Francois

    2010-10-01

    The lanthanide compounds containing unsymmetrical β-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical β-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral meso, (R,S)-) of the β-diketones and their respective N-phenylimines exhibit quite identical absorption spectra with intense broad band centered at 360 and 380 nm, respectively. The designed blue-emitting unsymmetrical β-diketone acts as a very efficient sensitizer of the EuIII emission and does so in the near-UV region. The introduction of [2.2]paracyclophane moiety in the β-diketones allows to expand the excitation wavelength of the lanthanide complex up to 500 nm and to obtain the relatively high overall quantum yield for the europium ion.

  13. Phthalamide-lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N.; Petoud, Stephane; Cohen, Seth M.; Xu, Jide

    2005-03-08

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  14. Salicylamide-lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N.; Petoud, Stephane; Cohen, Seth; Xu, Jide

    2002-01-01

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one salicylamidyl moiety. Also provided are probes incorporating the salicylamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  15. Salicylamide-lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N [Berkeley, CA; Petoud, Stephane [Berkeley, CA; Cohen, Seth [Boston, MA; Xu, Jide [Berkeley, CA

    2008-07-29

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one salicylamidyl moiety. Also provided are probes incorporating the salicylamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  16. Salicylamide-lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N.; Petoud, Stephane; Cohen, Seth; Xu, Jide

    2006-03-28

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one salicylamidyl moiety. Also provided are probes incorporating the salicylamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  17. Phthalamide-lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N [Berkeley, CA; Petoud, Stephane [Pittsburgh, PA; Cohen, Seth [Boston, MA; Xu, Jide [Berkeley, CA

    2008-10-28

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  18. Phthalamide lanthanide complexes for use as luminescent markers

    DOEpatents

    Raymond, Kenneth N.; Petoud, Stephane; Cohen, Seth M.; Xu, Jide

    2003-01-01

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  19. Lanthanide corroles: a new class of macrocyclic lanthanide complexes.

    PubMed

    Buckley, Heather L; Anstey, Mitchell R; Gryko, Daniel T; Arnold, John

    2013-04-18

    The first examples of lanthanide corroles are prepared by two synthetic routes. (Mes2(p-OMePh)corrole)La·4.5DME (1·4.5DME) and (Mes2(p-OMePh)corrole)Tb·4DME (2·4DME) are prepared from the free base corrole and Ln((NSiMe3)2)3, while (Mes2(p-OMePh)corrole)Gd·TACNMe3 (3·TACNMe3) is prepared by metathesis of the recently reported Li3 corrole and GdCl3.

  20. Lanthanide Complexes as a Test for Evidence of Life

    NASA Technical Reports Server (NTRS)

    Benavides, Jeannette

    1998-01-01

    The objective of this research is to advance the understanding of the interaction of lanthanide metals with biological organic molecules and to develop a technique to detect these compounds in the solid state and in situ in Mars and other planetary bodies. The detection of these complexes should provide evidence of life past or present. In addition, detection of the metals alone will provide important information about the geological history of a planetary body. Lanthanides were chosen as our focus of interest because they form very stable complexes with organic molecules in solution and they produce intense luminescence in the ultraviolet and visible spectra. The rare earth complexes available are mostly synthetic for diverse applications in medicine. There is not much work done on the complexes that form in nature. Lanthanides have many applications and they are mined aR over the world, however, since the interest has been only in the elements, the analytical techniques employed destroy any organic ligands that may be present. In order to determine if and which lanthanide complexes form in nature and their concentration, soil samples have been collected from areas rich in soluble lanthanide compounds like phosphates and also rich in vegetation. The soil samples will be analyzed and the lanthanide complexes if present will be isolated and characterized. A spectrometer to detect the lanthanide complexes in situ and in the solid state will be designed. In this workshop, the research approach and its implications will be discussed.

  1. Remarkable luminescence properties of lanthanide complexes with asymmetric dodecahedron structures.

    PubMed

    Miyata, Kohei; Nakagawa, Tetsuya; Kawakami, Ryuhei; Kita, Yuki; Sugimoto, Katsufumi; Nakashima, Takuya; Harada, Takashi; Kawai, Tsuyoshi; Hasegawa, Yasuchika

    2011-01-10

    The distorted coordination structures and luminescence properties of novel lanthanide complexes with oxo-linked bidentate phosphane oxide ligands--4,5-bis(diphenylphosphoryl)-9,9-dimethylxanthene (xantpo), 4,5-bis(di-tert-butylphosphoryl)-9,9-dimethylxanthene (tBu-xantpo), and bis[(2-diphenylphosphoryl)phenyl] ether (dpepo)--and low-vibrational frequency hexafluoroacetylacetonato (hfa) ligands are reported. The lanthanide complexes exhibit characteristic square antiprism and trigonal dodecahedron structures with eight-coordinated oxygen atoms. The luminescence properties of these complexes are characterized by their emission quantum yields, emission lifetimes, and their radiative and nonradiative rate constants. Lanthanide complexes with dodecahedron structures offer markedly high emission quantum yields (Eu: 55-72 %, Sm: 2.4-5.0 % in [D(6)]acetone) due to enhancement of the electric dipole transition and suppression of vibrational relaxation. These remarkable luminescence properties are elucidated in terms of their distorted coordination structures.

  2. Luminogenic "clickable" lanthanide complexes for protein labeling.

    PubMed

    Candelon, Nicolas; Hădade, Niculina D; Matache, Mihaela; Canet, Jean-Louis; Cisnetti, Federico; Funeriu, Daniel P; Nauton, Lionel; Gautier, Arnaud

    2013-10-14

    Development of lanthanide-based luminescent "switch-on" systems via azide-alkyne [3+2] cycloaddition is described. We used these for non-specific protein labeling and as tags for specific and selective activity-based protein labeling.

  3. Methyltrihydroborate complexes of the lanthanides and actinides

    SciTech Connect

    Shinomoto, R.S.

    1984-11-01

    Reaction of MC1/sub 4/ (M = Zr, Hf, U, Th, Np) with LiBH/sub 3/CH/sub 3/ in chlorobenzene produces volatile, hexane-soluble M(BH/sub 3/CH/sub 3/)/sub 4/. Crystal structures are monomeric, tetrahedral species. Lewis base adducts prepared include U(BH/sub 3/CH/sub 3/)/sub 4/.THT, Th(BH/sub 3/CH/sub 3/)/sub 4/.L (L = THF (tetrahydrofuran), THT (tetrahydrothiophene), SMe/sub 2/, OMe/sub 2/), U(BH/sub 3/CH/sub 3/)/sub 4/.2L (L = THF, pyridine, NH/sub 3/), Th(BH/sub 3/CH/sub 3/)/sub 4/.2L (L = THF, THT, py, NH/sub 3/), M(BH/sub 3/CH/sub 3/)/sub 4/.L-L (M = U, Th; L-L = dme (1,2-dimethoxyethane), bmte (bis(1,2-methylthio)ethane), tmed (N,N,N',N'-tetramethylethylenediamine), dmpe (1,2-dimethylphosphinoethane)) and Th(BH/sub 3/CH/sub 3/)/sub 4/.1/2 OEt/sub 2/. Reaction of MC1/sub 3/ (M = Ho, Yb, Lu) with LiBH/sub 3/CH/sub 3/ in diethyl ether produces volatile, toluene-soluble M(BH/sub 3/CH/sub 3/)/sub 3/.OEt/sub 2/. Other Lewis base adducts prepared from M(BH/sub 3/CH/sub 3/)/sub 3/.OEt/sub 2/ include Ho(BH/sub 3/CH/sub 3/)/sub 3/.L (L = THT, THF, py), Ho(BH/sub 3/CH/sub 3/)/sub 3/.2L (L = THT, THF, py), Ho(BH/sub 3/CH/sub 3/)/sub 3/.tmed, Ho(BH/sub 3/CH/sub 3/)/sub 3/.3/2 L-L (L-L = dmpe, bmte), Yb(BH/sub 3/CH/sub 3/)/sub 3/.3/2 dmpe, Yb(BH/sub 3/Ch/sub 3/).L (L = THF, dme), Yb(BH/sub 3/CH/sub 3/)/sub 3/.2THF, and Lu(BH/sub 3/CH/sub 3/)/sub 3/.THF. By structural criteria, the bonding in actinide and lanthanide methyltrihydroborate complexes is primarily ionic in character even though they display covalent-like physical properties. Spectroscopic measurements indicate that there is some degree of covalent bonding in U(BH/sub 3/CH/sub 3/)/sub 4/.

  4. Luminescent chiral lanthanide(III) complexes as potential molecular probes

    PubMed Central

    Muller, Gilles

    2009-01-01

    This perspective gives an introduction into the design of luminescent lanthanide(III)-containing complexes possessing chiral properties and used to probe biological materials. The first part briefly describes general principles, focusing on the optical aspect (i.e. lanthanide luminescence, sensitization processes) of the most emissive trivalent lanthanide ions, europium and terbium, incorporated into molecular luminescent edifices. This is followed by a short discussion on the importance of chirality in the biological and pharmaceutical fields. The second part is devoted to the assessment of the chiroptical spectroscopic tools available (typically circular dichroism and circularly polarized luminescence) and the strategies used to introduce a chiral feature into luminescent lanthanide(III) complexes (chiral structure resulting from a chiral arrangement of the ligand molecules surrounding the luminescent center or presence of chiral centers in the ligand molecules). Finally, the last part illustrates these fundamental principles with recent selected examples of such chiral luminescent lanthanide-based compounds used as potential probes of biomolecular substrates. PMID:19885510

  5. Synthesis and chemistry of yttrium and lanthanide metal complexes

    SciTech Connect

    Evans, W.J.

    1991-09-01

    The objective of this research project is to determine the special features of complexes of yttrium and the lanthanide metals which will allow the design and synthesis of materials with unique chemical, physical, and catalytic properties. Past studies of yttrium and lanthanide metal alkyl and hydride complexes stabilized by cyclopentadienyl co-ligands have shown that a substantial, often singular, organometallic chemistry is available via these metals. More extensive utilization of the chemical opportunities available through yttrium and the lanthanides would be possible, however, if stabilizing ancillary ligand systems less sensitive to oxidation and protonolysis than cyclopentadienides could be developed. Alkoxide ligands are attractive in this regard and our recent research had focused on alkoxides and the special opportunities they can provide to these metals. 6 refs., 10 figs.

  6. Experimental and Theoretical Studies on Biologically Active Lanthanide (III) Complexes

    NASA Astrophysics Data System (ADS)

    Kostova, I.; Trendafilova, N.; Georgieva, I.; Rastogi, V. K.; Kiefer, W.

    2008-11-01

    The complexation ability and the binding mode of the ligand coumarin-3-carboxylic acid (HCCA) to La(III), Ce(III), Nd(III), Sm(III), Gd(III) and Dy(III) lanthanide ions (Ln(III)) are elucidated at experimental and theoretical level. The complexes were characterized using elemental analysis, DTA and TGA data as well as 1H NMR and 13C NMR spectra. FTIR and Raman spectroscopic techniques as well as DFT quantum chemical calculations were used for characterization of the binding mode and the structures of lanthanide(III) complexes of HCCA. The metal—ligand binding mode is predicted through molecular modeling and energy estimation of different Ln—CCA structures using B3LYP/6-31G(d) method combined with a large quasi-relativistic effective core potential for lanthanide ion. The energies obtained predict bidentate coordination of CCA- to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen. Detailed vibrational analysis of HCCA, CCA- and Ln(III) complexes based on both calculated and experimental frequencies confirms the suggested metal—ligand binding mode. The natural bonding analysis predicts strongly ionic character of the Ln(III)-CCA bonding in the- complexes studied. With the relatively resistant tumor cell line K-562 we obtained very interesting in-vitro results which are in accordance with our previously published data concerning the activity of lanthanide(III) complexes with other coumarin derivatives.

  7. Detection of bacterial spores with lanthanide-macrocycle binary complexes.

    PubMed

    Cable, Morgan L; Kirby, James P; Levine, Dana J; Manary, Micah J; Gray, Harry B; Ponce, Adrian

    2009-07-15

    The detection of bacterial spores via dipicolinate-triggered lanthanide luminescence has been improved in terms of detection limit, stability, and susceptibility to interferents by use of lanthanide-macrocycle binary complexes. Specifically, we compared the effectiveness of Sm, Eu, Tb, and Dy complexes with the macrocycle 1,4,7,10-tetraazacyclododecane-1,7-diacetate (DO2A) to the corresponding lanthanide aquo ions. The Ln(DO2A)(+) binary complexes bind dipicolinic acid (DPA), a major constituent of bacterial spores, with greater affinity and demonstrate significant improvement in bacterial spore detection. Of the four luminescent lanthanides studied, the terbium complex exhibits the greatest dipicolinate binding affinity (100-fold greater than Tb(3+) alone, and 10-fold greater than other Ln(DO2A)(+) complexes) and highest quantum yield. Moreover, the inclusion of DO2A extends the pH range over which Tb-DPA coordination is stable, reduces the interference of calcium ions nearly 5-fold, and mitigates phosphate interference 1000-fold compared to free terbium alone. In addition, detection of Bacillus atrophaeus bacterial spores was improved by the use of Tb(DO2A)(+), yielding a 3-fold increase in the signal-to-noise ratio over Tb(3+). Out of the eight cases investigated, the Tb(DO2A)(+) binary complex is best for the detection of bacterial spores.

  8. Detection of Bacterial Spores with Lanthanide-Macrocycle Binary Complexes

    PubMed Central

    Cable, Morgan L.; Kirby, James P.; Levine, Dana J.; Manary, Micah J.; Gray, Harry B.; Ponce, Adrian

    2009-01-01

    The detection of bacterial spores via dipicolinate-triggered lanthanide luminescence has been improved in terms of detection limit, stability, and susceptibility to interferents by use of lanthanide-macrocycle binary complexes. Specifically, we compared the effectiveness of Sm, Eu, Tb and Dy complexes with the macrocycle 1,4,7,10-tetraazacyclododecane-1,7-diacetate (DO2A) to the corresponding lanthanide aquo ions. The Ln(DO2A)+ binary complexes bind dipicolinic acid (DPA), a major constituent of bacterial spores, with greater affinity and demonstrate significant improvement in bacterial spore detection. Of the four luminescent lanthanides studied, the terbium complex exhibits the greatest dipicolinate binding affinity (100-fold greater than Tb3+ alone, and 10-fold greater than other Ln(DO2A)+ complexes) and highest quantum yield. Moreover, the inclusion of DO2A extends the pH range over which Tb-DPA coordination is stable, reduces the interference of calcium ions nearly 5-fold, and mitigates phosphate interference 1000-fold compared to free terbium alone. In addition, detection of Bacillus atrophaeus bacterial spores was improved by the use of Tb(DO2A)+, yielding a 3-fold increase in the signal-to-noise ratio over Tb3+. Out of the eight cases investigated, the Tb(DO2A)+ binary complex is best for the detection of bacterial spores. PMID:19537757

  9. The synthesis, design and applications of lanthanide cored complexes

    NASA Astrophysics Data System (ADS)

    Phelan, Gregory David

    Novel luminescent materials based on lanthanide cored complexes have been designed and synthesized. The complexes consist of a beta-diketone ligand chelated to a lanthanide metal such as europium or gadolinium. A series of beta-diketone ligands were designed and synthesized. The ligands consist of a polycyclic aromatic sensitizer, phenanthrene, and a second functional group. The second groups consisted of another unit of phenanthrene, a dendritic structure, or a fluorinated alkyl chain. The europium complexes have been incorporated into organic light emitting devices that have a major emission at 615 nm and a maximum brightness of 300 cd/m2. The gadolinium complexes were used to dope into the resulting organic light emitting devices to help improve the efficiency of the device. The use of the gadolinium complexes results in a 25 fold increase in efficiency.

  10. Lanthanide macrocyclic complexes, 'quantum dyes': optical properties and significance

    NASA Astrophysics Data System (ADS)

    Vallarino, Lidia M.; Harlow, Patrick M.; Leif, Robert C.

    1993-05-01

    Macrocylic complexes of the lanthanide (III) ions were functionalized to permit their attachment to antibodies, nucleic acid probes, and any other species capable of specific binding. The Eu(III) complex was found to possess a combination of properties (water solubility, inertness to metal release, ligand-sensitized luminescence, reactive peripheral functionalities) that make it suitable as a luminescent marker for bio-substrates. Its coupling to avidin was achieved, and the properties of the resulting conjugate were investigated.

  11. Complexation of lanthanides and actinides by acetohydroxamic acid

    SciTech Connect

    Taylor, R.J.; Sinkov, S.I.; Choppin, G.R.

    2008-07-01

    Acetohydroxamic acid (AHA) has been proposed as a suitable reagent for the complexant-based, as opposed to reductive, stripping of plutonium and neptunium ions from the tributylphosphate solvent phase in advanced PUREX or UREX processes designed for future nuclear-fuel reprocessing. Stripping is achieved by the formation of strong hydrophilic complexes with the tetravalent actinides in nitric acid solutions. To underpin such applications, knowledge of the complexation constants of AHA with all relevant actinide (5f) and lanthanide (4f) ions is therefore important. This paper reports the determination of stability constants of AHA with the heavier lanthanide ions (Dy-Yb) and also U(IV) and Th(IV) ions. Comparisons with our previously published AHA stability-constant data for 4f and 5f ions are made. (authors)

  12. Helical lanthanide(III) complexes with chiral nonaaza macrocycle.

    PubMed

    Gregoliński, Janusz; Starynowicz, Przemysław; Hua, KimNgan T; Lunkley, Jamie L; Muller, Gilles; Lisowski, Jerzy

    2008-12-31

    The chiral nonaazamacrocyclic amine L, which is a reduction product of the 3 + 3 Schiff base macrocycle, wraps around the lanthanide(III) ions to form enantiopure helical complexes. These Ce(III), Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Er(III), Yb(III) and Lu(III) complexes have been isolated in enantiopure form and have been characterized by spectroscopic methods. X-ray crystal structures of the Ln(III) complexes with L show that the thermodynamic product of the complexation of the RRRRRR-isomer of the macrocycle is the (M)-helical complex in the case of Ce(III), Pr(III), Nd(III) and Eu(III). In contrast, the (P)-helical complex is the thermodynamic product in the case of Yb(III) and Lu(III). The NMR and CD spectra show that the (M)-helicity for the kinetic complexation product of the RRRRRR-isomer of the macrocycle is preferred for all investigated lanthanide(III) ions, while the preferred helicity of the thermodynamic product is (M) for the early lanthanide(III) ions and (P) for the late lanthanide(III) ions. In the case of the late lanthanide(III) ions, a slow inversion of helicity between the kinetic (M)-helical product and the thermodynamic (P)-helical product is observed in solution. For Er(III), Yb(III) and Lu(III) both forms have been isolated in pure form and characterized by NMR and CD. The analysis of 2D NMR spectra of the Lu(III) complex reveals the NOE correlations that prove that the helical structure is retained in solution. The NMR spectra also reveal large isotopic effect on the 1H NMR shifts of paramagnetic Ln(III) complexes, related to NH/ND exchange. Photophysical measurements show that L(RRRRRR) appears to favor an efficient 3pipi*-to-Ln energy transfer process taking place for Eu(III) and Tb(III), but these Eu(III)- and Tb(III)-containing complexes with L(RRRRRR) lead to small luminescent quantum yields due to an incomplete intersystem crossing (isc) transfer, a weak efficiency of the luminescence sensitization by the ligand, and

  13. Magnetic circular dichroism of porphyrin lanthanide M3+ complexes.

    PubMed

    Andrushchenko, Valery; Padula, Daniele; Zhivotova, Elena; Yamamoto, Shigeki; Bouř, Petr

    2014-10-01

    Lanthanide complexes exhibit interesting spectroscopic properties yielding many applications as imaging probes, natural chirality amplifiers, and therapeutic agents. However, many properties are not fully understood yet. Therefore, we applied magnetic circular dichroism (MCD) spectroscopy, which provides enhanced information about the underlying electronic structure to a series of lanthanide compounds. The metals in the M(3+) state included Y, La, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu; the spectra were collected for selected tetraphenylporphin (TPP) and octaethylporphin (OEP) complexes in chloroform. While the MCD and UV-VIS absorption spectra were dominated by the porphyrin signal, metal binding significantly modulated them. MCD spectroscopy was found to be better suited to discriminate between various species than absorption spectroscopy alone. The main features and trends in the lanthanide series observed in MCD and absorption spectra of the complexes could be interpreted at the Density Functional Theory (DFT) level, with effective core potentials on metal nuclei. The sum over state (SOS) method was used for simulation of the MCD intensities. The combination of the spectroscopy and quantum-chemical computations is important for understanding the interactions of the metals with the organic compounds.

  14. Photoacoustic spectroscopy study on lanthanide complexes with aromatic carboxylic acid in silica gels

    NASA Astrophysics Data System (ADS)

    Yang, Y.-T.; Zhang, S.-Y.

    2005-06-01

    Using a sol-gel process, lanthanide complexes Ln (Sal)3.HO (Ln^3+: Nd^3+, Tb^3+; Sal: salicylic acid) are incorporated into silica gels by the hydrolysis and condensation of tetraethoxysilane (TEOS). After heat treatment at 150 °C for the lanthanide complexes in gels, the photoacoustic (PA) intensity of the ligand changes remarkably, while this difference can not be observed for the samples without heat treatment. Different PA intensities of lanthanide complexes in silica gels can be interpreted by comparison them with their luminescence spectra. The formation of lanthanide complex in silica gel is discussed by two aspects: radiative and nonradiative processes.

  15. Energetic lanthanide complexes: coordination chemistry and explosives applications

    NASA Astrophysics Data System (ADS)

    Manner, V. W.; Barker, B. J.; Sanders, V. E.; Laintz, K. E.; Scott, B. L.; Preston, D. N.; Sandstrom, M.; Reardon, B. L.

    2014-05-01

    Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with 'tailor made' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

  16. Energetic Lanthanide Complexes: Coordination Chemistry and Explosives Applications

    NASA Astrophysics Data System (ADS)

    Manner, Virginia; Barker, Beau; Sanders, Eric; Laintz, Kenneth; Scott, Brian; Preston, Daniel; Sandstrom, Mary; Reardon, Bettina

    2013-06-01

    Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with ``tailor made'' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

  17. Pyridinophane platform for stable lanthanide(III) complexation.

    PubMed

    Castro, Goretti; Bastida, Rufina; Macías, Alejandro; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2013-05-20

    A detailed investigation of the solid state and solution structures of lanthanide(III) complexes with the macrocyclic ligand 2,11,20-triaza[3.3.3](2,6)pyridinophane (TPP) is reported. The solid state structures of 14 different Ln(3+) complexes have been determined using X-ray crystallography. The ligand is coordinating to the Ln(3+) ion by using its six nitrogen atoms, while nitrate or triflate anions and water molecules complete the metal coordination environments. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by DFT calculations (TPSSh model) performed in aqueous solution. The structures obtained from these calculations for the complexes with the lightest Ln(3+) ions (La-Sm) are in very good agreement with those determined by the analysis of the Ln(3+)-induced paramagnetic shifts. A structural change occurs across the lanthanide series at Sm(3+); the complexes of the large Ln(3+) ions (La-Nd) are chiral due to the nonplanar conformation of the macrocycle, and present effective C3v symmetries in solution as a consequence of a fast interconversion of two enantiomeric forms with C3 symmetry. The activation free energy for this enantiomerization process, as estimated by using DFT calculations, amounts to 33.0 kJ·mol(-1). The TPP ligand in the complexes of the heaviest Ln(3+) ions (Eu-Lu) presents a half-chair conformation, which results in C(s) symmetries in solution.

  18. Lanthanide complexes of azidophenacyl-DO3A as new synthons for click chemistry and the synthesis of heterometallic lanthanide arrays.

    PubMed

    Tropiano, Manuel; Kenwright, Alan M; Faulkner, Stephen

    2015-04-07

    Lanthanide complexes of azidophenacyl DO3A are effective substrates for click reactions with ethyne derivatives, giving rise to aryl triazole appended lanthanide complexes, in which the aryl triazole acts as an effective sensitising chromophore for lanthanide luminescence. They also undergo click chemistry with propargylDO3A derivatives, giving rise to heterometallic complexes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Magnetic Interactions in a Series of Homodinuclear Lanthanide Complexes.

    PubMed

    Comba, Peter; Großhauser, Michael; Klingeler, Rüdiger; Koo, Changhyun; Lan, Yanhua; Müller, Dennis; Park, Jaena; Powell, Annie; Riley, Mark J; Wadepohl, Hubert

    2015-12-07

    A series of seven isostructural homodinuclear lanthanide complexes are reported. The magnetic properties (ac and dc SQUID measurements) are discussed on the basis of the X-ray structural properties which show that the two lanthanide sites are structurally different. MCD spectroscopy of the dysprosium(III) and neodymium(III) complexes ([Dy(III)2(L)(OAc)4](+) and [Nd(III)2(L)(OAc)4](+)) allowed us to thoroughly analyze the ligand field, and high-frequency EPR spectroscopy of the gadolinium(III) species ([Gd(III)2(L)(OAc)4](+)) showed the importance of dipolar coupling in these systems. An extensive quantum-chemical analysis of the dysprosium(III) complex ([Dy(III)2(L)(OAc)4](+)), involving an ab initio (CASSCF) wave function, explicit spin-orbit coupling (RASSI-SO), and a ligand field analysis (Lines model and Stevens operators), is in full agreement with all experimental data (SQUID, HF-EPR, MCD) and specifically allowed us to accurately simulate the experimental χT versus T data, which therefore allowed us to establish a qualitative model for all relaxation pathways.

  20. Effect of Lanthanide Complex Structure on Cell Viability and Association

    PubMed Central

    2015-01-01

    A systematic study of the effect of hydrophobicity and charge on the cell viability and cell association of lanthanide metal complexes is presented. The terbium luminescent probes feature a macrocyclic polyaminocarboxylate ligand (DOTA) in which the hydrophobicity of the antenna and that of the carboxyamide pendant arms are independently varied. Three sensitizing antennas were investigated in terms of their function in vitro: 2-methoxyisophthalamide (IAM(OMe)), 2-hydroxyisophthalamide (IAM), and 6-methylphenanthridine (Phen). Of these complexes, Tb-DOTA-IAM exhibited the highest quantum yield, although the higher cell viability and more facile synthesis of the structurally related Tb-DOTA-IAM(OMe) platform renders it more attractive. Further modification of this latter core structure with carboxyamide arms featuring hydrophobic benzyl, hexyl, and trifluoro groups as well as hydrophilic amino acid based moieties generated a family of complexes that exhibit high cell viability (ED50 > 300 μM) regardless of the lipophilicity or the overall complex charge. Only the hexyl-substituted complex reduced cell viability to 60% in the presence of 100 μM complex. Additionally, cellular association was investigated by ICP-MS and fluorescence microscopy. Surprisingly, the hydrophobic moieties did not increase cell association in comparison to the hydrophilic amino acid derivatives. It is thus postulated that the hydrophilic nature of the 2-methoxyisophthalamide antenna (IAM(OMe)) disfavors the cellular association of these complexes. As such, responsive luminescent probes based on this scaffold would be appropriate for the detection of extracellular species. PMID:24901440

  1. Preparation and Properties of Transparent Ultrathin Lanthanide-Complex Films.

    PubMed

    Li, Yali; Xu, Yang; Wang, Yige

    2016-07-25

    Highly transparent ultrathin films (UTFs) based on alternative layer-by-layer assembly of Eu- and Tb-based lanthanide complexes (LCs) and Mg-Al-layered double hydroxide (LDH) nanosheets are reported herein. UV-visible absorption and fluorescence spectroscopy showed an orderly growth of the two types of ultrathin films upon increasing the number of deposition cycles. AFM and SEM measurements indicate that the films feature periodic layered structures as well as uniform surface morphology. Luminescent investigations reveal that (LCs/LDH)n UTFs can detect Fe(3+) with relative selectivity and high sensitivity (Stern-Volmer constant KSV =8.43×10(3)  L mol(-1) ); this suggests that (LCs/LDH)n UTFs could be a promising luminescent probe for selectively sensing Fe(3+) ion.

  2. Fluoride Binding and Crystal-Field Analysis of Lanthanide Complexes of Tetrapicolyl-Appended Cyclen.

    PubMed

    Blackburn, Octavia A; Kenwright, Alan M; Jupp, Andrew R; Goicoechea, Jose M; Beer, Paul D; Faulkner, Stephen

    2016-06-20

    Lanthanide complexes of tetrapicolyl cyclen displayed remarkably high affinities for fluoride (log K≈5) in water, and were shown to form 1:1 complexes. The behaviour of these systems can be rationalised by changes to the magnitude of the crystal-field parameter, B20 . However, such changes are not invariably accompanied by a change in sign of this parameter: for early lanthanides, the N8 donor set with a coordinated axial water molecule ensures that the magnetic anisotropy has the opposite sense to that observed in the analogous dehydrated lanthanide complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Highly Luminescent Lanthanide Complexes of 1 Hydroxy-2-pyridinones

    SciTech Connect

    University of California, Berkeley; Lawrence National Laboratory; Raymond, Kenneth; Moore, Evan G.; Xu, Jide; Jocher, Christoph J.; Castro-Rodriguez, Ingrid; Raymond, Kenneth N.

    2007-11-01

    The synthesis, X-ray structure, stability, and photophysical properties of several trivalent lanthanide complexes formed from two differing bis-bidentate ligands incorporating either alkyl or alkyl ether linkages and featuring the 1-hydroxy-2-pyridinone (1,2-HOPO) chelate group in complex with Eu(III), Sm(III) and Gd(III) are reported. The Eu(III) complexes are among some of the best examples, pairing highly efficient emission ({Phi}{sub tot}{sup Eu} {approx} 21.5%) with high stability (pEu {approx} 18.6) in aqueous solution, and are excellent candidates for use in biological assays. A comparison of the observed behavior of the complexes with differing backbone linkages shows remarkable similarities, both in stability and photophysical properties. Low temperature photophysical measurements for a Gd(III) complex were also used to gain insight into the electronic structure, and were found to agree with corresponding TD-DFT calculations for a model complex. A comparison of the high resolution Eu(III) emission spectra in solution and from single crystals also revealed a more symmetric coordination geometry about the metal ion in solution due to dynamic rotation of the observed solid state structure.

  4. Zirconium(IV)-Benzene Phosphonate Coordination Polymers: Lanthanide and Actinide Extraction and Thermal Properties.

    PubMed

    Luca, Vittorio; Tejada, Juan J; Vega, Daniel; Arrachart, Guilhem; Rey, Cyrielle

    2016-08-15

    Coordination polymers with different P/(Zr + P) molar ratios were prepared by combining aqueous solutions of Zr(IV) and benzenephosphonate derivatives. 1,3,5-Benzenetrisphosphonic acid (BTP) as well as phosphonocarboxylate derivatives in which carboxylate substitutes one or two of the phosphonate groups were chosen as the building blocks. The precipitates obtained on combining the two solutions were not X-ray amorphous but rather were indicative of poorly ordered materials. Hydrothermal treatment did not alter the structure of the materials produced but did result in improved crystalline order. The use of HF as a mineralizing agent during hydrothermal synthesis resulted in the crystallization of at least three relatively crystalline phases whose structure could not be determined owing to the complexity of the diffraction patterns. Gauging from the similarity of the diffraction patterns of all the phases, the poorly ordered precipitates and crystalline materials appeared to have similar underlying structures. The BTP-based zirconium phosphonates all showed a higher selectivity for lanthanides and thorium compared with cations such as Cs(+), Sr(2+), and Co(2+). Substitution of phosphonate groups by carboxylate groups did little to alter the pattern of selectivity implying that selectivity in the system was entirely determined by the -POH group with little influence from the -COOH groups. Samples with the highest phosphorus content showed the highest extraction efficiencies for lanthanide elements, especially the heavy lanthanides such as Dy(3+) and Ho(3+) with separation factors of around four with respect to La(3+). In highly acid solutions (4 M HNO3) there was a pronounced variation in extraction efficiency across the lanthanide series. In situ, nonambient diffraction was performed on ZrBTP-0.8 loaded with Th, Ce, and a complex mixture of lanthanides. In all cases the crystalline Zr2P2O7 pyrophosphate phase was formed at ∼800 °C demonstrating the versatility of

  5. A bridge to coordination isomer selection in lanthanide(III) DOTA-tetraamide complexes.

    PubMed

    Vipond, Jeff; Woods, Mark; Zhao, Piyu; Tircsó, Gyula; Ren, Jimin; Bott, Simon G; Ogrin, Doug; Kiefer, Garry E; Kovacs, Zoltan; Sherry, A Dean

    2007-04-02

    Interest in macrocyclic lanthanide complexes such as DOTA is driven largely through interest in their use as contrast agents for MRI. The lanthanide tetraamide derivatives of DOTA have shown considerable promise as PARACEST agents, taking advantage of the slow water exchange kinetics of this class of complex. We postulated that water exchange in these tetraamide complexes could be slowed even further by introducing a group to sterically encumber the space above the water coordination site, thereby hindering the departure and approach of water molecules to the complex. The ligand 8O2-bridged DOTAM was synthesized in a 34% yield from cyclen. It was found that the lanthanide complexes of this ligand did not possess a water molecule in the inner coordination sphere of the bound lanthanide. The crystal structure of the ytterbium complex revealed that distortions to the coordination sphere were induced by the steric constraints imposed on the complex by the bridging unit. The extent of the distortion was found to increase with increasing ionic radius of the lanthanide ion, eventually resulting in a complete loss of symmetry in the complex. Because this ligand system is bicyclic, the conformation of each ring in the system is constrained by that of the other; in consequence, inclusion of the bridging unit in the complexes means only a twisted square, antiprismatic coordination geometry is observed for lanthanide complexes of 8O2-bridged DOTAM.

  6. Anion effects in the extraction of lanthanide 2-thenoyltrifluoroacetone complexes into an ionic liquid

    SciTech Connect

    Jensen, Mark P.; Beitz, James V.; Rickert, Paul G.; Borkowski, Marian; Laszak, Ivan; Dietz, Mark L.

    2012-07-01

    The extraction of trivalent lanthanides from an aqueous phase containing 1 M NaClO{sub 4} into the room temperature ionic liquid 1-butyl-3-methylimidazolium nonafluoro-1-butane sulfonate by the beta-diketone extractant 2-thenoyltrifluoroacetone (Htta) was studied. Radiotracer distribution, absorption spectroscopy, time-resolved laser-induced fluorescence spectroscopy, and X-ray absorption fine structure measurements point to the extraction of multiple lanthanide species. At low extractant concentrations, fully hydrated aqua cations of the lanthanides are present in the ionic liquid phase. As the extractant concentration is increased 1:2 and 1:3 lanthanide:tta species are observed. In contrast, 1:4 Ln:tta complexes were observed in the extraction of lanthanides by Htta into 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. (authors)

  7. Formation and stability of lanthanide complexes and their encapsulation into polymeric microspheres

    SciTech Connect

    Mumper, R.J.; Jay, M.

    1992-10-15

    The complexation of lanthanides (Ln) with dicarbonyl compounds (acetylacetone, acac; ethyl acetoacetate; 3-ethyl-2,4-pentanedione; 2,4-hexanedione; 3-methyl-2,4-pentanedione; and diethyl malonate) was investigated using a potentiometric titration technique. The ability of a dicarbonyl compound to complex with the lanthanide elements was greatly dependent on its pK{sub a} and on the pH of the titrated solution. Selected lanthanide complexes (Ln complexes) were incorporated into spherical poly(L-lactic acid)(PLA) matrices and irradiated in a nuclear reactor with neutrons to produce short-lived high-energy {Beta}-particle-emitting radioisotopes. The lanthanides investigated (Ho, Dy, Sm, and La) were chosen on the basis of their physical and nuclear properties. A transition element (Re) was also studied. The small decrease in the ionic radii of the lanthanides with increasing atomic number led to (a) greater ability to extract and complex from an aqueous solution with complexing agents, (b) larger formation and stability constants for the Ln complexes, (c) increased solubility of the Ln complexes in chloroform, and (d) increase in the maximum percent incorporation of the stable lanthanides in PLA spheres. Ho(aca) was found to be the most promising candidate of the complexes studied on the basis of the above observations and due to the favorable physical properties of {sup 165}Ho and nuclear properties of {sup 166}Ho. 21 refs., 5 figs., 4 tabs.

  8. Photo-reactive charge trapping memory based on lanthanide complex.

    PubMed

    Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V A L

    2015-10-09

    Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 10(4) s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

  9. Photo-reactive charge trapping memory based on lanthanide complex

    NASA Astrophysics Data System (ADS)

    Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V. A. L.

    2015-10-01

    Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 104 s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

  10. Photo-reactive charge trapping memory based on lanthanide complex

    PubMed Central

    Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V. A. L.

    2015-01-01

    Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 104 s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices. PMID:26449199

  11. Theoretical, spectral characterization and antineoplastic activity of new lanthanide complexes.

    PubMed

    Kostova, Irena; Trendafilova, Natasha; Momekov, Georgi

    2008-01-01

    The new cerium(III), lanthanum(III) and neodymium(III) complexes were synthesized in view of their application as cytotoxic agents. The complexes were characterized by different physicochemical methods: elemental analysis, mass spectrometry, (1)H NMR, (13)C NMR and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligand. The vibrational analysis showed that in the complexes the ligand coordinates to the metal ion through both deprotonated hydroxyl groups, however participation of the carbonyl groups in the coordination to the metal ion was also suggested. Geometry optimization of 3,3'-(ortho-pyridinomethylene)di-[4-hydroxycoumarin] H(2)(o-pyhc), (H(2)L) and its dianionic forms, o-pyhc(2-), (L(2-)) were carried out at AM1 and PM3 levels as well as using density functional theory with Becke's three parameter hybrid method and correlation functional of Lee, Yang and Parr (B3LYP) with 6-31G(d) basis set. The optimized geometries of the neutral ligand isomers were stabilized by two asymmetrical intramolecular O-H...O hydrogen bonds (HBs). The conformational search showed four low-energy dianionic species (o-pyhc(2-)) on the potential energy surface. Molecular electrostatic potential calculations showed that the most preferred sites for electrophilic attack in H(2)(o-pyhc) and o-pyhc(2-) are the carbonyl oxygen atoms. The evaluation of the cytotoxic activity of the novel lantanide complexes on HL-60 myeloid cells revealed, that they are potent cytotoxic agents. The cerium complex was found to exhibit superior activity in comparison to the lanthanum, and neodymium species, the latter being the least active. Taken together our data give us a reason to conclude that the newly synthesized lanthanide complexes should be a subset to further more detailed pharmacological and toxicological evaluation.

  12. Anion and solvent induced chirality inversion in macrocyclic lanthanide complexes.

    PubMed

    Gerus, Aleksandra; Slepokura, Katarzyna; Lisowski, Jerzy

    2013-11-04

    A series of the lanthanide(III) or yttrium(III) complexes of the type [LnL(NO3)(H2O)2](NO3)2, [LnL(NO3)(H2O)](NO3)2, [LnL(H2O)2](NO3)3, and [LnLCl(H2O)2]Cl2 where L is an all-R or all-S enantiomer (L(R) or L(S)) of the chiral hexaaza macrocycle, 2(R),7(R),18(R),23(R)- or 2(S),7(S),18(S),23(S)-1,8,15,17,24,31-hexaazatricyclo[25.3.1.1.0.0]-dotriaconta-10,12,14,26,28,30-hexaene, and Ln(III) = Sm(III), Tb(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), or Y(III), have been synthesized and structurally characterized. The crystal structure of the free macrocycle shows a highly twisted molecule, preorganized for the formation of helical complexes. The crystal structures of the lanthanide(III) complexes show two different diastereomeric forms of the macrocycle with different configurations at the stereogenic amine nitrogen atoms: (RRRR) or (RSRS) (denoted as L(RI) and L(RII), respectively). The L(RI) diastereomeric form of the nitrate derivatives [LnL(NO3)(H2O)](NO3)2 (Ln = Ho, Er) and [LnL(H2O)2](NO3)3 (Ln = Tm, Yb, Lu) convert slowly to the L(RII) form in methanol or acetonitrile solutions, while this process is not observed for the L(RI) diastereomers of analogous chloride derivatives [LnL(H2O)2]Cl3 (Ln = Tm, Yb, Lu). On the other hand, the L(RI) → L(RII) conversion for these Tm(III), Yb(III), and Lu(III) chloride derivatives can be triggered by the addition of external nitrate anions. The circular dichroism (CD) and (1)H NMR data indicate initial fast exchange of axial chloride for axial nitrate ligand, followed by slow chirality inversion of the equatorial macrocyclic ligand.

  13. Synthesis, structural, photophysical and electrochemical studies of various d-metal complexes of btp [2,6-bis(1,2,3-triazol-4-yl)pyridine] ligands that give rise to the formation of metallo-supramolecular gels.

    PubMed

    Byrne, Joseph P; Kitchen, Jonathan A; Kotova, Oxana; Leigh, Vivienne; Bell, Alan P; Boland, John J; Albrecht, Martin; Gunnlaugsson, Thorfinnur

    2014-01-07

    2,6-Bis(1,2,3-triazol-4-yl)pyridine (btp) is a terdentate binding motif that is synthesised modularly via the CuAAC reaction. Herein, we present the synthesis of ligands 1 and 2 and the investigation of the coordination chemistry, photophysical behaviour and electrochemistry of complexes of these with a number of d-metal ions (e.g. Ru(II), Ir(III), Ni(II) and Pt(II)). The X-ray crystal structures of ligand 1 and the complexes [Ru·2(2)](PF6)Cl, [Ni·1(2)](PF6)Cl and [Ir·1Cl3] are also presented. All of the complexes displayed non-classical triazolyl C-H···Cl(-) hydrogen bonding. All but one complex showed no metal-based luminescence at room temperature, while all of the Pt(ii) complexes displayed luminescence at 77 K. The electrochemistry of the Ru(II) complexes was also studied and these complexes were found to have higher oxidation potentials than analogous compounds. The redox behaviour of [RuL2](2+) complexes with both 1 and 2 was nearly identical, while [Ru·1Cl2(DMSO)] was oxidised at significantly lower potential. We also show that the Ru(II) complex of 2, [Ru·2(2)](PF6)Cl, gave rise to the formation of a metallo-supramolecular gel, the morphology of which was studied using scanning electron and helium ion microscopy.

  14. Efficient electroluminescence from new lanthanide (Eu3+, Sm3+) complexes.

    PubMed

    Yu, Jiangbo; Zhou, Liang; Zhang, Hongjie; Zheng, Youxuan; Li, Huanrong; Deng, Ruiping; Peng, Zeping; Li, Zhefeng

    2005-03-07

    The syntheses, structures, and electroluminescent properties are described for two new lanthanide complexes Ln(HFNH)3phen [HFNH = 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)hexane-1,3-dione; phen = 1,10-phenanthroline; Ln = Eu3+ (1), Sm3+ (2)]. Both complexes exhibit bright photoluminescence at room temperature (RT) due to the characteristic emission of Eu3+ and Sm3+ ion. Several devices using the two complexes as emitters were fabricated. The performances of these devices are among the best reported for devices using europium complex and samarium complex as emitters. The device based on 1 with the structure ITO/TPD (50 nm)/1:CBP (10%, 40 nm)/BCP (20 nm)/AlQ (30 nm)/LiF (1 nm)/Al (200 nm) exhibits the maximum brightness of 957 cd/m2, current efficiency of 4.14 cd/A, and power efficiency of 2.28 lm/W with a pure red Eu3+ ion emission. Especially, at the high brightness of 200 cd/m2, the device of 1 still has a high current efficiency of 2.15 cd/A. The device of 2 with a three-layer structure of ITO/TPD (50 nm)/2 (50 nm)/BCP (20 nm)/LiF (1 nm)/Al (200 nm) gives the maximum brightness of 42 cd/m2, current efficiency of 0.18 cd/A. By the comparison of the electroluminescent properties of devices based on Eu(TTA3phen (TTA = 2-thenoyltrifluoroacteonate) and 1, we conclude that the polyfluoration on the alkyl group of the ligand and the introduction of the long conjugate naphthyl group into the ligand improve the efficiency of 1-doped devices, especially at high current densities.

  15. A Bridge to Coordination Isomer Selection in Lanthanide(III) DOTA-tetraamide Complexes

    PubMed Central

    Vipond, Jeff; Woods, Mark; Zhao, Piyu; Tircso, Gyula; Ren, Jimin; Bott, Simon G.; Ogrin, Doug; Kiefer, Garry E.; Kovacs, Zoltan; Sherry, A.Dean

    2008-01-01

    Interest in macrocyclic lanthanide complexes such as DOTA is driven largely through interest in their use as contrast agents for MRI. The lanthanide tetraamide derivatives of DOTA have shown considerable promise as PARACEST agents, taking advantage of the slow water exchange kinetics of this class of complex. We postulated that water exchange in these tetraamide complexes could be slowed even further by introducing a group to sterically encumber the space above the water coordination site, thereby hindering the departure and approach of water molecules to the complex. The ligand 8O2-bridged-DOTAM was synthesized in a 34% yield from cyclen. It was found that the lanthanide complexes of this ligand did not possess a water molecule in the inner coordination sphere of the bound lanthanide. The crystal structure of the ytterbium complex revealed that distortions to the coordination sphere were induced by the steric constraints imposed on the complex by the bridging unit. The extent of the distortion was found to increase with increasing ionic radius of the lanthanide ion, eventually resulting in a complete loss of symmetry in the complex. Because this ligand system is bicyclic, the conformation of each ring in the system is constrained by that of the other, in consequence inclusion of the bridging unit in the complexes means only a twisted square antiprismatic coordination geometry is observed for complexes of 8O2-bridged-DOTAM. PMID:17295475

  16. Complications in complexation kinetics for lanthanides with DTPA using dye probe molecules in aqueous solution

    DOE PAGES

    Larsson, K.; Cullen, T. D.; Mezyk, S. P.; ...

    2017-05-17

    The complexation kinetics for the polyaminopolycarboxylic ligand DTPA to lanthanides in acidic aqueous solution were investigated using the dye ligand displacement technique and stopped-flow spectroscopy. Significant rate differences were obtained for different dye probes used, indicating that the kinetics of the dissociation of the dye molecule significantly impacts the overall measured kinetics when using this common methodology. The conditions of the solution also influenced the dye-lanthanide-DTPA interactions, which reconciled previously disparate data in the literature.

  17. Preparation of N,N-dialkylcarbamato lanthanide complexes by extraction of lanthanide ions from aqueous solution into hydrocarbons.

    PubMed

    Armelao, Lidia; Belli Dell'Amico, Daniela; Biagini, Paolo; Bottaro, Gregorio; Chiaberge, Stefano; Falvo, Paola; Labella, Luca; Marchetti, Fabio; Samaritani, Simona

    2014-05-19

    Lanthanides are easily extracted as N,N-dibutylcarbamato complexes from aqueous solutions of their chlorides into heptane solutions of dibutylamine saturated with CO2. The products are recovered in high yields and are soluble in hydrocarbons. The derivatives [Ln(O2CNBu2)3]n [Ln = Nd (1), Eu (2), Tb (3)], [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] [Ln = Tb (4), Sm (5), Eu (6)], and [Sm4(CO3)(O2CNBu2)10], 7, have thus been obtained. The crystal and molecular structure of 4 has been solved; the samarium and europium complexes 5 and 6 were found to be isostructural. Mass spectra of the complexes 1-3, 4, and 7 (in MeCN/toluene) reveal that equilibria are present in solution. Compound 2 has been reacted in toluene with NHBz2 in the presence of CO2 affording [NH2Bz2][Eu(O2CNBz2)4], 8, through a ligand exchange process. By thermal treatment, 8 afforded [Eu(O2CNBz2)3]n, 9. With a similar procedure [Sm(O2CNBz2)3]n, 10, was obtained from 5. According to the photoluminescence study carried out on solid samples of 2, 4, 5, 7, and 8, the metal centered f-f transitions represent the only effective way to induce lanthanide luminescence in these complexes.

  18. Metal induced folding: synthesis and conformational analysis of the lanthanide complexes of two 44-membered hydrazone macrocycles.

    PubMed

    Klein, Jörg M; Clegg, Jack K; Saggiomo, Vittorio; Reck, Lisa; Lüning, Ulrich; Sanders, Jeremy K M

    2012-04-07

    Six new lanthanide complexes of two 44-membered macrocycles have been prepared and characterised in solution. An analysis of the conformations of the free macrocycles and their lanthanide complexes both in solution (2D NMR) and in solid state (X-ray crystallography) demonstrate that the complexation induces changes in folding of the macrocycles.

  19. Thermodynamic and Spectroscopic Studies of Lanthanides(III) Complexation with Polyamines in Dimethyl Sulfoxide

    SciTech Connect

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Melchior, Andrea; Portanova, Roberto; Tolazzi, Marilena; Choppin, Gregory R.; Wang, Zheming

    2008-01-01

    The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands bound to the lanthanides except in the case of tren, in which only pendant N bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen in order to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine ligands. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from ~8 to ~10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of ΔGj°, ΔHj° and TΔSj° for the complexation of ethylenediamine (en), dien, trien, tren and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed.

  20. Survey of factors determining the circularly polarised luminescence of macrocyclic lanthanide complexes in solution.

    PubMed

    Bruce, James I; Parker, David; Lopinski, Stefan; Peacock, Robert D

    2002-07-01

    The development of emissive lanthanide complexes as structural or reactive probes to signal changes in their local chiral or ionic environment has been inhibited by the lack of understanding of correlating structural and electronic spectral information. The definition of relatively rigid enantiopure macrocyclic lanthanide complexes, whose inter- and intramolecular exchange dynamics have been defined, offers scope for remedying this situation. Chiral axially symmetric lanthanide complexes in solution give rise to large emission dissymmetry values (g(em)) in CPL spectra. The sign and magnitude of g(em) are determined by the degree of twist about the principal axis, which is predicted to be a maximum at +/-22.5 degrees, and by the site symmetry and local ligand field. In particular, the polarisability of the ligand donor atoms, especially for any axial donor, is very important. Examples of each case are discussed for structurally related cationic Eu(III) complexes.

  1. Nature of chiral-induced equilibrium shifts in racemic labile lanthanide complexes

    SciTech Connect

    Wu, Shuguang; Hilmes, G.L.; Riehl, J.P. )

    1989-03-23

    An analysis of the chiral-induced equilibrium shift of racemic D{sub 3} tris-terdendate complexes of lanthanides with 2,6-pyridinedicarboxylate is presented in terms of the associated/dissociated models of Schipper. Results are presented which indicate that the so-called Pfeiffer effect in these lanthanide complexes is best described by the dissociated model, as was determined for similar labile transition-metal complexes. The nature of the chiral discriminatory interaction is shown to be largely electrostatic by measurements in mixed solvents of varying dielectric constant.

  2. Synthesis and characterisation of bis-cyclen based dinuclear lanthanide complexes.

    PubMed

    Gunnlaugsson, Thorfinnur; Harte, Andrew J

    2006-04-21

    The design and synthesis of several bis-macrocyclic cyclen (1,4,7,10-tetraazacyclododecane) ligands and their corresponding lanthanum or europium complexes is described; these dinuclear lanthanide systems were made by connecting two macrocyclic cyclen moieties through a rigid, covalent, p-xylylenediamide bridge or a flexible aliphatic hexane bridge. These ligands were subsequently functionalised with six acetamide pendant arms (CONR1R2: R1 = R2 = H or CH3, or R1 = H, R2 = CH3). The corresponding lanthanide bis-complexes were then formed by reaction with La(III) and Eu(III) triflates, yielding overall cationic (+VI charged) complexes.

  3. [Thermometry by measuring the chemical shift of lanthanide complex].

    PubMed

    Konstanczak, P; Wust, P; Sander, B; Schründer, S; Frenzel, T; Wlodarczyk, W; Vogl, T; Müller, G; Felix, R

    1997-02-01

    In the long-term, non-invasive thermometry is vital for the continued clinical and technological development of regional hyperthermia. In magnetic resonance tomography. T1 relaxation time, diffusion and proton resonance frequency are used to measure temperature distributions. When used clinically in the pelvic region, all of these methods are plagued with errors and artefacts on account of the tissue relationships, tissue changes under hyperthermia, physiological and stochastic movements, inhomogeneities, drift phenomena and instabilities. We tested the relationship between the temperature and the chemical shift of a methyl group of a lanthanide complex with central atom praseodymium (Pr-MOE-DO3A. Schering AG). To do this we used cylindrical phantoms containing a 5-mmol-solution of this temperature-sensitive substance. High resolution spectra and relaxation times were determined in a Bruker AMX at 11.5 T. A calibration curve was then recorded by a Siemens Magnetom SP63 at 1.5 T. Local temperature distributions were determined using the chemical shift imaging method, with a matrix size of 16 x 8 and a narrow-band excitation pulse. The temperature distribution was created using a Nd:YAG laser applicator. At a distance of -25.7 ppm from the water line, we found a singlet line with a temperature-dependent chemical shift of 0.13 ppm/C. In the phantom experiment we found that the chemical shift had a linear relationship with a gradient independent of the surroundings, and a temperature resolution of +/-0.6 degree C. With a concentration of 1 mmol/l, a matrix size of 8 x 8 and a measurement period of 5 s per acquisition, phantom measurements using the CSI method produced a signal to noise ratio of 3.5 per acquisition, i.e a measurement period of 10 to 20 s per spectrum. Our in vitro data show that spectroscopic temperature measurement using a temperature-sensitive praseodymium complex with a therapeutically practical concentration of 1 mmol/l already appears to be

  4. Site-selective hydrolysis of tRNA by lanthanide metal complexes

    SciTech Connect

    Hayashi, Nobuhiro ); Takeda, Naoya; Yashiro, Morio; Watanabe, Kimitsuna; Komiyama, Makoto ); Shiiba, Tetsuro )

    1993-12-22

    tRNA[sup Phe] is site-selectively hydrolyzed by lanthanide metal complexes (Ce(III), Eu(III), La(III)) of hexaimine macrocyclic ligands. The selectivities of the complexes are much higher than those of the metal ions and are strongly dependent on the ligand structure. The tertiary structure of tRNA is essential for the site-selective scission.

  5. Luminescent trimethoprim-polyaminocarboxylate lanthanide complex conjugates for selective protein labeling and time-resolved bioassays

    PubMed Central

    Reddy, D. Rajasekhar; Pedró Rosa, Laura E.; Miller, Lawrence W.

    2011-01-01

    Labeling proteins with long-lifetime emitting lanthanide (III) chelate reporters enables sensitive, time-resolved luminescence bioaffinity assays. Heterodimers of trimethoprim (TMP) covalently linked to various cs124-sensitized, polyaminocarboxylate chelates stably retain lanthanide ions and exhibit quantum yields of europium emission up to 20% in water. A time-resolved, luminescence resonance energy transfer (LRET) assay showed that TMP-polyaminocarboxylates bind to Escherichia coli dihydrofolate reductase (eDHFR) fusion proteins with nanomolar affinity in purified solutions and in bacterial lysates. The ability to selectively impart terbium or europium luminescence to fusion proteins in complex physiological mixtures bypasses the need for specific antibodies and simplifies sample preparation. PMID:21619068

  6. Six-coordinate lanthanide complexes: slow relaxation of magnetization in the dysprosium(III) complex.

    PubMed

    Na, Bo; Zhang, Xue-Jing; Shi, Wei; Zhang, Yi-Quan; Wang, Bing-Wu; Gao, Chen; Gao, Song; Cheng, Peng

    2014-11-24

    A series of six-coordinate lanthanide complexes {(H3O)[Ln(NA)2]⋅H2O}n (H2NA=5-hydroxynicotinic acid; Ln=Gd(III) (1⋅Gd); Tb(III) (2⋅Tb); Dy(III) (3⋅Dy); Ho(III) (4⋅Ho)) have been synthesized from aqueous solution and fully characterized. Slow relaxation of the magnetization was observed in 3⋅Dy. To suppress the quantum tunneling of the magnetization, 3⋅Dy diluted by diamagnetic Y(III) ions was also synthesized and magnetically studied. Interesting butterfly-like hysteresis loops and an enhanced energy barrier for the slow relaxation of magnetization were observed in diluted 3⋅Dy. The energy barrier (Δ(τ)) and pre-exponential factor (τ0) of the diluted 3⋅Dy are 75 K and 4.21×10(-5) s, respectively. This work illustrates a successful way to obtain low-coordination-number lanthanide complexes by a framework approach to show single-ion-magnet-like behavior.

  7. Self-assembly and photophysical properties of lanthanide dinuclear triple-helical complexes

    SciTech Connect

    Piguet, C.; Bernardinelli, G.; Williams, A.F. ); Buenzli, J.C.G. ); Hopfgartner, G. )

    1993-09-08

    The dinucleating ligand bis[1-methyl-2-(6[prime]-[1[double prime]-(3,5-dimethoxybenzyl)benzimidazol-2[double prime]-yl]pyrid-2[prime]-yl)benzimidazol-5-yl]methane (L) reacts with lanthanide perchlorates to give dinuclear 2:3 complexes [Ln[sub 2](L)[sub 3

  8. A new class of macrocyclic lanthanide complexes for cell labeling and magnetic resonance imaging applications.

    PubMed

    Zheng, Quan; Dai, Houquan; Merritt, Matthew E; Malloy, Craig; Pan, Cai Yuan; Li, Wen-Hong

    2005-11-23

    Lanthanide complexes have wide applications in biochemical research and biomedical imaging. We have designed and synthesized a new class of macrocyclic lanthanide chelates, Ln/DTPA-PDA-C(n), for cell labeling and magnetic resonance imaging (MRI) applications. Two lipophilic Gd3+ complexes, Gd/DTPA-PDA-C(n) (n = 10, 12), labeled a number of cultured mammalian cells noninvasively at concentrations as low as a few micromolar. Cells took up these agents rapidly and showed robust intensity increases in T1-weighed MR images. Labeled cells showed normal morphology and doubling time as control cells. In addition to cultured cells, these agents also labeled primary cells in tissues such as dissected pancreatic islets. To study the mechanism of cellular uptake, we applied the technique of diffusion enhanced fluorescence resonance energy transfer (DEFRET) to determine the cellular localization of these lipophilic lanthanide complexes. After loading cells with a luminescent complex, Tb/DTPA-PDA-C10, we observed DEFRET between the Tb3+ complex and extracellular, but not intracellular, calcein. We concluded that these cyclic lanthanide complexes label cells by inserting two hydrophobic alkyl chains into cell membranes with the hydrophilic metal binding site facing the extracellular medium. As the first imaging application of these macrocyclic lanthanide chelates, we labeled insulin secreting beta-cells with Gd/DTPA-PDA-C12. Labeled cells were encapsulated in hollow fibers and were implanted in a nude mouse. MR imaging of implanted beta-cells showed that these cells could be followed in vivo for up to two weeks. The combined advantages of this new class of macrocyclic contrast agents ensure future imaging applications to track cell movement and localization in different biological systems.

  9. Molecular spectrum of lanthanide complexes with 2,3-dichlorobenzoic acid and 2,2-bipyridine.

    PubMed

    He, Shu-Mei; Sun, Shu-Jing; Zheng, Jun-Ru; Zhang, Jian-Jun

    2014-04-05

    With 2,3-dichlorobenzoic acid as the first ligands and 2,2'-bipyridine as the second ligands, the lanthanide complexes [Ln(2,3-DClBA)3bipy]2 [Ln=Nd(a), Sm(b), Eu(c), Tb(d), Dy(e), Ho(f)] have been synthesized. By using Infrared (IR) and Raman (R) spectra, the characteristics of the groups can be identified. The bands of lanthanide complexes have been analyzed and attributed, and clearly demonstrated with the use of the complementarity of IR and R. The experiment reveals that the bands of complexes are affected by lanthanide elements (Ln). The frequency of stretching vibration and breathing vibration of ring, together with the stretching vibration of the carbonyl group (νCO), tends to be rising as the atomic number of lanthanide increasing. Meanwhile, crystallography data demonstrate that the six carbonyl groups have different bond length and bond angle, which can lead to different vibration frequency. The second derivatives of IR show that there are multiple vibration frequencies existing in the symmetrical stretching vibration of the carbonyl group (νsCO). Therefore the second derivative of IR spectrum is a characteristic band of different coordination modes of carbonyl group.

  10. Methods to increase the luminescence of lanthanide (III) macrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Quagliano, John R.; Leif, Robert C.; Vallarino, Lidia M.; Williams, Steven A.

    2000-04-01

    Simultaneous detection of both a Eu(III) and a Sm(III) Quantum Dye is now possible because the enhanced luminescence of the Eu(III) and Sm(III) macrocycles occurs in the same solution and with excitation at the same wavelengths between 350 to 370 nm. Since DAPI is also excited between 350 to 370 nm, it is possible to use common excitation optics and a single dichroic mirror for measuring two molecular species and DNA. The narrow emissions of these macrocycles can be detected with negligible overlap between themselves or with DAPI-stained DNA. This will permit precise pixel by pixel ratio measurements of the Eu(III) macrocycle to Sm(III) macrocycle, and of each macrocycle to DNA> This technology should be applicable to antibodies, FISH, comparative genomic hybridization, and chromosome painting. Cofluorescence of the Tb(III)-macrocycle has also been obtained under different conditions. The luminescence of these lanthanide macrocycles can be observed with conventional fluorescence instrumentation previously unattainable low levels. Thus, it will be possible to employ narrow bandwidth lanthanide luminescent tags to identify three molecular species with a conventional microscope.

  11. Homodinuclear lanthanide complexes of phenylthiopropionic acid: synthesis, characterization, cytotoxicity, DNA cleavage, and antimicrobial activity.

    PubMed

    Shiju, C; Arish, D; Kumaresan, S

    2013-03-15

    Lanthanide complexes of La(III), Pr(III), Nd(III), Sm(III), and Ho(III) with phenylthiopropionic acid were synthesized and characterized by elemental analysis, mass, IR, electronic spectra, molar conductance, TGA, and powder XRD. The results show that the lanthanide complexes are homodinuclear in nature. The two lanthanide ions are bridged by eight oxygen atoms from four carboxylate groups. Thermal decomposition profiles are consistent with the proposed formulations. Powder XRD studies show that all the complexes are amorphous in nature. Antimicrobial studies indicate that these complexes exhibit more activity than the ligand itself. The DNA cleavage activity of the ligand and its complexes were assayed on Escherichia coli DNA using gel electrophoresis in the presence of H(2)O(2). The result shows that the Pr(III) and Nd(III) complexes have completely cleaved the DNA. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa) and colon cancer cells (HCT116) and it was found that the La(III) and Nd(III) complexes are more active than the corresponding Pr(III), Sm(III), Ho(III) complexes, and the free ligand on both the cancer cells.

  12. Structural, magnetic and luminescent properties of lanthanide complexes with N-salicylideneglycine.

    PubMed

    Vančo, Ján; Trávníček, Zdeněk; Kozák, Ondřej; Boča, Roman

    2015-04-28

    A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)₂(H₂O)₂]∙H₂O (1-6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution.

  13. Structural, Magnetic and Luminescent Properties of Lanthanide Complexes with N-Salicylideneglycine

    PubMed Central

    Vančo, Ján; Trávníček, Zdeněk; Kozák, Ondřej; Boča, Roman

    2015-01-01

    A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)2(H2O)2]∙H2O (1–6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution. PMID:25927576

  14. Lanthanide complexes as luminogenic probes to measure sulfide levels in industrial samples.

    PubMed

    Thorson, Megan K; Ung, Phuc; Leaver, Franklin M; Corbin, Teresa S; Tuck, Kellie L; Graham, Bim; Barrios, Amy M

    2015-10-08

    A series of lanthanide-based, azide-appended complexes were investigated as hydrogen sulfide-sensitive probes. Europium complex 1 and Tb complex 3 both displayed a sulfide-dependent increase in luminescence, while Tb complex 2 displayed a decrease in luminescence upon exposure to NaHS. The utility of the complexes for monitoring sulfide levels in industrial oil and water samples was investigated. Complex 3 provided a sensitive measure of sulfide levels in petrochemical water samples (detection limit ∼ 250 nM), while complex 1 was capable of monitoring μM levels of sulfide in partially refined crude oil.

  15. Lanthanide complexes of 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one

    SciTech Connect

    Sitran, S; Fregona, D. ); Faraglia, G. )

    1990-01-01

    The title ligand (H(Dh), dehydroacetic acid) reacts with lanthanide(III) acetates in anhydrous methanol to form complexes of formula (M(Dh){sub 3}(MeOH)). When hydrated lanthanide acetates are used, hydrated compounds such as (Ce(Dh){sub 3}(H{sub 2}O)) or (Eu(Dh){sub 3}(H{sub 2}O)).H{sub 2}O are obtained. The reaction of lanthanum triacetate with H(Dh) yields the mixed complex (La(Dh){sub 2}(O{sub 2}CMe)), formation of the 1:3 complex also being unfavored in the presence of a large ligand excess. The complexes have been characterized by infrared and NMR ({sup 1}H and {sup 13}C) spectroscopy and by thermogravimetric measurements.

  16. Synthesis and luminescence properties of lanthanide complexes with a new tripodal ligands featuring salicylamide arms.

    PubMed

    Song, Xue-Qin; Dong, Wen-Kui; Zhang, Yu-Jie; Liu, Wei-Sheng

    2010-01-01

    A series of luminescent lanthanide complexes with a new tripodal ligand featuring salicylamide arms, 2,2',2''-nitrilotris(2-furfurylaminoformylphenoxy)triethylamine (L), were synthesized and characterized by elemental analysis, IR and molar conductivity measurements. Photophysical properties of the complexes were studied by means of UV-vis absorption and steady-state luminescence spectroscopy. Excited-state luminescence lifetimes and quantum yield of the complexes were determined. Luminescence studies demonstrated that the tripodal ligand featuring salicylamide arms exhibits a good antennae effect with respect to the Tb(III) and Dy(III) ion due to efficient intersystem crossing and ligand to metal energy transfer. From a more general perspective, this work offers interesting perspectives for the development of efficient luminescent stains and enlarges the arsenal for developing novel luminescent lanthanide complexes of salicylamide derivatives. Copyright (c) 2009 John Wiley & Sons, Ltd.

  17. A series of binuclear lanthanide(III) complexes: Crystallography, antimicrobial activity and thermochemistry properties studies

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-Ying; Ren, Ning; Xu, Su-Ling; Zhang, Jian-Jun; Zhang, Da-Hai

    2015-02-01

    A series of novel lanthanide complexes with the general formula [Ln(3,4-DClBA)3phen]2 (Ln = Ho(1), Nd(2), Sm(3), Dy(4), Eu(5), Tb(6), Yb(7) and Er(8), 3,4-DClBA = 3,4-dichlorobenzoate, phen = 1,10-phenanthroline) were prepared at room temperature and characterized. The crystal structures of complexes 1-8 have been determined by single crystal X-ray diffraction. These complexes are isomorphous and lanthanide ions are all eight-coordinated to oxygen atoms and nitrogen atoms with distorted square-antiprism geometry. The thermal decomposition mechanism and TG-FTIR spectra of gaseous products of thermal decomposition processes for complexes 1-8 were acquired through TG/DSC-FTIR system. The heat capacities of complexes 1-8 were measured using DSC technology and fitted to a polynomial equation by the least-squares method. Complexes 3-6 display characteristic lanthanide emission bands in the visible region. Meanwhile, these complexes exhibit in good antimicrobial activity against Candida albicans, Escherichia coli, and Staphylococcus aureu.

  18. Multicolour optical coding from a series of luminescent lanthanide complexes with a unique antenna.

    PubMed

    Wartenberg, Nicolas; Raccurt, Olivier; Bourgeat-Lami, Elodie; Imbert, Daniel; Mazzanti, Marinella

    2013-03-04

    The bis-tetrazolate-pyridine ligand H(2)pytz sensitises efficiently the visible and/or near-IR luminescence emission of ten lanthanide cations (Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb). The Ln(III) complexes present sizeable quantum yields in both domains with a single excitation source. The wide range of possible colour combinations in water, organic solvents and the solid state makes the complexes very attractive for labelling and encoding.

  19. Structural studies of lanthanide(III) 1,2-ethylene-diphosphonic acid complexes

    SciTech Connect

    McIlwraith, H.; Zhang, J.; Rogers, R.D.

    1995-12-31

    1,2-Ethylenediphosphonic acid can be classified in a class of extractants known as thermally unstable complexants (TUCS). Extraction accomplished using TUCS ligands can be followed by thermal degradation of the extractant. Despite their proposed utility in separation, few structures of lanthanide(III)/TUCS complexes are known. Structural studies can help us to understand the extraction mechanism and the interaction between metal ions and the ligand.

  20. Neutral “Cp-Free” Silyl-Lanthanide(II) Complexes: Synthesis, Structure, and Bonding Analysis

    PubMed Central

    2015-01-01

    Complexes featuring lanthanide silicon bonds represent a research area still in its infancy. Herein, we report a series of Cp-free lanthanide (+II) complexes bearing σ-bonded silyl ligands. By reactions of LnI2 (Ln = Yb, Eu, Sm) either with a 1,4-oligosilanyl dianion [K-Si(SiMe3)2SiMe2SiMe2Si(SiMe3)2-K)] (1) or with 2 (Me3Si)3SiK (3) the corresponding neutral metallacyclopentasilanes ({Me2Si(Me3Si)2Si}2)Ln·(THF)4 (Ln = Yb (2a), Eu (2b), Sm (2c)), or the disilylated complexes ({Me3Si}3Si)2Ln·(THF)3 (Ln = Yb (4a), Eu (4b), Sm (4c)), were selectively obtained. Complexes 2b, 2c, 4b, and 4c represent the first examples of structurally characterized Cp-free Eu and Sm complexes with silyl ligands. In both series, a linear correlation was observed between the Ln–Si bond lengths and the covalent radii of the corresponding lanthanide metals. Density functional theory calculations were also carried out for complexes 2a–c and 4a–c to elucidate the bonding situation between the Ln(+II) centers and Si. PMID:26132550

  1. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand.

    PubMed

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-25

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions.

  2. A novel ethacrynic acid sensor based on a lanthanide porphyrin complex in a PVC matrix.

    PubMed

    Zhang, X B; Guo, C C; Xu, J B; Shen, G L; Yu, R Q

    2000-05-01

    Lanthanide porphyrin complexes synthesized by a solid state method were used to prepare a novel ethacrynic acid (EA) sensor. The sensor, based on pentane-2,4-dionato(meso-tetraphenylporphinato)terbium [TbTPP(acac)] with an optimized membrane composition, exhibits a Nernstian response to EA- ion in the concentration range 7.4 x 10(-6)-1.0 x 10(-1) mol l-1 with a pH range from 3.2 to 6.8 and a fast response time of 30 s. The electrode shows improved selectivity towards EA- ion with respect to common co-existing ions compared with the previously reported EA sensor. As electroactive materials, lanthanide porphyrin complexes show better potentiometric response characteristics than copper porphyrin complexes. The effect of solvent mediators and lipophilic ion additives was studied and the experimental conditions were optimized. The electrode was applied to the determination of EA in human urine samples with satisfactory results.

  3. Discrete site surface complexation constants for lanthanide adsorption to bacteria as determined by experiments and linear free energy relationships.

    PubMed

    Ngwenya, Bryne T; Magennis, Marisa; Olive, Valerie; Mosselmans, J Fred W; Ellam, Robert M

    2010-01-15

    Bacteria are abundant in many natural and engineered environments where they are thought to exert important controls on the cycling, mobility, bioavailability, and toxicity of metal contaminants. In order to probe their role in moderating the behavior of lanthanides, pH-dependent adsorption edges of 13 individual lanthanides and yttrium to the Gram-negative bacterium Pantoea agglomerans were used to generate discrete site surface complexation constants. The calculated surface complexation constants were compared with stability constants estimated using linear free energy relationships based on a number of hydroxyl-containing ligands. The experimental data suggests that lanthanide adsorption edges below pH 6.5 are consistent with adsorption to phosphate groups for the light and some of the middle lanthanides (La to Gd), whereas some of the middle and heavy lanthanides appear to favor carboxyl co-ordination (Tb to Yb), although exceptions occur in each grouping. The experimentally derived surface complexation constants for carboxyl coordination were of similar magnitude to stability constants estimated from linear free energy correlations using fulvic acid stability constants. The implication is that the adsorption of lanthanides to bacterial surfaces could be modeled reasonably well using lanthanide stability constants for natural organic matter, except perhaps at low pH where phosphate binding dominates.

  4. Highly luminescent bis-diketone lanthanide complexes with triple-stranded dinuclear structure.

    PubMed

    Li, Hong-Feng; Yan, Peng-Fei; Chen, Peng; Wang, Yan; Xu, Hui; Li, Guang-Ming

    2012-01-21

    A new bis-β-diketone, 3,3'-bis(4,4,4-trifluoro-1,3-dioxobutyl)biphenyl (BTB), has been designed and prepared for the synthesis of a series of dinuclear lanthanide complexes [Ln(2)(BTB)(3)(C(2)H(5)OH)(2)(H(2)O)(2)] [Ln = Eu (1), Gd (2)], [Ln(2)(BTB)(3)(DME)(2)] [Ln = Nd (3), Yb (4); DME = ethylene glycol dimethyl ether] and [Eu(2)(BTB)(3)(L)(2)] [L = 2,2-bipydine (5); 1,10-phenanthroline (6); 4,7-diphenyl-1,10-phenanthroline (7)]. Complexes 1-7 have been characterized by various spectroscopic techniques and their photophysical properties are investigated. X-ray crystallographical analysis reveals that complexes 1, 3 and 4 adopt triple-stranded dinuclear structures which are formed by three bis-bidentate ligands with two lanthanide ions. The complexes 1 and 3-7 display strong visible red or NIR luminescence upon irradiation at ligand band around 372 nm, depending on the choice of the lanthanide. The solid-state photoluminescence quantum yields and the lifetimes of Eu(3+) complexes are determined and described.

  5. Magnetic Anisotropies in Rhombic Lanthanide(III) Complexes Do Not Conform to Bleaney's Theory.

    PubMed

    Castro, Goretti; Regueiro-Figueroa, Martín; Esteban-Gómez, David; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2016-04-04

    We report a complete set of magnetic susceptibilities of lanthanide complexes with a macrocyclic ligand based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform containing four hydroxyethyl pendant arms (L(1)). The [LnL(1)](3+) complexes are isostructural along the lanthanide series from Ce(3+) to Yb(3+), with the only structural change observed along the series being the monotonous shortening of the Ln-donor distances due to lanthanide contraction. The (1)H NMR spectra point to a D2 symmetry of the [LnL(1)](3+) complexes in aqueous solution, which provides a unique opportunity for analysis of the rhombic magnetic anisotropies with an unequivocal location of the magnetic axes. The contact contributions for the observed paramagnetic shifts have been estimated with density functional theory calculations on the [GdL(1)](3+) complex. Subsequently, the pseudocontact shifts could be factored out, thereby giving access to the axial and rhombic contributions of the magnetic susceptibility tensor. Our results show that the calculated magnetic anisotropies do not follow the trends predicted by Bleaney's theory, particularly in the case of Ho(3+) and Er(3+) complexes.

  6. Highly luminescent lanthanide complexes with novel bis-β-diketone ligand: synthesis, characterization and photoluminescent properties.

    PubMed

    Li, Hong-Feng; Li, Guang-Ming; Chen, Peng; Sun, Wen-Bin; Yan, Peng-Fei

    2012-11-01

    A biphenyl-linked bis-β-diketone ligand, 3,3'-bis(3-phenyl-3-oxopropanol)biphenyl (BPB) has been prepared for the syntheses of a series of dinuclear lanthanide complexes. The ligand bears two benzoyl β-diketonate sites linked by a 3,3'-biphenyl spacer. Reaction of the doubly negatively charged bis-bidenate ligand with lanthanide ions forms triple-stranded dinuclear complexes Ln(2)(BPB)(3) (Ln=Nd (1), Sm (2), Eu (3), Yb (4) and Gd (5)). Electrospray mass spectrometry is used to identify the formation of the triple-stranded dinuclear complexes 1-5, which have been further characterized by various spectroscopic techniques. The complexes display strong visible and NIR luminescence upon excitation at ligands bands around 360 nm, depending on the choice of the lanthanides, and the emission quantum yields and luminescence lifetimes of 2-3 have been determined. It shows that the biphenyl-linked ligand BPB is a more efficient sensitizer than the monodiketone ligand DBM (dibenzoylmethane), through the comparisons of Ln(2)(BPB)(3) and Ln(DBM)(3) on their photoluminescent properties.

  7. Highly luminescent lanthanide complexes with novel bis-β-diketone ligand: Synthesis, characterization and photoluminescent properties

    NASA Astrophysics Data System (ADS)

    Li, Hong-Feng; Li, Guang-Ming; Chen, Peng; Sun, Wen-Bin; Yan, Peng-Fei

    2012-11-01

    A biphenyl-linked bis-β-diketone ligand, 3,3'-bis(3-phenyl-3-oxopropanol)biphenyl (BPB) has been prepared for the syntheses of a series of dinuclear lanthanide complexes. The ligand bears two benzoyl β-diketonate sites linked by a 3,3'-biphenyl spacer. Reaction of the doubly negatively charged bis-bidenate ligand with lanthanide ions forms triple-stranded dinuclear complexes Ln2(BPB)3 (Ln = Nd (1), Sm (2), Eu (3), Yb (4) and Gd (5)). Electrospray mass spectrometry is used to identify the formation of the triple-stranded dinuclear complexes 1-5, which have been further characterized by various spectroscopic techniques. The complexes display strong visible and NIR luminescence upon excitation at ligands bands around 360 nm, depending on the choice of the lanthanides, and the emission quantum yields and luminescence lifetimes of 2-3 have been determined. It shows that the biphenyl-linked ligand BPB is a more efficient sensitizer than the monodiketone ligand DBM (dibenzoylmethane), through the comparisons of Ln2(BPB)3 and Ln(DBM)3 on their photoluminescent properties.

  8. Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base difunctional catalysts for transesterification.

    PubMed

    Zeng, Ruijie; Sheng, Hongting; Zhang, Yongcang; Feng, Yan; Chen, Zhi; Wang, Junfeng; Chen, Man; Zhu, Manzhou; Guo, Qingxiang

    2014-10-03

    A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid-base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

  9. Evolution of Luminescent Supramolecular Lanthanide M2nL3n Complexes from Helicates and Tetrahedra to Cubes.

    PubMed

    Li, Xiao-Zhen; Zhou, Li-Peng; Yan, Liang-Liang; Yuan, Da-Qiang; Lin, Chen-Sheng; Sun, Qing-Fu

    2017-06-21

    Lanthanide-containing molecules have many potential applications in material science and biology, that is, luminescent sensing/labling, MRI, magnetic refrigeration, and catalysis among others. Coordination-directed self-assembly has shown great power in the designed construction of well-defined supramolecular systems. However, application of this strategy to the lanthanide edifices is challenging due to the complicated and greatly labile coordination numbers and geometries for lanthanides. Here we demonstrate a sensitive structural switching phenomenon during the stereocontrolled self-assembly of a group of Ln2nL3n (Ln for lanthanides, L for organic ligands, and n = 1, 2, 4) compounds. Systematic variation of the offset distances between the two chelating arms on the bis(tridentate) ligands dictated the final outcomes of the lanthanide assembly, ranging from Ln2L3 helicates and Ln4L6 tetrahedra to Ln8L12 cubes. Remarkably, the borderline case leading to the formation of a mixture of the helicate and the tetrahedron was clearly revealed. Moreover, the concentration-dependent self-assembly of an unprecedented cubic Ln8L12 complex was also confirmed. The luminescent lanthanide cubes can serve as excellent turn-off sensors in explosives detection, featuring high selectivity and sensitivity toward picric acid. All complexes were confirmed by NMR, ESI-TOF-MS, and single crystal X-ray diffraction studies. Our results provide valuable design principles for the coordination self-assembly of multinuclear functional lanthanide architectures.

  10. Purification of recombinant BtpA and Ycf3, proteins involved in membrane protein biogenesis in Synechocystis PCC 6803.

    PubMed

    Schwabe, Tatjana M E; Gloddek, Kirsten; Schluesener, Daniela; Kruip, Jochen

    2003-03-25

    The gene products Ycf3 (hypothetical chloroplast open reading frame) and BtpA (biogenesis of thylakoid protein) are thought to be involved in the biogenesis of the membrane protein complex photosystem I (PSI) from Synechocystis PCC 6803. PSI consists of 12 different subunits and binds more than 100 cofactors, making it a model protein to study different aspects of membrane protein biogenesis. For a detailed biophysical characterization of Ycf3 and BtpA pure proteins must be available in sufficient quantities. Therefore we cloned the corresponding genes into expression vectors. To facilitate purification we created His-tagged versions of Ycf3 and BtpA in addition to the unmodified forms. Immobilized metal affinity chromatography (IMAC) yielded His-tagged proteins which were used for the production of antibodies. Purification strategies for non-tagged proteins could also be established: Ycf3 could be purified in soluble form using a two-step purification in which ammonium sulfate precipitation was combined with anion-exchange chromatography (IEC). BtpA had to be purified from inclusion bodies by two-consecutive IEC steps under denaturing conditions. An optimized refolding protocol was established that yielded pure BtpA. In all cases, MALDI-TOF peptide mass fingerprinting (PMF) was used to confirm protein identity. Initially, size exclusion chromatography and CD-spectroscopy were used for biophysical characterization of the proteins. Both Ycf3 and BtpA show homo-oligomerization in vitro. In summary, purification protocols for Ycf3 and BtpA have been designed that yield pure proteins which can be used to probe the molecular function of these proteins for membrane protein biogenesis.

  11. Enantiomeric self-recognition in homo- and heterodinuclear macrocyclic lanthanide(III) complexes.

    PubMed

    Lisowski, Jerzy

    2011-06-20

    The controlled formation of lanthanide(III) dinuclear μ-hydroxo-bridged [Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes (where X = H(2)O, NO(3)(-), or Cl(-)) of the enantiopure chiral macrocycle L is reported. The (1)H and (13)C NMR resonances of these complexes have been assigned on the basis of COSY, NOESY, TOCSY, and HMQC spectra. The observed NOE connectivities confirm that the dimeric solid-state structure is retained in solution. The enantiomeric nature of the obtained chiral complexes and binding of hydroxide anions are reflected in their CD spectra. The formation of the dimeric complexes is accompanied by a complete enantiomeric self-recognition of the chiral macrocyclic units. The reaction of NaOH with a mixture of two different mononuclear lanthanide(III) complexes, [Ln(1)L](3+) and [Ln(2)L](3+), results in formation of the heterodinuclear [Ln(1)Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes as well as the corresponding homodinuclear complexes. The formation of the heterodinuclear complex is directly confirmed by the NOESY spectra of [EuLuL(2)(μ-OH)(2)(H(2)O)(2)](4+), which reveal close contacts between the macrocyclic unit containing the Eu(III) ion and the macrocyclic unit containing the Lu(III) ion. While the relative amounts of homo- and heterodinuclear complexes are statistical for the two lanthanide(III) ions of similar radii, a clear preference for the formation of heterodinuclear species is observed when the two mononuclear complexes contain lanthanide(III) ions of markedly different sizes, e.g., La(III) and Yb(III). The formation of heterodinuclear complexes is accompanied by the self-sorting of the chiral macrocyclic units based on their chirality. The reactions of NaOH with a pair of homochiral or racemic mononuclear complexes, [Ln(1)L(RRRR)](3+)/[Ln(2)L(RRRR)](3+), [Ln(1)L(SSSS)](3+)/[Ln(2)L(SSSS)](3+), or [Ln(1)L(rac)](3+)/[Ln(2)L(rac)](3+), results in mixtures of homochiral, homodinuclear and homochiral, heterodinuclear complexes. On the contrary, no

  12. First examples of ternary lanthanide 5-aminoisophthalate complexes: Hydrothermal syntheses and structures of lanthanide coordination polymers with 5-aminoisophthalate and oxalate

    NASA Astrophysics Data System (ADS)

    Liu, Chong-Bo; Wen, Hui-Liang; Tan, Sheng-Shui; Yi, Xiu-Guang

    2008-05-01

    Two new lanthanide coordination polymers with mixed-carboxylates, [Ln(OX)(HAPA)(H 2O)] n[Ln = Eu ( 1), Ho ( 2); H 2APA = 5-aminoisophthalic acid; OX = oxalate] were obtained by hydrothermal reactions, and characterized by single crystal X-ray diffraction, elemental analysis and IR spectra. Complexes 1 and 2 are both 3-D supramolecular structure, in which lanthanide ions are bridged by oxalate and 5-aminoisophthalate ligands forming 2-D metal-organic framework, and 2-D networks are further architectured to form 3-D supramolecular structures by hydrogen bonds. The two carboxylate groups of H 2APA ligand are all deprotonated and exhibit chelating and bridging bidentate coordination modes, respectively, and the amino group in HAPA presents - NH3+ in the titled complexes. The thermogravimetric analysis was carried out to examine the thermal stability of the titled complexes. And the photoluminescence property of 1 was investigated.

  13. Ionic versus covalent character in lanthanide complexes. A hybrid density functional study

    NASA Astrophysics Data System (ADS)

    Adamo, Carlo; Maldivi, Pascale

    1997-04-01

    The geometric structures and harmonic vibrational frequencies of La, Gd and Lu trihalides have been investigated by a hybrid density functional/Hartree-Fock approach coupled with a relativistic effective core potential. The adequacy of this electronic protocol is confirmed by the fairly good agreement with experimental data and with those obtained by more expensive post-HF computations. A detailed analysis of the electronic density has been performed using the natural bond localization procedure and its recent extension to natural electronic resonance theory to understand the role of charge transfer in the bonding of lanthanide complexes. This approach underlines the role of electrostatic interactions in the lanthanide-halogen bond, even if a charge transfer mechanism plays a role, especially in the more weakly bonded bromide and iodide derivatives.

  14. Optimizing millisecond time scale near-infrared emission in polynuclear chrome(III)-lanthanide(III) complexes.

    PubMed

    Aboshyan-Sorgho, Lilit; Nozary, Homayoun; Aebischer, Annina; Bünzli, Jean-Claude G; Morgantini, Pierre-Yves; Kittilstved, Kevin R; Hauser, Andreas; Eliseeva, Svetlana V; Petoud, Stéphane; Piguet, Claude

    2012-08-01

    This work illustrates a simple approach for optimizing long-lived near-infrared lanthanide-centered luminescence using trivalent chromium chromophores as sensitizers. Reactions of the segmental ligand L2 with stoichiometric amounts of M(CF(3)SO(3))(2) (M = Cr, Zn) and Ln(CF(3)SO(3))(3) (Ln = Nd, Er, Yb) under aerobic conditions quantitatively yield the D(3)-symmetrical trinuclear [MLnM(L2)(3)](CF(3)SO(3))(n) complexes (M = Zn, n = 7; M = Cr, n = 9), in which the central lanthanide activator is sandwiched between the two transition metal cations. Visible or NIR irradiation of the peripheral Cr(III) chromophores in [CrLnCr(L2)(3)](9+) induces rate-limiting intramolecular intermetallic Cr→Ln energy transfer processes (Ln = Nd, Er, Yb), which eventually produces lanthanide-centered near-infrared (NIR) or IR emission with apparent lifetimes within the millisecond range. As compared to the parent dinuclear complexes [CrLn(L1)(3)](6+), the connection of a second strong-field [CrN(6)] sensitizer in [CrLnCr(L2)(3)](9+) significantly enhances the emission intensity without perturbing the kinetic regime. This work opens novel exciting photophysical perspectives via the buildup of non-negligible population densities for the long-lived doubly excited state [Cr*LnCr*(L2)(3)](9+) under reasonable pumping powers.

  15. Comparison of covalency in the complexes of trivalent actinide and lanthanide cations.

    PubMed

    Jensen, Mark P; Bond, Andrew H

    2002-08-21

    The complexes of trivalent actinide (Am(III) and Cm(III)) and lanthanide (Nd(III) and Sm(III)) cations with bis(2,4,4-trimethylpentyl)phosphinic acid, bis(2,4,4-trimethylpentyl)monothiophosphinic acid, and bis(2,4,4-trimethylpentyl)dithiophosphinic acid in n-dodecane have been studied by visible absorption spectroscopy and X-ray absorption fine structure (XAFS) measurements in order to understand the chemical interactions responsible for the great selectivity the dithiophosphinate ligand exhibits for trivalent actinide cations in liquid-liquid extraction. Under the conditions studied, each type of ligand displays a different coordination mode with trivalent f-element cations. The phosphinate ligand coordinates as hydrogen-bonded dimers, forming M(HL2)3. Both the oxygen and the sulfur donor of the monothiophosphinate ligand can bind the cations, affording both bidentate and monodentate ligands. The dithiophosphinate ligand forms neutral bidentate complexes, ML3, with no discernible nitrate or water molecules in the inner coordination sphere. Comparison of the Cm(III), Nd(III), and Sm(III) XAFS shows that the structure and metal-donor atom bond distances are indistinguishable within experimental error for similarly sized trivalent lanthanide and actinide cations, despite the selectivity of bis(2,4,4-trimethylpentyl)dithiophosphinic acid for trivalent actinide cations over trivalent lanthanide cations.

  16. Comparison of covalency in the complexes of trivalent actinide and lanthanide cations.

    SciTech Connect

    Jensen, M. P.; Bond, A. H.; Chemistry

    2002-08-21

    The complexes of trivalent actinide (Am(III) and Cm(III)) and lanthanide (Nd(III) and Sm(III)) cations with bis(2,4,4-trimethylpentyl)phosphinic acid, bis(2,4,4-trimethylpentyl)monothiophosphinic acid, and bis(2,4,4-trimethylpentyl)dithiophosphinic acid in n-dodecane have been studied by visible absorption spectroscopy and X-ray absorption fine structure (XAFS) measurements in order to understand the chemical interactions responsible for the great selectivity the dithiophosphinate ligand exhibits for trivalent actinide cations in liquid-liquid extraction. Under the conditions studied, each type of ligand displays a different coordination mode with trivalent f-element cations. The phosphinate ligand coordinates as hydrogen-bonded dimers, forming M(HL{sub 2}){sub 3}. Both the oxygen and the sulfur donor of the monothiophosphinate ligand can bind the cations, affording both bidentate and monodentate ligands. The dithiophosphinate ligand forms neutral bidentate complexes, ML{sub 3}, with no discernible nitrate or water molecules in the inner coordination sphere. Comparison of the Cm(III), Nd(III), and Sm(III) XAFS shows that the structure and metal-donor atom bond distances are indistinguishable within experimental error for similarly sized trivalent lanthanide and actinide cations, despite the selectivity of bis(2,4,4-trimethylpentyl)dithiophosphinic acid for trivalent actinide cations over trivalent lanthanide cations.

  17. Polymer thin films containing Eu(III) complex as lanthanide lasing medium

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasuchika; Wada, Yuji; Yanagida, Shozo; Kawai, Hideki; Yasuda, Naoki; Nagamura, Toshihiko

    2003-10-01

    Direct evidence of lanthanide(III) lasing using Eu(III) complex in polymer thin films (threshold level <0.05 mJ) is reported. The thin film consists of polystyrene containing Eu(III) complexes based on two criteria: (1) Higher emission quantum yield of Eu(III) complexes, which increases the rs (energy density), and (2) faster radiation rate at large B (Einstein coefficient). The microcavity was constructed by coating a glass substrate with a film having a high refractive index. The film thickness was found to be 1.71 mm. The threshold level for laser transmission was found to be <0.05 mJ.

  18. Lanthanide Complexes of Substituted β-Diketone Hydrazone Derivatives: Synthesis, Characterization, and Biological Activities.

    PubMed

    Hegazy, W H; Al-Motawaa, I H

    2011-01-01

    A series of β-diketone hydrazone derivatives have been synthesized through condensation of β-diketone with aromatic aldehydes followed by reaction with phenylhydrazine. The structure of the ligands and intermediates are well defined through elemental and spectroscopic analyses. These hydrazones are potential ligands toward lanthanide metal ions. New complexes of trivalent Scandium, Yttrium, Lanthanum, and Cerium have been synthesized. The composition of these complexes is discussed on the basis of elemental analyses, IR, magnetic moments, and thermal analyses. The prepared complexes were screened for antibacterial and antifungal properties and have exhibited potential activity.

  19. Phosphate ester hydrolysis by hydroxo complexes of trivalent lanthanides stabilized by 4-imidazolecarboxylate.

    PubMed

    Aguilar-Pérez, Francisco; Gómez-Tagle, Paola; Collado-Fregoso, Elisa; Yatsimirsky, Anatoly K

    2006-11-13

    The anion of 4-imidazolecarboxylic acid (HL) stabilizes hydroxo complexes of trivalent lanthanides of the type ML(OH)+ (M = La, Pr) and M2L(n)(OH)(6-n) (M = La, n = 2; M = Pr, n = 2, 3; M = Nd, Eu, Dy, n = 1-3). Compositions and stability constants of the complexes have been determined by potentiometric titrations. Spectrophotometric and (1)H NMR titrations with Nd(III) support the reaction model for the formation of hydroxo complexes proposed on the basis of potentiometric results. Kinetics of the hydrolysis of two phosphate diesters, bis(4-nitrophenyl) phosphate (BNPP) and 2-hydroxypropyl 4-nitrophenyl phosphate (HPNPP), and a triester, 4-nitrophenyl diphenyl phosphate (NPDPP), in the presence of hydroxo complexes of five lanthanides were studied as a function of pH and metal and ligand concentrations. With all lanthanides and all substrates, complexes with the smallest n, that is M2L2(OH)4 for La and Pr and M2L(OH)5 for Nd, Eu, and Dy, exhibited the highest catalytic activity. Strong inhibitory effects by simple anions (Cl-, NO3-, (EtO)2PO2-, AcO-) were observed indicating high affinity of neutral hydroxo complexes toward anionic species. The catalytic activity decreased in the order La > Pr > Nd > Eu > Dy for both diester substrates and was practically independent of the nature of cation for a triester substrate. The efficiency of catalysis, expressed as the ratio of the second-order rate constant for the ester cleavage by the hydroxo complex to the second-order rate constant for the alkaline hydrolysis of the respective substrate, varied from ca. 1 for NPDPP to 10(2) for HPNPP and to 10(5) for BNPP. The proposed mechanism of catalytic hydrolysis involves reversible bridging complexation of a phosphodiester to the binuclear active species followed by attack on the phosphoryl group by bridging hydroxide (BNPP) or by the alkoxide group of the deprotonated substrate (HPNPP).

  20. In vitro studies of lanthanide complexes for the treatment of osteoporosis.

    PubMed

    Mawani, Yasmin; Cawthray, Jacqueline F; Chang, Stanley; Sachs-Barrable, Kristina; Weekes, David M; Wasan, Kishor M; Orvig, Chris

    2013-05-07

    Lanthanide ions, Ln(III), are of interest in the treatment of bone density disorders because they are found to accumulate preferentially in bone (in vivo), have a stimulatory effect on bone formation, and exhibit an inhibitory effect on bone degradation (in vitro), altering the homeostasis of the bone cycle. In an effort to develop an orally active lanthanide drug, a series of 3-hydroxy-4-pyridinone ligands were synthesized and eight of these ligands (H1 = 3-hydroxy-2-methyl-1-(2-hydroxyethyl)-4-pyridinone, H2 = 3-hydroxy-2-methyl-1-(3-hydroxypropyl)-4-pyridinone, H3 = 3-hydroxy-2-methyl-1-(4-hydroxybutyl)-4-pyridinone, H4 = 3-hydroxy-2-methyl-1-(2-hydroxypropyl)-4-pyridinone, H5 = 3-hydroxy-2-methyl-1-(1-hydroxy-3-methylbutan-2-yl)-4-pyridinone, H6 = 3-hydroxy-2-methyl-1-(1-hydroxybutan-2-yl)-4-pyridinone, H7 = 1-carboxymethyl-3-hydroxy-2-methyl-4-pyridinone, H8 = 1-carboxyethyl-3-hydroxy-2-methyl-4-pyridinone) were coordinated to Ln(3+) (Ln = La, Eu, Gd, Lu) forming stable tris-ligand complexes (LnL(3), L = 1(-), 2(-), 3(-), 4(-), 5(-), 6(-), 7(-) and 8(-)). The dissociation (pK(an)) and metal ligand stability constants (log β(n)) of the 3-hydroxy-4-pyridinones with La(3+) and Gd(3+) were determined by potentiometric titrations, which demonstrated that the 3-hydroxy-4-pyridinones form stable tris-ligand complexes with the lanthanide ions. One phosphinate-EDTA derivative (H(5)XT = bis[[bis(carboxymethyl)amino]methyl]phosphinate) was also synthesized and coordinated to Ln(3+) (Ln = La, Eu, Lu), forming the potassium salt of [Ln(XT)](2-). Cytotoxicity assays were carried out in MG-63 cells; all the ligands and metal complexes tested were observed to be non-toxic to this cell line. Studies to investigate the toxicity, cellular uptake and apparent permeability (P(app)) of the lanthanide ions were conducted in Caco-2 cells where it was observed that [La(XT)](2-) had the greatest cell uptake. Binding affinities of free lanthanide ions (Ln = La, Gd and Lu), metal

  1. Synthesis and luminescence properties of lanthanide complexes with a new tripodal ligand featuring N-thenylsalicylamide arms.

    PubMed

    Song, Xue-Qin; Zheng, Qing-Fang; Wang, Li; Liu, Wei-Sheng

    2012-01-01

    To explore the relationship between the structure of the ligands and the luminescent properties of the lanthanide complexes, luminescent lanthanide complexes of a new tripodal ligand, featuring N-thenylsalicylamide arms, were synthesized and characterized by elemental analysis, IR and TGA measurements. Photophysical properties of the complexes were studied by means of UV - visible absorption and steady-state luminescence spectroscopy. The results of UV - vis spectra indicate that metal binding does not disturb the electronic structure of the ligand. Excited-state luminescence lifetimes and quantum yields of the complexes were determined. The photoluminescence analysis suggested that there is an efficient ligand - Ln(III) energy transfer for the Tb(III) complex, and the ligand is an efficient 'antenna' for Tb(III). From a more general perspective, the results demonstrated the potential application of the lanthanide complex as luminescent materials in material chemistry.

  2. Highly emitting near-infrared lanthanide "encapsulated sandwich" metallacrown complexes with excitation shifted toward lower energy.

    PubMed

    Trivedi, Evan R; Eliseeva, Svetlana V; Jankolovits, Joseph; Olmstead, Marilyn M; Petoud, Stéphane; Pecoraro, Vincent L

    2014-01-29

    Near-infrared (NIR) luminescent lanthanide complexes hold great promise for practical applications, as their optical properties have several complementary advantages over organic fluorophores and semiconductor nanoparticles. The fundamental challenge for lanthanide luminescence is their sensitization through suitable chromophores. The use of the metallacrown (MC) motif is an innovative strategy to arrange several organic sensitizers at a well-controlled distance from a lanthanide cation. Herein we report a series of lanthanide “encapsulated sandwich” MC complexes of the form Ln3+ [12-MC(Zn(II),quinHA)-4]2[24-MC(Zn(II),quinHA)-8] (Ln3+ [Zn(II)MC(quinHA)]) in which the MC framework is formed by the self-assembly of Zn2+ ions and tetradentate chromophoric ligands based on quinaldichydroxamic acid (quinHA). A first-generation of luminescent MCs was presented previously but was limited due to excitation wavelengths in the UV. We report here that through the design of the chromophore of the MC assembly, we have significantly shifted the absorption wavelength toward lower energy (450 nm). In addition to this near-visible inter- and/or intraligand charge transfer absorption, Ln3+ [Zn(II)MC(quinHA)] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLn(L) = 2.88(2)%, τobs = 150.7(2) μs; Nd3+, QLn(L) = 1.35(1)%, τobs = 4.11(3) μs; Er3+, QLn(L) = 3.60(6)·10–2%, τobs = 11.40(3) μs), and excellent photostability. Quantum yields of Nd3+ and Er3+ MCs in the solid state and in deuterated solvents, upon excitation at low energy, are the highest values among NIR-emitting lanthanide complexes containing C–H bonds. The versatility of the MC strategy allows modifications in the excitation wavelength and absorptivity through the appropriate design of the ligand sensitizer, providing a highly efficient platform with tunable properties.

  3. Antineoplastic activity of new lanthanide (cerium, lanthanum and neodymium) complex compounds.

    PubMed

    Kostova, Irena; Kostova, Raina; Momekov, Georgi; Trendafilova, Natasha; Karaivanova, Margarita

    2005-01-01

    Cerium (III), lanthanum (III) and neodymium (III) complexes with 3,3'-benzylidenebis[4-hydroxycoumarin] were synthesized in view of their application as cytotoxic agents. The complexes were characterized by different physicochemical methods: elemental analysis, mass spectrometry, 1H NMR, 13C NMR and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligand. The vibrational analysis showed that in the complexes the ligand coordinated to the metal ion through both deprotonated hydroxyl groups; however, participation of the carbonyl groups in the coordination to the metal ion was also suggested. The evaluation of the cytotoxic activity of the novel lanthanide complexes on HL-60 myeloid cells revealed that they are potent cytotoxic agents. The cerium complex was found to exhibit superior activity in comparison to the lanthanum and neodymium coordination compounds, the latter being the least active. Our data give us reason to conclude that the newly synthesized lanthanide complexes should be submitted to further more detailed pharmacological and toxicological evaluation.

  4. Highly selective recovery of phosphopeptides using trypsin-assisted digestion of precipitated lanthanide-phosphoprotein complexes.

    PubMed

    Güzel, Yüksel; Rainer, Matthias; Mirza, Munazza R; Messner, Christoph B; Bonn, Günther K

    2013-05-21

    The basic idea of this study was to recover phosphopeptides after trypsin-assisted digestion of precipitated phosphoproteins using trivalent lanthanide ions. In the first step, phosphoproteins were extracted from the protein solution by precipitation with La(3+) and Ce(3+) ions, forming stable pellets. Additionally, the precipitated lanthanide-phosphoprotein complexes were suspended and directly digested on-pellet using trypsin. Non-phosphorylated peptides were released into the supernatants by enzymatic cleavage and phosphopeptides remained bound on the precipitated pellet. Further washing steps improved the removal of non-phosphorylated peptides. For the recovery of phosphopeptides the precipitated pellets were dissolved in 3.7% hydrochloric acid. The performance of this method was evaluated by several experiments using MALDI-TOF MS measurements and delivered the highest selectivity for phosphopeptides. This can be explained by the overwhelming preference of lanthanides for binding to oxygen-containing anions such as phosphates. The developed enrichment method was evaluated with several types of biological samples, including fresh milk and egg white. The uniqueness and the main advantages of the presented approach are the enrichment on the protein-level and the recovery of phosphopeptides on the peptide-level. This allows much easier handling, as the number of molecules on the peptide level is unavoidably higher, by complicating every enrichment strategy.

  5. New sandwich-type lanthanide complexes based on closed-macrocyclic Schiff base and phthalocyanine molecules.

    PubMed

    Gao, Feng; Feng, Xiaowan; Yang, Liu; Chen, Xiaoyu

    2016-04-25

    Two new sandwich-type lanthanide complexes with the general formula [(Pc)2Ln3(L)(OAc)(OCH3)2] (Ln(3+) = Dy(3+) () and Er(3+) ()) were successfully synthesized and structurally characterized based on closed-macrocyclic Schiff base and phthalocyanine molecules. The magnetic properties and structure-property relationship in this multi-decker system were investigated. Interestingly, the corresponding dysprosium complex shows typical single-molecule magnetic behavior with ferromagnetic dipole-dipole interactions and the slow relaxation of magnetization.

  6. Cationic lanthanide complexes of neutral tripodal N,O ligands: enthalpy versus entropy-driven podate formation in water.

    PubMed

    Bravard, Florence; Rosset, Caroline; Delangle, Pascale

    2004-07-07

    The cationic lanthanide complexes of two neutral tripodal N,O ligands, tpa (tris[(2-pyridyl)methyl]amine) and tpaam (tris[6-((2-N,N-diethylcarbamoyl)pyridyl)methyl]amine) are studied in water. The analysis of the proton lanthanide induced NMR shifts indicate that there is no abrupt structural change in the middle of the rare-earth series. Unexpectedly, the formation constant values of the lanthanide podates of tpaam and tpa in D2O at 298 K are similar, suggesting that the addition of the three amide groups to the ligand tpa does not lead to any increase in stability of the lanthanide complexes of tpaam in respect to tpa, even though the amide groups are coordinated to the metal in aqueous solution. The measurement of the enthalpy and entropy changes of the complexation reactions shows that the two similar ligands tpa and tpaam have different driving forces for lanthanide complexation. Indeed, the formation of tpa podates benefits from an exothermic enthalpy change associated with a small entropy change, whereas the complexation reaction with tpaam is clearly entropy-driven though opposed by a positive enthalpy change. The hydration states of the europium complexes were measured by luminescence and show the coordination of 4-5 water ligands in [Eu(tpa)]3+ whereas there are only 2 in [Eu(tpaam)]3+. Therefore the heptadentate ligand tpaam releases the translational entropy of more water molecules than does the tetradentate ligand tpa.

  7. Synthesis and characterization of dinuclear heterometallic lanthanide complexes exhibiting MRI and luminescence response.

    PubMed

    Mamedov, Ilgar; Parac-Vogt, Tatjana N; Logothetis, Nikos K; Angelovski, Goran

    2010-06-28

    A molecule bearing a macrocyclic DOTA-type chelator and an acyclic chelator based on the 5-aminoisophthalamide diethylenediaminetetraacid (5A-PADDTA) was synthesized by linking these two moieties via an amide bond. The ligand has the possibility to complex two identical or different lanthanide ions, depending on the desire for its potential application. Luminescence studies involving titrations of the Eu(3+) or Gd(3+) complex with Tb(3+) confirm the formation of heterometallic complexes, as well as the presence of different species in the solution. Comparative (1)H NMR spectra of the ligand, its Eu(3+) complex, and that containing both Eu(3+) and Tb(3+) proves the existence of respective monometallic or bimetallic species. NMR diffusion measurements on 5A-PADDTA as a model compound indicate the formation of aggregates upon the addition of Y(3+) (chosen as a diamagnetic analogue of lanthanide ions). Hydration values were calculated from the respective luminescence lifetime values. They show the dominance of a q = 1 species for both ions in monometallic complexes, or q = 1 and q = 2 species of ions in aggregated complexes, for DOTA and 5A-PADDTA chelators, respectively.

  8. Using Functionalized Silyl Ligands To Suppress Solvent Coordination to Silyl Lanthanide(II) Complexes

    PubMed Central

    2017-01-01

    The reaction of the potassium 1,3-trisilanediide Me2Si[Si(Me3Si)2K]2 with SmI2 and YbI2 was found to give the respective disilylated complexes Me2Si[Si(Me3Si)2]2Sm·2THF and Me2Si[Si(Me3Si)2]2Yb·2THF. Desolvation of coordinated solvent molecules in these complexes made their handling difficult. However, using a number of functionalized silanide ligands, complexes with a diminished number or even no coordinated solvent molecules were obtained ((R3Si)2Ln(THF)x (x = 0–3)). The structures of all new lanthanide compounds were determined by X-ray single-crystal structure analysis. NMR spectroscopic analysis of some Yb–silyl complexes pointed at highly ionic interactions between the silyl ligands and the lanthanides. This bonding picture was supported by DFT calculations at the B3PW91/Basis1 level of theory. Detailed theoretical analysis of a disilylated Eu(II) complex suggests that its singly occupied molecular orbitals (SOMOs) are very close in energy to the ligand silicon lone pairs (HOMO), and SQUID magnetometry measurements of the complex showed a deviation from the expected behavior for a free Eu(II) ion, which might be due to a ligand–metal interaction. PMID:28398724

  9. Density functional theory investigations of the trivalent lanthanide and actinide extraction complexes with diglycolamides.

    PubMed

    Wang, Cong-Zhi; Lan, Jian-Hui; Wu, Qun-Yan; Zhao, Yu-Liang; Wang, Xiang-Ke; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-06-21

    At present, designing novel ligands for efficient actinide extraction in spent nuclear fuel reprocessing is extremely challenging due to the complicated chemical behaviors of actinides, the similar chemical properties of minor actinides (MA) and lanthanides, and the vulnerability of organic ligands in acidic radioactive solutions. In this work, a quantum chemical study on Am(III), Cm(III) and Eu(III) complexes with N,N,N',N'-tetraoctyl diglycolamide (TODGA) and N,N'-dimethyl-N,N'-diheptyl-3-oxapentanediamide (DMDHOPDA) has been carried out to explore the extraction behaviors of trivalent actinides (An) and lanthanides (Ln) with diglycolamides from acidic media. It has been found that in the 1 : 1 (ligand : metal) and 2 : 1 stoichiometric complexes, the carbonyl oxygen atoms have stronger coordination ability than the ether oxygen atoms, and the interactions between metal cations and organic ligands are substantially ionic. The neutral ML(NO3)3 (M = Am, Cm, Eu) complexes seem to be the most favorable species in the extraction process, and the predicted relative selectivities are in agreement with experimental results, i.e., the diglycolamide ligands have slightly higher selectivity for Am(III) over Eu(III). Such a thermodynamical priority is probably caused by the higher stabilities of Eu(III) hydration species and Eu(III)-L complexes in aqueous solution compared to their analogues. In addition, our thermodynamic analysis from water to organic medium confirms that DMDHOPDA has higher extraction ability for the trivalent actinides and lanthanides than TODGA, which may be due to the steric hindrance of the bulky alkyl groups of TODGA ligands. This work might provide an insight into understanding the origin of the actinide selectivity and a theoretical basis for designing highly efficient extractants for actinide separation.

  10. Selected spectroscopic and magnetic properties of lanthanide complexes in polyimide XU-218

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; Shillady, D. D.; Vallarino, L. M.; Gootee, W. A.; Smailes, D. L.

    1987-01-01

    Polyimide XU-218 films containing approximately 5 wt pct of Eu(III), Gd(III), Tb(III), and Er(III) were prepared, and the effects of complexing each of the metals with the following four ligands were investigated: N-phenylphthalamate (NPPA), 2,4-pentanedionate (AcAc), 1,3-diphenyl 1,3-propanedionate (DBM), and a new hexa-aza-macrocyclic (MAC) ligand. The tris-chelated complexes of the mononegative ligands NPPA, AcAc, and DBM produced transparent, flexible films, which had magnetic and spectral properties very similar to those of the parent lanthanide complexes, while complexes of MAC showed problems due to the presence of lattice water and yielded dark brittle films. AcAc caused little or no effect on the glass transition temperature (Tg), while NPPA and DBM complexes lowered Tg to 269-290 C, and MAC indicated moisture by inflexion at 95-100 C with a true Tg at 320 C. All lanthanide-containing films were paramagnetic.

  11. Brilliant Sm, Eu, Tb and Dy chiral lanthanide complexes withstrong circularly polarized luminescence

    SciTech Connect

    Petoud, Stephane; Muller, Gilles; Moore, Evan G.; Xu, Jide; Sokolnicki, Jurek; Riehl, James P.; Le, Uyen; Cohen, Seth M.; Raymond,Kenneth N.

    2006-07-10

    The synthesis, characterization and luminescent behavior of trivalent Sm, Eu, Dy and Tb complexes of two enantiomeric, octadentate, chiral, 2-hydroxyisophthalamide ligands are reported. These complexes are highly luminescent in solution. Functionalization of the achiral parent ligand with a chiral 1-phenylethylamine substituent on the open face of the complex in close proximity to the metal center yields complexes with strong circularly polarized luminescence (CPL) activity. This appears to be the first example of a system utilizing the same ligand architecture to sensitize four different lanthanide cations and display CPL activity. The luminescence dissymmetry factor, g{sub lum}, recorded for the Eu(III) complex is one of the highest values reported, and this is the first time the CPL effect has been demonstrated for a Sm(III) complex with a chiral ligand. The combination of high luminescence intensity with CPL activity should enable new bioanalytical applications of macromolecules in chiral environments.

  12. Brilliant Sm, Eu, Tb, and Dy Chiral Lanthanide Complexes with Strong Circularly Polarized Luminescence

    PubMed Central

    Petoud, Stéphane; Muller, Gilles; Moore, Evan G.; Xu, Jide; Sokolnicki, Jurek; Riehl, James P.; Le, Uyen N.; Cohen, Seth M.; Raymond, Kenneth N.

    2009-01-01

    The synthesis, characterization, and luminescent behavior of trivalent Sm, Eu, Dy, and Tb complexes of two enantiomeric, octadentate, chiral, 2-hydroxyisophthalamide ligands are reported. These complexes are highly luminescent in solution. Functionalization of the achiral parent ligand with a chiral 1-phenylethylamine substituent on the open face of the complex in close proximity to the metal center yields complexes with strong circularly polarized luminescence (CPL) activity. This appears to be the first example of a system utilizing the same ligand architecture to sensitize four different lanthanide cations and display CPL activity. The luminescence dissymmetry factor, glum, recorded for the Eu(III) complex is one of the highest values reported, and this is the first time the CPL effect has been demonstrated for a Sm(III) complex with a chiral ligand. The combination of high luminescence intensity with CPL activity should enable new bioanalytical applications of macromolecules in chiral environments. PMID:17199285

  13. The btp [2,6-bis(1,2,3-triazol-4-yl)pyridine] binding motif: a new versatile terdentate ligand for supramolecular and coordination chemistry.

    PubMed

    Byrne, Joseph P; Kitchen, Jonathan A; Gunnlaugsson, Thorfinnur

    2014-08-07

    Ligands containing the btp [2,6-bis(1,2,3-triazol-4-yl)pyridine] motif have appeared with increasing regularity over the last decade. This class of ligands, formed in a one pot ‘click’ reaction, has been studied for various purposes, such as for generating d and f metal coordination complexes and supramolecular self-assemblies, and in the formation of dendritic and polymeric networks, etc. This review article introduces btp as a novel and highly versatile terdentate building block with huge potential in inorganic supramolecular chemistry. We will focus on the coordination chemistry of btp ligands with a wide range of metals, and how it compares with other classical pyridyl and polypyridyl based ligands, and then present a selection of applications including use in catalysis, enzyme inhibition, photochemistry, molecular logic and materials, e.g. polymers, dendrimers and gels. The photovoltaic potential of triazolium derivatives of btp and its interactions with anions will also be discussed.

  14. Luminescent lanthanide complexes with macrocyclic N-oxides

    NASA Astrophysics Data System (ADS)

    Pietraszkiewicz, Marek; Karpiuk, Jerzy; Pietraszkiewicz, Oksana

    1998-11-01

    Bicyclic ligand incorporating 3,3‧-biisoquinoline-2,2‧-dioxide unit fused with 1,10-diaza-18-crown-6 and 6,6‧-dicarboxy-2,2‧-bipyridine forms luminescent mononuclear and binuclear europium(III) complexes, respectively, that are stable in water solution. The presence of interfering ions, such as phosphate and Ca(II), caused a slight increase in the quantum yield of Eu(III) emission in the case of bicyclic ligand, and some loss of luminescence efficiency in the case of acyclic Eu(III) complex upon UV irradiation. This feature makes the bicyclic complex very attractive for practical applications in time-resolved fluorimetric immunoassays.

  15. Lanthanide complexes based on a diazapyridinophane platform containing picolinate pendants.

    PubMed

    Roca-Sabio, Adrián; Bonnet, Célia S; Mato-Iglesias, Marta; Esteban-Gómez, David; Tóth, Éva; de Blas, Andrés; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos

    2012-10-15

    A new macrocyclic ligand, N,N'-bis[(6-carboxy-2-pyridyl)methyl]-2,11-diaza[3.3](2,6)pyridinophane (H(2)BPDPA), was prepared, and its coordination properties toward the Ln(III) ions were investigated. The hydration numbers (q) obtained from luminescence lifetime measurements in aqueous solution of the Eu(III) and Tb(III) complexes indicate that they contain one inner-sphere water molecule. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by theoretical calculations performed at the density functional theory (B3LYP) level. The minimum-energy conformation calculated for the Yb(III) complex is in excellent agreement with the experimental structure in solution, as demonstrated by analysis of the Yb(III)-induced paramagnetic (1)H shifts. Nuclear magnetic relaxation dispersion (NMRD) profiles and (17)O NMR measurements recorded on solutions of the Gd(III) complex were used to determine the parameters governing the relaxivity. The results show that this system is endowed with a relatively fast water-exchange rate k(ex)(298) = 63 × 10(6) s(-1). Thermodynamic stability constants were determined by pH-potentiometric titration at 25 °C in 0.1 M KCl. The stability constants, which fall within the range logK(LnL) = 12.5-14.2, point to a relatively low stability of the complexes primarily as a consequence of the low basicity of the ligand.

  16. 17O NMR study of diamagnetic and paramagnetic lanthanide(III)-DOTA complexes in aqueous solution.

    PubMed

    Fusaro, Luca; Luhmer, Michel

    2014-08-18

    The complexes between the polyaminocarboxylate DOTA ligand and the whole series of stable lanthanide(III) metal ions, except Gd(3+), were studied in aqueous solution by (17)O NMR. For all of the paramagnetic systems, the (17)O NMR signals of both the nonchelating (O1) and chelating (O2) oxygen atoms could be detected, and for some of them, the signals of both the SAP and TSAP (TSAP') conformational isomers were also observed. Line width data analysis reveals that signal broadening is not dominated by paramagnetic relaxation enhancement, as it was believed to be. The data indicate that quadrupole relaxation and, for some complexes, chemical exchange between the SAP and TSAP isomers are the major contributions to the (17)O NMR line width at 25 °C. Besides, the Fermi contact and pseudocontact contributions to the observed lanthanide-induced shifts could be extracted. The (17)O hyperfine coupling constants determined for O2 in the SAP and TSAP isomers are similar to each other and to the values reported for several Gd(III) complexes comprising fast-exchanging ligands. Interestingly, the results suggest that (17)O NMR should prove to be useful for the study of highly paramagnetic Gd(III) complexes of nonlabile ligands.

  17. Group 13 and lanthanide complexes with mixed O,S anionic ligands derived from maltol.

    PubMed

    Monga, Vishakha; Patrick, Brian O; Orvig, Chris

    2005-04-18

    Four mixed O,S binding ligand precursors derived from maltol (3-hydroxy-2-methyl-4-pyrone) have been chelated to gallium(III), indium(III), and lanthanide(III) ions to yield a series of metal complexes. The four ligand precursors include two pyranthiones, 3-hydroxy-2-methyl-4-pyranthione, commonly known as thiomaltol (Htma), and 2-ethyl-3-hydroxy-4-pyranthione, commonly known as ethylthiomaltol (Hetma), and two pyridinethiones, 3-hydroxy-2-methyl-4(H)-pyridinethione (Hmppt) and 3-hydroxy-1,2-dimethyl-4-pyridinethione (Hdppt). Dimeric forms of the pyridinethiones, Hmppt dimer and Hdppt dimer, were also isolated and characterized. Complete characterization of the monomeric organic compounds is reported including acidity constants and crystal structures of Htma, Hetma, and Hdppt dimer. Reacting the four monomeric ligand precursors with Ga(3+) and In(3+) ions yielded new tris(bidentate ligand) complexes. X-ray-quality crystals of the fac isomer of Ga(tma)(3) were also obtained. New complexes with a range of lanthanides (Ln(3+)) were also synthesized with the two pyranthiones, Htma and Hetma. The synthesis reactions yielded complexes of the type LnL(3).xH(2)O and LnL(2)(OH).xH(2)O, as indicated by elemental analysis and spectroscopic evidence such as mass spectral data and IR and NMR spectra.

  18. Synthesis, characterization and anticancer activities of two lanthanide(III) complexes with a nicotinohydrazone ligand

    NASA Astrophysics Data System (ADS)

    Xu, Zhou-Qin; Mao, Xian-Jie; Jia, Lei; Xu, Jun; Zhu, Tao-Feng; Cai, Hong-Xin; Bie, Hong-Yan; Chen, Ru-Hua; Ma, Tie-liang

    2015-12-01

    Two isostructural acylhydrazone based complexes, namely [Ce(penh)2(H2O)4](NO3)3·4H2O (1) and [Sm(penh)2(NO3)2](NO3)·C2H5OH (2) (penh = 2-acetylpyridine nicotinohydrazone), have been obtained and characterized by physico-chemical and spectroscopic methods. The ten-coordinated lanthanide metal ion in each complex is surrounded by two independent tridentate neutral acylhydrazones with two ON2 donor sets. The other four coordination oxygen atoms are from four water molecules and two bidentate nitrate anions for complexes 1 and 2, respectively, thus giving distorted bicapped square antiprism geometry. Both complexes have excellent antitumor activity towards human pancreatic cancer (PATU8988), human colorectal cancer (lovo) and human gastric cancer(SGC7901) cell line. Furthermore, the cell apoptosis of complex 1 is detected by AnnexinV/PI flow cytometry.

  19. VX and VG chemical warfare agents bidentate complexation with lanthanide ions.

    PubMed

    Dennison, Genevieve H; Sambrook, Mark R; Johnston, Martin R

    2014-01-07

    Investigations into V-agent interaction with 1,10-phenanthroline nitrate Ln(III) complexes (Eu and Tb) were carried out using luminescence and UV-Vis spectroscopy. Addition of several equivalents of agent resulted in the loss of luminescence intensity and the observation of free 1,10-phenanthroline by UV-Vis. We propose a displacement mechanism in which the V-agent acts as a bidentate ligand to the lanthanide ion. Association constants were determined by luminescence titrations and found to be 10(5) mol(-1) dm(3).

  20. αvβ3-Integrin-targeting lanthanide complex: synthesis and evaluation as a tumor-homing luminescent probe.

    PubMed

    Ito, Takeo; Inoue, Masaki; Akamatsu, Kanako; Kusaka, Eriko; Tanabe, Kazuhito; Nishimoto, Sei-ichi

    2011-06-15

    The application of lanthanide complexes in the time-resolved fluorescence imaging of living cells has emerged in the last few decades, providing high-contrast images of cells through detection of the delayed emission. In the present study, we synthesized novel trivalent lanthanide complexes containing the cyclic peptide c(RGDfK) to visualize the α(v)β(3)-integrin-expressing tumor cells. Conjugation of c(RGDfK) with the macrocyclic bipyridine ligand had little effect on the fluorescence properties of the complex, indicating that the coordinated lanthanide ion was well isolated from the peptide. Bright luminescence images of α(v)β(3)-integrin-expressing U87-MG cells were successfully obtained by employing the probes.

  1. Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

    SciTech Connect

    Zhao Jing; Liang Jingjing; Pan Yingli; Zhang Yong; Jia Dingxian

    2011-06-15

    Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en){sub 2}(dien)({eta}{sup 2}-SbSe{sub 4})] (Ln=Ce(1a), Nd(1b)), [Ln(en){sub 2}(dien)(SbSe{sub 4})] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)({mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4})]{sub {infinity}} (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)({eta}{sup 2}-SbSe{sub 4})] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe{sub 4}]{sup 3-} acts as a monodentate ligand mono-SbSe{sub 4}, a bidentate chelating ligand {eta}{sup 2}-SbSe{sub 4} or a tridentate bridging ligand {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} to the lanthanide(III) center depending on the Ln{sup 3+} ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with E{sub g} between 2.08 and 2.51 eV. - Graphical Abstract: Two structural types of lanthanide(III) selenidoantimonates are formed in both en-dien and en-trien mixed polyamines across lanthanide series, indicating the lanthanide contraction effect on the structures of the lanthanide(III) selenidoantimonates. Highlights: > Two structural types of lanthanide selenidoantimonates are prepared across the lanthanide series in both Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) systems. > The [SbSe{sub 4}]{sup 3-} anion acts as a mono-SbSe{sub 4}, a {eta}{sup 2}-SbSe{sub 4} or a {mu}-{eta}{sup 1},{eta}{sup 2}-SbSe{sub 4} ligand to the Ln{sup 3+} ions. > The soft base ligand [SbSe{sub 4}]{sup 3-} can be controlled to coordinate to the Ln{sup 3+} ions with en+dien and en+trien as co-ligands.

  2. Complexation of Lanthanides with Nitrate at Variable Temperatures: Thermodynamics and Coordination Modes

    SciTech Connect

    Rao, Linfeng; Tian, Guoxin

    2008-12-10

    Complexation of neodymium(III) with nitrate was studied at variable temperatures (25, 40, 55 and 70 C) by spectrophotometry and microcalorimetry. The NdNO{sub 3}{sup 2+} complex is weak and becomes slightly stronger as the temperature is increased. The enthalpy of complexation at 25 C was determined by microcalorimetry to be small and positive, (1.5 {+-} 0.2) kJ {center_dot} mol{sup -1}, in good agreement with the trend of the stability constant at variable temperatures. Luminescence emission spectra and lifetime of Eu(III) in nitrate solutions suggest that inner-sphere and bidentate complexes form between trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) and nitrate in aqueous solutions. Specific Ion Interaction approach (SIT) was used to obtain the stability constants of NdNO{sub 3}{sup 2+} at infinite dilution and variable temperatures.

  3. Grafting of lanthanide complexes on silica surfaces: a theoretical investigation.

    PubMed

    Del Rosal, Iker; Gerber, Iann C; Poteau, Romuald; Maron, Laurent

    2010-06-03

    Grafting catalysts on a surface leads to heterogeneous catalysts with well-defined active sites. However, the grafting mode of a lanthanum complex onto silica remains unknown. To shed light on this grafting reaction, different studies have been achieved in the framework of density functional theory. The silica substrate hydroxylated at 700 degrees C has been simulated both by molecular and periodic models. The created molecular models are in agreement with the rigidity of the ligand, the surface density of silanol groups, and the different spectroscopic data of a silica surface partially dehydroxylated at 700 degrees C. Two possible models of surface have henceforth been considered: the first one with one isolated silanol and the second one with two vicinal silanols linked by a siloxane bridge. The thermodynamics of a grafting reaction of lanthanum catalysts on these models has also been investigated. This reaction leads to thermodynamically stable structures that reveal different types of grafting: monografted, bigrafted, or bigrafted after breaking of a Si-O-Si bridge. Similarly to experimental approaches, coordination of triphenylphosphine oxide (O=PPh(3)) has also been considered as a probe of the grafting mode. A good agreement between the theoretical and the experimental spectroscopic values has systematically been found, but none of the grafting modes seem to be more relevant. Accordingly, it is necessary to consider in subsequent studies that all grafting modes coexist, increasing the difficulty to theoretically investigate multistep reactions.

  4. Sparkle/PM7 Lanthanide Parameters for the Modeling of Complexes and Materials

    PubMed Central

    Dutra, José Diogo L.; Filho, Manoel A. M.; Rocha, Gerd B.; Freire, Ricardo O.; Simas, Alfredo M.; Stewart, James J. P.

    2013-01-01

    The recently published Parametric Method number 7, PM7, is the first semiempirical method to be successfully tested by modeling crystal structures and heats of formation of solids. PM7 is thus also capable of producing results of useful accuracy for materials science, and constitutes a great improvement over its predecessor, PM6. In this article, we present Sparkle Model parameters to be used with PM7 that allow the prediction of geometries of metal complexes and materials which contain lanthanide trications. Accordingly, we considered the geometries of 224 high-quality crystallographic structures of complexes for the parameterization set and 395 more for the validation of the parameterization for the whole lanthanide series, from La(III) to Lu(III). The average unsigned error for Sparkle/PM7 for the distances between the metal ion and its coordinating atoms is 0.063Å for all lanthanides, ranging from a minimum of 0.052Å for Tb(III) to 0.088Å for Ce(III), comparable to the equivalent errors in the distances predicted by PM7 for other metals. These distance deviations follow a gamma distribution within a 95% level of confidence, signifying that they appear to be random around a mean, confirming that Sparkle/PM7 is a well-tempered method. We conclude by carrying out a Sparkle/PM7 full geometry optimization of two spatial groups of the same thulium-containing metal organic framework, with unit cells accommodating 376 atoms, of which 16 are Tm(III) cations; the optimized geometries were in good agreement with the crystallographic ones. These results emphasize the capability of the use of the Sparkle Model for the prediction of geometries of compounds containing lanthanide trications within the PM7 semiempirical model, as well as the usefulness of such semiempirical calculations for materials modeling. Sparkle/PM7 is available in the software package MOPAC2012, at no cost for academics and can be obtained from http://openmopac.net. PMID:24163641

  5. Synthesis and chemistry of yttrium and lanthanide metal complexes. Progress report, March 15, 1991--March 14, 1992

    SciTech Connect

    Evans, W.J.

    1991-09-01

    The objective of this research project is to determine the special features of complexes of yttrium and the lanthanide metals which will allow the design and synthesis of materials with unique chemical, physical, and catalytic properties. Past studies of yttrium and lanthanide metal alkyl and hydride complexes stabilized by cyclopentadienyl co-ligands have shown that a substantial, often singular, organometallic chemistry is available via these metals. More extensive utilization of the chemical opportunities available through yttrium and the lanthanides would be possible, however, if stabilizing ancillary ligand systems less sensitive to oxidation and protonolysis than cyclopentadienides could be developed. Alkoxide ligands are attractive in this regard and our recent research had focused on alkoxides and the special opportunities they can provide to these metals. 6 refs., 10 figs.

  6. The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid.

    PubMed

    Mian, Federica; Bottaro, Gregorio; Seraglia, Roberta; Cavazzini, Marco; Quici, Silvio; Armelao, Lidia

    2016-10-18

    In this study, we present the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu(3+) ⊂1, Dy(3+) ⊂9) with different ligand topologies in the presence of dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid). Macrocyclic (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, DO3A, 9) and acyclic (1,4,7-triazaheptane-1,1,7,7-tetraacetic acid, DTTA, 1) ligands have been selected to form a ratiometric pair in which Dy(3+) ⊂9 acts as a reference and Eu(3+) ⊂1 acts as a probe for the recognition of DPA. The pair of luminescent complexes in water reveals the capability to work as a DPA luminescent sensor. The change of emission intensity of Eu(3+) indicates the occurrence of a new sensitization path for the lanthanide cation through excitation of DPA. NMR evidence implies the presence of free 1 and mass spectrometry shows the formation of emitting [EuDPA2 ](-) as a result of a ligand exchange reaction.

  7. Lanthanide-cyclodextrin complexes as probes for elucidating optical purity by NMR spectroscopy

    SciTech Connect

    Wenzel, T.J.; Bogyo, M.S.; Lebeau, E.L. )

    1994-06-01

    A multidentate ligand is bonded to cyclodextrins by the reaction of diethylenetriaminepentaacetic dianhydride with 6-mono- and 2-mono(ethylenediamine) derivatives of cyclodextrin. Adding Dy(III) to the cyclodextrin derivatives enhances the enantiomeric resolution in the [sup 1]H NMR spectra of carbionoxamine maleate, doxylamine succinate, pheniramine maleate, propranolol hydrochloride, and tryptophan. The enhancement is more pronounced with the secondary derivative. The Dy(III)-induced shifts can be used to elucidate the geometry of cyclodextrin-substrate inclusion complexes. Lanthanide-induced shifts are reported for complexes of aspartame, tryptophan, propranolol, and 1-anilino-8-naphthalenesulfonate with cyclodextrins, and the relative magnitudes of the shifts agree with previously reported structures of the complexes. 37 refs., 9 figs., 5 tabs.

  8. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with α-hydroxyisobutyric acid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Ewing, William C; Scott, Brian L; Runde, Wolfgang

    2012-12-17

    Despite the wide range of applications of α-hydroxyisobutyric acid (HIBA) in biochemical processes, pharmaceutical formulations, and group and elemental separations of lanthanides and actinides, the structures and geometries of lanthanide-HIBA complexes are still not well understood. We reacted HIBA with lanthanides in aqueous solution at pH = 5 and synthesized 14 lanthanide-HIBA complexes of the formula [Ln(HIBA)(2)(H(2)O)(2)](NO(3))·H(2)O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14)), isolating single crystals (1-7, 10, and 11) and powders (8, 9, and 12-14). Both single-crystal and powder X-ray diffraction studies reveal a two-dimensional extended structure across the entire lanthanide series. The environment around the eight-coordinated Ln(III) atom is best described as a distorted dodecahedron, where HIBA acts as a monoanionic tridentate ligand with one carboxylato oxygen atom and one hydroxyl oxygen atom chelating to one Ln(III) center. The carboxylato oxygen atom from a second HIBA ligand bridges to a neighboring Ln(III) atom to form a two-dimensional extended structure. While the coordination mode for HIBA is identical across the lanthanide series, three different structure types are found for La, Ce-Ho, and Er-Lu. Solution characterization using (13)C NMR further confirmed a single solution complex under the crystallization conditions. Raman and UV-vis-NIR absorbance and diffuse reflectance spectra of HIBA-Ln(III) complexes were also measured.

  9. A series of three-dimensional architectures constructed from lanthanide-substituted polyoxometalosilicates and lanthanide cations or lanthanide-organic complexes as linkers.

    PubMed

    An, Haiyan; Zhang, Hua; Chen, Zhaofei; Li, Yangguang; Liu, Xuan; Chen, Hao

    2012-07-21

    Six 3D architectures based on lanthanide-substituted polyoxometalosilicates, KLn[(H(2)O)(6)Ln](2)[(H(2)O)(4)LnSiW(11)O(39)](2)·nH(2)O (Ln = La 1, n = 42; Ce 2, n = 40), H[(H(2)O)(6)Nd](2)[(H(2)O)(7)Nd][(H(2)O)(4)NdSiW(11)O(39)][(H(2)O)(3)NdSiW(11)O(39)]·13H(2)O (3), H(2)K(2)[(Hpic)(H(2)O)(5)Ln](2)[(H(2)O)(4)LnSiW(11)O(39)](2)·nH(2)O (Ln = La 4, n = 18.5; Ce 5, n = 35; Nd 6, n = 36; Hpic = 4-picolinic acid), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, TG analysis, powder X-ray diffraction and single crystal X-ray diffraction. Compounds 1 and 2 are isostructural, built up of lanthanide-substituted polyoxoanions [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) linked by Ln(3+) cations to form a 3D open framework with 1D channels. The polyoxoanion [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) consists of two α(1)-type mono-Ln-substituted Keggin anions. When Nd(3+) ion was used instead of La(3+) or Ce(3+) ions, compound 3 with a different structure was obtained, containing two kinds of polyoxoanions [{(H(2)O)(4)Nd(SiW(11)O(39))}(2)](10-) and [{(H(2)O)(3)Nd(SiW(11)O(39))}(2)](10-) which are connected together by Nd(3+) ions to yield a 3D framework. When 4-picolinic acid was added to the reaction system of 1-3, isostructural compounds 4-6 were obtained, constructed from the polyoxoanions [{(H(2)O)(4)Ln(SiW(11)O(39))}(2)](10-) linked by picolinate-chelated lanthanide centers to form a 3D channel framework. From a topological viewpoint, the 3D nets of 1, 2, 4, 5 and 6 exhibit a (3,6)-connected rutile topology, whereas the 3D structure of 3 possesses a rare (3,3,6,10)-connected topology. The magnetic properties of 2, 3, 5 and 6 have been studied by measuring their magnetic susceptibilities in the temperature range 2-300 K.

  10. Lanthanide-organic complexes based on polyoxometalates: Solvent effect on the luminescence properties

    SciTech Connect

    Tang Qun; Liu Shuxia; Liang Dadong; Ma Fengji; Ren Guojian; Wei Feng; Yang Yuan; Li Congcong

    2012-06-15

    A series of lanthanide-organic complexes based on polyoxometalates (POMs) [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}][W{sub 6}O{sub 19}] (Ln=La(1), Ce(2), Sm(3), Eu(4), Gd(5); DNBA=3,5-dinitrobenzoate; DMF=N,N-dimethylformamide) has been synthesized. These complexes consist of [W{sub 6}O{sub 19}]{sup 2-} and dimeric [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}]{sup 2+} cations. The luminescence properties of 4 are measured in solid state and different solutions, respectively. Notably, the emission intensity increases gradually with the increase of solvent permittivity, and this solvent effect can be directly observed by electrospray mass spectrometry (ESI-MS). The analyses of ESI-MS show that the eight coordinated solvent DMF units of dimeric cation are active. They can move away from dimeric cations and exchange with solvent molecules. Although the POM anions escape from 3D supramolecular network, the dimeric state structure of [Ln{sub 2}(DNBA){sub 4}]{sup 2+} remains unchanged in solution. The conservation of red luminescence is attributed to the maintenance of the aggregated state structures of dimeric cations. - Graphical abstract: 3D POMs-based lanthanide-organic complexes performed the solvent effect on the luminescence property. The origin of such solvent effect can be understood and explained on the basis of the existence of coordinated active sites by the studies of ESI-MS. Highlights: Black-Right-Pointing-Pointer The solvent effect on the luminescence property of POMs-based lanthanide-organic complexes. Black-Right-Pointing-Pointer ESI-MS analyses illuminate the correlation between the structure and luminescence property. Black-Right-Pointing-Pointer The dimeric cations have eight active sites of solvent coordination. Black-Right-Pointing-Pointer The aggregated state structure of dimer cation remains unchanged in solution. Black-Right-Pointing-Pointer Luminescence associating with ESI-MS is a new method for investigating the interaction of complex and solvent.

  11. A series of dinuclear lanthanide complexes with slow magnetic relaxation for Dy2 and Ho2.

    PubMed

    Zhang, Jin; Zhang, Haifeng; Chen, Yanmei; Zhang, Xiangfei; Li, Yahong; Liu, Wei; Dong, Yaping

    2016-10-18

    The employment of a new Schiff base ligand, 2-{[(2-hydroxy-3-methoxybenzyl)imino]methyl}naphthalen-1-ol (H2L), in 4f-metal chemistry has led to the formation of seven new isostructural lanthanide(iii) complexes. More specifically the 1 : 1 reaction of Ln(NO3)3·6H2O and H2L in ethanol in the presence of 3 equivalents of pyridine yielded seven dinuclear complexes of compositions [Ln2L2(NO3)2(C2H5OH)2]·0.5py (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Yb (7); py = pyridine). The structures of the isomorphous complexes 1-7 were determined by single-crystal X-ray crystallography. X-ray crystallography data reveal that each compound is neutral, and contains two doubly-deprotonated ligands, two chelated nitrates and two coordinated ethanol molecules. The two Ln(III) atoms in 1-7 are doubly bridged by the two phenolato oxygen atoms of two L(2-) ligands. Each of the two lanthanide ions is eight-coordinated and possesses distorted dodecahedron geometry. Dc magnetic susceptibility studies in the 2-300 K range reveal probably a weak antiferromagnetic interaction for 2, 3 and 6, and a ferromagnetic interaction at low temperature for 4 and 5. Complexes 4 and 5 show slow magnetic relaxation behavior. The Ueff for 4 of 66.7 K is a relatively high value among the reported Dy2 SMMs. Complex 5 is a very rare example of a Ho2 compound which exhibits slow magnetic relaxation.

  12. Synthesis, structure and luminescence properties of lanthanide complex with a new tetrapodal ligand featuring salicylamide arms

    SciTech Connect

    Song Xueqin; Wen Xiaoguang; Liu Weisheng; Wang Daqi

    2010-01-15

    A new tetrapodal ligand 1,1,1-tetrakis{l_brace}[(2'-(2-furfurylaminoformyl))phenoxyl]methyl{r_brace}methane (L) has been prepared and their coordination chemistry with Ln{sup III} ions has been investigated. The structure of {l_brace}[Ln{sub 4}L{sub 3}(NO{sub 3}){sub 12}].H{sub 2}O{r_brace}{sub i}nfinity (Ln=Nd, Eu)] shows the binodal 4,3-connected three-dimensional interpenetration coordination polymers with topology of a (8{sup 6}){sub 3}(8{sup 3}){sub 4} notation. [DyL(NO{sub 3}){sub 3}(H{sub 2}O){sub 2}].0.5CH{sub 3}OH and [ErL(NO{sub 3}){sub 3}(H{sub 2}O) (CH{sub 3}OH)].CH{sub 3}COCH{sub 3} is a 1:1 mononuclear complex with interesting supramolecular features. The structure of [NdL(H{sub 2}O){sub 6}].3ClO{sub 4}.3H{sub 2}O is a 2:1 mononuclear complex which further self-assembled through hydrogen bond to form a three-dimensional supramolecular structures. The result presented here indicates that both subtle variation of the terminal group and counter anions can be applied in the modulation of the overall molecular structures of lanthanide complex of salicylamide derivatives due to the structure specialties of this type of ligand. The luminescence properties of the Eu{sup III} complex are also studied in detail. - Grapical Abstract: We present here a series of zero- to three-dimensional lanthanide coordination structures and luminescence properties of Eu(III) complex of a new tetrapodal ligand.

  13. Enhancing the photocytotoxic potential of curcumin on terpyridyl lanthanide(III) complex formation.

    PubMed

    Hussain, Akhtar; Somyajit, Kumar; Banik, Bhabatosh; Banerjee, Samya; Nagaraju, Ganesh; Chakravarty, Akhil R

    2013-01-07

    Lanthanide(III) complexes [Ln(R-tpy)(cur)(NO3)2] (Ln = La(III) in 1, 2; Gd(III) in 5, 6) and [Ln(R-tpy)(scur)(NO3)2] (Ln = La(III) in 3, 4; Gd(III) in 7, 8), where R-tpy is 4′-phenyl-2,2′:6′,2′′-terpyridine (ph-tpy in 1, 3, 5, 7), 4′-(1-pyrenyl)-2,2′:6′,2′′-terpyridine (py-tpy in 2, 4, 6, 8), Hcur is curcumin (in 1, 2, 5, 6) and Hscur is diglucosylcurcumin (in 3, 4, 7, 8), were prepared and their DNA photocleavage activity and photocytotoxicity studied. Complexes [La(ph-tpy)(cur)(NO3)2] (1) and [Gd(ph-tpy)(cur)(NO3)2] (5) were structurally characterized. The complexes in aqueous-DMF showed an absorption band near 430 nm and an emission band near 515 nm when excited at 420 nm. The complexes are moderate binders to calf-thymus DNA. They cleave plasmid supercoiled DNA to its nicked circular form in UV-A (365 nm) and visible light (454 nm) via (1)O2 and ˙OH pathways. The complexes are remarkably photocytotoxic in HeLa cells in visible light (λ = 400–700 nm) and are non-toxic in the dark. FACScan analysis of the HeLa cells treated with 2 and 4 showed cell death via an apoptotic pathway. Nuclear localization of 1–4 is evidenced from confocal imaging on HeLa cells. The hydrolytic instability of curcumin gets significantly reduced upon binding to the lanthanide ions while retaining its photocytotoxic potential.

  14. Determination of tetracycline in milk by using nucleotide/lanthanide coordination polymer-based ternary complex.

    PubMed

    Tan, Hongliang; Ma, Chanjiao; Song, Yonghai; Xu, Fugang; Chen, Shouhui; Wang, Li

    2013-12-15

    The meta-organic coordination polymers have been emerged as fascinating nanomaterials because of their tunable nature. In this work, we employed lanthanide coordination polymer self-assembled from adenosine monophosphate (AMP) and europium ion (Eu(3+)) as receptor reagent and citrate (Cit) as ancillary ligand to construct a fluorescent sensor for the detection of tetracycline (Tc) in milk. The co-coordination of Cit and Tc with Eu(3+) on the surface of the coordination polymer AMP/Eu leads to the formation of ternary complex which emitted strong fluorescence due to the removal of coordinated water molecules and an intramolecular energy transfer from Tc to Eu(3+). The fluorescent intensity of Eu(3+) displayed a good linear response to Tc concentrations in the range of 0.1-20 μM with a detection limit of 60 nM. This method was successfully applied to determine the levels of Tc in milk, which is the first application of coordination polymer as a fluorescent sensor in real sample. Compared with other Eu(3+)-based fluorescent methods for Tc detection, the presented method allows simple, direct analysis of Tc without requiring special reaction media or complicated prepreparation processes. This straightforward strategy could be extended to the preparation of other lanthanide coordination polymer-based fluorescent probes for applications in biosensing, imaging, drug delivery, and so on. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Magnetic anisotropy in surface-supported single-ion lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Stoll, Paul; Bernien, Matthias; Rolf, Daniela; Nickel, Fabian; Xu, Qingyu; Hartmann, Claudia; Umbach, Tobias R.; Kopprasch, Jens; Ladenthin, Janina N.; Schierle, Enrico; Weschke, Eugen; Czekelius, Constantin; Kuch, Wolfgang; Franke, Katharina J.

    2016-12-01

    Single-ion lanthanide-organic complexes can provide stable magnetic moments with well-defined orientation for spintronic applications on the atomic level. Here, we show by a combined experimental approach of scanning tunneling microscopy and x-ray absorption spectroscopy that dysprosium-tris(1,1,1-trifluoro-4-(2-thienyl)-2,4-butanedionate) (Dy (tta) 3 ) complexes deposited on a Au(111) surface undergo a molecular distortion, resulting in distinct crystal field symmetry imposed on the Dy ion. This leads to an easy-axis magnetization direction in the ligand plane. Furthermore, we show that tunneling electrons hardly couple to the spin excitations, which we ascribe to the shielded nature of the 4 f electrons.

  16. Syntheses and structural characterization of trivalent lanthanide complexes of p-sulfonatothiacalix[4]arene

    NASA Astrophysics Data System (ADS)

    Guo, Qian-ling; Zhu, Wen-xiang; Ma, Shu-lan; Yuan, Da-qiang; Dong, Shu-jing; Xu, Miao-qiong

    2004-03-01

    The X-ray crystallographic studies are reported for the water-soluble trivalent lanthanide complexes of the macrocyclic p-sulfonatothiacalix[4]arene [Gd(H 2O) 6((CH 3) 2SO)( p-sulfonatothiacalix[4]arene)]·H 3O +·5H 2O ( 1) and Na[Nd(H 2O) 6((CH 3) 2SO)( p-sulfonatothiacalix[4]arene)]·3H 2O ( 2). The complexes are isostructural and belong to monoclinic system, C2/m space group. The Ln 3+ metal ion is coordinated by the thiacalixarene ligand via the sulfonato group, and also ligated by an oxygen atom of a dimethyl sulfoxide (DMSO) molecule that occupies the cavity of the thiacalixarene and six aqua ligands. The thiacalixarenes are linked by the coordinated water molecules through hydrogen bonding to form a 2D polymer. The p-sulfonatothiacalixarenes maintain the clay-like bi-layer structure in the coordination network.

  17. Advances in the development of lanthanide macrocyclic complexes as luminescent biomarkers

    NASA Astrophysics Data System (ADS)

    Adeyiga, Adedoyin M.; Harlow, Patrick M.; Vallarino, Lidia M.; Leif, Robert C.

    1996-05-01

    The development of peripherally substituted europium(III)-macrocycles suitable as luminescent bio-markers was continued in three related areas. (1) Protocols were established for the coupling of NCS-substituted Eu-macrocycles to proteins and for the mounting on microscope slides of particles labeled with luminescent Eu-macrocycles. The emission/excitation spectra of the dried, slide-mounted particles were investigated. (2) A procedure was developed for the synthesis of lanthanide-macrocycles having a single peripheral functionality. The structure and properties of the mono-functionalized macrocyclic complexes were established. (3) A study was undertaken to explore whether the emission intensity of the Eu-macrocycles can be increased by energy transfer from yttrium(III) complexes. Preliminary results have shown that a considerable luminescence enhancement can be achieved by this method. The results obtained in these three areas are evaluated in the light of the research reported by other investigators.

  18. Sub-monolayer film growth of a volatile lanthanide complex on metallic surfaces

    PubMed Central

    Chen, Jinjie; Edelmann, Kevin; Wulfhekel, Wulf

    2015-01-01

    Summary We deposited a volatile lanthanide complex, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)terbium(III), onto metal surfaces of Cu(111), Ag(111) and Au(111) in vacuum and observed well-ordered sub-monolayer films with low temperature (5 K) scanning tunneling microscopy. The films show a distorted three-fold symmetry with a commensurate structure. Scanning tunneling spectroscopy reveals molecular orbitals delocalized on the ligands of the molecule. Our results imply that this complex can be transferred onto the metal substrates without molecular decomposition or contamination of the surface. This new rare-earth-based class of molecules broadens the choice of molecular magnets to study with scanning tunneling microscopy. PMID:26733215

  19. Synthesis, crystal structures, and properties of oxovanadium(IV)-lanthanide(III) heteronuclear complexes.

    PubMed

    Shi, Wei; Chen, Xiao-Yan; Zhao, Yan-Nan; Zhao, Bin; Cheng, Peng; Yu, Ao; Song, Hai-Bin; Wang, Hong-Gen; Liao, Dai-Zheng; Yan, Shi-Ping; Jiang, Zong-Hui

    2005-08-19

    A new series of oxovanadium(IV)-lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)](3)21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)} 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)}8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)](1.5)} 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H(6)TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2- unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2- ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2- ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2- ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)-lanthanide(III) coordination polymers and thus enlarge the realm of 3d-4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.

  20. Evidence for adduct formation at the semiconductor-solution interface. Photoluminescent properties of cadmium selenide in the presence of lanthanide. beta. -diketonate complexes

    SciTech Connect

    Murphy, C.J.; Ellis, A.B. )

    1990-04-05

    Photoluminescence (PL) measurements of etched, single-crystal n-CdSe demonstrate that the semiconductor surface engages in adduct formation with a family of lanthanide {beta}-diketonate complexes, Ln(fod){sub 3} (Ln = lanthanide; fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato anion), in isooctane ambient.

  1. Step by Step Assembly of Polynuclear Lanthanide Complexes with a Phosphonated Bipyridine Ligand.

    PubMed

    Souri, Nabila; Tian, Pingping; Lecointre, Alexandre; Lemaire, Zoé; Chafaa, Salah; Strub, Jean-Marc; Cianférani, Sarah; Elhabiri, Mourad; Platas-Iglesias, Carlos; Charbonnière, Loïc J

    2016-12-19

    The synthesis of the octadentate ligand L (LH8 = ((([2,2'-bipyridine]-6,6'-diylbis(methylene))bis(azanetriyl))tetrakis(methylene))tetrakis(phosphonic acid)) is reported. The coordination of L with various lanthanide cations was monitored by absorption and luminescence spectrophotometric titration experiments (Ln = Tb, Yb), potentiometry (Ln = La, Eu, Lu), and mass spectrometry (Ln = Tb). It was found that L forms very stable mononuclear (LnL) species in aqueous solutions (log K = 19.80(5), 19.5(2), and 19.56(5) for La, Eu, and Lu, respectively) with no particular trend along the series. Spectroscopic data showed the Ln cations to be enclosed in the cavity formed by the octadentate ligand, thereby shielding the metal from interactions with water molecules in the first coordination sphere. When more than one equivalent of cations is added, the formation of polynuclear [(LnL)2Lnx] complexes (x = 1-3) can be observed, the presence of which could be confirmed by electrospray and MALDI mass spectrometry experiments. DFT modeling of the mononuclear (LnL) complexes indicated that the coordination of the cation in the cavity of the ligand results in a very asymmetric charge distribution, with a region of small negative electrostatic potential on the hemisphere composed of the chromophoric bipyridyl moiety and an electron-rich domain at the opposite hemisphere around the four phosphonate functions. DFT further showed that this polarization is most likely at the origin of the strong interactions between the (LnL) complexes and the incoming additional cations, leading to the formation of the polynuclear species. (1)H and (31)P NMR were used to probe the possible exchange of the lanthanide complexed in the cavity of the ligand in D2O, revealing no detectable exchange after 4 weeks at 80 °C and neutral pD, therefore pointing out an excellent kinetic inertness.

  2. Visible-near-infrared luminescent lanthanide ternary complexes based on beta-diketonate using visible-light excitation.

    PubMed

    Sun, Lining; Qiu, Yannan; Liu, Tao; Feng, Jing; Deng, Wei; Shi, Liyi

    2015-11-01

    We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible-light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3 phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401-460 nm), the complexes show characteristic visible (Sm(3+)) as well as near-infrared (Sm(3+), Nd(3+), Yb(3+), Er(3+), Tm(3+), Pr(3+)) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near-infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications.

  3. Photophysical properties of Lanthanide Dinuclear complexes with p-tert-butylcalix[8]arene[sup 1,2

    SciTech Connect

    Buenzli, J.-C.G.; Froidevaux, P. ); Harrowfield, J.M. )

    1993-07-21

    The macrocyclic octaphenol p-tert-butylcalix[8]arene (LH[sub 8]) was reacted with lanthanide(III) ions in dimethylformamide (DMF) containing triethylamine to obtain both homo- and heterodinuclear neutral complexes of composition [(Ln1:Ln2)LH[sub 2](DMF)[sub 5

  4. Isoquinoline-based lanthanide complexes: bright NIR optical probes and efficient MRI agents.

    PubMed

    Caillé, Fabien; Bonnet, Célia S; Buron, Frédéric; Villette, Sandrine; Helm, Lothar; Petoud, Stéphane; Suzenet, Franck; Tóth, Eva

    2012-02-20

    In the objective of developing ligands that simultaneously satisfy the requirements for MRI contrast agents and near-infrared emitting optical probes that are suitable for imaging, three isoquinoline-based polyaminocarboxylate ligands, L1, L2 and L3, have been synthesized and the corresponding Gd(3+), Nd(3+) and Yb(3+) complexes investigated. The specific challenge of the present work was to create NIR emitting agents which (i) have excitation wavelengths compatible with biological applications and (ii) are able to emit a sufficient number of photons to ensure sensitive NIR detection for microscopic imaging. Here we report the first observation of a NIR signal arising from a Ln(3+) complex in aqueous solution in a microscopy setup. The lanthanide complexes have high thermodynamic stability (log K(LnL) =17.7-18.7) and good selectivity for lanthanide ions versus the endogenous cations Zn(2+), Cu(2+), and Ca(2+) thus preventing transmetalation. A variable temperature and pressure (17)O NMR study combined with nuclear magnetic relaxation dispersion measurements yielded the microscopic parameters characterizing water exchange and rotation. Bishydration of the lanthanide cation in the complexes, an important advantage to obtain high relaxivity for the Gd(3+) chelates, has been demonstrated by (17)O chemical shifts for the Gd(3+) complexes and by luminescence lifetime measurements for the Yb(3+) analogues. The water exchange on the three Gd(3+) complexes is considerably faster (k(ex)(298) = (13.9-15.4) × 10(6) s(-1)) than on commercial Gd(3+)-based contrast agents and proceeds via a dissociative mechanism, as evidenced by the large positive activation volumes for GdL1 and GdL2 (+10.3 ± 0.9 and +10.6 ± 0.9 cm(3) mol(-1), respectively). The relaxivity of GdL1 is doubled at 40 MHz and 298 K in fetal bovine serum (r(1) = 16.1 vs 8.5 mM(-1) s(-1) in HEPES buffer), due to hydrophobic interactions between the chelate and serum proteins. The isoquinoline core allows for the

  5. Complexes of lanthanides with aromatic and polyheteroatomic macrocyclic ethers. Complexes with 1,4,7,10,13,16-hexaoxacyclooctadecane

    SciTech Connect

    Martynova, T.N.; Nikulina, L.D.

    1988-02-01

    Complexes of salts of rare-earth metals with 18-crown-6 have been synthesized in media of polar organic solvents. Their physicochemical properties, as well as the influence of the nature of the rare-earth metals and the anions of the lanthanide salts on the composition and properties of the compounds obtained, have been studied. It has been established that complexes with a 1:1 metal:ligand ratio form, regardless of the synthesis conditions. The anion has an influence on the degree of hydration of the complexes obtained, as well as on their thermal stability. Thermal investigation have been carried out, and the paths of thermal degradation of the complexes have been determined.

  6. Binary lanthanide(III)/nitrate and ternary lanthanide(III)/nitrate/chloride complexes in an ionic liquid containing water: optical absorption and luminescence studies.

    PubMed

    Ansari, Seraj A; Liu, Lisheng; Rao, Linfeng

    2015-02-14

    The formation of binary Ln(iii)/nitrate and ternary Ln(iii)/nitrate/chloride complexes in a water-saturated ionic liquid, 1-butyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)imide (denoted BumimTf(2)N), was investigated by absorption spectrophotometry and luminescence spectroscopy. Four successive binary complexes, Nd(NO(3))(2+), Nd(NO(3))(2)(+), Nd(NO(3))(3), and Nd(NO(3))(4)(-), were identified, and their stability constants in water-saturated BumimTf(2)N are several orders of magnitude higher than those in aqueous solutions, but much lower than those observed in dry BumimTf(2)N. The complexation of lanthanides with nitrate in wet BumimTf(2)N proceeds via the replacement of water molecules by bidentate nitrate anions from the inner solvation spheres of Ln(3+) cations. In the absence of nitrate, the precipitation of Ln(iii)/chloride complex(es) occurs at low ratios of C(Cl)/C(Ln) (<6) in BumimTf(2)N, which precludes the determination of stability constants of binary Ln(iii)/chloride complexes by spectrophotometry or luminescence spectroscopy. However, using a competition approach, the formation of two ternary complexes, Ln(NO(3))(3)Cl(2)(2-) and Ln(NO(3))(2)Cl(4)(3-), has been observed and their stability constants in wet BumimTf(2)N were determined. Data indicate that both nitrate and chloride are stronger ligands than water for lanthanides in BumimTf(2)N.

  7. Basis for sensitive and selective time-delayed luminescence detection of hydroxyl radical by lanthanide complexes.

    PubMed

    Peterson, Katie L; Margherio, Maximilian J; Doan, Phi; Wilke, Kyle T; Pierre, Valérie C

    2013-08-19

    Molecular probes for the detection of hydroxyl radical (HO•) by time-delayed luminescence spectroscopy directly in water at neutral pH with high sensitivity and selectivity are presented. The bimolecular probes consist of a lanthanide complex with open coordination sites and a reactive pre-antenna composed of an aromatic acid or amide; the latter binds to and sensitizes terbium emission upon hydroxylation by HO•. These probes exhibit long luminescence lifetimes compatible with time-delayed measurements that remove interfering background fluorescence from the sample. Six different reactive pre-antenna (benzoate, benzamide, isophthalate, isophthalamide, trimesate, and trimesamide) and two different terbium complexes [Tb-(1,4,7,10-tetraazacyclododecane-1,4,7-tris(acetic acid)) (Tb-DO3A) and Tb-(1,4,7,10-tetraazacyclododecane-1,7-bis(acetic acid)) (Tb-DO2A)] were evaluated. Of these the trimesamide/Tb-DO3A system enables the most sensitive detection of HO• with an about 1000-fold increase in metal-centered time-delayed emission upon hydroxylation of the pre-antenna to 2-hydroxytrimesamide. Excellent selectivity for both the trimesamide/Tb-DO3A and trimesate/Tb-DO3A systems over other reactive oxygen and nitrogen species are observed. Notably, the increase in metal-centered luminescence intensity is not associated with a decrease in the hydration number (q) of Tb-DO3A, suggesting that the antenna is interacting with the lanthanide via a second sphere coordination environment or that coordination by the antenna occurs by displacement of one or more of the carboxylate arms of DO3A. Formation of a weak ternary complex Tb-DO3A•hydroxytrimesamide was confirmed by temperature-dependent titration and a decrease in K(app) with increasing temperature.

  8. Increasing the luminescence of lanthanide(III) macrocyclic complexes by the use of polymers and lanthanide enhanced luminescence

    NASA Astrophysics Data System (ADS)

    Leif, Robert C.; Becker, Margie C.; Bromm, Alfred J., Jr.; Vallarino, Lidia M.; Williams, Steven A.; Yang, Sean

    2001-05-01

    A Eu (III)-macrocycle-isothiocyanate, Quantum DyeTM, has been reacted with lysine homo- and hetero-peptides to give polymers with multiple luminescent side chains. Contrary to the concentration quenching that occurs with conventional organic fluorophores, the attachment of multiple Quantum Dyes to a polymer results in a concomitant increase in luminescence. The emission intensity of the peptide-bound Quantum Dye units is approximately linearly related to their number. The attachment of peptides containing multiple lanthanide (III) macrocycles to analyte-binding species is facilitated by employing solid-phase technology. Bead-bound peptides are first labeled with multiple Quantum Dye units, then conjugated to an antibody, and finally released from the bead by specific cleavage with Proteinase K unedr physiological conditions. Since the luminescence of lanthanide(III) macrocycles is enhanced by the presence of GD(III) or Y(III) ions in a micellar system, a significant increase in signal can be achieved by attaching a polymer labeled with multiple Quantum Dye units to an analyte- binding species, such as a monoclonal antibody, or by taking advantage of the luminescence enhancing effects of Gd(III) or Y(III), or by both approaches concomitantly. A comparison between the integrated intensity and lifetime measurements of the Eu(III)-macrocycle under a variety of conditions show that the signal increase caused by Gd(III) can not be explained solely by the increase in lifetime, and must result in significant part from an energy transfer process invloving donors not directly bound to the Eu(III).

  9. DISTRIBUTION OF LANTHANIDE AND ACTINIDE ELEMENTS BETWEEN BIS-(2-ETHYLHEXYL)PHOSPHORIC ACID AND BUFFERED LACTATE SOLUTIONS CONTAINING SELECTED COMPLEXANTS

    SciTech Connect

    Rudisill, Tracy S.; Diprete, David P.; Thompson, Major C.

    2013-04-15

    With the renewed interest in the closure of the nuclear fuel cycle, the TALSPEAK process is being considered for the separation of Am and Cm from the lanthanide fission products in a next generation reprocessing plant. However, an efficient separation requires tight control of the pH which likely will be difficult to achieve on a large scale. To address this issue, we measured the distribution of lanthanide and actinide elements between aqueous and organic phases in the presence of complexants which were potentially less sensitive to pH control than the diethylenetriaminepentaacetic (DTPA) used in the process. To perform the extractions, a rapid and accurate method was developed for measuring distribution coefficients based on the preparation of lanthanide tracers in the Savannah River National Laboratory neutron activation analysis facility. The complexants tested included aceto-, benzo-, and salicylhydroxamic acids, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and ammonium thiocyanate (NH{sub 4}SCN). The hydroxamic acids were the least effective of the complexants tested. The separation factors for TPEN and NH{sub 4}SCN were higher, especially for the heaviest lanthanides in the series; however, no conditions were identified which resulted in separations factors which consistently approached those measured for the use of DTPA.

  10. Syntheses, crystal structures, magnetic and luminescence properties of five novel lanthanide complexes of nitronyl nitroxide radical

    SciTech Connect

    Wang, Ya-Li; Gao, Yuan-Yuan; Ma, Yue; Wang, Qing-Lun; Li, Li-Cun; Liao, Dai-Zheng

    2013-06-01

    Five novel Ln(III) complexes based on a new nitronyl nitroxide radical have been synthesized, characterized structurally and magnetically: [Ln(hfac)₃(NITPh-3-Br-4-OMe)₂] (Ln(III)=Eu(1), Gd(2), Tb(3), Dy(4), Ho(5); hfac=hexafluoroacetylacetonate; and NITPh-3-Br-4-OMe=2-3´-Br-4´-methoxyphenyl-4,4,5,5 -tetramethylimidazoline-1-oxyl-3-oxide). The single-crystal structures analyses show that these complexes have similar mononuclear tri-spin structures, in which central Ln(III) ions are all eight coordinated by three hfac molecules and two NITPh-3-Br-4-OMe radicals. The variable-temperature magnetic susceptibility studies reveal the antiferromagnetic interactions between the paramagnetic ions (Ln(III) and radicals) in complexes 1, 2, 3 and 5 and ferromagnetic interaction in complex 4. The luminescence characterizations of complexes Eu(1), Tb(3) and Dy(4) are also studied in this paper. - Graphical abstract: Using a novel halogen phenyl-substituted nitronyl-nitroxide radical, we obtained and characterized five isostructural lanthanide mononuclear tri-spin compounds. Highlights: • A new halogen phenyl-substituted nitronyl-nitroxide radical was designed. • Five new Ln(III) radical complexes have been synthesized and characterized. • The reasonable evaluation the magnetic interactions between Ln(III) ions and radical is meaningful. • These complexes show good luminescent properties.

  11. Thermodynamic, spectroscopic, and computational studies of lanthanide complexation with Diethylenetriaminepentaacetic acide: temperature effect and coordination modes

    SciTech Connect

    Guoxin Tian; Leigh R. Martin; Zhiyong Zhang; Linfeng Rao

    2011-04-01

    Stability constants of two DTPA (diethylenetriaminepentaacetic acid) complexes with lanthanides (ML2- and MHL-, where M stands for Nd and Eu and L stands for diethylenetriaminepentaacetate) at 10, 25, 40, 55, and 70 degrees C were determined by potentiometry, absorption spectrophotometry, and luminescence spectroscopy. The enthalpies of complexation at 25 degrees C were determined by microcalorimetry. Thermodynamic data show that the complexation of Nd3þ and Eu3þ with DTPA is weakened at higher temperatures, a 10-fold decrease in the stability constants of ML2- and MHL- as the temperature is increased from 10 to 70 degrees C. The effect of temperature is consistent with the exothermic enthalpy of complexation directly measured by microcalorimetry. Results by luminescence spectroscopy and density functional theory (DFT) calculations suggest that DTPA is octa-dentate in both the EuL2- and EuHL- complexes and, for the first time, the coordination mode in the EuHL- complex was clarified by integration of the experimental data and DFT calculations. In the EuHL- complex, the Eu is coordinated by an octa-dentate H(DTPA) ligand and a water molecule, and the protonation occurs on the oxygen of a carboxylate group.

  12. Thermodynamics of Self-Assembly of Dicarboxylate Ions with Binuclear Lanthanide Complexes

    PubMed Central

    Sørensen, Thomas Just; Hill, Leila R; Faulkner, Stephen

    2015-01-01

    Self-assembly of a range of carboxylic acids (benzoic acid, dinicotinic acid, nicotinic acid, and isophthalic acid) with the europium complex of 5-nitro-α,α′-bis(DO3Ayl)-m-xylene (where DO3A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) has been explored to establish the thermodynamics of binding in a range of solvent systems and in a range of aqueous buffer solutions. In this system, profound effects are observed as a consequence of competition by the hydroxide ion, which outcompetes even dinicotinate at high pH. In the case of isophthalate, which binds most strongly, and dinicotinate, both enthalpic and entropic contributions to binding have been identified. The europium complex with 5-nitro-α,α′-bis(DO3Ayl)-m-xylene is found to have a solution structure significantly different from the related europium complex of 5-amino-α,α′-bis(DO3Ayl)-m-xylene. It is found that phosphate binds strongly to the europium complex of the nitro derivate but not to the europium complex of amino derivative. Lactate, citrate, and pyruvate also bind strongly to 5-nitro-α,α′-bis(Eu⋅DO3Ayl)-m-xylene, and it is concluded that the solution structure of this binuclear lanthanide complex is significantly different from that of the amino-substituted complex. PMID:26478847

  13. Lanthanide complexes derived from hexadentate macrocyclic ligand: synthesis, spectroscopic and thermal investigation.

    PubMed

    Chandra, Sulekh; Tyagi, Monika; Rani, Soni; Kumar, Sumit

    2010-02-01

    The lanthanide complexes derived from (3,5,13,15-tetramethyl 2,6,12,16,21-22-hexaazatricyclo[15.3.I(1-17)I(7-11)]cosa-1(21),2,5,7,9,11(22),12,15,17,19-decane) were synthesized. The complexes were found to have general composition [Ln(L)X(2).H(2)O]X, where Ln=La(3+), Ce(3+), Nd(3+), Sm(3+) and Eu(3+) and X=NO(3)(-) and Cl(-). The ligand was characterized by elemental analyses, IR, Mass, and (1)H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinates through four nitrogen atoms of azomethine groups and two nitrogen of pyridine ring. The lanthanum complexes are diamagnetic while the other Ln(III) complexes are paramagnetic. The spectral parameters i.e. nephelauxetic ratio (beta), covalency factor (b(1/2)), Sinha parameter (delta%) and covalency angular overlap parameter (eta) have been calculated from absorption spectra of Nd(III) and Sm(III) complexes. These parameters suggest the metal-ligand covalent bonding. In the present study, the complexes were found to have coordination number nine.

  14. Lanthanide complexes derived from hexadentate macrocyclic ligand: Synthesis, spectroscopic and thermal investigation

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Tyagi, Monika; Rani, Soni; Kumar, Sumit

    2010-02-01

    The lanthanide complexes derived from (3,5,13,15-tetramethyl 2,6,12,16,21-22-hexaazatricyclo[15.3.I 1-17I 7-11]cosa-1(21),2,5,7,9,11(22),12,15,17,19-decane) were synthesized. The complexes were found to have general composition [Ln(L)X 2·H 2O]X, where Ln = La 3+, Ce 3+, Nd 3+, Sm 3+ and Eu 3+ and X = NO 3- and Cl -. The ligand was characterized by elemental analyses, IR, Mass, and 1H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinates through four nitrogen atoms of azomethine groups and two nitrogen of pyridine ring. The lanthanum complexes are diamagnetic while the other Ln(III) complexes are paramagnetic. The spectral parameters i.e. nephelauxetic ratio ( β), covalency factor ( b1/2), Sinha parameter ( δ%) and covalency angular overlap parameter ( η) have been calculated from absorption spectra of Nd(III) and Sm(III) complexes. These parameters suggest the metal-ligand covalent bonding. In the present study, the complexes were found to have coordination number nine.

  15. H4octapa: highly stable complexation of lanthanide(III) ions and copper(II).

    PubMed

    Kálmán, Ferenc Krisztián; Végh, Andrea; Regueiro-Figueroa, Martín; Tóth, Éva; Platas-Iglesias, Carlos; Tircsó, Gyula

    2015-03-02

    The acyclic ligand octapa(4-) (H4octapa = 6,6'-((ethane-1,2-diylbis((carboxymethyl)azanediyl))bis(methylene))dipicolinic acid) forms stable complexes with the Ln(3+) ions in aqueous solution. The stability constants determined for the complexes with La(3+), Gd(3+), and Lu(3+) using relaxometric methods are log KLaL = 20.13(7), log KGdL = 20.23(4), and log KLuL = 20.49(5) (I = 0.15 M NaCl). High stability constants were also determined for the complexes formed with divalent metal ions such as Zn(2+) and Cu(2+) (log KZnL = 18.91(3) and log KCuL = 22.08(2)). UV-visible and NMR spectroscopic studies and density functional theory (DFT) calculations point to hexadentate binding of the ligand to Zn(2+) and Cu(2+), the donor atoms of the acetate groups of the ligand remaining uncoordinated. The complexes formed with the Ln(3+) ions are nine-coordinated thanks to the octadentate binding of the ligand and the presence of a coordinated water molecule. The stability constants of the complexes formed with the Ln(3+) ions do not change significantly across the lanthanide series. A DFT investigation shows that this is the result of a subtle balance between the increased binding energies across the 4f period, which contribute to an increasing complex stability, and the parallel increase of the absolute values of the hydration free energies of the Ln(3+) ions. In the case of the [Ln(octapa)(H2O)](-) complexes the interaction between the amine nitrogen atoms of the ligand and the Ln(3+) ions is weakened along the lanthanide series, and therefore the increased electrostatic interaction does not overcome the increasing hydration energies. A detailed kinetic study of the dissociation of the [Gd(octapa)(H2O)](-) complex in the presence of Cu(2+) shows that the metal-assisted pathway is the main responsible for complex dissociation at pH 7.4 and physiological [Cu(2+)] concentration (1 μM).

  16. Structure of the Toll/interleukin 1 receptor (TIR) domain of the immunosuppressive Brucella effector BtpA/Btp1/TcpB.

    PubMed

    Kaplan-Türköz, Burcu; Koelblen, Thomas; Felix, Christine; Candusso, Marie-Pierre; O'Callaghan, David; Vergunst, Annette C; Terradot, Laurent

    2013-11-01

    BtpA/Btp1/TcpB is a virulence factor produced by Brucella species that possesses a Toll interleukin-1 receptor (TIR) domain. Once delivered into the host cell, BtpA interacts with MyD88 to interfere with TLR signalling and modulates microtubule dynamics. Here the crystal structure of the BtpA TIR domain at 3.15 Å is presented. The structure shows a dimeric arrangement of a canonical TIR domain, similar to the Paracoccus denitrificans Tir protein but secured by a unique long N-terminal α-tail that packs against the TIR:TIR dimer. Structure-based mutations and multi-angle light scattering experiments characterized the BtpA dimer conformation in solution. The structure of BtpA will help with studies to understand the mechanisms involved in its interactions with MyD88 and with microtubules.

  17. The photofragmentation of gas phase lanthanide complexes: Experimental and ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Jiangchao

    Dissociative laser-driven photoreactions of open-shell lanthanide metal-organic complexes are analyzed from experimental and computational aspects. Experimental analysis, based on time-of-flight mass spectrometry suggests the most probable pathway for the photoreactions. A sequence of intermediates and the distribution of final products are identified. The computational analysis, based on excited-state ab initio molecular dynamics with surface hopping, is implemented at the DFT level of theory. Computational treatment prompts the mechanism of laser-driven photoreactions at time ranges from femtoseconds to picoseconds. The experimental and computational analyses agree on several key products of photoreactions. Branching between two reaction pathways, ligand ejection versus cracking, is observed and explained. The results obtained are of importance for basic studies of processes beyond the Born-Oppenheimer approximation and for nano-electronics application of laser-assisted chemical vapor deposition of insulators with super-high dielectric constant.

  18. Luminescence detection of rare-earth ions by energy transfer from counteranion to crown ether-lanthanide ion complexes

    SciTech Connect

    Tran, C.D.; Zhang, Weifeng )

    1990-04-15

    A novel method has been developed to enhance the sensitivity and selecitivity of the luminescence detection for lanthanide ions. In this method, the lanthanide ion, crown ether, and benzoate were compartmentalized into an ion pair complex in order to eliminate the quenching and to induce the energy transfer so that the luminescence detection for the lanthanide ions can be selectively enhanced. The molecular organization is achieved by using a crown ether such as 18-crown-6 or 15-crown-5 as the synergistic extracting agent and benzoate as the counterion to selectively extract the rare-earth ions from water into an organic solvent where they are subsequently determined by luminescence technique. Compared to lanthanide ions in aqueous solutions, the luminescence intensity of the extracted ion pair complexes is substantially enhanced. The luminescence intensities of the Tb{sup 3+}, Eu{sup 3+}, and Dy{sup 3+} ions were enhanced up to 4 times when they were extracted into ethyl acetate or into chloroform. The total enhancement by the extraction and energy transfer processes can, therefore, be up to 67 times. The mechanism of energy transfer and the use of this technique to measure the selective extractions of Tb{sup 3+}, Eu{sup 3+}, and Dy{sup 3+} ions are discussed.

  19. Thermodynamic and structural description of europium complexation in 1-octanol solution

    SciTech Connect

    Charbonnel, M.C.; Vu, T.H.; Boubals, N.; Couston, L.

    2008-07-01

    Polydentate N-bearing ligands such as bis-triazinyl-pyridines (BTPS) are interesting extractants for actinide(III)/lanthanide(III) separation. A description of europium complexation in 1-octanol solutions was undertaken to enhance the knowledge of the extraction mechanisms. Time- Resolved Laser-Induced Fluorescence (TRLIF) spectroscopy allows determination of the first solvation shell for europium(III) nitrate, chloride, and perchlorate with different amounts of water. Europium nitrate complexation by iPr-BTP was then studied by TRLIF and microcalorimetry; the stability constant related to the formation of Eu(BTP){sub 3}{sup 3+} is similar by both techniques (log {beta}{sub 3} = 11.3 {+-} 0.5). The difference of solvation of the cation seems to have an influence on the thermodynamic properties related to the complexation with organic ligands. (authors)

  20. Lanthanide(III) and lead(II) complexes of a chiral nonaaza macrocyclic amine based on 1,2-diaminocyclopentane.

    PubMed

    Gregoliński, Janusz; Ślepokura, Katarzyna; Lisowski, Jerzy

    2015-10-07

    The macrocyclic nonaaza 3 + 3 amine based on diaminocyclopentane forms enantiopure helical complexes with lanthanide(III) ions. In contrast to analogous complexes based on 1,2-trans-diaminocyclohexane, no clear helicity process is observed. Crystal structures of these compounds show tight helical wrapping of the macrocycle around the lanthanide(III) ion leading to the formation of a double helix. In contrast, more "open" conformation is observed for the free macrocycle. Similar double-helical conformation of the ligand was also observed for the lead(II) complex. In the case of this complex the NMR spectra indicate a dynamic process in which the C2-symmetric molecule observed in the solid state gives rise to an effective, averaged D3-symmetry in solution at elevated temperatures.

  1. Synthesis and characterization of lanthanide complexes of DO3A-alkylphosphonates.

    PubMed

    Mamedov, Ilgar; Mishra, Anurag; Angelovski, Goran; Mayer, Hermann A; Pålsson, Lars-Olof; Parker, David; Logothetis, Nikos K

    2007-12-07

    Eight DO3A-based lanthanide(III) complexes bearing ester protected and unprotected phosphonate groups at variable distances from the macrocyclic moiety have been synthesized and analyzed. The ligands were made by straightforward four-step synthetic procedures and purified with preparative RP-HPLC, after which they were used to prepare gadolinium(III) and europium(III) complexes. Relaxometric experiments were performed on the Gd(III) complexes at 300 MHz, varying the pH of the solutions or the concentration of human serum albumin (HSA). It was found that when the pH of the medium was changed from neutral to pH 4 the longitudinal relaxivity of GdDO3A-ethylphosphonate and GdDO3A-propylphosphonate complexes increased by 50% and 60%, respectively. Diethyl esters of these complexes did not change longitudinal relaxivity in the same pH range but their transverse relaxivity increased upon binding to HSA. 31P NMR experiments on Eu(III) complexes showed a change in the chemical shift of both acid complexes in the same region where the highest relaxivity changes were observed and proved the stability of the complexes in the investigated pH range, while no shift was observed for the diester complexes. Luminescence studies on europium(III) complexes additionally supported observations obtained by NMR methods. The change in the form of the luminescence emission spectra, and the reduction in the q value upon addition of HSA proved the ternary adduct formation between the charge neutral diester complexes and HSA. Similarly, the change in the emission spectra showing a phosphonate bound structure at pH 7 to a species where the phosphonate oxygen is not coordinated at pH 4 in parallel with the increase of q value is supporting the hypothesis that the deprotonation of phosphonates is the main reason for the distinct relaxivity change from slightly acidic to the neutral solution media.

  2. Photoactivated DNA cleavage and anticancer activity of pyrenyl-terpyridine lanthanide complexes.

    PubMed

    Hussain, Akhtar; Gadadhar, Sudarshan; Goswami, Tridib K; Karande, Anjali A; Chakravarty, Akhil R

    2012-04-01

    Lanthanide(III) complexes [Ln(R-tpy)(acac)(NO(3))(2)] (Ln = La(III) in 1, 2; Gd(III) in 4, 5) and [Ln(py-tpy)(sacac)(NO(3))(2)] (Ln = La(III), 3; Gd(III), 6), where R-tpy is 4'-phenyl-2,2':6',2″-terpyridine (ph-tpy in 1, 4), 4'-(1-pyrenyl)-2,2':6',2″-terpyridine (py-tpy in 2, 3, 5 and 6), acac is acetylacetonate and sacac is 4-hydroxy-6-{4-[(β-d-glucopyranoside)oxy]phenyl}hex-3,5-dien-2-onate, were prepared to study their DNA photocleavage activity and photocytotoxicity. Complexes [La(ph-tpy)(acac)(EtOH)(NO(3))(2)] (1a) and [Gd(ph-tpy)(acac)(NO(3))(2)] (4) were characterized by X-ray crystallography. The 1:1 electrolytic complexes bind to calf thymus DNA. The py-tpy complexes cleave pUC19 DNA and exhibit remarkable photocytotoxicity in HeLa cells in UV-A light of 365 nm with apoptotic cell death (IC(50): ∼40 nM in light, >200 μM in dark). Confocal microscopy using HeLa cells reveal primarily cytosolic localization of the complexes.

  3. Syntheses, characterization, biological activities and photophysical properties of lanthanides complexes with a tetradentate Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Taha, Ziyad A.; Ajlouni, Abdulaziz M.; Al Momani, Waleed; Al-Ghzawi, Abeer A.

    2011-10-01

    A tetradentate Schiff base ligand L (N,N'-bis(1-naphthaldimine)-o-phenylenediamine) was prepared from the condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine in a molar ratio of 2:1. New eight lanthanide metal complexes [Ln L(NO 3) 2(H 2O) x](NO 3) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, x = 0 for Nd, Sm, 1 for La, Gd, Pr, Nd, Dy, and 2 for Tb} were prepared. The characterization and nature of bonding of these complexes were elucidated by elemental analysis, spectral analysis ( 1H NMR, FT-IR, UV-vis), molar conductivity measurements, luminescence spectra and thermogravimetric studies. Analytical and spectral data revealed that the ligand L coordinates to the central Ln(III) ions by its two imine nitrogen atoms and two phenolic oxygen atoms with 1:1 stoichiometry. Under the excitation with 329 nm at room temperature, Tb and Dy complexes exhibited characteristic luminescence of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of Ln(III) complexes found to exhibit antibacterial activities against a number of pathogenic bacteria. We found that the antioxident activity of Ln(III) complexes on DPPH rad is concentration dependent and higher than that of the free ligand L.

  4. Synthesis and Biological Activities of Lanthanide (III) Nitrate Complexes with N-(2-hydroxynaphthalen-1-yl) methylene) Nicotinohydrazide Schiff Base.

    PubMed

    Hijazi, Ahmed K; Taha, Ziyad A; Ajlouni, Abdulaziz M; Al-Momani, Waleed M; Idris, Idris M; Hamra, Eman A

    2016-01-01

    The field of coordination chemistry has registered a phenomenal growth during the last few decades. It is well known that precious metals have been used for medicinal purposes for at least 3500 years. At that time, precious metals were believed to benefit health because of their rarity, but research has now well established the link between medicinal properties of inorganic drugs and specific biological properties. The current study was designed to explain the synthesis and characterization of the lanthanide (III) nitrate complexes with N-(2-hydroxynaphthalen-1-yl) methylene) nicotinohydrazide schiff base and to evaluate the antibacterial and the antioxidant activities of the schiff base and it's lanthanide ion complexes. Antimicrobial activity of the Lanthanide (III) nitrate complexes with N-(2- hydroxynaphthalen-1-yl) methylene) nicotinohydrazide schiff base was estimated by minimum inhibitory concentration (MIC, µg/mL) using a micro-broth dilution method for different clinical isolates such as Eschereshia coli and Enterococcus faecalis. The antioxidant activities of the ligand and its lanthanide complexes were tested using a UV-Visible spectrophotometer by preparing 5x10-4M of all tested samples and DPPH in Dimethyl sulphoxide (DMSO). Our present study has shown that moderate antimicrobial activity exists against both ligand and its complexes. There was no significant difference between Gram-positive and Gram-negative bacteria towards the tested ligand and its complexes. The free ligand has scavenging activity between 13-21 % while all complexes are more efficient in quenching DPPH than free ligand. The results obtained herein indicate that the ligand and its complexes have a considerable antibacterial activity as well as antioxidant activity in quenching DPPH. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. Deactivation pathways of the electronic excitation of ions of lanthanide complexes in polymers with functional groups

    NASA Astrophysics Data System (ADS)

    Sveshnikova, E. B.; Ermolaev, V. L.; Shablya, A. V.; Goĭkhman, M. Ya.; Yakimanskiĭ, A. V.; Podeshvo, I. V.; Kudryavtsev, V. V.

    2007-05-01

    Complexes Eu(TTA)3phen and Eu(MBTA)3phen, as well as complexes Tb(MBTA)3phen and Tb(TTA)3phen, which do not luminesce in solutions, are shown to luminesce in polymer films (TTA is thenoyltrifluoroacetone, MBTA is n-methoxybenzoyltrifluoroacetone, and phen is o-phenanthroline). Luminescence of complexes of Eu and Tb in films of a polymer, poly(methylene-bis-anthranilamide) 1,6-hexamethylenedicarboxylic acid (PAA-5), having a high concentration of functional anthranilate groups, is studied. From the behavior of the luminescence intensity (I lum), the luminescence decay time, and the luminescence spectra of complexes of these lanthanides in polymer films, the following regular features were revealed. (i) During the film preparation at 90°C, Ln complexes are attached to PAA-5 via anthranilate groups. (ii) Irradiation of these films in the range of the absorption band of ligands (TTA or MBTA) leads to deactivation of the electronic excitation of ions according to the diketone detachment mechanism and to further binding of complexes to polymers. In this case, I lum(Eu(III)) decreases because the introduction of anthranilate groups of the polymer into the first coordination sphere of Eu(III) complexes enhances the nonradiative deactivation of these ions, whereas I lum(Tb(III)) increases since the introduction of these groups suppresses the nonradiative deactivation of Tb complexes through triplet states of ligands (TTA and MBTA). (iii) Upon storage of films in the dark (20°C), complexes detach themselves from the polymer and return to their initial structure. In PAA-5 films into which Eu and Tb complexes were simultaneously introduced, the color of the emission from the irradiation spot changes from red to green.

  6. Equilibrium and Formation/Dissociation Kinetics of some Lanthanide(III)-PCTA complexes

    PubMed Central

    Tircsó, Gyula; Kovács, Zoltán; Sherry, A. Dean

    2008-01-01

    The protonation constants (KiH) of 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9,-triacetic acid (PCTA) and stability constants of complexes formed between this pyridine containing macrocycle and several different metal ions have been determined in 1.0 M KCl, 25°C and compared to previous literature values. The first protonation constant was found to be 0.5-0.6 log units higher than the value reported previously and a total five protonation steps were detected (log KiH = 11.36, 7.35, 3.83, 2.12 and 1.29). The stability constants of complexes formed between PCTA and Mg2+, Ca2+, Cu2+ and Zn2+ were also somewhat higher than those previously reported but this difference could be largely attributed to the higher first protonation constant of the ligand. Stability constants of complexes formed between PCTA and the Ln3+ series of ions and Y3+ were determined by using an “out-of-cell” potentiometric method. These values ranged from log K = 18.15 for Ce(PCTA) to log K = 20.63 for Yb(PCTA), increasing along the lanthanide series in proportion to decreasing Ln3+ cation size. The rates of complex formation for Ce(PCTA), Eu(PCTA), Y(PCTA) and Yb(PCTA) were followed by conventional UV-VIS spectroscopy in the pH range pH=3.5 - 4.4. First order rate constants (saturation kinetics) obtained for different ligand / metal ion ratios were consistent with rapid formation of a diprotonated intermediate, Ln(H2PCTA)2+. The stabilities of the intermediates as determined from the kinetic data were 2.81, 3.12, 2.97 and 2.69 log K units for Ce(H2PCTA), Eu(H2PCTA), Y(H2PCTA) and Yb(H2PCTA), respectively. Rearrangement of these intermediates to the fully chelated complexes was the rate determining step and the rate constant (kr) for this process was found to be inversely proportional to the proton concentration. The formation rates (kOH) increased with a decrease in lanthanide ion size (9.68×107 M-1s-1, 1.74×108 M-1s-1, 1.13×108 M-1s-1 and 1.11×109 M-1s-1 for Ce

  7. Study of lanthanide complexes with salicylic acid by photoacoustic and fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Yue-tao; Zhang, Shu-yi

    2004-07-01

    Solid complexes Ln(Sal) 3·H 2O (Sal: salicylic acid; Ln: La 3+, Nd 3+, Eu 3+, Tb 3+) are synthesized, and their photoacoustic (PA) spectra in the UV-Vis region have been recorded. PA intensities of central lanthanide ions are interpreted in terms of the probability of nonradiative transitions. It is found that PA intensity of the ligand increases in the order of Tb(Sal) 3·H 2O < La(Sal) 3·H 2O < Eu(Sal) 3·H 2O < Nd(Sal) 3·H 2O. Different PA intensities of the ligand are interpreted by comparison with the fluorescence spectra. Ternary complexes Eu(Sal) 3Phen and Tb(Sal) 3Phen (Phen: 1,10-phenanthroline) are synthesized. Compared with their binary complexes, PA intensity of the ligand Sal decreases for Eu(Sal) 3Phen, while the reverse is true for that of Tb(Sal) 3Phen. The luminescence of Eu 3+ increases remarkably when Phen is introduced, and luminescence of Tb 3+ decreases greatly when Phen is added. The intramolecular energy transfer and relaxation processes in the complexes are discussed from two aspects: radiative and nonradiative relaxations.

  8. Equilibrium and kinetic studies of lanthanide complexes of macrocyclic polyamino carboxylates

    SciTech Connect

    Kumar, K.; Chang, C.A.; Tweedle, M.F. )

    1993-03-03

    The stability constants (log K[sub LnL]) of lanthanide complexes of macrocyclic polyamino carboxylates, LnL (where Ln is Ce[sup 3+], Gd[sup 3+], and Lu[sup 3+] and L is DO3A = 1,4,7,10-tetraazacyclododecane-1,3,7-triacetic acid and HP-DO3A = 10-(hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid), have been determined at 25.0 [plus minus] 0.1[degree]C and [mu] = 0.1 ((CH[sub 3])[sub 4]NCl). The stability constants of lanthanide complexes of DO3A increase with the decreasing ionic radii or increasing charge density of Ln[sup 3+]. For L = HP-DO3A, the stability constant of GdL is greater than that of CeL; however the stability constants of GdL and LuL are similar. The protonation constants, K[sub H] (M[sup [minus]1]), of the LnL complexes have been determined at 25.0 [plus minus] 0.1[degree]C and [mu] = 1.0 (NaCl), and the values are 18 [plus minus] 3 for Ce(DO3A), 115 [plus minus] 8 for Gd(DO3A), 11 [plus minus] 1 for Ce(HP-DO3A), and 240 [plus minus] 25 for Gd(HP-DO3A). The rates of acid-assisted dissociation of the protonated complexes, ML(H), have been measured at 25.0 [plus minus] 0.1[degree]C and [mu] = 1.0 (NaCl). Direct, k[sub d] (s[sup [minus]1]), and acid-assisted, k[sub 1] (M[sup [minus]1] s[sup [minus]1]), dissociation rate constants are k[sub d] = (1.8 [plus minus] 0.8) [times] 10[sup [minus]3] and k[sub 1] = (1.12 [plus minus] 0.04) [times] 10[sup [minus]1] for Ce(DO3A) and k[sub d] = (1.4 [plus minus] 0.2) [times] 10[sup [minus]4] and k[sub 1] = (2.00 [plus minus] 0.04) [times] 10[sup [minus]3] for Ce(HP-DO3A). The rates of dissociation of the other complexes are first order in acid at low [H[sup +

  9. Synthesis and X-ray crystal structures of amine bis(phenolate) lanthanide complexes containing alkali metal cation

    NASA Astrophysics Data System (ADS)

    Ma, Mengtao; Xu, Xiaoping; Yao, Yingming; Zhang, Yong; Shen, Qi

    2005-04-01

    Three lanthanide "ate" complexes L 2YbM(THF) n supported by amine bis(phenolate) ligand [L=Me 2NCH 2CH 2N{CH 2-(2-O-C 6H 2-Bu t2-2,4)} 2; M=Li, n=2 ( 1); M=Na, n=2 ( 2); M=K, n=3 ( 3)] were synthesized by the metathesis reactions of LM 2 with anhydrous YbCl 3 in 2:1 molar ratio in high yield. All the complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The influence of the alkali metal ions on the molecular structure of these lanthanide complexes has been elucidated.

  10. Preparation, structure, and luminescence of dinuclear lanthanide complexes of a novel imine-amine phenolate macrocycle

    SciTech Connect

    Matthews, K.D.; Kahwa, I.A. ); Williams, D.J. )

    1994-03-30

    Metal-free condensation of 2,6-diformyl-p-cresol with 3,6-dioxa-1,8-octanediamine followed by reduction with sodium tetrahydroborate and addition of lanthanide(III) nitrate salts, in that order, yield (slowly) crystalline dinuclear complexes of a novel imine-amine phenolate macrocycle 2. The decacoordination geometry of the identical Pr[sup 3+] ions in a C[sub 2v] 4A,6B-extended dodecahedron made up of two bidentate NO[sub 3]-ions, two phenolate and two either oxygens, and one imine and one amine nitrogens. Dinuclear lanthanide complexes of 2 appear to be more stable than those of the totally reduced chelate 2 in alcoholic media. The Tb[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]-OH and (La[sub 0.97]Tb[sub 0.03])[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]OH compounds exhibit strong Tb[sup 3+] ([sup 5]D[sub 4] [yields] [sup 7]F[sub J]) emission sensitized by the single state of 2 at both 77 and 295 K. No Tb[sup 3+]-Tb[sup 3+] self-quenching or N-H trapping effects are observed at 77 K (decay rate is 598 s[sup [minus]1]); the coordination cavities of 2 are therefore potentially good hosts for Tb[sup 3+] in luminescent diagnostic agents. At room temperature the complex decay kinetics of Tb[sup 3+] in Tb[sub 2]2(NO[sub 3])[sub 4][center dot]1.2CH[sub 3]OH are similar to those of Tb[sub 2]1(NO[sub 3])[sub 4][center dot]H[sub 2]O. But for the dilute complex, (La[sub 0.97]-Tb[sub 0.03])[sub 2]2(NO[sub 3])[sub 4][center dot]1.35CH[sub 3]OH, unusual thermal equilibration of the ligand triplet and Tb[sup 3+] [sup 5]D[sub 4] states occurs at room temperature; the ligand-to-Tb[sup 3+] energy-transfer rate is [approx]4.36 x 10[sup 4] s[sup [minus]1], while Tb[sup 3+]-to-ligand back-energy-transfer is [approx]7.1 x 10[sup 4] s[sup [minus]1].

  11. Heptanuclear lanthanide [Ln7] clusters: from blue-emitting solution-stable complexes to hybrid clusters.

    PubMed

    Canaj, Angelos B; Tsikalas, George K; Philippidis, Aggelos; Spyros, Apostolos; Milios, Constantinos J

    2014-09-07

    The use of LH3 (2-(β-naphthalideneamino)-2-hydroxymethyl-1-propanol) and aibH (2-amino-isobutyric acid) in 4f chemistry has led to the isolation of eight new isostructural lanthanide complexes. More specifically, the reaction of the corresponding lanthanide nitrate salt with LH3 and aibH in MeOH, under solvothermal conditions in the presence of NEt3, led to the isolation and characterization of seven complexes with the general formulae [Ln(III)7(OH)2(L')9(aib)]·4MeOH (Ln = Gd, ·4MeOH; Tb, ·4MeOH; Dy, ·4MeOH; Ho, ·4MeOH; Er, ·4MeOH; Tm, ·4MeOH; Yb, ·4MeOH L' = the dianion of the Schiff base between naphthalene aldehyde and 2-amino-isobutyric acid). Furthermore, the isostructural Y(III) analogue, cluster [Y(III)7(OH)2(L')9(aib)]·4MeOH (·4MeOH), was synthesized in a similar manner to . The structure of all eight clusters describes a distorted [M(III)6] octahedron which encapsulates a seventh M(III) ion in an off-centre fashion. Dc magnetic susceptibility studies in the 5-300 K range for complexes reveal the presence of dominant antiferromagnetic exchange interactions within the metallic clusters as evidenced by the negative Weiss constant, θ, while ac magnetic susceptibility measurements show temperature and frequency dependent out-of-phase signals for the [Dy(III)7] analogue (·4MeOH), suggesting potential single molecule magnetism character. Furthermore, for complex , simulation of its dc magnetic susceptibility data yielded very weak antiferromagnetic interactions within the metallic centres. Solid-state emission studies for all clusters display ligand-based emission, while extended 1D and 2D NMR studies for ·4MeOH reveal that the species retain their structural integrity in solution. In addition, TGA measurements for , and revealed excellent thermal stability up to 340 °C for the clusters.

  12. Identification of emissive lanthanide complexes suitable for cellular imaging that resist quenching by endogenous anti-oxidants.

    PubMed

    Poole, Robert A; Montgomery, Craig P; New, Elizabeth J; Congreve, Aileen; Parker, David; Botta, Mauro

    2007-07-07

    Excited state quenching by urate and ascorbate of selected europium and terbium(III) macrocyclic complexes has been assessed and related to the ease of complex visualisation by optical microscopy inside various living cells, e.g. CHO, COS and NIH 3T3. It is the relative insensitivity of certain sterically encumbered complexes to dynamic quenching by urate that favours their usage for in cellulo applications. Non-covalent binding of the complex by protein also shields the excited lanthanide(III) ion from collisional quenching; this effect is most marked for a cationic triamide complex, [Ln.1](3+), consistent with its ease of visualisation by luminescence microscopy.

  13. The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes.

    PubMed

    Gregson, Matthew; Lu, Erli; Mills, David P; Tuna, Floriana; McInnes, Eric J L; Hennig, Christoph; Scheinost, Andreas C; McMaster, Jonathan; Lewis, William; Blake, Alexander J; Kerridge, Andrew; Liddle, Stephen T

    2017-02-03

    Across the periodic table the trans-influence operates, whereby tightly bonded ligands selectively lengthen mutually trans metal-ligand bonds. Conversely, in high oxidation state actinide complexes the inverse-trans-influence operates, where normally cis strongly donating ligands instead reside trans and actually reinforce each other. However, because the inverse-trans-influence is restricted to high-valent actinyls and a few uranium(V/VI) complexes, it has had limited scope in an area with few unifying rules. Here we report tetravalent cerium, uranium and thorium bis(carbene) complexes with trans C=M=C cores where experimental and theoretical data suggest the presence of an inverse-trans-influence. Studies of hypothetical praseodymium(IV) and terbium(IV) analogues suggest the inverse-trans-influence may extend to these ions but it also diminishes significantly as the 4f orbitals are populated. This work suggests that the inverse-trans-influence may occur beyond high oxidation state 5f metals and hence could encompass mid-range oxidation state actinides and lanthanides. Thus, the inverse-trans-influence might be a more general f-block principle.

  14. The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes

    NASA Astrophysics Data System (ADS)

    Gregson, Matthew; Lu, Erli; Mills, David P.; Tuna, Floriana; McInnes, Eric J. L.; Hennig, Christoph; Scheinost, Andreas C.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Kerridge, Andrew; Liddle, Stephen T.

    2017-02-01

    Across the periodic table the trans-influence operates, whereby tightly bonded ligands selectively lengthen mutually trans metal-ligand bonds. Conversely, in high oxidation state actinide complexes the inverse-trans-influence operates, where normally cis strongly donating ligands instead reside trans and actually reinforce each other. However, because the inverse-trans-influence is restricted to high-valent actinyls and a few uranium(V/VI) complexes, it has had limited scope in an area with few unifying rules. Here we report tetravalent cerium, uranium and thorium bis(carbene) complexes with trans C=M=C cores where experimental and theoretical data suggest the presence of an inverse-trans-influence. Studies of hypothetical praseodymium(IV) and terbium(IV) analogues suggest the inverse-trans-influence may extend to these ions but it also diminishes significantly as the 4f orbitals are populated. This work suggests that the inverse-trans-influence may occur beyond high oxidation state 5f metals and hence could encompass mid-range oxidation state actinides and lanthanides. Thus, the inverse-trans-influence might be a more general f-block principle.

  15. Spectroscopic, luminescence, electrochemical and antimicrobial studies of lanthanide complexes of bis-benzimidazole derived ligands

    NASA Astrophysics Data System (ADS)

    Siddiqi, Zafar A.; Shahid, Anjuli M.; Khalid, Mohd.; Sharma, Prashant K.; Siddique, Armeen

    2013-04-01

    The lanthanide complexes of [1,2-bis(benzimidazole-2-yl)ethane dihydrochloride], L1·2HCl and [1,4-bis(benzimidazole-2-onium)butane dihydrochloride], L2·2HCl having molecular formulae [Ln(L1)2Cl3H2O] and [Ln(L2)2Cl3H2O]·2H2O (Ln = La3+, Pr3+, Nd3+ and Gd3+), respectively, were prepared and characterized through IR, 1H and 13C NMR, ESI-mass, UV-visible and luminescence spectroscopic techniques. TGA data suggested presence of the coordinated and the lattice water. The oscillator strengths of the f-f transitions and the covalency parameters (β, b1/2 and δ) have been evaluated from the electronic spectral data. The proposed octa coordinate geometry for the complexes has been ascertained from the molecular model computations. CV studies indicate formation of stable quasi-reversible redox couples PrIII/IV, Nd III/IV and GdIII/IV in solution. The in vitro antimicrobial activities of the complexes have been evaluated against gram +ve and gram -ve bacteria and fungi.

  16. Lipophilic ternary complexes in liquid-liquid extraction of trivalent lanthanides

    SciTech Connect

    Lumetta, Gregg J.; Levitskaia, Tatiana G.; Latesky, Stanley; Henderson, Renesha V.; Edwards, Emilio A.; Braley, Jenifer C.; Sinkov, Sergey I.

    2012-03-01

    The formation of ternary complexes between lanthanide ions [Nd(III) or Eu(III)], octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO), and bis-(2-ethylhexyl)phosphoric acid (HDEHP) was probed by liquid-liquid extraction and spectroscopic techniques. Equilibrium modeling of data for the extraction of Nd(III) or Eu(III) from lactic acid media into n-dodecane solutions of CMPO and HDEHP indicates the predominant extracted species are of the type [Ln(AHA){sub 2}(A)] and [Ln(CMPO)(AHA){sub 2}(A)], where Ln = Nd or Eu and A represents the DEHP{sup -} anion. FTIR (for both Eu and Nd) and visible spectrophotometry (in the case of Nd) indicate the formation of the [Ln(CMPO)(A){sup 3}] complexes when CMPO is added to n-dodecane solutions of the LnA{sub 3} compounds. Both techniques indicate a stronger propensity of CMPO to complex Nd(III) versus Eu(III).

  17. The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes

    PubMed Central

    Gregson, Matthew; Lu, Erli; Mills, David P.; Tuna, Floriana; McInnes, Eric J. L.; Hennig, Christoph; Scheinost, Andreas C.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Kerridge, Andrew; Liddle, Stephen T.

    2017-01-01

    Across the periodic table the trans-influence operates, whereby tightly bonded ligands selectively lengthen mutually trans metal–ligand bonds. Conversely, in high oxidation state actinide complexes the inverse-trans-influence operates, where normally cis strongly donating ligands instead reside trans and actually reinforce each other. However, because the inverse-trans-influence is restricted to high-valent actinyls and a few uranium(V/VI) complexes, it has had limited scope in an area with few unifying rules. Here we report tetravalent cerium, uranium and thorium bis(carbene) complexes with trans C=M=C cores where experimental and theoretical data suggest the presence of an inverse-trans-influence. Studies of hypothetical praseodymium(IV) and terbium(IV) analogues suggest the inverse-trans-influence may extend to these ions but it also diminishes significantly as the 4f orbitals are populated. This work suggests that the inverse-trans-influence may occur beyond high oxidation state 5f metals and hence could encompass mid-range oxidation state actinides and lanthanides. Thus, the inverse-trans-influence might be a more general f-block principle. PMID:28155857

  18. Thermally unstable complexants: Stability of lanthanide/actinide complexes, thermal instability of the ligands, and applications in actinide separations

    SciTech Connect

    Nash, K.L.; Rickert, P.G.

    1993-01-01

    Water soluble complexing agents are commonly used in separations to enhance the selectivity of both ion exchange and solvent extraction processes. Applications of this type in the treatment of nuclear wastes using conventional complexing agents have found mixed success due to the nature of the complexants. In addition, the residual solutions containing these species have led to potentially serious complications in waste storage. To overcome some of the limitations of carboxylic acid and aminopolycarboxylate ligands, the authors have initiated a program to investigate the complexing ability, thermal/oxidative instability, and separation potential of a group of water soluble organophosphorus compounds which they call Thermally Unstable Complexants, or simply TUCS. Complexants of this type appear to be superior to conventional analogues in a number of respects. In this report, they summarize their research to date on the actinide/lanthanide complexes with a series of substituted methanediphosphonic acids, the kinetics of their oxidative decomposition, and a few applications which have been developed for their use.

  19. Thermally unstable complexants: Stability of lanthanide/actinide complexes, thermal instability of the ligands, and applications in actinide separations

    SciTech Connect

    Nash, K.L.; Rickert, P.G.

    1991-01-01

    Water soluble complexing agents are commonly used in separations to enhance the selectivity of both ion exchange and solvent extraction processes. Applications of this type in the treatment of nuclear wastes using conventional complexing agents have found mixed success due to the nature of the complexants. In addition, the residual solutions containing these species have led to potentially serious complications in waste storage. To overcome some of the limitations of carboxylic acid and aminopolycarboxylate ligands, we have initiated a program to investigate the complexing ability, thermal/oxidative instability, and separation potential of a group of water soluble organophosphorus compounds which we call Thermally Unstable Complexants, or simply TUCS. Complexants of this type appear to be superior to conventional analogues in a number of respects. In this report, we will summarize our research to date on the actinide/lanthanide complexes with a series of substituted methanediphosphonic acids, the kinetics of their oxidative decomposition, and a few applications which have been developed for their use. 17 refs., 5 figs., 3 tab.

  20. Synthesis of mixed Cp/Tp(Me2) lanthanide complexes from lanthanocene precursors and their structures and reactivities.

    PubMed

    Han, Fuyan; Zhang, Jie; Han, Yanan; Zhang, Zhengxing; Chen, Zhenxia; Weng, Linhong; Zhou, Xigeng

    2009-02-16

    Reaction of Cp(2)LnCl with 1 equiv of KTp(Me2) in toluene gives the mixed Tp(Me2)/Cp lanthanide complexes Cp(2)Ln(Tp(Me2)) (Ln = Yb (1a), Er (1b), Dy (1c)), while unexpected complexes CpLn(Tp(Me2))Cl(THF) (Ln = Yb (2a), Er (2b.THF), Dy (2c), Y (2d)) are obtained when the reactions are carried out in THF. Complex 2b can also be formed by the reaction of CpErCl(2)(THF)(3) with 1 equiv of KTp(Me2) in THF. Moreover, complex 1a can also be obtained from the reaction of Cp(3)Yb and KTp(Me2). The results not only represent an efficient and versatile method for the synthesis of mixed Cp/Tp(Me2) lanthanide complexes but also provide new insight into the reactivity of Cp(2)LnCl. Furthermore, the reactivities of complexes 1a-c toward proton-donating reagents are examined. It has been found that 1b reacts with benzotriazole (C(6)H(4)NHN(2)) in THF to yield a lanthanide metallomacrocyclic complex [(Tp(Me2))CpEr(mu-N(3)C(6)H(4))](3) (3), while the reaction of 1a with 1 equiv of 2-aminopyridine in THF gives an unexpected oxide complex [(Tp(Me2))Yb(2-HNC(5)H(4)N)](2)(mu-O) (4). Presumably, the oxide ligand of compound 4 results from adventitious water. In addition, treatment of 1c with 2 equiv of 3,5-dimethylpyrazole yields a completely Cp-abstracted product (Tp(Me2))Dy(Pz(Me2))(2)(THF) (5), which can also be directly obtained from a three-component reaction of Cp(2)DyCl, KTp(Me2), and 3,5-dimethylpyrazole in THF. These results further indicate that the new mixed Tp(Me2)/Cp lanthanide complexes are practical and versatile precursors for the synthesis of poly(pyrazolyl)borate lanthanide derivatives. All new compounds have been characterized by elemental analysis and spectroscopic methods. The structures of complexes 1a,b and 2-5 have also been determined through single-crystal X-ray diffraction analysis.

  1. Chiral mononuclear lanthanide complexes and the field-induced single-ion magnet behaviour of a Dy analogue.

    PubMed

    Lin, Shuang-Yan; Wang, Chao; Zhao, Lang; Wu, Jianfeng; Tang, Jinkui

    2015-01-07

    Three pairs of homochiral mononuclear lanthanide complexes, with the general formula [LnH4LRRRRRR/SSSSSS(SCN)2](SCN)2·xCH3OH·yH2O(Ln = Dy (R/S-Dy1), Ho (R/S-Ho1) and Er (R/S-Er1)), have been obtained via self-assembly between chiral macrocyclic ligands and the respective thiocyanates, all of which show a saddle-type conformation with seven-coordinated metal ions. Magnetic measurements revealed that the Dy complex shows field-induced single-ion magnet behaviour, which is rarely reported in a seven-coordinated lanthanide-based SIM encapsulated in a macrocyclic ligand. The absolute configuration of all enantiomers was determined by single crystal X-ray crystallography and confirmed by electronic CD and VCD spectra.

  2. The Lanthanide Contraction Revisited

    SciTech Connect

    Seitz, Michael; Oliver, Allen G.; Raymond, Kenneth N.

    2007-04-19

    A complete, isostructural series of lanthanide complexes (except Pm) with the ligand TREN-1,2-HOIQO has been synthesized and structurally characterized by means of single-crystal X-ray analysis. All complexes are 1D-polymeric species in the solid state, with the lanthanide being in an eight-coordinate, distorted trigonal-dodecahedral environment with a donor set of eight unique oxygen atoms. This series constitutes the first complete set of isostructural lanthanide complexes with a ligand of denticity greater than two. The geometric arrangement of the chelating moieties slightly deviates across the lanthanide series, as analyzed by a shape parameter metric based on the comparison of the dihedral angles along all edges of the coordination polyhedron. The apparent lanthanide contraction in the individual Ln-O bond lengths deviates considerably from the expected quadratic decrease that was found previously in a number of complexes with ligands of low denticity. The sum of all bond lengths around the trivalent metal cation, however, is more regular, showing an almost ideal quadratic behavior across the entire series. The quadratic nature of the lanthanide contraction is derived theoretically from Slater's model for the calculation of ionic radii. In addition, the sum of all distances along the edges of the coordination polyhedron show exactly the same quadratic dependency as the Ln-X bond lengths. The universal validity of this coordination sphere contraction, concomitant with the quadratic decrease in Ln-X bond lengths, was confirmed by reexamination of four other, previously published, almost complete series of lanthanide complexes. Due to the importance of multidentate ligands for the chelation of rare-earth metals, this result provides a significant advance for the prediction and rationalization of the geometric features of the corresponding lanthanide complexes, with great potential impact for all aspects of lanthanide coordination.

  3. Metal complex formation with 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid: an approach to potential lanthanide ion selective reagents

    SciTech Connect

    Chang, C.A.; Rowland, M.E.

    1983-12-21

    The principles of designing lanthanide (Ln) ion selective macrocyclic reagents are discussed. Factors such as the size of the metal ion, the cavity size of the ligand, the stereochemical constraint imposed on the ligand, and the overall coordination number of the multidentate ligand are considered. On the basis of these principles, the macromonocyclic ligand 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid (dacda) has been prepared and characterized. stability constants of dacda complexes of various metal ions are reported. Except for a few metal ions such as copper (II), lead (II), and cadmium (II), dacda shows unique selectivity toward lanthanide ions as a group. Also, for the first time in aqueous solution for a multidentate ligand, the stability constants for Ln-ligand complexes decrease with increasing atomic number for heavy lanthanides and remain roughly unchanged for the lighter lanthanides. These data are discussed, and the structures of the complexes are proposed. 3 figures, 1 table.

  4. Lanthanide-to-lanthanide energy-transfer processes operating in discrete polynuclear complexes: can trivalent europium be used as a local structural probe?

    PubMed

    Zaïm, Amir; Eliseeva, Svetlana V; Guénée, Laure; Nozary, Homayoun; Petoud, Stéphane; Piguet, Claude

    2014-09-15

    This work, based on the synthesis and analysis of chemical compounds, describes a kinetic approach for identifying intramolecular intermetallic energy-transfer processes operating in discrete polynuclear lanthanide complexes, with a special emphasis on europium-containing entities. When all coordination sites are identical in a (supra)molecular complex, only heterometallic communications are experimentally accessible and a Tb → Eu energy transfer could be evidenced in [TbEu(L5)(hfac)6] (hfac = hexafluoroacetylacetonate), in which the intermetallic separation amounts to 12.6 Å. In the presence of different coordination sites, as found in the trinuclear complex [Eu3(L2)(hfac)9], homometallic communication can be induced by selective laser excitation and monitored with the help of high-resolution emission spectroscopy. The narrow and non-degenerated character of the Eu((5)D0 ↔ (7)F0) transition excludes significant spectral overlap between donor and acceptor europium cations. Intramolecular energy-transfer processes in discrete polynuclear europium complexes are therefore limited to short distances, in agreement with the Fermi golden rule and with the kinetic data collected for [Eu3(L2)(hfac)9] in the solid state and in solution. Consequently, trivalent europium can be considered as a valuable local structural probe in discrete polynuclear complexes displaying intermetallic separation in the sub-nanometric domain, a useful property for probing lanthanido-polymers.

  5. Ultrasonic assisted preparation of lanthanide-oleate complexes for the synthesis of multifunctional monodisperse upconversion nanoparticles for multimodal imaging

    NASA Astrophysics Data System (ADS)

    Tang, Shu-Hua; Wang, Jianing; Yang, Cheng-Xiong; Dong, Lu-Xi; Kong, Deling; Yan, Xiu-Ping

    2014-06-01

    The synthesis of multifunctional monodisperse upconversion nanoparticles (UCNPs) of high quality is highly desired for bioimaging. Lanthanide-oleate complexes are excellent precursors for the synthesis of high quality UCNPs with controllable size and shape. In this work, lanthanide-oleate complexes were prepared by an ultrasonic assisted procedure, and used as precursors for further synthesis of multifunctional monodisperse NaYF4:59%Yb3+,0.5% Tm3+@NaYF4:20%Gd3+ nanoparticles without the need for further purification. Heavy doping of Yb3+ in the core and incorporation of Gd3+ in the shell made the UCNPs promising for upconversion luminescence (UCL), magnetic resonance (MR) and computed tomography (CT) multimodal imaging. The nanoparticles were further functionalized with bombesin peptide for in vivo UCL/MR/CT imaging of prostate tumors.The synthesis of multifunctional monodisperse upconversion nanoparticles (UCNPs) of high quality is highly desired for bioimaging. Lanthanide-oleate complexes are excellent precursors for the synthesis of high quality UCNPs with controllable size and shape. In this work, lanthanide-oleate complexes were prepared by an ultrasonic assisted procedure, and used as precursors for further synthesis of multifunctional monodisperse NaYF4:59%Yb3+,0.5% Tm3+@NaYF4:20%Gd3+ nanoparticles without the need for further purification. Heavy doping of Yb3+ in the core and incorporation of Gd3+ in the shell made the UCNPs promising for upconversion luminescence (UCL), magnetic resonance (MR) and computed tomography (CT) multimodal imaging. The nanoparticles were further functionalized with bombesin peptide for in vivo UCL/MR/CT imaging of prostate tumors. Electronic supplementary information (ESI) available: Experimental details and additional figures and tables. See DOI: 10.1039/c4nr00806e

  6. Nanoparticles speckled by ready-to-conjugate lanthanide complexes for multimodal imaging

    NASA Astrophysics Data System (ADS)

    Biju, Vasudevanpillai; Hamada, Morihiko; Ono, Kenji; Sugino, Sakiko; Ohnishi, Takashi; Shibu, Edakkattuparambil Sidharth; Yamamura, Shohei; Sawada, Makoto; Nakanishi, Shunsuke; Shigeri, Yasushi; Wakida, Shin-Ichi

    2015-09-01

    Multimodal and multifunctional contrast agents receive enormous attention in the biomedical imaging field. Such contrast agents are routinely prepared by the incorporation of organic molecules and inorganic nanoparticles (NPs) into host materials such as gold NPs, silica NPs, polymer NPs, and liposomes. Despite their non-cytotoxic nature, the large size of these NPs limits the in vivo distribution and clearance and inflames complex pharmacokinetics, which hinder the regulatory approval for clinical applications. Herein, we report a unique method that combines magnetic resonance imaging (MRI) and fluorescence imaging modalities together in nanoscale entities by the simple, direct and stable conjugation of novel biotinylated coordination complexes of gadolinium(iii) to CdSe/ZnS quantum dots (QD) and terbium(iii) to super paramagnetic iron oxide NPs (SPION) but without any host material. Subsequently, we evaluate the potentials of such lanthanide-speckled fluorescent-magnetic NPs for bioimaging at single-molecule, cell and in vivo levels. The simple preparation and small size make such fluorescent-magnetic NPs promising contrast agents for biomedical imaging.

  7. Highly Luminescent Salts Containing Well-Shielded Lanthanide-Centered Complex Anions and Bulky Imidazolium Countercations

    SciTech Connect

    Tang, Si-Fu; Lorbeer, Chantal; Wang, Xinjiao; Ghosh, Pushpal; Mudring, Anja-Verena

    2014-09-02

    Four salts containing imidazolium cations and europium(III)- or terbium(III)-centered complex anions have been successfully synthesized from an ethanol/H2O solution. The single-crystal X-ray diffraction analyses reveal that these compounds have a common formula of [R][Ln(DETCAP)4] [R = 1-ethyl-3-methylimidazolium (C2mim), Ln = Eu (1) and Tb (2); R = 1-butyl-3-methylimidazolium (C4mim), Ln = Eu (3) and Tb (4); DETCAP = diethyl-2,2,2-trichloroacetylphosphoramidate], in which the lanthanide centers are chelated by four chelating pseudo-β-diketonate ligands (DETCAP)-, forming the respective complex anions. Their thermal behaviors and stabilities were also investigated to study the role of the length of the side chain in the cations. Fluorescence measurements at both room temperature and liquid-nitrogen temperature show that these materials show intense characteristic europium(III) or terbium(III) emissions and have long decay times. Their overall quantum yields were determined to be in the range of 30–49%.

  8. Catalytic hydrolysis of phosphate diesters by lanthanide(III) cryptate (2.2.1) complexes

    SciTech Connect

    Oh, Soon Jin; Song, Hwa Song; Wang, Dongmok

    1996-06-19

    Lanthanide(III) Cryptate (2.2.1) chlorides (Ln(2.2.1)Cl{sub 3}; Ln = La (1a), Ce(1b), and Eu(1c); (2.2.1) = 4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane) are effective for the catalytic hydrolysis of bis(4-nitrophenyl) phophate. Kinetic studies reveal that the europium(III) complex (1c) catalyzes the hydrolysis to produce 6 equiv of 4-nitrophenol with a significant rate (k{sub 1} = 1.5 x 10{sup {minus}4} s{sup {minus}1} at 0.40 mM) at pH 8.5 and 50 {degrees}C. The catalytic activity of the complexes is increased with decreasing the ionic size, i.e. La < Ce < Eu. While the use of hydrogen peroxide further increases the activity of 1b (k{sub 1} = 1.6 x 10{sup {minus}3},at 0.40 mM), the presence of molecular oxygen does not affect the activity at all.

  9. Synthesis and evaluation of lanthanide ion DOTA-tetraamide complexes bearing peripheral hydroxyl groups.

    PubMed

    Pasha, Azhar; Lin, Mai; Tircsó, Gyula; Rostollan, Cynthia L; Woods, Mark; Kiefer, Garry E; Sherry, A Dean; Sun, Xiankai

    2009-03-01

    The use of lanthanide-based contrast agents for magnetic resonance imaging has become an integral component of this important diagnostic modality. These inert chelates typically possess high thermodynamic stability constants that serve as a predictor for in vivo stability and low toxicity. Recently, a new class of contrast agents was reported having a significantly lower degree of thermodynamic stability while exhibiting biodistribution profiles indicative of high stability under biological conditions. These observations are suggestive that the nature of contrast agent stability is also dependent upon the kinetics of complex dissociation, a feature of potential importance when contemplating the design of new chelates for in vivo use. We present a study of the kinetics of acid-catalyzed dissociation, thermodynamic stability, serum stability, and biodistribution of a series of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-tetraamide complexes that have been substituted with peripheral hydroxyl groups. The data indicate that these nontraditional contrast agents exhibit in vivo stability comparable to that of agents with much higher log K (ML) values, demonstrating the important contribution of kinetic inertness.

  10. Nanoparticles speckled by ready-to-conjugate lanthanide complexes for multimodal imaging.

    PubMed

    Biju, Vasudevanpillai; Hamada, Morihiko; Ono, Kenji; Sugino, Sakiko; Ohnishi, Takashi; Shibu, Edakkattuparambil Sidharth; Yamamura, Shohei; Sawada, Makoto; Nakanishi, Shunsuke; Shigeri, Yasushi; Wakida, Shin-ichi

    2015-09-28

    Multimodal and multifunctional contrast agents receive enormous attention in the biomedical imaging field. Such contrast agents are routinely prepared by the incorporation of organic molecules and inorganic nanoparticles (NPs) into host materials such as gold NPs, silica NPs, polymer NPs, and liposomes. Despite their non-cytotoxic nature, the large size of these NPs limits the in vivo distribution and clearance and inflames complex pharmacokinetics, which hinder the regulatory approval for clinical applications. Herein, we report a unique method that combines magnetic resonance imaging (MRI) and fluorescence imaging modalities together in nanoscale entities by the simple, direct and stable conjugation of novel biotinylated coordination complexes of gadolinium(III) to CdSe/ZnS quantum dots (QD) and terbium(III) to super paramagnetic iron oxide NPs (SPION) but without any host material. Subsequently, we evaluate the potentials of such lanthanide-speckled fluorescent-magnetic NPs for bioimaging at single-molecule, cell and in vivo levels. The simple preparation and small size make such fluorescent-magnetic NPs promising contrast agents for biomedical imaging.

  11. Lanthanide and transition metal complexes of bioactive coumarins: molecular modeling and spectroscopic studies.

    PubMed

    Georgieva, I; Mihaylov, Tz; Trendafilova, N

    2014-06-01

    The present paper summarizes theoretical and spectroscopic investigations on a series of active coumarins and their lanthanide and transition metal complexes with application in medicine and pharmacy. Molecular modeling as well as IR, Raman, NMR and electronic spectral simulations at different levels of theory were performed to obtain important molecular descriptors: total energy, formation energy, binding energy, stability, conformations, structural parameters, electron density distribution, molecular electrostatic potential, Fukui functions, atomic charges, and reactive indexes. The computations are performed both in gas phase and in solution with consideration of the solvent effect on the molecular structural and energetic parameters. The investigations have shown that the advanced computational methods are reliable for prediction of the metal-coumarin binding mode, electron density distribution, thermodynamic properties as well as the strength and nature of the metal-coumarin interaction (not experimentally accessible) and correctly interpret the experimental spectroscopic data. Known results from biological tests for cytotoxic, antimicrobial, anti-fungal, spasmolytic and anti-HIV activities on the studied metal complexes are reported and discussed.

  12. Application of lanthanide induced shifts for the determination of solution structures of metal ion-extractant complexes

    SciTech Connect

    Kalina, D.G.

    1984-01-01

    An analysis of the induced shifts in the nuclear magnetic resonance (NMR) spectra of extractants complexed to paramagnetic lanthanide ions has been performed. The complexes of a number of monofunctional and bifunctional extractants have been examined and assigned solution structures by minimizing the differences between the observed shifts and those calculated using a computer analysis in which the potential configurations of the complexes were generated. Complexes of monofunctional extractants were calculated to have coordination geometries quite similar to those observed in related compounds by crystallographic techniques. For the bifunctional extractants, differentiation between monodentate and bidentate coordination seems possible. 23 references, 2 figures, 7 tables.

  13. Cyanomethylene-bis(phosphonate)-based lanthanide complexes: structural, photophysical, and magnetic investigations.

    PubMed

    Maxim, Catalin; Branzea, Diana G; Tiseanu, Carmen; Rouzières, Mathieu; Clérac, Rodolphe; Andruh, Marius; Avarvari, Narcis

    2014-03-03

    The syntheses, structural investigations, magnetic and photophysical properties of a series of 10 lanthanide mononuclear complexes, containing the heteroditopic ligand cyanomethylene-bis(5,5-dimethyl-2-oxo-1,3,2λ(5)-dioxa-phosphorinane) (L), are described. The crystallographic analyses indicate two structural types: in the first one, [Ln(III)(L)3(H2O)2]·H2O (Ln = La, Pr, Nd), the metal ions are eight-coordinated within a square antiprism geometry, while the second one, [Ln(III)(L)3(H2O)]·8H2O (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er), contains seven-coordinated Ln(III) ions within distorted monocapped trigonal prisms. Intermolecular hydrogen bonding between nitrogen atoms of the cyano groups, crystallization, and coordination water molecules leads to the formation of extended supramolecular networks. Solid-state photophysical investigations demonstrate that Eu(III) and Tb(III) complexes possess intense luminescence with relatively long excited-state lifetimes of 530 and 1370 μs, respectively, while Pr(III), Dy(III), and Ho(III) complexes have weak intensity luminescence characterized by short lifetimes ranging between a few nanoseconds to microseconds. The magnetic properties for Pr(III), Gd(III), Tb(III), Dy(III), and Ho(III) complexes are in agreement with isolated Ln(III) ions in the solid state, as suggested by the single-crystal X-ray analyses. Alternating current (ac) susceptibility measurements up to 10 kHz reveal that only the Ho(III) complex shows a frequency-dependent ac response, with a relaxation mode clearly observed at 1.85 K around 4500 Hz.

  14. Thermodynamic stability, kinetic inertness and relaxometric properties of monoamide derivatives of lanthanide(III) DOTA complexes.

    PubMed

    Tei, Lorenzo; Baranyai, Zsolt; Gaino, Luca; Forgács, Attila; Vágner, Adrienn; Botta, Mauro

    2015-03-28

    A complete thermodynamic and kinetic solution study on lanthanide(III) complexes with monoacetamide (DOTAMA, L1) and monopropionamide (DOTAMAP, L2) derivatives of DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was undertaken with the aim to elucidate their stability and inertness in aqueous media. The stability constants of GdL1 and GdL2 are comparable, whereas a more marked difference is found in the kinetic inertness of the two complexes. The formation of the Eu(III) and Ce(III) complexes takes place via the formation of the protonated intermediates which can deprotonate and transform into the final complex through a OH(-) assisted pathway. GdL2 shows faster rates of acid catalysed decomplexation with respect to GdL1, which has a kinetic inertness comparable to GdDOTA. Nevertheless, GdL2 is one order of magnitude more inert than GdDO3A. A novel DOTAMAP-based bifunctional chelating ligand and its deoxycholic acid derivative (L5) were also synthesized. Since the coordinated water molecule in GdL2 is characterized by an exchange rate ca. two orders of magnitude greater than in GdL1, the relaxivity of the macromolecular derivatives of L5 should not be limited by the slow water exchange process. The relaxometric properties of the supramolecular adduct of GdL5 with human serum albumin (HSA) were investigated in aqueous solution by measuring the magnetic field dependence of the (1)H relaxivity which, at 20 MHz and 298 K, shows a 430% increase over that of the unbound GdL5 chelate. Thus, Gd(III) complexes with DOTAMAP macrocyclic ligands can represent good candidates for the development of stable and highly effective bioconjugate systems for molecular imaging applications.

  15. Aromatic Lateral Substituents Influence the Excitation Energies of Hexaaza Lanthanide Macrocyclic Complexes: A Wave Function Theory and Density Functional Study.

    PubMed

    Rabanal-León, Walter A; Murillo-López, Juliana A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2015-09-24

    The high interest in lanthanide chemistry, and particularly in their luminescence, has been encouraged by the need of understanding the lanthanide chemical coordination and how the design of new luminescent materials can be affected by this. This work is focused on the understanding of the electronic structure, bonding nature, and optical properties of a set of lanthanide hexaaza macrocyclic complexes, which can lead to potential optical applications. Here we found that the DFT ground state of the open-shell complexes are mainly characterized by the manifold of low lying f states, having small HOMO-LUMO energy gaps. The results obtained from the wave function theory calculations (SO-RASSI) put on evidence the multiconfigurational character of their ground state and it is observed that the large spin-orbit coupling and the weak crystal field produce a strong mix of the ground and the excited states. The electron localization function (ELF) and the energy decomposition analysis (EDA) support the idea of a dative interaction between the macrocyclic ligand and the lanthanide center for all the studied systems; noting that, this interaction has a covalent character, where the d-orbital participation is evidenced from NBO analysis, leaving the f shell completely noninteracting in the chemical bonding. From the optical part we observed in all cases the characteristic intraligand (IL) (π-π*) and ligand to metal charge-transfer (LMCT) bands that are present in the ultraviolet and visible regions, and for the open-shell complexes we found the inherent f-f electronic transitions on the visible and near-infrared region.

  16. Lanthanide complexes of macrocyclic polyoxovanadates by VO4 units: synthesis, characterization, and structure elucidation by X-ray crystallography and EXAFS spectroscopy.

    PubMed

    Nishio, Masaki; Inami, Shinnosuke; Katayama, Misaki; Ozutsumi, Kazuhiko; Hayashi, Yoshihito

    2012-01-16

    Reactions of a tetravanadate anion, [V(4)O(12)](4-), with a series of lanthanide(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et(4)N)(6)[Ln(III)V(9)O(27)] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6)], (Et(4)N)(5)[(H(2)O)Ho(III)(V(4)O(12))(2)] (7), and (Et(4)N)(7)[Ln(III)V(10)O(30)] [Ln = Er (8), Tm (9), Yb (10), Lu (11)]. Lanthanide complexes 1-11 are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes 1-6 are composed of a square-antiprism eight-coordinated Ln(III) center with a macrocyclic polyoxovanadate that is constructed from nine VO(4) tetrahedra through vertex sharing. The structure of 7 is composed of a seven-coordinated Ho(III) center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H(2)O ligand. Lanthanide complexes 8-11 have a six-coordinated Ln(III) center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L(III) absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln-O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile.

  17. Evidence of different stoichiometries for the limiting carbonate complexes across the lanthanide(III) series: a capillary electrophoresis-mass spectrometry study.

    PubMed

    Philippini, Violaine; Vercouter, Thomas; Aupiais, Jean; Topin, Sylvain; Ambard, Chrystel; Chaussé, Annie; Vitorge, Pierre

    2008-05-01

    The electrophoretic mobilities (mu ep,Ln) of twelve lanthanides (not Ce, Pr and Yb) were measured by CE-ICP-MS in 0.15 and 0.5 mol L(-1) Alk2 CO3 aqueous solutions for Alk+ = Li+, Na+, K+ and Cs+. In 0.5 mol L(-1) solutions, two different mu ep,Ln values were found for the light (La to Nd) and the heavy (Dy to Tm) lanthanides, which suggests two different stoichiometries for the carbonate limiting complexes. These results are consistent with a solubility study that attests the Ln(CO3)3(3-) and Ln(CO3)4(5-) stoichiometries for the heavy (small) and the light (big) lanthanides, respectively. The Alk+ counterions influence the mu ep,Ln Alk2 CO3 values, but not the overall shape of the mu ep,Ln Alk2 CO3 plots as a function of the lanthanide atomic numbers: the counterions do not modify the stoichiometries of the inner sphere complexes. The influence of the Alk+ counterions decreases in the Li+ > Na+ > K+ > Cs+ series. The K3,Ln stepwise formation constants of the Ln(CO3)3(3-) complexes slightly increase with the atomic numbers of the lanthanides while K4,Ln, the stepwise formation constants of Ln(CO3)4(5-) complexes, slightly decrease from La to Tb, and is no longer measurable for heavier lanthanides.

  18. Contrasting enantioselective DNA preference: chiral helical macrocyclic lanthanide complex binding to DNA.

    PubMed

    Zhao, Chuanqi; Ren, Jinsong; Gregoliński, Janusz; Lisowski, Jerzy; Qu, Xiaogang

    2012-09-01

    There is great interest in design and synthesis of small molecules which selectively target specific genes to inhibit biological functions in which particular DNA structures participate. Among these studies, chiral recognition has been received much attention because more evidences have shown that conversions of the chirality and diverse conformations of DNA are involved in a series of important life events. Here, we report that a pair of chiral helical macrocyclic lanthanide (III) complexes, (M)-Yb[L(SSSSSS)](3+) and (P)-Yb[L(RRRRRR)](3+), can enantioselectively bind to B-form DNA and show remarkably contrasting effects on GC-rich and AT-rich DNA. Neither of them can influence non-B-form DNA, nor quadruplex DNA stability. Our results clearly show that P-enantiomer stabilizes both poly(dG-dC)(2) and poly(dA-dT)(2) while M-enantiomer stabilizes poly(dA-dT)(2), however, destabilizes poly(dG-dC)(2). To our knowledge, this is the best example of chiral metal compounds with such contrasting preference on GC- and AT-DNA. Ligand selectively stabilizing or destabilizing DNA can interfere with protein-DNA interactions and potentially affect many crucial biological processes, such as DNA replication, transcription and repair. As such, bearing these unique capabilities, the chiral compounds reported here may shed light on the design of novel enantiomers targeting specific DNA with both sequence and conformation preference.

  19. Revealing and tuning the core, structure, properties and function of polymer micelles with lanthanide-coordination complexes.

    PubMed

    Wang, Junyou; Groeneveld, Andrea; Oikonomou, Maria; Prusova, Alena; Van As, Henk; van Lent, Jan W M; Velders, Aldrik H

    2016-01-07

    Controlling self-assembly processes is of great interest in various fields where multifunctional and tunable materials are designed. We here present the versatility of lanthanide-complex-based micelles (Ln-C3Ms) with tunable coordination structures and corresponding functions (e.g. luminescence and magnetic relaxation enhancement). Micelles are prepared by charge-driven self-assembly of a polycationic-neutral diblock copolymer and anionic coordination complexes formed by Ln(III) ions and the bis-ligand L2EO4, which contains two dipicolinic acid (DPA) ligand groups (L) connected by a tetra-ethylene oxide spacer (EO4). By varying the DPA/Ln ratio, micelles are obtained with similar size but with different stability, different aggregation numbers and different oligomeric and polymeric lanthanide(III) coordination structures in the core. Electron microscopy, light scattering, luminescence spectroscopy and magnetic resonance relaxation experiments provide an unprecedented detailed insight into the core structures of such micelles. Concomitantly, the self-assembly is controlled such that tunable luminescence or magnetic relaxation with Eu-C3Ms, respectively, Gd-C3Ms is achieved, showing potential for applications, e.g. as contrast agents in (pre)clinical imaging. Considering the various lanthanide(III) ions have unique electron configurations with specific physical chemical properties, yet very similar coordination chemistry, the generality of the current coordination-structure based micellar design shows great promise for development of new materials such as, e.g., hypermodal agents.

  20. Preparation and Quality Control of the [153Sm]-Samarium Maltolate Complex as a Lanthanide Mobilization Product in Rats

    PubMed Central

    Naseri, Zohreh; Hakimi, Amir; Jalilian, Amir R.; Nemati Kharat, Ali; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

    2011-01-01

    Development of lanthanide detoxification agents and protocols is of great importance in management of overdoses. Due to safety of maltol as a detoxifying agent in metal overloads, it can be used as a lanthanide detoxifying agent. In order to demonstrate the biodistribution of final complex, [153Sm]-samarium maltolate was prepared using Sm-153 chloride (radiochemical purity >99.9%; ITLC and specific activity). The stability of the labeled compound was determined in the final solution up to 24h as well as the partition coefficient. Biodistribution studies of Sm-153 chloride, [153Sm]-samarium maltolate were carried out in wild-type rats comparing the critical organ uptakes. Comparative study for Sm3+ cation and the labeled compound was conducted up to 48 h, demonstrating a more rapid wash out for the labeled compound. The effective and biological half lives of 2.3 h and 2.46h were calculated for the complex. The data suggest the detoxification property of maltol formulation for lanthanide overdoses. PMID:21773065

  1. Mechanistic insights into the luminescent sensing of organophosphorus chemical warfare agents and simulants using trivalent lanthanide complexes.

    PubMed

    Dennison, Genevieve H; Johnston, Martin R

    2015-04-20

    Organophosphorus chemical warfare agents (OP CWAs) are potent acetylcholinesterase inhibitors that can cause incapacitation and death within minutes of exposure, and furthermore are largely undetectable by the human senses. Fast, efficient, sensitive and selective detection of these compounds is therefore critical to minimise exposure. Traditional molecular-based sensing approaches have exploited the chemical reactivity of the OP CWAs, whereas more recently supramolecular-based approaches using non-covalent interactions have gained momentum. This is due, in part, to the potential development of sensors with second-generation properties, such as reversibility and multifunction capabilities. Supramolecular sensors also offer opportunities for incorporation of metal ions allowing for the exploitation of their unique properties. In particular, trivalent lanthanide ions are being increasingly used in the OP CWA sensing event and their use in supramolecular sensors is discussed in this Minireview. We focus on the fundamental interactions of simple lanthanide systems with OP CWAs and simulants, along with the development of more elaborate and complex systems including those containing nanotubes, polymers and gold nanoparticles. Whilst literature investigations into lanthanide-based OP CWA detection systems are relatively scarce, their unique and versatile properties provide a promising platform for the development of more efficient and complex sensing systems into the future.

  2. Preparation and quality control of the [sm]-samarium maltolate complex as a lanthanide mobilization product in rats.

    PubMed

    Naseri, Zohreh; Hakimi, Amir; Jalilian, Amir R; Nemati Kharat, Ali; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

    2011-01-01

    Development of lanthanide detoxification agents and protocols is of great importance in management of overdoses. Due to safety of maltol as a detoxifying agent in metal overloads, it can be used as a lanthanide detoxifying agent. In order to demonstrate the biodistribution of final complex, [(153)Sm]-samarium maltolate was prepared using Sm-153 chloride (radiochemical purity >99.9%; ITLC and specific activity). The stability of the labeled compound was determined in the final solution up to 24h as well as the partition coefficient. Biodistribution studies of Sm-153 chloride, [(153)Sm]-samarium maltolate were carried out in wild-type rats comparing the critical organ uptakes. Comparative study for Sm(3+) cation and the labeled compound was conducted up to 48 h, demonstrating a more rapid wash out for the labeled compound. The effective and biological half lives of 2.3 h and 2.46h were calculated for the complex. The data suggest the detoxification property of maltol formulation for lanthanide overdoses.

  3. Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol

    SciTech Connect

    Rogers, R.D.; Rollins, A.N.; Etzenhouser, R.D.; Voss, E.J.; Bauer, C.B. )

    1993-08-04

    The complexation reactions of MCl[sub 3][center dot]nH[sub 2]O (M = Y, La-Pr, Sm-Lu) with pentaethylene glycol (EO5) and MCl[sub 3][center dot]nH[sub 2]O (M = La, Ce, Pr, Eu, Gd) with 18-crown-6 in 1:1 molar ratios in 3:1 CH[sub 3]CN:CH[sub 3]OH were investigated. X-ray structural analysis of 21 crystalline complexes were carried out. Comparison of all the crystalline complexes studied reveals that polyethylene glycols exhibit a helical wrapping pattern around the lanthanide ions, while the crown ethers attempt to fold around these cations. This feature of polyether complexation of the lanthanide(III) chlorides may be responsible for the ready isolation of EO5 complexes for all lanthanides and the lack of direct coordination of 18-crown-6 past M = Tb in normal 1:1 complexation reactions.

  4. Structural study of trivalent lanthanide and actinide complexes formed upon solvent extraction.

    PubMed

    Gannaz, Benoît; Antonio, Mark R; Chiarizia, Renato; Hill, Clément; Cote, Gérard

    2006-10-14

    The coordination of the trivalent 4f ions, Ln = Nd3+, Eu3+ and Yb3+, as well as the trivalent 5f ion, Am3+, with diamide and dialkylphosphoric acid extractants, individually and in combination, was studied by use of X-ray absorption spectroscopy. These studies provide metrical information about the interatomic interactions between the f-ions (M3+) and the ligands, dihexylphosphoric acid (HDHP) and N,N'-dimethyl-N,N'-dioctylhexylethoxymalonamide (DMDOHEMA), that is of practical relevance to the control of metal-ligand binding in liquid-liquid extraction systems for the separation of trivalent actinide ions, An3+, from trivalent lanthanide ions, Ln3+. Through systematic variations of extraction conditions and extractant combinations, we have found that the HDHP complexes with M3+ involve MO6 coordination and distant M...P interactions, whereas the DMDOHEMA complexes with M3+ involve MO8 coordination. The combination of the EXAFS results with ancillary extraction data and IR results facilitates descriptions of the stoichiometries and structures of the molecular species formed in solution upon liquid-liquid extraction and leads to a new understanding of the binary extraction systems in terms of the strength and selectivity of An3+- vs. Ln3+-ligand interactions. This fundamental structure information affords insight into solvent extraction processes that are of contemporary and practical importance in heavy element chemistry and to environmentally related issues arising from the separation and disposal of radioactive materials, particularly actinides and selected fission products, in the field of nuclear waste reprocessing research.

  5. Heterodimetallic [LnLn′] Lanthanide Complexes: Toward a Chemical Design of Two-Qubit Molecular Spin Quantum Gates

    PubMed Central

    2015-01-01

    A major challenge for realizing quantum computation is finding suitable systems to embody quantum bits (qubits) and quantum gates (qugates) in a robust and scalable architecture. An emerging bottom-up approach uses the electronic spins of lanthanides. Universal qugates may then be engineered by arranging in a molecule two interacting and different lanthanide ions. Preparing heterometallic lanthanide species is, however, extremely challenging. We have discovered a method to obtain [LnLn′] complexes with the appropriate requirements. Compound [CeEr] is deemed to represent an ideal situation. Both ions have a doubly degenerate magnetic ground state and can be addressed individually. Their isotopes have mainly zero nuclear spin, which enhances the electronic spin coherence. The analogues [Ce2], [Er2], [CeY], and [LaEr] have also been prepared to assist in showing that [CeEr] meets the qugate requirements, as revealed through magnetic susceptibility, specific heat, and EPR. Molecules could now be used for quantum information processing. PMID:25203521

  6. A general method for preparing lanthanide oxide nanoparticles via thermal decomposition of lanthanide(III) complexes with 1-hydroxy-2-naphthoic acid and hydrazine ligands

    NASA Astrophysics Data System (ADS)

    Parimalagandhi, Karuppannan; Premkumar, Thathan; Vairam, Sundararajan

    2016-09-01

    Six new lanthanide(III) complexes (i.e., [Ln(L)2(NA)1.5]·3H2O, where Ln=La(III), Pr(III), Nd(III), Sm(III), Gd(III), and Ce(III) and L and NA indicate N2H4 and C10H6(1-O)(2-COO), respectively) with 1-hydroxy-2-naphthoic acid [C10H6(1-O)(2-COOH)] and hydrazine (N2H4) as co-ligands were characterized by elemental, FTIR, UV-visible, and XRD techniques. In the FT-IR spectra, the N-N stretching frequency in the range of 981-949 cm-1 demonstrates evidence of the presence of coordinated N2H4, indicating the bidentate bridging nature of hydrazine in the complexes. These complexes show symmetric and asymmetric COO- stretching from 1444 to 1441 cm-1 and 1582 to 1557 cm-1, respectively, indicating bidentate coordination. TG-DTA studies revealed that the compounds underwent endothermic dehydration from 98 to 110 °C. This was followed by the exothermic decomposition of oxalate intermediates to yield the respective metal oxides as the end products. From SEM images, the average size of the metal oxide particles prepared by thermal decomposition of the complexes was determined to be 39-42 nm. The powder X-ray and SEM coupled with energy dispersive X-ray (EDX) studies revealed the presence of the respective nano-sized metal oxides. The kinetic parameters of the decomposition of the complexes were calculated using the Coats-Redfern equation.

  7. Core–shell Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses: Preparation and their effects on photoluminescence of lanthanide complexes

    SciTech Connect

    Kang, Jie; Li, Yuan; Chen, Yingnan; Wang, Ailing; Yue, Bin; Qu, Yanrong; Zhao, Yongliang; Chu, Haibin

    2015-11-15

    Highlights: • Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses were prepared via the Stöber process. • Sm and Dy complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. • The complex-doped Ag@SiO{sub 2} composites show stronger luminescent intensities than pure complexes. • The luminescent intensities of the composites strongly depend on the SiO{sub 2} shell thickness. - Abstract: Three kinds of almost spherical core–shell Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses (10, 25 and 80 nm) were prepared via the Stöber process. The Ag core nanoparticles were prepared by reducing silver nitrate with sodium citrate. The size, morphology and structure of core–shell Ag@SiO{sub 2} nanoparticles were characterized by transmission electron microscopy. Subsequently, eight kinds of lanthanide complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. The composition of the lanthanide complexes was characterized by elemental analysis, IR and UV spectra. Finally, lanthanide complexes were attached to the surface of Ag@SiO{sub 2} nanoparticles to form lanthanide-complex-doped Ag@SiO{sub 2} nanocomposites. The results show that the complex-doped Ag@SiO{sub 2} nanocomposites display much stronger luminescence intensities than the lanthanide complexes. Furthermore, the luminescence intensities of the lanthanide-complex-doped Ag@SiO{sub 2} nanocomposites with SiO{sub 2} shell thickness of 25 nm are stronger than those of the nanocomposites with SiO{sub 2} shell thickness of 10 and 80 nm.

  8. Insights into bonding interactions and excitation energies of 3d-4f mixed lanthanide transition metal macrocyclic complexes.

    PubMed

    Rabanal-León, Walter A; Murillo-López, Juliana A; Arratia-Pérez, Ramiro

    2016-12-07

    In this contribution, a computational study of equatorial bound tetranuclear macrocycle (butylene linked) [LnZn(HOM(Bu))](3+) (Ln = La(3+), Ce(3+)) complexes was carried out. Here, the electronic structure, bonding interaction and excitation energies were studied within the relativistic density functional theory framework. From the electronic structure analysis, the frontier molecular orbitals (FMOs) were strongly localized in the d-orbitals of the Zn centers and the f-orbitals of the lanthanide ions. Besides, the inner MOs were found to exhibit a π-character from the organic part of the macrocyclic chain. EDA-NOCV was used as a tool for evaluating the bonding interaction, taking the trinuclear metallomacrocycle (ZnHOM(Bu)) and the lanthanide center as fragments. This analysis showed that the interaction between these fragments was slightly covalent; with this covalency being the result of a charge transfer from the metallomacrocyclic ring to the lanthanide. This phenomenon was observed in the deformation density channels obtained from the EDA-NOCV study; in which π- and σ-charge transfer was observed. Finally, the TD-DFT study of the excitation energies evidenced three sets of bands: the first set with the highest intensity represented the ligand to metal charge transfer bands; the second set could be attributed to the 3d-4f electronic transitions between the metal centers; and the third set represented the f-f bands found for the open-shell cerium complex. This class of complexes accomplishes the "antenna effect" principle, which states that highly absorptive transition-metal (TM) complexes can be used to enhance the luminescence of poorly emissive systems, and are introduced in this study as self-sensitizer bimetallic d-f systems with potential applications in near infra-red (NIR) technologies.

  9. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: the role of 4f electrons.

    PubMed

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Liu, Yang; Yang, Dong-Sheng

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Møller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  10. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons

    SciTech Connect

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng; Liu Yang

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  11. A thermodynamical and structural study on the complexation of trivalent lanthanides with a polycarboxylate based concrete superplasticizer.

    PubMed

    Fröhlich, Daniel R; Maiwald, Martin M; Taube, Franziska; Plank, Johann; Panak, Petra J

    2017-03-21

    The complexation of trivalent lanthanides with a commercial polycarboxylate based concrete superplasticizer (Glenium® 51) is investigated using different spectroscopic techniques. Time-resolved laser fluorescence spectroscopy (TRLFS) in combination with a charge neutralization model is used to determine temperature dependent conditional stability constants (log β'(T)) for the complexation of Eu(iii) with Glenium® 51 in 0.1 mol kg(-1) NaCl solution in the temperature range of 20-90 °C. Only one complex species is observed, and log β'(T) (given in kg per mol eq) shows a very slight increase with temperature from 7.5 to 7.9. The related conditional molar reaction enthalpy (ΔrH'm) and entropy (ΔrS'm) obtained using the Van't Hoff equation show that the complexation reaction is slightly endothermic and entropy driven. The thermodynamic investigations are complemented by structural data for complexes formed with Gd(iii) or Tb(iii) and Glenium® 51 using extended X-ray absorption fine structure (EXAFS) spectroscopy. The results imply a non-chelate coordination of the trivalent metals through approximately three carboxylic functions of the polycarboxylate comb polymer which are attached predominantly in a bidentate fashion to the lanthanide under the given experimental conditions.

  12. Unexpected Changes in the Population of Coordination Isomers for the Lanthanide Ion Complexes of DOTMA-Tetraglycinate.

    PubMed

    Kumas, Cemile; Fernando, W Shirangi; Zhao, Piyu; Regueiro-Figueroa, Martín; Kiefer, Garry E; Martins, André F; Platas-Iglesias, Carlos; Sherry, A Dean

    2016-09-19

    Lanthanide complexes with DOTA-tetraglycinate (DOTA-(gly)4) heavily favor the square antiprismatic (SAP) coordination isomer in aqueous solution, a structural feature that has made them useful as water-based paraCEST agents. In an effort to create amide-based paraCEST agents with rapid water exchange rates, we prepared the analogous tetraglycinate complexes with DOTMA, a ligand known to favor the twisted square antiprismatic (TSAP) coordination structures. Unexpectedly, NMR investigations show that the LnDOTMA-(gly)4 complexes, like the LnDOTA-(gly)4 complexes, also favor the SAP isomers in solution. This observation led to density functional theory (DFT) calculations in order to identify the energy terms that favor the SAP structures in lanthanide complexes formed with macrocyclic DOTA- and DOTMA-tetraamide ligands. The DFT calculations revealed that, regardless the nature of the ligand, the TSAP isomers present more negative hydration energies than the SAP counterparts. The extent to which the TSAP isomer is stabilized varies, however, depending on the ligand structure, resulting in different isomeric populations in solution.

  13. Unusually sharp dependence of water exchange rate versus lanthanide ionic radii for a series of tetraamide complexes.

    PubMed

    Zhang, Shanrong; Wu, Kuangcong; Sherry, A Dean

    2002-04-24

    The tetraamide ligand, DOTA-tetra(glycine ethyl ester), forms complexes with the lanthanide(III) cations that exist in solution predominantly as the square antiprism structure with single, slowly exchanging inner-sphere water molecule. Variable-temperature 1H and 17O NMR studies revealed that the bound water lifetimes in these complexes were sharply dependent upon the ionic radius of Ln3+ cation. A novel lanthanide-induced shift technique was used to unmask the bound water 17O resonance of SmL3+ and YL3+ complexes from the bulk water resonance. The bound water lifetime (tauM298) was approximately 800 mus in the EuL3+ complex but became much shorter (several microseconds) for Ln3+ cations with larger and smaller ionic radii. This demonstrates that water exchange is exquisitely fine-tuned in this macrocyclic tetraamide system and that a variety of Ln3+ complexes meet with the exchange requirement, Deltaomega*tauM >/= 1, necessary for an efficient MT agent.

  14. Complexation of Sn2Se6 with lanthanide(III) centers influenced by ethylene polyamines: Solvothermal syntheses, crystal structures, and optical properties of lanthanide selenidostannates

    NASA Astrophysics Data System (ADS)

    Tang, Chunying; Wang, Fang; Chen, Ruihong; Jiang, Wenqing; Zhang, Yong; Jia, Dingxian

    2013-08-01

    Lanthanide selenidostannates (H3O)n[Ce(tepa)(μ-1κ2:2κ2-Sn2Se6)]n (1), [{Yb(tepa)(μ-OH)}2(μ-1κ:2κ-Sn2Se6)]n·nH2O (2), [Htrien]2[{Ln(trien)(tren)}2(μ-1κ:2κ-Sn2Se6)][Sn2Se6] (Ln=Ce(3), Nd(4)) and [{Yb(dien)2}2(μ-OH)2]Sn2Se6 (5) were solvothermally prepared in different ethylene polyamines. The Sn2Se6 unit connects [Ce(tepa)]3+ and [{Yb(tepa)(μ-OH)}2]4+ fragments with tetradentate μ-1κ2Se1,Se2:2κ2Se5,Se6 and bidentate μ-1κSe1:2κSe5 bridging coordination modes in tepa, to form polymers 1 and 2, respectively. It joins two [Ln(trien)(tren)]3+ fragments as a μ-1κSe1:2κSe5 ligand to form binuclear complexes 3 and 4 in trien. Unlike the Sn2Se6 units in 1-4 that bind with Ln(III) centers as Se-donor ligands, the Sn2Se6 unit in 5 exists as a discrete ion. The syntheses of 1-5 show that the ethylene polyamines play an important role in the complexation of Sn2Se6 ligand with Ln(III) centers. Compounds 1-5 exhibit optical band gaps in the range of 2.09-2.42 eV, which are influenced by the complexation of Sn2Se6 with Ln(III) centers.

  15. Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

    SciTech Connect

    Wang Yige; Wang Li; Li Huanrong Liu Peng; Qin Dashan; Liu Binyuan; Zhang Wenjun; Deng Ruiping; Zhang Hongjie

    2008-03-15

    Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data. - Graphical abstract: Novel stable luminescent organic-inorganic hybrid titania thin film with high transparency activated by in-situ formed lanthanide complexes have been obtained at room temperature via a simple one-pot synthesis approach by using TTFA-modified titanium precursor with amphiphilic triblock copolymer P123. The obtained hybrid thin film displays bright red (or green), near-monochromatic luminescence due to the in-situ formed lanthanide complex.

  16. Microwave assisted synthesis, spectroscopic, electrochemical and DNA cleavage studies of lanthanide(III) complexes with coumarin based imines.

    PubMed

    Kapoor, Puja; Fahmi, Nighat; Singh, R V

    2011-12-01

    The present work stems from our interest in the synthesis, characterization and biological evaluation of lanthanide(III) complexes of a class of coumarin based imines which have been prepared by the interaction of hydrated lanthanide(III) chloride with the sodium salts of 3-acetylcoumarin thiosemicarbazone (ACTSZH) and 3-acetylcoumarin semicarbazone (ACSZH) in 1:3 molar ratio using thermal as well as microwave method. Characterization of the ligands as well as the metal complexes have been carried out by elemental analysis, melting point determinations, molecular weight determinations, magnetic moment, molar conductance, IR, (1)H NMR, (13)C NMR, electronic, EPR, X-ray powder diffraction and mass spectral studies. Spectral studies confirm ligands to be monofunctional bidentate and octahedral environment around metal ions. The redox behavior of one of the synthesized metal complex was investigated by cyclic voltammetry. Further, free ligands and their metal complexes have been screened for their antimicrobial as well as DNA cleavage activity. The results of these findings have been presented and discussed.

  17. Fluorescent studies on the interaction of DNA and ternary lanthanide complexes with cinnamic acid-phenanthroline and antibacterial activities testing.

    PubMed

    Sun, Hui-Juan; Wang, Ai-Ling; Chu, Hai-Bin; Zhao, Yong-Liang

    2015-03-01

    Twelve lanthanide complexes with cinnamate (cin(-) ) and 1,10-phenanthroline (phen) were synthesized and characterized. Their compositions were assumed to be RE(cin)3 phen (RE(3+)  = La(3+) , Pr(3+) , Nd(3+) , Sm(3+) , Eu(3+) , Gd(3+) , Tb(3+) , Dy(3+) , Ho(3+) , Tm(3+) , Yb(3+) , Lu(3+) ). The interaction mode between the complexes and DNA was investigated by fluorescence quenching experiment. The results indicated the complexes could bind to DNA and the main binding mode is intercalative binding. The fluorescence quenching constants of the complexes increased from La(cin)3 phen to Lu(cin)3 phen. Additionally, the antibacterial activity testing showed that the complexes exhibited excellent antibacterial ability against Escherichia coli, and the changes of antibacterial ability are in agreement with that of the fluorescence quenching constants.

  18. Peptide-lanthanide cation equilibria in aqueous phase. I. Bound shifts for L-carnosine-praseodymium complexes

    NASA Astrophysics Data System (ADS)

    Mossoyan, J.; Asso, M.; Benlian, D.

    L-Carnosine complexes of Pr 3+ were characterized in aqueous solution by 1H NMR and potentiometric titration. A rigorous treatment of chemical shifts and pH variation data with lanthanide concentration is presented. Two different forms of the peptide ligand, forming simultaneously two complexes, were taken into account. At low pH values the cation is only coordinated at the carboxylate site of the ligand in a weak complex ( β2 = 6) whereas in neutral solution a stronger complex ( β1 = 37) is present as a consequence of the deprotonation of the imidazole ring. The computation of induced bound shifts † 2 and Δ1 for resonating nuclei of the peptide in both forms yields consistent figures. These provide the experimental basis for a conformational model which is usually not obtainable for labile complexes with low stability constants.

  19. A novel CMPO-functionalized task specific ionic liquid: synthesis, extraction and spectroscopic investigations of actinide and lanthanide complexes.

    PubMed

    Mohapatra, Prasanta K; Kandwal, Pankaj; Iqbal, Mudassir; Huskens, Jurriaan; Murali, Mallekav S; Verboom, Willem

    2013-04-07

    A novel CMPO (carbamoylmethylphosphine oxide) based task specific ionic liquid (TSIL) with an NTf(2)(-) counter anion was synthesized and evaluated for actinide/lanthanide extraction from acidic feed solutions using several room temperature ionic liquids (RTILs). The extraction data were compared with those obtained with CMPO in the same set of RTILs and also in the molecular diluent, n-dodecane. The extracted species were analyzed by the conventional slope analysis method and the extraction followed an ion-exchange mechanism. The nature of bonding in the extracted complexes was investigated by various spectroscopic techniques such as FT-IR and UV-visible spectroscopy.

  20. Modeling the magnetic properties of lanthanide complexes: relationship of the REC parameters with Pauling electronegativity and coordination number.

    PubMed

    Baldoví, José J; Gaita-Ariño, Alejandro; Coronado, Eugenio

    2015-07-28

    In a previous study, we introduced the Radial Effective Charge (REC) model to study the magnetic properties of lanthanide single ion magnets. Now, we perform an empirical determination of the effective charges (Zi) and radial displacements (Dr) of this model using spectroscopic data. This systematic study allows us to relate Dr and Zi with chemical factors such as the coordination number and the electronegativities of the metal and the donor atoms. This strategy is being used to drastically reduce the number of free parameters in the modeling of the magnetic and spectroscopic properties of f-element complexes.

  1. Secret lanthanides.

    PubMed

    Sturza, C M

    2014-09-15

    Lanthanides are a group of 15 chemical elements which, together with their salts, have come to be used in the last decade as homoeopathic remedies. The effective introduction of lanthanides and their salts into the clinical use, as homoeopathic remedies was based on the idea of Jan Scholten, MD to relate their physicochemical properties shown in the periodic table of elements to their homoeopathic potential. The lanthanides and their salts were prepared as homoeopathic remedies by Pharmacist Robert Münz.

  2. High nuclearity complexes of lanthanide involving tetrathiafulvalene ligands: structural, magnetic, and photophysical properties.

    PubMed

    Pointillart, Fabrice; Le Guennic, Boris; Golhen, Stéphane; Cador, Olivier; Maury, Olivier; Ouahab, Lahcène

    2013-02-04

    The reaction between the tetrakis(2-pyridyl-N-oxidemethylthio)tetrathiafulvalene ligand (L) and Ln(hfac)(3)·2H(2)O precursors (where hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate anion and Ln = Tb(III) (1), Dy(III) (2), Er(III) (3), and Yb(III) (4) and (4b)) leads to the formation of five tetranuclear complexes of formula [Ln(4)(hfac)(12)(L)(2)](n)·xCHCl(3)·yC(6)H(14) (n = 1, x = 2, y = 0 for (1), (2), and (4), n = 1, x = 4 for (3), and n = 2, x = 2.5, y = 1 for (4b)). Their X-ray structures reveal that the surrounding of each Ln(III) center is filled by two N-oxide groups coming from two different ligands L. These tetranuclear complexes have the highest nuclearity which is reported until now for coordination compounds of lanthanide involving TTF-based ligands. Direct current (dc) measurements highlight the paramagnetic behavior of the compounds with a significant crystal field effect. The temperature dependences of static magnetic measurements for 4 have been fitted. The ground state corresponds to M(J) = ±5/2 while the first excited state (M(J) = ±3/2) was localized at +214 cm(-1) which was well correlated with the luminescence transition. UV-visible absorption properties have been experimentally measured and rationalized by time-dependent density functional theory (TD-DFT) calculations. Upon irradiation at 77 K and room temperature, in the range 24390-20835 cm(-1), both compounds 3 and 4 display a metal-centered luminescence attributed to (4)I(13/2) → (4)I(15/2) (6660 cm(-1)) and (2)F(5/2) → (2)F(7/2) (signal centered around the value of 9966 cm(-1)) transitions, respectively. The observed six transitions could be attributed to the M(J) state splitting due to the existence of two Yb1 and Yb2 ions with slightly different polyhedra in 4.

  3. Spectroscopic studies of lanthanide complexes of varying nuclearity based on a compartmentalised ligand.

    PubMed

    Olea-Román, Daniela; Bélanger-Desmarais, Nicolas; Flores-Álamo, Marcos; Bazán, Claudia; Thouin, Félix; Reber, Christian; Castillo-Blum, Silvia E

    2015-10-21

    The synthesis, characterization and solid-state luminescence spectroscopy of mononuclear (f), heterodinuclear (d-f) and heterotrinuclear (d-f-d) coordination compounds with the compartmental ligand N,N'-bis(3-hydroxyl salicylidene)benzene-1,2-diamine (H2L) are reported. The trivalent lanthanide ions Nd(III), Sm(III), Eu(III), Gd(III), Tb(III) and Dy(III) as single metal centres or in combination with either Zn(II) or Ni(II) were coordinated. Compounds are characterised by elemental analyses, IR, 1D and 2D solution (1)H and (13)C NMR spectroscopy, measurements of magnetic moments and solid state UV-Vis-NIR reflectance, luminescence and Raman spectroscopy techniques. Crystal structures of the dinuclear compounds [SmZn(O2NO)3(L)(OH2)]·EtOH and [DyZn(O2NO)2(Cl)(L)(EtOH)]·3EtOH and the trinuclear compound [TbZn2(L)2(Cl)2(OH2)](NO3)·EtOH are presented, where samarium(iii) displays a coordination number of ten, with a bicapped cubic geometry, while for the dysprosium compound a nine-coordinated environment with a tricapped trigonal prismatic geometry is shown. Their crystals belong to the triclinic system and the P1[combining macron] space group. The coordination number for terbium(iii) in the trinuclear complex is nine, with a tricapped trigonal prismatic geometry, and its crystal belongs to the monoclinic system, space group C2/c. For these three compounds, the zinc ion stabilises a penta-coordinated environment with square pyramid geometry. All mononuclear and dinuclear compounds are neutral, whereas the trinuclear complexes are ionic. The results of DFT theoretical calculations for the ligand (H2L) are used to assign the ligand singlet and triplet excited state energy levels. Luminescence studies of the neodymium compounds indicate that the ligand is a sensitizer for NIR emitters.

  4. Yttrium and lanthanide complexes having a chiral phosphanylamide in the coordination sphere.

    PubMed

    Panda, Tarun K; Gamer, Michael T; Roesky, Peter W

    2006-01-23

    The chiral phosphanylamides {N(R-CHMePh)(PPh(2))}(-) and {N(S-CHMePh)(PPh(2))}(-) were introduced into rare earth chemistry. Transmetalation of the enantiomeric pure lithium compounds Li{N(R-CHMePh)(PPh(2))} (1a) and Li{N(S-CHMePh)(PPh(2))} (1b) with lanthanide bis(phosphinimino)methanide dichloride [{CH(PPh(2)NSiMe(3))(2)}LnCl(2)](2) in a 2:1 molar ratio in THF afforded the enantiomeric pure complexes [{CH(PPh(2)NSiMe(3))(2)}Ln(Cl){eta(2)-N(R-CHMePh)(PPh(2))}] (Ln = Er (2a), Yb (3a), Lu (4a)) and [{CH(PPh(2)NSiMe(3))(2)}Ln(Cl){eta(2)-N(S-CHMePh)(PPh(2))}] (Ln = Er (2b), Yb (3b), Lu (4b)). The solid-state structures of 2a and 3a,b were established by single-crystal X-ray diffraction. Attempts to synthesize compounds 3 in a one-pot reaction starting from K{CH(PPh(2)NSiMe(3))(2)}, YbCl(3), and 1 resulted in the lithium chloride incorporated complex [{(Me(3)SiNPPh(2))(2)CH}Yb(mu-Cl)(2)LiCl(THF)(2)] (5). In an alternative approach to give chiral rare earth compounds in a one-pot reaction 1a or 1b was reacted with LnCl(3) and K(2)C(8)H(8) to give the enantiomeric pure cyclooctatetraene compounds [{eta(2)-N(R-CHMePh)(PPh(2))}Ln(eta(8)-C(8)H(8))] (Ln = Y (6a), Er (7a), Yb (8)) and [{eta(2)-N(S-CHMePh)(PPh(2))}Ln(eta(8)-C(8)H(8))] (Ln = Y (6b), Er (7b)). The structures of 6a,b, 7a, and 8 were confirmed by single-crystal X-ray diffraction in the solid state.

  5. A series of lanthanoid selenidoantimonates(V): rare examples of lanthanoid selenidoantimonates based on dinuclear lanthanide complexes.

    PubMed

    Xiao, Hong-Ping; Zhou, Jian; Zhao, Rong-Qing; Zhang, Wei-bing; Huang, Yong

    2015-04-07

    A series of new lanthanoid selenidoantimonates(V) [Ln(en)(tepa)SbSe4] (Ln = La (Ia), Ce (Ib), Pr (Ic); en = ethylenediamine, tepa = tetraethylenepentamine) and [Ln2(tepa)2(μ-OH)2Cl2]-{[Ln(tepa)]2(μ-OH)2(SbSe4)2} (Ln = Y (IIa), Sm (IIb), Gd (IIc), Tb (IId), Dy (IIe), and Tm (IIf)) were solvothermally synthesized and structurally characterized. The structures of Ia-c consist of neutral molecules [Ln(en)(tepa)SbSe4], where the tetrahedral [SbSe4](3-) anion acts as a ligand to chelate the [Ln(en)(tepa)](3+) cation. The structures of IIa-f contain isolated dinuclear [Ln2(tepa)2(μ-OH)2Cl2](2+) cations built up from two [Ln(tepa)Cl](2+) ions linked by two -OH bridging groups and organic decorated {[Ln(tepa)]2(μ-OH)2(SbSe4)2}(2-) anions based on two [Ln(tepa)SbSe4] units bridged by two -OH groups. Although a few lanthanoid selenidoantimonates(V) under solvothermal conditions have been reported, their lanthanide complexes normally appear mononuclear. Hence, IIa-f are rare examples of lanthanoid selenidoantimonates based on dinuclear lanthanide complexes. A preliminary investigation of nine lanthanoid selenidoantimonates(V) shows that the well-known lanthanide contraction has a significant influence on the formation of lanthanoid selenidoantimonates(V) under solvothermal conditions. The absorption edges of all compounds have been investigated by UV-vis spectroscopy, and density functional theory calculations for Ia and IIc have also been performed.

  6. Lanthanide Chemistry: From Coordination in Chemical Complexes Shaping Our Technology to Coordination in Enzymes Shaping Bacterial Metabolism.

    PubMed

    Martinez-Gomez, Norma Cecilia; Vu, Huong N; Skovran, Elizabeth

    2016-10-17

    Lanthanide chemistry has only been extensively studied for the last 2 decades, when it was recognized that these elements have unusual chemical characteristics including fluorescent and potent magnetic properties because of their unique 4f electrons.1,2 Chemists are rapidly and efficiently integrating lanthanides into numerous compounds and materials for sophisticated applications. In fact, lanthanides are often referred to as "the seeds of technology" because they are essential for many technological devices including smartphones, computers, solar cells, batteries, wind turbines, lasers, and optical glasses.3-6 However, the effect of lanthanides on biological systems has been understudied. Although displacement of Ca(2+) by lanthanides in tissues and enzymes has long been observed,7 only a few recent studies suggest a biological role for lanthanides based on their stimulatory properties toward some plants and bacteria.8,9 Also, it was not until 2011 that the first biochemical evidence for lanthanides as inherent metals in bacterial enzymes was published.10 This forum provides an overview of the classical and current aspects of lanthanide coordination chemistry employed in the development of technology along with the biological role of lanthanides in alcohol oxidation. The construction of lanthanide-organic frameworks will be described. Examples of how the luminescence field is rapidly evolving as more information about lanthanide-metal emissions is obtained will be highlighted, including biological imaging and telecommunications.11 Recent breakthroughs and observations from different exciting areas linked to the coordination chemistry of lanthanides that will be mentioned in this forum include the synthesis of (i) macrocyclic ligands, (ii) antenna molecules, (iii) coordination polymers, particularly nanoparticles, (iv) hybrid materials, and (v) lanthanide fuel cells. Further, the role of lanthanides in bacterial metabolism will be discussed, highlighting the

  7. Synthesis and Characterization of DOTA-(amide)4 Derivatives: Equilibrium and Kinetic Behavior of Their Lanthanide(III) Complexes

    PubMed Central

    Pasha, Azhar; Benyó, Enikő Tircsóné; Brücher, Ernő

    2009-01-01

    Lanthanide complexes of tetraamide derivatives of DOTA are of interest today because of their application as chemical exchange saturation transfer (CEST) agents for magnetic resonance imaging (MRI). The protonation constants of some simple tetraamide derivatives of DOTA and the stability constants of the complexes formed with some endogenous metal ions, namely Mg2+, Ca2+, Cu2+, Zn2+, and lanthanide(III) ions, have been studied. These complexes were found to be considerably less stable than the corresponding [M(DOTA)]2− complexes, largely due to the lower basicity of the tetraamide ligands. The Mg2+ and Ca2+ complexes are well described by formation of only ML species at equilibrium while the Zn2+ and Cu2+ complexes exhibit one and two additional deprotonation steps above a pH of around 6, respectively. The extra deprotonation that occurs at high pH for the [Zn{DOTA-(amide)4}]2+ complexes has been assigned to an amide deprotonation by 1H NMR spectroscopy. The first deprotonation step for the Cu2+ complexes was traced to formation of the ternary hydroxo complexes ML(OH) (by UV/Vis spectrophotometry) while the second step corresponds to deprotonation of an amide group to form ML(OH)H−1-type complexes. The trends in the stability constants of the [Ln{DOTA-(amide)4}]3+ complexes follow similar trends with respect to ion size as those reported previously for the corresponding [Ln(DOTA)]− complexes, but again, the stability constants are about 10–11 orders of magnitude lower. A kinetic analysis of complex formation has shown that complexes are directly formed between a Ln3+ cation and fully deprotonated L without formation of a protonated intermediate. [Ln{DOTA-(MeAm)4}]3+ complex formation occurs at a rate that is two to three orders of magnitude slower than those of the corresponding [Ln(DOTA)]− complexes, while the variation in complex formation rates with Ln3+ ion size is opposite to that observed for the corresponding [Ln(DOTA)]− complexes. The Ce3+ and

  8. Would the solvent effect be the main cause of band shift in the theoretical absorption spectrum of large lanthanide complexes?

    NASA Astrophysics Data System (ADS)

    Freire, Ricardo O.; Rodrigues, Nailton M.; Rocha, Gerd B.; Gimenez, Iara F.; da Costa Junior, Nivan B.

    2011-06-01

    As most reactions take place in solution, the study of solvent effects on relevant molecular properties - either by experimental or theoretical methods - is crucial for the design of new processes and prediction of technological properties. In spite of this, only few works focusing the influence of the solvent nature specifically on the spectroscopic properties of lanthanide complexes can be found in the literature. The present work describes a theoretical study of the solvent effect on the prediction of the absorption spectra for lanthanide complexes, but other possible relevant factors have been also considered such as the molecular geometry and the excitation window used for interaction configuration (CI) calculations. The [Eu(ETA) 2· nH 2O] +1 complex has been chosen as an ideal candidate for this type of study due to its small number of atoms (only 49) and also because the absorption spectrum exhibits a single band. Two Monte Carlo simulations were performed, the first one considering the [Eu(ETA) 2] +1 complex in 400 water molecules, evidencing that the complex presents four coordinated water molecules. The second simulation considered the [Eu(ETA) 2·4H 2O] +1 complex in 400 ethanol molecules, in order to evaluate the solvent effect on the shift of the maximum absorption in calculated spectra, compared to the experimental one. Quantum chemical studies were also performed in order to evaluate the effect of the accuracy of calculated ground state geometry on the prediction of absorption spectra. The influence of the excitation window used for CI calculations on the spectral shift was also evaluated. No significant solvent effect was found on the prediction of the absorption spectrum for [Eu(ETA) 2·4H 2O] +1 complex. A small but significant effect of the ground state geometry on the transition energy and oscillator strength was also observed. Finally it must be emphasized that the absorption spectra of lanthanide complexes can be predicted with great accuracy

  9. Sensitization of visible and NIR emitting lanthanide(III) ions in noncentrosymmetric complexes of hexafluoroacetylacetone and unsubstituted monodentate pyrazole.

    PubMed

    Ahmed, Zubair; Iftikhar, K

    2013-11-07

    A series of highly volatile eight-coordinate air and moisture stable lanthanide complexes of the type [Ln(hfaa)3(L)2] (Ln = Pr (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), and Yb (10); hfaa = anion of hexafluoroacetylacetone and L = pyrazole) have been synthesized and characterized by elemental analysis, IR, ESI-MS(+), and NMR studies. Single-crystal X-ray structures have been determined for the Eu(III) and Dy(III) complexes. These complexes crystallize in the monoclinic space group P2(1)/c. The lanthanide ion in each of these complexes is eight-coordinate with six oxygen atoms from three hfaa and two N-atoms from two pyrazole units, forming a coordination polyhedron best describable as a distorted square antiprism. The NMR spectra reveal that both the pyrazole units remain attached to the metal in solution and the β-diketonate and pyrazole protons are shifted in opposite directions in the case of paramagnetic complexes. The lanthanide-induced chemical shifts are dipolar in nature. The hypersensitive transitions of Nd(III), Ho(III), and Er(III) are sensitive to the environment (solvent), which is reflected by the oscillator strength and band shape of these transitions. The band shape due to the hypersensitive transition of Nd(III) in noncoordinating chloroform and dichloromethane is similar to those of the typical eight-coordinate Nd(III) β-diketonate complexes. The quantum yield and lifetime of Pr(III), Eu(III), Tb(III), Dy(III), and Tm(III) in visible and Pr(III), Nd(III), Dy(III), Ho(III), Er(III) Tm(III), and Yb(III) in the NIR region are sizable. The environment around these metal ions is asymmetric, which leads to increased radiative rates and luminescence efficiencies. The quantum yield of the complexes reveal that ligand-to-metal energy transfer follows the order Eu(III) > Tb(III) ≫ Pr(III) > Dy(III) > Tm(III). Both ligands (hfaa and pyrazole) are good sensitizers for all the visible and NIR emitters effectively, except for Tb

  10. Use of dipicolinate-based complexes for producing ion-imprinted polystyrene resins for the extraction of yttrium-90 and heavy lanthanide cations.

    PubMed

    Chauvin, Anne-Sophie; Bünzli, Jean-Claude G; Bochud, François; Scopelliti, Rosario; Froidevaux, Pascal

    2006-09-06

    Highly selective separation of yttrium (and lanthanides) is of interest for the design of radiopharmaceuticals, and an efficient method based on the ion-imprinting concept is proposed here. The synthesis and structural, thermodynamic and photophysical characterization of complexes of trivalent yttrium and lanthanides with two new vinyl derivatives of dipicolinic acid, HL1 and L2, are described. The feasibility of using ion-imprinted resins for yttrium and lanthanide separation is demonstrated. The resins were obtained by copolymerization with styrene and divinylbenzene and subsequent acid treatment to remove the metal ion. High-resolution Eu luminescence experiments revealed that the geometry of the complexation sites is well preserved in the imprinted polymers. The ion-imprinted polymer based on HL1 proved to be particularly well adapted for yttrium extraction, having a sizeable capacity (8.9+/-0.2 mg g(-1) resin) and a fast rate of extraction (t(1/2)=1.7 min). In addition, lighter and heavier lanthanide ions are separated. Finally, the resin displays high selectivity for yttrium and lanthanide cations against alkali and alkaline earth metals. For instance, in a typical experiment, 10 mg of yttrium was extracted from 5 g of milk ash sample by 2 g of the resin. The good separation properties displayed by the resin based on HL1 open interesting perspectives for the production of highly pure (90)Y and radiolanthanides for medical applications, and for trace analysis of these radiochemicals in food and in the environment.

  11. Mononuclear Lanthanide Complexes: Energy-Barrier Enhancement by Ligand Substitution in Field-Induced Dy(III) SIMs.

    PubMed

    Biswas, Sourav; Bejoymohandas, Kochan S; Das, Sourav; Kalita, Pankaj; Reddy, Mundalapudi L P; Oyarzabal, Itziar; Colacio, Enrique; Chandrasekhar, Vadapalli

    2017-07-17

    The sequential reaction of 2-((6-(hydroxymethyl)pyridin-2-yl)-methyleneamino)phenol (LH2), LnCl3·6H2O, and 1,1,1-trifluoroacetylacetone (Htfa) in the presence of Et3N afforded [Ln(LH) (tfa)2] [Ln = Dy(3+) (1), Ln = Tb(3+) (2), and Ln = Gd(3+) (3)], while under the same reaction conditions, but in the absence of the coligand, another series of mononuclear complexes, namely, [Ln(LH)2]·Cl·2MeOH] [Ln = Dy(3+) (4) and Tb(3+) (5)] are obtained. Single-crystal X-ray diffraction analysis revealed that the former set contains a mono-deprotonated [LH](-) and two tfa ligands, while the latter set comprises of two mono-deprotonated [LH](-) ligands that are nearly perpendicular to each other at an angle of 86.9°. Among these complexes, 2 exhibited a ligand-sensitized lanthanide-characteristic emission. Analyses of the alternating current susceptibility measurements reveal the presence of single-molecule magnet behavior for 1 and 4, in the presence of direct-current field, with effective energy barriers of 4.6 and 44.4 K, respectively. The enhancement of the effective energy barrier of the latter can be attributed to the presence of a large energy gap between the ground and first excited Kramers doublets, triggered by the change in coordination environments around the lanthanide centers.

  12. 19F-lanthanide complexes with increased sensitivity for 19F-MRI: optimization of the MR acquisition.

    PubMed

    Chalmers, Kirsten H; Kenwright, Alan M; Parker, David; Blamire, Andrew M

    2011-10-01

    Fluorine-19 magnetic resonance methods offer advantages for molecular or cellular imaging in vivo due to the absence of radioactivity, lack of naturally occurring background signal, and the ability to easily combine measurements with anatomical MRI. Previous studies have shown that (19) F-MRI sensitivity is limited to millimolar concentrations by slow longitudinal relaxation. In this study, a new class of macrocyclic fluorinated lanthanide complexes is investigated where relaxation rates are significantly shortened by proximity of the fluorine group to a paramagnetic lanthanide ion located within the same molecule. Longitudinal and transverse relaxation rates are field dependent and in the range 50-150 s(-1) and 70-200 s(-1), respectively, at 7 T. Relaxation rates in these complexes are a function of the molecular structure and are independent of concentration at biologically relevant levels, so can be used as criteria to optimize imaging acquisition. Phantom experiments at 7 T indicate a lower limit for detection by imaging of 20 μM.

  13. Lanthanide tetramethoxyborate complexes isolated from reductive amination of 2,6-diformyl-p-cresol

    SciTech Connect

    Matthews, K.D.; Kahwa, I.A. ); Johnson, M.P.; Mague, J.T.; McPherson, G.L. )

    1993-04-14

    Treatment of a hot methanolic solution of 2,6-diformyl-p-cresol (1 mmol), 3,6-dioxa-1,8-octanediamine (2 mmol), and a lanthanide(III) nitrate (1 mmol) with sodium cyanotrihydroborate (1.5 mmol) unexpectedly yields a mixture of isostructural but totally different compounds, [Ln(B(OCH[sub 3])[sub 4])(NO[sub 3])[sub 2](CH[sub 3]OH)[sub 2

  14. Synthesis, characterisation and biological evaluation of lanthanide(III) complexes with 3-acetylcoumarin-o-aminobenzoylhydrazone (ACAB).

    PubMed

    Gudasi, Kalagouda B; Shenoy, Rashmi V; Vadavi, Ramesh S; Patil, Manjula S; Patil, Siddappa A

    2005-09-01

    Lanthanide(III) complexes of the general formula [Ln(ACAB)(2)(NO(3))(2)(H(2)O)(2)].NO(3).H(2)O where Ln=La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III) and Y(III), ACAB=3-acetylcoumarin-o-aminobenzoylhydrazone have been isolated and characterised based on elemental analyses, molar conductance, IR, (1)H- and (13)C-NMR, UV, TG/DTA and EPR spectral studies. The ligand behaves in bidentate fashion coordinating through hydrazide >C=O and nitrogen of >C=N. A coordination number of ten is assigned to the complexes. Antibacterial and Antifungal studies indicate an enhancement of activity of the ligand on complexation.

  15. Chemistry of carbonyl sulfide. Final report, 1 July 1983-30 June 1984. [Lanthanide complexes of monothiocarbamates

    SciTech Connect

    Hinkley, C.C.; Dunkerton, L.V.; Tyrell, J.

    1984-01-01

    This report details research into the chemical properties ad structure of carbonyl sulfide, COS. Lanthanide complexes of monothiocarbamates have been prepared and investigations of displacement reactions begun. Diels-adler reactions of COS have been investigated as have COS ene reactions. Theoretical calculations of the structures of COS-metal complexes have been performed. These calculations indicate a preference for bonding by Ti and Fe to the oxygen end of COs forming a linear complex. In the case of nickel, bonding is to the C-S bond. In all cases the C-S bond is substantially lengthened, suggesting resultant elimination of sulfur. Additional calculations have been carried out on H/sub 4/Ti(COS), Ti(OCO), Ti(SCS), and Ti(H/sub 2/S), but only preliminary results are available on these systems. 10 references, 2 figures, 4 tables.

  16. Challenging lanthanide relaxation theory: erbium and thulium complexes that show NMR relaxation rates faster than dysprosium and terbium analogues.

    PubMed

    Funk, Alexander M; Harvey, Peter; Finney, Katie-Louise N A; Fox, Mark A; Kenwright, Alan M; Rogers, Nicola J; Senanayake, P Kanthi; Parker, David

    2015-07-07

    Measurements of the proton NMR paramagnetic relaxation rates for several series of isostructural lanthanide(III) complexes have been performed in aqueous solution over the field range 1.0 to 16.5 Tesla. The field dependence has been modeled using Bloch-Redfield-Wangsness theory, allowing values for the electronic relaxation time, Tle and the magnetic susceptibility, μeff, to be estimated. Anomalous relaxation rate profiles were obtained, notably for erbium and thulium complexes of low symmetry 8-coordinate aza-phosphinate complexes. Such behaviour challenges accepted theory and can be interpreted in terms of changes in Tle values that are a function of the transient ligand field induced by solvent collision and vary considerably between Ln(3+) ions, along with magnetic susceptibilities that deviate significantly from free-ion values.

  17. Metal-promoted synthesis, characterization, crystal structure and RNA cleavage ability of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes.

    PubMed

    Kozłowski, Michał; Kierzek, Ryszard; Kubicki, Maciej; Radecka-Paryzek, Wanda

    2013-09-01

    New 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes were formed in the metal-induced one-step [1+2] condensation reaction between 2,6-diacetylpyridine and 2-aminobenzoylhydrazide in the presence of lanthanide (La(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Ho(3+), Er(3+), Tm(3+) or Yb(3+)) nitrates as template agents. The analytical and spectral characterizations of all the compounds were correlated with the single crystal X-ray structural determination of Eu(3+), Gd(3+), Tb(3+), Dy(3+) and Er(3+) nitrate complexes. The Eu(3+), Gd(3+), Tb(3+)and Dy(3+) complexes of pentadentate 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) with the N3O2 set of donor atoms display a high and relatively rare coordination number of 11, whereas the Er(3+) ion complex is 9-coordinated, which is consistent with the lanthanide contraction phenomenon. The scission of 21-mer RNA was assessed for Eu(3+), Gd(3+) and Tb(3+) nitrate complexes. Lanthanide complexes not covalently attached to the oligonucleotide are able to cleave RNA at the target site in a sequence-selective or non-selective manner depending on the presence of protecting 12-mer 2'OMe RNA.

  18. Extraction study of lanthanide nitrato complexes - the adogen-464NO/sub 3/ - NH/sub 4/NO/sub 3/ system

    SciTech Connect

    Sokolowska, A.; Siekierski, S.

    1983-01-01

    Extraction of lanthanides and yttrium was studied in the interval of ammonium nitrate concentrations from 1 to 10M, and of Adogen-464 nitrate concentrations from 0.00039 to 0.39M. From the aqueous phase separation factor and from the published stability constant for europium (Eu), stability constants for 1:1 complexes of lanthanum (La), neodymium (Nd), gadolinium (Gd), holmium (Ho), thulium (Tm), lutetium (Lu) and yttrium (Y) have been determined, at 1M ammonium nitrate concentration. Results show that stability constant decreases from 2.7 for La to 2.3 for Lu. In the range of Adogen-464 nitrate concentrations employed, lanthanides from La to Nd appear in the organic phase as 1:5 complexes, whereas lanthanides heavier than Nd appear also as 1:4 complexes. Relative values (with regard to lanthanum) of Gibbs energy, enthalpy (from the temperture effect) and entropy for formation of 1:5 complexes, and the position of yttrium within lanthanides have been determined. Conclusions are that the extracted 1:4 and 1:5 complexes are of the inner sphere type, with nitrate ions acting as bidentate ligands, and that the contribution from covalency to bonding is the same in the aquo ion and in the 1:5 nitrato complex. 5 figures, 1 table.

  19. Mechanism of ionic recognition by polymer-supported reagents: immobilized tetramethylmalonamide and the complexation of lanthanide ions.

    PubMed

    Yang, Yijia; Alexandratos, Spiro D

    2010-02-01

    The mechanism of ionic recognition by polymer-supported reagents is probed with cross-linked polystyrene modified with tetramethylmalonamide (TMMA) ligands. The substrates are lanthanide ions in 0.001-8 M HCl and HNO(3) solutions. The results fall into three regions of acid concentration: low, mid, and high. In HCl, distribution coefficients are low in 0.001 to 2 M, increase in 4 and 6 M, and then decrease in 8 M HCl. In the low-acid region, the metal ion remains with its waters of hydration and does not coordinate to the carbonyl oxygens. As the acid concentration exceeds 2 M, protonation of the amide occurs to form an iminium moiety, electrostatically attracting the anionic lanthanide complex through ion-exchange and releasing waters of hydration. At high acid concentration, the apparent affinity decreases due to competition by the large excess of chloride ions for the ion-exchange sites. The affinity sequence in 6 M HCl is Tb > Dy > Eu > Gd > Ho > Sm > Er > Tm > Yb > Lu > Nd > Ce > La. The TMMA-Ln interaction is due to recognition since there is a point of maximum affinity across the series rather than a monotonic trend. The trends are comparable in HNO(3). A comparison of the distribution coefficients at the maxima (6 M HCl and 4 M HNO(3)) shows nitrate to have greater values than chloride due to a hydration effect, as also indicated by results from H(2)SO(4).

  20. Pentavalent lanthanide nitride-oxides: NPrO and NPrO(-) complexes with N≡Pr triple bonds.

    PubMed

    Hu, Shu-Xian; Jian, Jiwen; Su, Jing; Wu, Xuan; Li, Jun; Zhou, Mingfei

    2017-05-01

    The neutral molecule NPrO and its anion NPrO(-) are produced via co-condensation of laser-ablated praseodymium atoms with nitric oxide in a solid neon matrix. Combined infrared spectroscopy and state-of-the-art quantum chemical calculations confirm that both species are pentavalent praseodymium nitride-oxides with linear structures that contain Pr≡N triple bonds and Pr=O double bonds. Electronic structure studies show that the neutral NPrO molecule features a 4f(0) electron configuration and a Pr(v) oxidation state similar to that of the isoelectronic PrO2(+) ion, while its NPrO(-) anion possesses a 4f(1) electron configuration and a Pr(iv) oxidation state. The neutral NPrO molecule is thus a rare lanthanide nitride-oxide species with a Pr(v) oxidation state, which follows the recent identification of the first Pr(v) oxidation state in the PrO2(+) and PrO4 complexes (Angew. Chem. Int. Ed., 2016, 55, 6896). This finding indicates that lanthanide compounds with oxidation states of higher than +IV are richer in chemistry than previously recognized.

  1. Aqueous complexation of trivalent lanthanide and actinide cations by N,N,N'{sub 2},N'-tetrakis(2-pyridylmethyl)ethylenediamine.

    SciTech Connect

    Beitz, J. V.; Ensor, D. D.; Jensen, M. P.; Morss, L. R.

    1999-06-16

    The aqueous complexation reactions of trivalent lanthanide and actinide cations with the hexadentate ligand N,N,N{prime},N{prime}-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), have been characterized using potentiometric and spectroscopic techniques in 0.1 M NaClO{sub 4} At 25 C, the stability constant of Am(TPEN){sup 3+} is two orders of magnitude larger than that of Sm(TPEN){sup 3+}, reflecting the stronger interactions of the trivalent actinide cations with softer ligands as compared to lanthanide cations.

  2. NMR and IR spectrometric studies of monoamide complexes with plutonium(IV) and lanthanide(III) nitrates

    SciTech Connect

    Berthon, C.; Chachaty, C.

    1995-08-01

    Monoamide (E) extractants are potential candidates to replace the tri-n-butyl phosphate (TBP) used in the reprocessing of nuclear fuels. In the present study we essentially used NMR ({sup 13}C and {sup 1}H) spectroscopy to identify the kinds of structural parameters conditioning the selectivity and efficiency of monoamide extractants. Information on nitrate groups bonded to the metallic ions and to the carbonyl moiety of monoamides was obtained by IR spectroscopy. The monoamides complexed with lanthanide(III) and plutonium(IV) nitrates were studied in benzene solution. Before obtaining conformational information from {sup 13}C relaxation times about the complexes, we first had to know the stoichiometries, to assign NMR spectra to the monoamides, and to check the fast exchange conditions. 59 refs., 9 figs., 9 tabs.

  3. Complexation of trivalent americium and lanthanides with terdentate 'N' donor ligands: the role of rigidity in the ligand structure.

    PubMed

    Bhattacharyya, Arunasis; Gadly, Trilochan; Pathak, Priyanath; Ghosh, Sunil K; Mohapatra, Manoj; Ghanty, Tapan K; Mohapatra, Prasanta K

    2014-08-28

    A systematic study on the Ln(3+) complexation behaviour with two terdentate 'N' donor ligands of varying structural rigidity, viz. 5,6-dimethyl-(1,2,4)-triazinylbipyridine (Me2TBipy) and 5,6-dimethyl-(1,2,4)-triazinylphenanthroline (Me2TPhen), is performed in the present work by UV-Vis spectrophotometry, time resolved fluorescence spectroscopy (TRFS) and electrospray ionization mass spectrometric (ESI-MS) studies. These studies indicate the formation of a 1 : 1 complex of La(3+), 1 : 2 complexes of Eu(3+) and Er(3+) with both the ligands. Density functional theoretical (DFT) study is carried out to determine the solution phase structure of the Eu(3+) complex considering the species (from UV-Vis spectrophotometry) and C2v site symmetry around the Eu(3+) ion (from TRFS study). Me2TPhen is found to be a stronger complexing ligand as compared to Me2TBipy irrespective of the Ln(3+) ions. The solid state crystal structure of the La(3+) complex of Me2TPhen is determined using the single crystal X-ray diffraction (SCXRD) technique. The complexation of the trivalent Am(3+) ion is also studied with both these ligands using UV-Vis spectrophotometric titrations which show the formation of 1 : 2 complexes with higher complexation constant values as compared to all the Ln(3+) ions studied, indicating the selectivity of these ligands for the trivalent actinides over the lanthanides.

  4. {sup 31}P NMR study of the complexation of TBP with lanthanides and actinides in solution and in a clay matrix

    SciTech Connect

    Hartzell, C.J.

    1994-07-24

    Goal was to use NMR to study TBP/lanthanide complexes in the interlayer or on edge sites of clays. Work in this laboratory yielded details of the complexation of Eu(NO{sub 3}){sub 3} and Pr(NO{sub 3}){sub 3} with TBP in hexane solution; this information is crucial to interpretation of results of NMR studies of the complexes exchanged into clays. The solution {sup 31}P-chemical shift values were improved by repeating the studies on the lanthanide salts dissolved directly into neat TBP. NMR studies of these neat solutions of the Eu(NO{sub 3}){sub 3}{lg_bullet}3TBP-complex and the Pr(NO{sub 3}){sub 3}{lg_bullet}3TBP-complex show that the {sup 31}P chemical shift remains relatively constant for TBP: lanthanide ratios below 3: 1. At higher ratios, the chemical shift approaches that of free TBP, indicating rapid exchange of TBP between the free and complexed state. Exchange of these complexes into the clay hectorite yielded discrete {sup 31}P-NMR signals for the Eu{lg_bullet}TBP complex at -190 ppm and free TBP at -6 ppm. Adsorption of the Pr{lg_bullet}TBP complex yielded broad signals at 76 ppm for the complex and -6 ppm for free TBP. There was no evidence of exchange between the incorporated complex and the free TBP.

  5. Secret Lanthanides

    PubMed Central

    Sturza, CM

    2014-01-01

    Abstract Lanthanides are a group of 15 chemical elements which, together with their salts, have come to be used in the last decade as homoeopathic remedies. The effective introduction of lanthanides and their salts into the clinical use, as homoeopathic remedies was based on the idea of Jan Scholten, MD to relate their physicochemical properties shown in the periodic table of elements to their homoeopathic potential. The lanthanides and their salts were prepared as homoeopathic remedies by Pharmacist Robert Münz. PMID:25408760

  6. Transition Metal and Lanthanide Compounds.

    DTIC Science & Technology

    hexamethylbenzene niobium and tantalum derivatives; and lanthanide nitrate complexes of certain macrocyclic polyethers and the use of macrocyclic polyether columns for lanthanide separations....New research results in the following areas are briefly described: The synthesis of polyphosphines and their metal complexes including polyphosphines...with terminal methyl and neopentyl groups; reactions of polypyrazolylborates with the metal complexes C5H5Co(CO)(R(f)I(R(f)= perfluoroalkyl group

  7. Preparation of new fluorophore lanthanide complexes-Cloisite nanohybrids using the tricationic Pr(III), Gd(III) and Dy(III) complexes with 9,10-phenanthrenequinone.

    PubMed

    Mallakpour, Shadpour; Behnamfar, Mohammad Taghi; Dinari, Mohammad; Hadadzadeh, Hassan

    2015-02-25

    New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite.

  8. BtpB, a novel Brucella TIR-containing effector protein with immune modulatory functions.

    PubMed

    Salcedo, Suzana P; Marchesini, María I; Degos, Clara; Terwagne, Matthieu; Von Bargen, Kristine; Lepidi, Hubert; Herrmann, Claudia K; Santos Lacerda, Thais L; Imbert, Paul R C; Pierre, Philippe; Alexopoulou, Lena; Letesson, Jean-Jacques; Comerci, Diego J; Gorvel, Jean-Pierre

    2013-01-01

    Several bacterial pathogens have TIR domain-containing proteins that contribute to their pathogenesis. We identified a second TIR-containing protein in Brucella spp. that we have designated BtpB. We show it is a potent inhibitor of TLR signaling, probably via MyD88. BtpB is a novel Brucella effector that is translocated into host cells and interferes with activation of dendritic cells. In vivo mouse studies revealed that BtpB is contributing to virulence and control of local inflammatory responses with relevance in the establishment of chronic brucellosis. Together, our results show that BtpB is a novel Brucella effector that plays a major role in the modulation of host innate immune response during infection.

  9. Synthesis, crystal structures, magnetic and luminescent properties of unique 1D p-ferrocenylbenzoate-bridged lanthanide complexes

    SciTech Connect

    Yan, P.F.; Zhang, F.M.; Li, G.M.; Zhang, J.W.; Sun, W.B.; Suda, M.; Einaga, Y.

    2009-07-15

    Treatments of p-ferrocenylbenzoate [p-NaOOCH{sub 4}C{sub 6}Fc, Fc=(eta{sup 5}-C{sub 5}H{sub 5})Fe(eta{sup 5}-C{sub 5}H{sub 4})] with Ln(NO{sub 3}){sub 3}.nH{sub 2}O afford seven p-ferrocenylbenzoate lanthanide complexes {l_brace}[Ln(OOCH{sub 4}C{sub 6}Fc){sub 2}(mu{sub 2}-OOCH{sub 4}C{sub 6}Fc){sub 2}(H{sub 2}O){sub 2}](H{sub 3}O){r_brace}{sub n} [Ln=Ce (1), Pr (2), Sm (3), Eu (4), Gd (5), Tb (6) and Dy (7)]. X-ray crystallographic analysis reveals that the isomorphous complexes {l_brace}[Ce(OOCH{sub 4}C{sub 6}Fc){sub 2}(mu{sub 2}-OOCH{sub 4}C{sub 6}Fc){sub 2}(H{sub 2}O){sub 2}](H{sub 3}O){r_brace}{sub n} (1) and {l_brace}[Pr(OOCH{sub 4}C{sub 6}Fc){sub 2}(mu{sub 2}-OOCH{sub 4}C{sub 6}Fc){sub 2}(H{sub 2}O){sub 2}](H{sub 3}O){r_brace}{sub n} (2) form a unique 1D double-bridged infinite chain structure bridged by mu{sub 2}-OOCH{sub 4}C{sub 6}Fc groups. Each Ln(III) ion adopts a dodecahedron coordination environment with eight coordinated oxygen atoms from two terminal monodentate coordinated FcC{sub 6}H{sub 4}COO{sup -} units, two terminal monodentate coordinated H{sub 2}O molecules and four mu{sub 2}-{sup -}OOCH{sub 4}C{sub 6}Fc units. The luminescent spectra reveal that only 4 and 6 exhibit characteristic emissions of lanthanide ions, Eu(III) and Tb(III) ions, respectively. The variable-temperature magnetic properties of 5 and 7 suggest that a ferromagnetic coupling between spin carriers may exist in 5. - Graphical abstract: Seven p-ferrocenylbenzoate lanthanide coordination polymers were synthesized. Given is the perspective view of a unique 1D double-bridged infinite chain structure of 1, excitation and emission spectra of 6 and plots of chi{sub m}T vs. T and chi{sub m}{sup -1} vs. T of 5.

  10. Lanthanide complexes of the chiral hexaaza macrocycle and its meso-type isomer: solvent-controlled helicity inversion.

    PubMed

    Gregoliński, Janusz; Slepokura, Katarzyna; Lisowski, Jerzy

    2007-09-17

    Lanthanide(III) complexes of the enantiopure chiral hexaaza tetraamine macrocycle L, 2(R),7(R),18(R),23(R)-1,8,15,17,24,31-hexaazatricyclo[25.3.1.1.0.0]-dotriaconta-10,12,14,26,28,30-hexaene, as well as of its meso-type 2(R),7(R),18(S),23(S)-isomeric macrocycle L1, have been synthesized and characterized by spectroscopic methods. The 2D NMR spectra confirm the identity of these complexes and indicate C2 symmetry of the [LnL]3+ and Cs symmetry of the [LnL1]3+ complexes. The crystal structures of the [PrL(NO3)(H2O)2](NO3)2, [EuL(NO3)(H2O)2](NO3)2, [DyL(NO3)2]2[Dy(NO3)5] x 5CH3CN, [YbL(NO3)2]2[Yb(NO3)5] x 5CH3CN, [YbL(H2O)2](NO3)3 x H2O, and [EuL1(NO3)(H2O)2]0.52[EuL1(NO3)2]0.48(NO3)1.52 x 0.48H2O complexes have been determined by single-crystal X-ray diffraction. In all complexes, the lanthanide(III) ions are coordinated by six nitrogen atoms of the macrocycle L or L1, but for each type of complex, the conformation of the macrocycle and the axial ligation are different. The crystallographic, NMR, and CD data show that the [YbL]3+ complex exists in two stable forms. Both forms of the Yb(III) complex have been isolated, and their interconversion was studied in various solvents. The two forms of [YbL]3+ complex correspond to two diastereomers of ligand L, which differ in the sense of the helical twist and the configuration at the stereogenic amine nitrogen atoms. In one of the stereoisomers, the macrocycle L of (RRRR) configuration at the stereogenic cyclohexane carbon atoms adopts the (RSRS) configuration at the amine nitrogen atoms, while in the other stereoisomer, the macrocycle L of (RRRR) configuration at the stereogenic cyclohexane carbon atoms adopts the (SSSS) configuration at the amine nitrogen atoms. The (RRRR)(RSRS) isomer is quantitatively converting to the (RRRR)(SSSS) isomer in water solution, while the reverse process is observed for an acetonitrile solution, thus representing the rare case of helicity inversion controlled by the solvent.

  11. Synthesis, crystal structures, magnetic and luminescent properties of unique 1D p-ferrocenylbenzoate-bridged lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Yan, P. F.; Zhang, F. M.; Li, G. M.; Zhang, J. W.; Sun, W. B.; Suda, M.; Einaga, Y.

    2009-07-01

    Treatments of p-ferrocenylbenzoate [ p-NaOOCH 4C 6Fc, Fc=( η5-C 5H 5)Fe( η5-C 5H 4)] with Ln(NO 3) 3· nH 2O afford seven p-ferrocenylbenzoate lanthanide complexes {[ Ln(OOCH 4C 6Fc) 2( μ2-OOCH 4C 6Fc) 2(H 2O) 2](H 3O)} n [ Ln=Ce ( 1), Pr ( 2), Sm ( 3), Eu ( 4), Gd ( 5), Tb ( 6) and Dy ( 7)]. X-ray crystallographic analysis reveals that the isomorphous complexes {[Ce(OOCH 4C 6Fc) 2( μ2-OOCH 4C 6Fc) 2(H 2O) 2](H 3O)} n ( 1) and {[Pr(OOCH 4C 6Fc) 2( μ2-OOCH 4C 6Fc) 2(H 2O) 2](H 3O)} n ( 2) form a unique 1D double-bridged infinite chain structure bridged by μ2-OOCH 4C 6Fc groups. Each Ln(III) ion adopts a dodecahedron coordination environment with eight coordinated oxygen atoms from two terminal monodentate coordinated FcC 6H 4COO - units, two terminal monodentate coordinated H 2O molecules and four μ2- -OOCH 4C 6Fc units. The luminescent spectra reveal that only 4 and 6 exhibit characteristic emissions of lanthanide ions, Eu(III) and Tb(III) ions, respectively. The variable-temperature magnetic properties of 5 and 7 suggest that a ferromagnetic coupling between spin carriers may exist in 5.

  12. Lanthanide(III) and Yttrium(III) Complexes of Benzimidazole-2-Acetic Acid: Synthesis, Characterisation and Effect of La(III) Complex on Germination of Wheat

    PubMed Central

    Gudasi, Kalagouda B.; Shenoy, Rashmi V.; Vadavi, Ramesh S.; Patil, Manjula S.; Patil, Siddappa A.; Hanchinal, Rayappa R.; Desai, Srinivas A.; Lohithaswa, H.

    2006-01-01

    The synthesis and characterisation of lanthanide(III) and yttrium(III) nitrate complexes of benzimidazole-2-acetic acid (HBIA) are reported. The complexes have been characterised by elemental analysis, molar conductance, magnetic studies, IR, 1H NMR, UV-visible, EPR, and TG/DTA studies. They have the stoichiometry [Ln3(BIA)2(NO3)7(H2O)4] · 3H2O where Ln=La(III), Pr(III), Nd(II), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), and Y(III). The effect of La(III) complex on germination, coleoptile, and root length of two local varieties of wheat DWR-195 and GW-349 for different treatment periods has been investigated. The complex was found to exhibit enhanced activity, compared to HBIA or metal salt alone at lower treatment periods. PMID:17497017

  13. Simultaneous characterization of extraction equilibria and back-extraction kinetics. Use of Arsenazo III to characterize lanthanide-bis(2,4,4-trimethylpentyl)phosphinic acid complexes in surfactant micelles

    SciTech Connect

    Inaba, K.; Muralidharan, S.; Freiser, H. )

    1993-06-01

    A novel metallochromic indicator method that simultaneously yields kinetic and extraction equilibrium information for metals has been developed. The use of arsenazo III to monitor the kinetics of dissociation of lanthanide-bis(2,4,4-trimethylpentyl)phosphinic acid (HBTMPP) complexes in polyethylene glycol tert-octylphenyl ether (Triton X-100) micelles is described as an example. The distribution and the dimerization constants of HBTMPP in these micelles resemble its values in the CHCl[sub 3]-H[sub 2]O system but the extraction equilibrium constants of the lanthanides, K[sub ex], are 4-6 orders of magnitude larger than the values in CHCl[sub 3]-H[sub 2]O. Two series of lanthanide-HBTMPP dimer complexes having ratios of 1:2.5 and 1:3 are extracted into the micelles, and for both series, the K[sub ex] values for the heavy lanthanides are higher than for the light lanthanides. The rate-limiting step in the dissociation of these complexes is their attack by H[sup +] and appears to proceed exclusively in the micellar phase under the conditions employed. The rate constants for the dissociation reaction are larger for the lighter lanthanides than those of heavier lanthanides. For a given metal, the 1:2.5 metal-dimer complex dissociates more readily than the 1:3 dimer complex. 17 refs., 5 figs., 2 tabs.

  14. Complexation studies with lanthanides and humic acid analyzed by ultrafiltration and capillary electrophoresis-inductively coupled plasma mass spectrometry.

    PubMed

    Kautenburger, Ralf; Beck, Horst Philipp

    2007-08-03

    For the long-term storage of radioactive waste, detailed information about geo-chemical behavior of radioactive and toxic metal ions under environmental conditions is necessary. Humic acid (HA) can play an important role in the immobilisation or mobilisation of metal ions due to complexation and colloid formation. Therefore, we investigate the complexation behavior of HA and its influence on the migration or retardation of selected lanthanides (europium and gadolinium as homologues of the actinides americium and curium). Two independent speciation techniques, ultrafiltration and capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS) have been compared for the study of Eu and Gd interaction with (purified Aldrich) HA. The degree of complexation of Eu and Gd in 25 mg l(-1) Aldrich HA solutions was determined with a broad range of metal loading (Eu and Gd total concentration between 10(-6) and 10(-4) mol l(-1)), ionic strength of 10 mM (NaClO4) and different pH-values. From the CE-ICP-MS electropherograms, additional information on the charge of the Eu species was obtained by the use of 1-bromopropane as neutral marker. To detect HA in the ICP-MS and separate between HA complexed and non complexed metal ions in the CE-ICP-MS, we have halogenated the HA with iodine as ICP-MS marker.

  15. Remarkably high asymmetric amplification in the chiral lanthanide complex-catalyzed hetero-Diels-Alder reaction: first example of the nonlinear effect in ML3 system

    PubMed

    Furuno; Hanamoto; Sugimoto; Inanaga

    2000-01-01

    [reaction: see text] A remarkably high asymmetric amplification was realized in the Yb[(R)-BNP]3-catalyzed hetero-Diels-Alder reaction as the first example in the metal/chiral ligand 1:3 system. The mechanism may be explained by the autogenetic formation of the enantiopure complex as the most active catalyst. The enantiomer-discriminative formation of homochiral ML3 complexes is quite general within the lanthanide metal ions with similar ionic radii to that of the ytterbium ion.

  16. Synthesis, crystal structure, and luminescent properties of 2-(2,2,2-trifluoroethyl)-1-indone lanthanide complexes.

    PubMed

    Li, Jingya; Li, Hongfeng; Yan, Pengfei; Chen, Peng; Hou, Guangfeng; Li, Guangming

    2012-05-07

    A new β-diketone, 2-(2,2,2-trifluoroethyl)-1-indone (TFI), which contains a trifluorinated alkyl group and a rigid indone group, has been designed and employed for the synthesis of two series of new TFI lanthanide complexes with a general formula [Ln(TFI)(3)L] [Ln = Eu, L = (H(2)O)(2) (1), bpy (2), and phen (3); Ln = Sm, L = (H(2)O)(2) (4), bpy (5), and phen (6); bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline]. X-ray crystallographic analysis reveals that complexes 1-6 are mononuclear, with the central Ln(3+) ion eight-coordinated by six oxygen atoms furnished by three TFI ligands and two O/N atoms from ancillary ligand(s). The room-temperature photoluminescence (PL) spectra of complexes 1-6 show strong characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions, and the substitution of the solvent molecules by bidentate nitrogen ligands essentially enhances the luminescence quantum yields and lifetimes of the complexes.

  17. Affinity Capillary Electrophoresis for Selective Control of Electrophoretic Mobility of Sialic Acid Using Lanthanide-Hexadentate Macrocyclic Polyazacarboxylate Complexes.

    PubMed

    Goto, Daiki; Ouchi, Kazuki; Shibukawa, Masami; Saito, Shingo

    2015-01-01

    It is difficult to control the electrophoretic mobility in order to obtain high resolution among saccharides in complex samples. We report herein on a new affinity capillary electrophoresis (ACE) method for an anionic monosaccharide, N-acetylneuraminic acid (Neu5Ac), which is important in terms of pathological diagnosis, using lanthanide-hexadentate macrocyclic polyazacarboxylate complexes (Ln-NOTA) as affinity reagents. It was shown that Ln-NOTA complexes increased the anionic mobility of Neu5Ac by approximately 40% through selective complexation with Neu5Ac. The extent of change in the mobility strongly depended on the type of central metal ion of Ln-NOTA. The stability constant (K) of Lu-NOTA with Neu5Ac was determined by ACE to be log Kb = 3.62 ± 0.04, which is the highest value among artificial receptors for Neu5Ac reported so far. Using this ACE, the Neu5Ac content in a glycoprotein sample, α1-acid glycoprotein (AGP), was determined after acid hydrolysis. Complete separation between Neu5Ac and hydrolysis products was successful by controlling the mobility to determine the concentration of Neu5Ac.

  18. Lanthanide(III) di- and tetra-nuclear complexes supported by a chelating tripodal tris(amidate) ligand

    DOE PAGES

    Brown, Jessie L.; Jones, Matthew B.; Gaunt, Andrew J.; ...

    2015-04-06

    Syntheses, structural, and spectroscopic characterization of multinuclear tris(amidate) lanthanide complexes is described. Addition of K3[N(o-PhNC(O)tBu)3] to LnX3 (LnX3 = LaBr3, CeI3, and NdCl3) in N,N-dimethylformamide (DMF) results in the generation of dinuclear complexes, [Ln(N(o-PhNC(O)tBu)3)(DMF)]2(μ-DMF) (Ln = La (1), Ce (2), Nd(3)), in good yields. Syntheses of tetranuclear complexes, [Ln(N(o-PhNC(O)tBu)3)]4 (Ln = Ce (4), Nd(5)), resulted from protonolysis of Ln[N(SiMe3)2]3 (Ln = Ce, Nd) with N(o-PhNCH(O)tBu)3. As a result, in the solid-state, complexes 1–5 exhibit coordination modes of the tripodal tris(amidate) ligand that are unique to the 4f elements and have not been previously observed in transition metal systems.

  19. Lanthanide(III) di- and tetra-nuclear complexes supported by a chelating tripodal tris(amidate) ligand

    SciTech Connect

    Brown, Jessie L.; Jones, Matthew B.; Gaunt, Andrew J.; Scott, Brian L.; MacBeth, Cora E.; Gordon, John C.

    2015-04-06

    Syntheses, structural, and spectroscopic characterization of multinuclear tris(amidate) lanthanide complexes is described. Addition of K3[N(o-PhNC(O)tBu)3] to LnX3 (LnX3 = LaBr3, CeI3, and NdCl3) in N,N-dimethylformamide (DMF) results in the generation of dinuclear complexes, [Ln(N(o-PhNC(O)tBu)3)(DMF)]2(μ-DMF) (Ln = La (1), Ce (2), Nd(3)), in good yields. Syntheses of tetranuclear complexes, [Ln(N(o-PhNC(O)tBu)3)]4 (Ln = Ce (4), Nd(5)), resulted from protonolysis of Ln[N(SiMe3)2]3 (Ln = Ce, Nd) with N(o-PhNCH(O)tBu)3. As a result, in the solid-state, complexes 1–5 exhibit coordination modes of the tripodal tris(amidate) ligand that are unique to the 4f elements and have not been previously observed in transition metal systems.

  20. Lanthanide amido complexes incorporating amino-coordinate-lithium bridged bis(indolyl) ligands: synthesis, characterization, and catalysis for hydrophosphonylation of aldehydes and aldimines.

    PubMed

    Zhu, Xiancui; Wang, Shaowu; Zhou, Shuangliu; Wei, Yun; Zhang, Lijun; Wang, Fenhua; Feng, Zhijun; Guo, Liping; Mu, Xiaolong

    2012-07-02

    Two series of new lanthanide amido complexes supported by bis(indolyl) ligands with amino-coordinate-lithium as a bridge were synthesized and characterized. The interactions of [(Me(3)Si)(2)N](3)Ln(III)(μ-Cl)Li(THF)(3) with 2 equiv of 3-(CyNHCH(2))C(8)H(5)NH in toluene produced the amino-coordinate-lithium bridged bis(indolyl) lanthanide amides [μ-{[η(1):η(1):η(1):η(1)-3-(CyNHCH(2))Ind](2)Li}Ln[N(SiMe(3))(2)](2)] (Cy = cyclohexyl, Ind = Indolyl, Ln = Sm (1), Eu (2), Dy (3), Yb (4)) in good yields. Treatment of [μ-{[η(1):η(1):η(1):η(1)-3-(CyNHCH(2))Ind](2)Li}Ln[N(SiMe(3))(2)](2)] with THF gave new lanthanide amido complexes [μ-{[η(1):η(1)-3-(CyNHCH(2))Ind](2)Li(THF)}Ln[N(SiMe(3))(2)](2)] (Ln = Eu (5), Dy (6), Yb (7)), which can be transferred to amido complexes 2, 3, and 4 by reflux the corresponding complexes in toluene. Thus, two series of rare-earth-metal amides could be reciprocally transformed easily by merely changing the solvent in the reactions. All new complexes 1-7 are fully characterized including X-ray structural determination. The catalytic activities of these new lanthanide amido complexes for hydrophosphonylation of both aromatic and aliphatic aldehydes and various substituted aldimines were explored. The results indicated that these complexes displayed a high catalytic activity for the C-P bond formation with employment of low catalyst loadings (0.1 mol % for aldehydes and 1 mol % for aldimines) under mild conditions. Thus, it provides a convenient way to prepare both α-hydroxy and α-amino phosphonates.

  1. Synthesis and luminescent properties of novel lanthanide(III) beta-diketone complexes with nitrogen p,p'-disubstituted aromatic ligands.

    PubMed

    Bellusci, Anna; Barberio, Giovanna; Crispini, Alessandra; Ghedini, Mauro; La Deda, Massimo; Pucci, Daniela

    2005-03-21

    Tris-beta-diketonate lanthanide(III) complexes (Ln = Eu, Er, Yb, Tb), of general formula [Ln(acac)3 L(m)], with chelating ligands such as 4,7-disubstituted-1,10-phenanthrolines and 4,4'-disubstituted-2,2'-bipyridines, have been synthesized and fully characterized. The inductive effects of the para-substituents on the aromatic N-donor ligands have been investigated both in the solid and in the solution states. Single-crystal X-ray structures have been determined for the diethyl 1,10-phenanthroline-4,7-dicarboxylate europium and 4,4'-dimethoxy-2,2'-bipyridine erbium derivatives, revealing a distorted square antiprismatic geometry around the lanthanide atom in both cases. The influence exerted by the p,p'-substituents with respect to the nitrogen coordinating atoms on the Ln-N bond distances is discussed comparing the geometrical parameters with those found for the crystal structures containing the fragments [Ln(III)(phen)] and [Ln(III)(bipy)] obtained from the Cambridge Structural Database. The influence exerted by the electron-attracting groups on the coordination ability of the ligands, that in some cases becomes lack of coordination of the lanthanide ions, has been also detected in solution where the loss of the ligand has been followed by UV-vis spectroscopy. Moreover, the use of relatively long alkoxy chains as substituents on the 1,10-phenanthroline ligand led to the formation of a promesogenic lanthanide complex, whose thermal behavior is encouraging for the synthesis of new lanthanide liquid-crystalline species.

  2. Photofragmentation of Gas-Phase Lanthanide Cyclopentadienyl Complexes: Experimental and Time-Dependent Excited-State Molecular Dynamics

    PubMed Central

    2015-01-01

    Unimolecular gas-phase laser-photodissociation reaction mechanisms of open-shell lanthanide cyclopentadienyl complexes, Ln(Cp)3 and Ln(TMCp)3, are analyzed from experimental and computational perspectives. The most probable pathways for the photoreactions are inferred from photoionization time-of-flight mass spectrometry (PI-TOF-MS), which provides the sequence of reaction intermediates and the distribution of final products. Time-dependent excited-state molecular dynamics (TDESMD) calculations provide insight into the electronic mechanisms for the individual steps of the laser-driven photoreactions for Ln(Cp)3. Computational analysis correctly predicts several key reaction products as well as the observed branching between two reaction pathways: (1) ligand ejection and (2) ligand cracking. Simulations support our previous assertion that both reaction pathways are initiated via a ligand-to-metal charge-transfer (LMCT) process. For the more complex chemistry of the tetramethylcyclopentadienyl complexes Ln(TMCp)3, TMESMD is less tractable, but computational geometry optimization reveals the structures of intermediates deduced from PI-TOF-MS, including several classic “tuck-in” structures and products of Cp ring expansion. The results have important implications for metal–organic catalysis and laser-assisted metal–organic chemical vapor deposition (LCVD) of insulators with high dielectric constants. PMID:24910492

  3. Responsive luminescent lanthanide complexes for sensing pH, pO2, and hydrogencarbonate in competitive aqueous media

    NASA Astrophysics Data System (ADS)

    Gunnlaugsson, Thorri; Parker, David; Williams, J. A. G.

    1999-05-01

    A series of chiral macrocyclic lanthanide complexes has been devised whose metal-based luminescence (Eu, Tb or Yb) is a function of a defined variable or set of variables. Complexes have been devised in which the lifetime or intensity of emission is a sensitive function of pH, pO2, or halide ion concentration. The pH dependent systems report either the excited state singlet pKa (Eu) or the triplet pKa of an integral phenanthridinium chromophore, with luminescence enhancements of over 500. The halide and oxygen dependent systems operate differently via a quenching of the intermediate excited aryl singlet and triplet states respectively. In addition, complexes have been devised in which reversible binding of hydrogencarbonate displaces two bound water molecules, leading to an enhancement of the metal- based emission intensity (Eu, (Delta) J equals 2) or lifetime. At the same time, pronounced changes in the polarization of emission occur, signalling changes in the helicity at the metal center. Hydrogencarbonate chelates preferentially in the concentration range 20 to 40 mM in the presence of phosphate, lactate, citrate and halide at physiological levels.

  4. Solution and Structural Investigations of Ligand Preorganization in Trivalent Lanthanide Complexes of Bicyclic Malonamides

    SciTech Connect

    Parks, Bevin W.; Gilbertson, Robert D.; Hutchison, J. E.; Rather Healey, Elisabeth; Weakley, Timothy J R; Rapko, Brian M.; Hay, Benjamin P.; Sinkov, Sergei I.; Broker, Grant A.; Rogers, Robin D.

    2006-02-20

    This report describes an investigation into the coordination chemistry of trivalentlanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution bindingaffinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-raycrystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogousacyclic malonamide. Results from the spectrophotometric titrations indicate that BMA exhibits a 10-100 times increase in binding affinity to Ln(III) over acyclic malonamide.In addition, BMA forms compounds with high ligand-metal ratios, even when competing with water and nitrate ligands for binding sites. The crystal structures exhibit nosignificant differences in the nature of the binding between Ln(III) and the BMA or acyclic malonamide. These results support the conclusion that rational ligand design canlead to compounds that enhance the binding affinities within a ligand class.

  5. Addition of a second lanthanide ion to increase the luminescence of europium(III) macrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Bromm, Alfred J., Jr.; Leif, Robert C.; Quagliano, John R.; Vallarino, Lidia M.

    1999-06-01

    At present, the microscopic visualization of luminescent labels containing lanthanide(III) ions, primarily europium(III), as light-emitting centers is best performed with time-gated instrumentation, which by virtually eliminating the background fluorescence results in an improved signal to noise ratio. However, the use of the europium(III) macrocycle, Quantum DyeTM, in conjunction with the strong luminescence enhancing effect (cofluorescence) of yttrium(III) or gadolinium(III), can eliminate the need for such specialized instrumentation. In the presence of Gd(III), the luminescence of the Eu-macrocycles can be conveniently observed with conventional fluorescence instrumentation at previously unattainable low levels. The Eu(III) 5DO yields 7F2 emission of the Eu-macrocycles was observed as an extremely sharp band with a maximum at 619 nm and a clearly resolved characteristic pattern. At very low Eu- macrocycle concentrations, another sharp emission was detected at 614 nm, arising from traces of Eu(III) present in even the purest commercially available gadolinium products. Discrimination of the resolved emissions of the Eu-macrocycle and Eu(III) contaminant should provide a means to further lower the limit of detection of the Eu-macrocycle.

  6. Nonaqueous method for dissolving lanthanide and actinide metals

    DOEpatents

    Crisler, L.R.

    1975-11-11

    Lanthanide and actinide beta-diketonate complex molecular compounds are produced by reacting a beta-diketone compound with a lanthanide or actinide element in the elemental metallic state in a mixture of carbon tetrachloride and methanol.

  7. Crystal structures, luminescent properties and thermal decomposition kinetics of lanthanide complexes with 2-chloro-4-fluorobenzoic acid and 2,2'-bipyridine

    NASA Astrophysics Data System (ADS)

    Sun, Shu-Jing; Zhang, Da-Hai; Zhang, Jian-Jun; Ye, Hong-Mei; Wang, Shu-Ping; Wu, Ke-Zhong

    2010-08-01

    A new family of lanthanide with the general formula [Ln(2-Cl-4-FBA) 3bipy] 2 (Ln = Nd( 1), Sm( 2), Eu( 3), and Ho( 4); 2-Cl-4-FBA = 2-chloro-4-fluorobenzoate; bipy = 2,2'-bipyridine) were synthesized and characterized by elemental analysis, molar conductance, and infrared, ultraviolet and luminescent spectroscopy, single-crystal X-ray diffraction, thermogravimetry and different thermogravimetry (TG-DTG) techniques. These compounds are iso-structural and the lanthanide ions are all nine coordinated via two bidentate chelating, two bidentate bridging and two bidentate chelating-bridging modes. Under excitation, the europium complex exhibited characteristic red fluorescence of Eu 3+ ion at room temperature. The non-isothermal kinetics was investigated by using NL-INT and Popescu methods. The mechanism functions of the first decomposition step of the title complexes were determined. Meanwhile, the thermodynamic parameters (Δ G ≠, Δ H ≠ and Δ S ≠) were also calculated.

  8. Luminescence and Electronic Spectral Studies of Some Synthesized Lanthanide Complexes Using Benzoic Acid Derivative and o-Phenanthroline.

    PubMed

    Wankar, Sneha; Limaye, S N

    2015-07-01

    Lanthanide complexes of p-nitrobenzoic acid(p-NBA) and o-phenanthroline(o-phen) namely [Ln2(Phen)2(p-NBA)3(NO3)2].2H2O where, Ln = Sm(III),Tb(III),Dy(III) and [Eu2(Phen)2(p-NBA)3].4H2O were synthesized and further characterized by Elemental analysis, UV spectroscopy, IR spectroscopy, (1)HNMR spectroscopy. Luminescence measurements were performed on all compounds in ethanolic solution. These complexes have showed narrow emission indicating that the organic ligands are better energy absorber and capable of transferring energy to the Ln (III) ion. Furthermore, we reported electronic spectral studies on [Eu2 (Phen)2 (p-NBA)3].4H2O in order to calculate following parameters, viz: Oscillator strength (f), Judd-Ofelt parameters Ωλ (λ = 2,4,6) and Radiative parameters. [Eu2 (o-Phen)2 (p-NBA)3].4H2O showed the strongest emission at 613 nm corresponds to (5)D0→(7)F2 hypersensitive transition, this emission is very sensitive to the environment. However, the larger value of Ω2 supports the presence of the hypersensitive transition (5)D0→(7)F2 which strictly depends on the nature of ligand. All electronic spectral parameters were calculated systemically.

  9. Synthesis and luminescent properties of the novel poly(ethylene-co-acrylic acid) films based on surface modification with lanthanide (Eu3+, Tb3+) complexes

    NASA Astrophysics Data System (ADS)

    Wu, Yuewen; Chu, Yang; Yu, Zhenjiang; Hao, Haixia; Wu, Qingyao; Xie, Hongde

    2017-10-01

    Two kinds of novel fluorescent films have been successfully synthesized by surface modification on the poly(ethylene-co-acrylic acid) films using the lanthanide (Eu3+, Tb3+) complexes. The process consists of three steps: conversion of carboxylic acid groups on the surface of the poly(ethylene-co-acrylic acid) films to acid chloride groups, synthesis of the lanthanide complexes bearing amino groups, and amidation to form the modified films. To characterize the modified films, Fourier transform infrared, thermogravimetric analysis, static water contact angle measurements and photoluminescence tests have been employed. Fourier transform infrared verifies the successful preparation of the lanthanide complexes and the modified poly(ethylene-co-acrylic acid) films. These films can emit strong characteristic red and green light under UV light excitation. In addition, the films both have short lifetime (1.14 ms and 1.21 ms), high thermal stability (Td = 408 °C and 411 °C) and, compared with unmodified ones, increased hydrophilicity. All these results suggest that the modified films have potential application as luminescent materials under high temperature.

  10. Novel polycarboxylated EDTA-type cyclodextrins as ligands for lanthanide binding: study of their luminescence, relaxivity properties of Gd(iii) complexes, and PM3 theoretical calculations.

    PubMed

    Maffeo, Davide; Lampropoulou, Maria; Fardis, Michael; Lazarou, Yannis G; Mavridis, Irene M; Mavridou, Despoina A I; Urso, Elena; Pratsinis, Harris; Kletsas, Dimitris; Yannakopoulou, Konstantina

    2010-04-21

    Novel -type cyclodextrin (CD) derivatives, , and , bearing 6, 7 and 8 bis(carboxymethyl)amino (iminodiacetic acid) groups, respectively, were prepared, and their complexation with Eu(iii), Tb(iii) and Gd(iii) ions was studied. Luminescence titrations and mass spectrometry showed formation of multimetal complexes ( 2 to 3, mainly 3 and exactly 4 metal ions), whereas luminescence lifetime measurements revealed the presence of exchangeable water molecules. Semiempirical quantum mechanical calculations, performed by the PM3 method and assessed by DFT calculations on model ligands, indicated efficient multi-metal complexation, in agreement with the experiment. The structures showed coordination of the metal ions in the outer primary side of the CDs via 4 carboxylate O atoms, 2 N atoms and a glucopyranose O atom per metal ion. Coordination of water molecules was also predicted, in accordance with experimental results. Calculated bond lengths and angles were in agreement with literature experimental values of lanthanide complexes. Calculated energies showed that complex stability decreases in the order > > . (1)H NMR molecular relaxivity measurements for the Gd(iii) complexes of , or in water afforded values 4 to 10 times higher than the relaxivity of a commercial contrast agent at 12 MHz, and 6 to 20 times higher at 100 MHz. Solutions of and Gd(iii) complexes in human blood plasma displayed relaxivity values at 100 MHz 7 and 12 times, respectively, higher than the commercial agent. MTT tests of the Gd(iii) complexes using human skin fibroblasts did not show toxicity. Attempts to supramolecularly sensitize the luminescence of the lanthanide complexes using various aromatic CD guests were ineffective, evidently due to large guest-metal distances and inefficient inclusion. The described lanthanide complexes, could be useful as contrast agents in MRI.

  11. Rationalization of Anomalous Pseudocontact Shifts and Their Solvent Dependence in a Series of C3-Symmetric Lanthanide Complexes.

    PubMed

    Vonci, Michele; Mason, Kevin; Suturina, Elizaveta A; Frawley, Andrew T; Worswick, Steven G; Kuprov, Ilya; Parker, David; McInnes, Eric J L; Chilton, Nicholas F

    2017-09-27

    Bleaney's long-standing theory of magnetic anisotropy has been employed with some success for many decades to explain paramagnetic NMR pseudocontact shifts, and has been the subject of many subsequent approximations. Here, we present a detailed experimental and theoretical investigation accounting for the anomalous solvent dependence of NMR shifts for a series of lanthanide(III) complexes, namely [LnL(1)] (Ln = Eu, Tb, Dy, Ho, Er, Tm, and Yb; L(1): 1,4,7-tris[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane), taking into account the effect of subtle ligand flexibility on the electronic structure. We show that the anisotropy of the room temperature magnetic susceptibility tensor, which in turn affects the sign and magnitude of the pseudocontact chemical shift, is extremely sensitive to minimal structural changes in the first coordination sphere of L(1). We show that DFT structural optimizations do not give accurate structural models, as assessed by the experimental chemical shifts, and thus we determine a magnetostructural correlation and employ this to evaluate the accurate solution structure for each [LnL(1)]. This approach allows us to explain the counterintuitive pseudocontact shift behavior, as well as a striking solvent dependence. These results have important consequences for the analysis and design of novel magnetic resonance shift and optical emission probes that are sensitive to the local solution environment and polarity.

  12. Paramagnetic lanthanide(III) complexes as pH-sensitive chemical exchange saturation transfer (CEST) contrast agents for MRI applications.

    PubMed

    Aime, Silvio; Barge, Alessandro; Delli Castelli, Daniela; Fedeli, Franco; Mortillaro, Armando; Nielsen, Flemming U; Terreno, Enzo

    2002-04-01

    The recently introduced new class of contrast agents (CAs) based on chemical exchange saturation transfer (CEST) may have a huge potential for the development of novel applications in the field of MRI. In this work we explored the CEST properties of a series of Lanthanide(III) complexes (Ln = Eu, Dy, Ho, Er, Tm, Yb) with the macrocyclic DOTAM-Gly ligand, which is the tetraglycineamide derivative of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). These complexes possess two pools of exchangeable protons represented by the coordinated water and the amide protons. Yb-DOTAM-Gly displays the most interesting CEST properties when its amide N-H resonance (16 ppm upfield H2O signal) is irradiated. Up to 70% suppression of the water signal is obtained at pH 8. As the exchange rate of amide protons is base-catalyzed, Yb-DOTAM-Gly results to be an efficient pH-responsive probe in the 5.5-8.1 pH range. Moreover, a ratiometric method has been set up in order to remove the dependence of the observed pH responsiveness from the absolute concentration of the paramagnetic agent. In fact, the use of a mixture of Eu-DOTAM-Gly and Yb-DOTAM-Gly, whose exchangeable proton pools are represented by the coordinated water (ca. 40 ppm downfield H2O signal at 312K) and amide protons, respectively, produces a pH-dependent CEST effect which is the function of the concentration ratio of the two complexes.

  13. Lanthanide(III) complexes that contain a self-immolative arm: potential enzyme responsive contrast agents for magnetic resonance imaging.

    PubMed

    Chauvin, Thomas; Torres, Susana; Rosseto, Renato; Kotek, Jan; Badet, Bernard; Durand, Philippe; Tóth, Eva

    2012-01-27

    Enzyme-responsive MRI-contrast agents containing a "self-immolative" benzylcarbamate moiety that links the MRI-reporter lanthanide complex to a specific enzyme substrate have been developed. The enzymatic cleavage initiates an electronic cascade reaction that leads to a structural change in the Ln(III) complex, with a concomitant response in its MRI-contrast-enhancing properties. We synthesized and investigated a series of Gd(3+) and Yb(3+) complexes, including those bearing a self-immolative arm and a sugar unit as selective substrates for β-galactosidase; we synthesized complex LnL(1), its NH(2) amine derivatives formed after enzymatic cleavage, LnL(2), and two model compounds, LnL(3) and LnL(4). All of the Gd(3+) complexes synthesized have a single inner-sphere water molecule. The relaxivity change upon enzymatic cleavage is limited (3.68 vs. 3.15 mM(-1) s(-1) for complexes GdL(1) and GdL(2), respectively; 37 °C, 60 MHz), which prevents application of this system as an enzyme-responsive T(1) relaxation agent. Variable-temperature (17)O NMR spectroscopy and (1)H NMRD (nuclear magnetic relaxation dispersion) analysis were used to assess the parameters that determine proton relaxivity for the Gd(3+) complexes, including the water-exchange rate (k(ex)(298), varies in the range 1.5-3.9×10(6) s(-1)). Following the enzymatic reaction, the chelates contain an exocyclic amine that is not protonated at physiological pH, as deduced from pH-potentiometric measurements (log K(H)=5.12(±0.01) and 5.99(±0.01) for GdL(2) and GdL(3), respectively). The Yb(3+) analogues show a PARACEST effect after enzymatic cleavage that can be exploited for the specific detection of enzymatic activity. The proton-exchange rates were determined at various pH values for the amine derivatives by using the dependency of the CEST effect on concentration, saturation time, and saturation power. A concentration-independent analysis of the saturation-power-dependency data was also applied. All these

  14. Calix[4]arenes as selective extracting agents. An NMR dynamic and conformational investigation of the lanthanide(III) and thorium(IV) complexes

    SciTech Connect

    Lambert, B.; Jacques, V.; Shivanyuk, A.; Matthews, S.E.; Tunayar, A.; Baaden, M.; Wipff, G.; Boehmer, V.; Desreux, J.F.

    2000-05-15

    The lanthanide and Th{sup 4+} complexes with calix[4]arene ligands substituted either on the narrow or at the wide rim by four coordinating groups behave totally differently as shown by an NMR investigation of the dia- and paramagnetic complexes. Solutions of complexes were prepared by reacting anhydrous metal perchlorate salts with the ligands in dry acetonitrile (CAUTION). Relaxation time T{sub 1} titrations of acetonitrile solutions of Gd{sup 3+} by calixarenes indicate that ligands substituted on the narrow rim form stable 1:1 complexes whether they feature four amide groups (1) or four phosphine oxide functions. In contrast, a ligand substituted by four (carbamoylmethyl)-diphenylphosphine oxide moieties on the wide rim (3) and its derivatives form polymeric species even at a 1:1 ligand/metal concentration ratio. Nuclear magnetic relaxation dispersion (NMRD) curves (relaxation rates 1/T{sub 1} vs magnetic field strength) of Gd{sup 3+}, Gd{sup 3+}{center_dot}1 and Gd{sup 3+}{center_dot}3 perchlorates in acetonitrile are analyzed by an extended version of the Solomon-Bloembergen-Morgan equations. A comparison of the calculated rotational correlation times {tau}{sub r} shows that ligand 3 forms oligomeric Gd{sup 3+} species. The chelates of ligand 1 are axially symmetric (C{sub 4} symmetry), and the paramagnetic shifts induced by the Yb{sup 3+} ion are accounted for quantitatively. The addition of water or of nitrate ions does not modify the geometry of the complex. The metal chelates of 3 and its derivatives adopt a C{sub 2} symmetry, and the paramagnetic shifts are interpreted on a semiquantitative basis only. Water and NO{sub 3}{sup {minus}} ions completely labilize the complexes of the heavy lanthanides. The very high selectivity of ligand 3 through the lanthanide series stems from a complex interplay of factors.

  15. New molecular motif for recognizing sialic acid using emissive lanthanide-macrocyclic polyazacarboxylate complexes: deprotonation of a coordinated water molecule controls specific binding.

    PubMed

    Ouchi, Kazuki; Saito, Shingo; Shibukawa, Masami

    2013-06-03

    A new molecular motif--lanthanide-macrocyclic polyazacarboxylate hexadentate complexes, Ln(3+)-ABNOTA--was found to specifically bind to sialic acid with strong emission enhancement and high affinity. The selectivity toward sialic acid over other monosaccharides was one of the highest among artificial receptors. Also, the novel binding mechanism was investigated in detail; binding selectivity is controlled by interactions between sialic acid and both the central metal and a hydroxyl group produced by deprotonation of a coordinated water molecule in the Ln(3+) complex.

  16. Construction of Polynuclear Lanthanide (Ln = Dy(III), Tb(III), and Nd(III)) Cage Complexes Using Pyridine-Pyrazole-Based Ligands: Versatile Molecular Topologies and SMM Behavior.

    PubMed

    Bala, Sukhen; Sen Bishwas, Mousumi; Pramanik, Bhaskar; Khanra, Sumit; Fromm, Katharina M; Poddar, Pankaj; Mondal, Raju

    2015-09-08

    Employment of two different pyridyl-pyrazolyl-based ligands afforded three octanuclear lanthanide(III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium(III) coordination cage, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semirigid pyridyl-pyrazolyl-based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centers. It is noteworthy here that construction of lanthanide complex itself is a challenging task in a ligand system as soft N-donor rich as pyridyl-pyrazol. We report herein some lanthanide complexes using ligand containing only one or two O-donors compare to five N-coordinating sites. The resultant multinuclear lanthanide complexes show interesting magnetic and spectroscopic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5 T direct current field, a typical characteristic feature of single-molecule magnet (SMM) behavior, indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behavior of the terbium complex, further confirmed by ac susceptibility measurement.

  17. Potentiometric study of binary complexes of 3-[(1 R)-1-hydroxy-2-(methylamino)ethyl]phenol hydrochloride with some lanthanide ions in aqueous and mixed solutions

    NASA Astrophysics Data System (ADS)

    Sharma, S. S.; Kadia, M. V.

    2014-12-01

    The complexation of lanthanide ions (Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Gd3+, Tb3+, and Dy3+) with 3-[(1 R)-1-hydroxy-2-(methylamino)ethyl]phenol hydrochloride was studied at different temperatures and different ionic strengths in aqueous solutions by Irving-Rossotti pH titration technique. Stepwise calculation, PKAS and BEST Fortran IV computer programs were used for determination of proton-ligand and metal-ligand stability constants. The formation of species like MA, MA2, and MA(OH) is considered in SPEPLOT. Thermodynamic parameters of complex formation (Δ G, Δ H, and Δ S) are also evaluated. Negative Δ G and Δ H values indicate that complex formation is favourable in these experimental conditions. The stability of complexes is also studied at in different solvent-aqueous (vol/vol). The stability series of lanthanide complexes has shown to have the "gadolinium break." Stability of complexes decreases with increase in ionic strength and temperature. Effect of systematic errors like effect of dissolved carbon dioxide, concentration of alkali, concentration of acid, concentration of ligand and concentration of metal have also been explained.

  18. Lanthanide(III) Complexes of Tripodal N-Donor Ligands: Structural Models for the Species Involved in Solvent Extraction of Actinides(III).

    PubMed

    Wietzke, Raphaël; Mazzanti, Marinella; Latour, Jean-Marc; Pécaut, Jacques; Cordier, Pierre-Yves; Madic, Charles

    1998-12-28

    The complexation of lanthanides(III) by the tripodal ligands tpa (tris[(2-pyridyl)methyl]amine) and tpza (tris[(2-pyrazinyl)methyl]amine) has been investigated by solution NMR studies and by X-ray crystallography. The crystallographic studies show that both tpa and the new ligand tpza form complexes with a 1:1 metal:ligand ratio in which the tripodal amine acts as a tetradentate ligand. For the tpa complexes the remaining coordination sites are occupied by chloride counterions to give 7-coordination (Eu, Tb, Lu) or by chloride counterions and a methanol molecule to give 8-coordination (Nd). In [Nd(tpza)(H(2)O)(3)(CH(3)CN)(3)](ClO(4))(3).3H(2)O the remaining coordination sites are occupied by water and acetonitrile molecules to give 10-coordination while the perchlorate counterions remain non coordinating. Tpza complexes have been isolated from acetonitrile solution and dissociate completely in methanol, while the complexes of the more basic tpa can be isolated from methanol and exist in water in equilibrium with the free ligand. Solvent extraction studies of lanthanides(III) and actinides(III) from nitric acid solutions show that the new ligand tpza is, unlike tpa, a selective complexant of actinides(III). Considering their structural analogy, this difference could be explained in terms of the electronic differences between the two ligands resulting in a stronger affinity of actinides(III) for the softer donor tpza.

  19. Self-aggregated dinuclear lanthanide(III) complexes as potential bimodal probes for magnetic resonance and optical imaging.

    PubMed

    Regueiro-Figueroa, Martín; Nonat, Aline; Rolla, Gabriele A; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Charbonnière, Loïc J; Botta, Mauro; Platas-Iglesias, Carlos

    2013-08-26

    Homodinuclear lanthanide complexes (Ln = La, Eu, Gd, Tb, Yb and Lu) derived from a bis-macrocyclic ligand featuring two 2,2',2''-(1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid chelating sites linked by a 2,6-bis(pyrazol-1-yl)pyridine spacer (H2L(3)) were prepared and characterized. Luminescence lifetime measurements recorded on solutions of the Eu(III) and Tb(III) complexes indicate the presence of one inner-sphere water molecule coordinated to each metal ion in these complexes. The overall luminescence quantum yields were determined (ϕ H2O = 0.01 for [Eu2(L(3))] and 0.50 for [Tb2(L(3))] in 0.01 M TRIS/HCl, pH 7.4; TRIS = tris(hydroxymethyl)aminomethane), pointing to an effective sensitization of the metal ion by the bispyrazolylpyridyl unit of the ligand, especially with Tb. The nuclear magnetic relaxation dispersion (NMRD) profiles recorded for [Gd2(L(3))] are characteristic of slowly tumbling systems, showing a low-field plateau and a broad maximum around 30 MHz. This suggests the occurrence of aggregation of the complexes giving rise to slowly rotating species. A similar behavior is observed for the analogous Gd(III) complex containing a 4,4'-dimethyl-2,2'-bipyridyl spacer ([Gd2(L(1))]). The relaxivity of [Gd2(L(3))] recorded at 0.5 T and 298 K (pH 6.9) amounts to 13.7 mM(-1)  s(-1). The formation of aggregates has been confirmed by dynamic light scattering (DLS) experiments, which provided mean particle sizes of 114 and 38 nm for [Gd2(L(1))] and [Gd2(L(3))], respectively. TEM images of [Gd2(L(3))] indicate the formation of nearly spherical nanosized aggregates with a mean diameter of about 41 nm, together with some nonspherical particles with larger size.

  20. Mechanisms of dielectric polarization in thermotropic liquid-crystalline complexes based on lanthanides

    NASA Astrophysics Data System (ADS)

    Dobrun, L. A.; Kovshik, A. P.; Ryumtsev, E. I.; Knyazev, A. A.; Galyametdinov, Yu. G.

    2016-06-01

    The components of the dielectric constant of a terbium-based liquid-crystalline complex have been measured in the frequency range of 350-5 × 106 Hz. The magnitude and sign of the dielectric anisotropy of the complex have been determined. Dispersion of the dielectric constants in the liquid-crystalline and isotropic phases has been found. The mechanisms responsible for the relaxation phenomena that appear in the studied sample have been determined. The time of dielectric relaxation, the activation energy, and the dipole moment of the complex have been obtained.

  1. A sandwich-type triple-decker lanthanide complex with mixed phthalocyanine and Schiff base ligands.

    PubMed

    Gao, Feng; Li, Yu-Yang; Liu, Cai-Ming; Li, Yi-Zhi; Zuo, Jing-Lin

    2013-08-21

    A new triple-decker dinuclear sandwich-type dysprosium complex based on both the phthalocyanine ligand and the tetradentate Schiff base ligand was synthesized, which is of interest for synthetic chemistry and also shows single-molecule magnetic behaviour.

  2. Lanthanide(III) complexes of some natural siderophores: a thermodynamic, kinetic and relaxometric study.

    PubMed

    Tircsó, Gyula; Garda, Zoltán; Kálmán, Ferenc K; Baranyai, Zsolt; Pócsi, István; Balla, György; Tóth, Imre

    2013-10-01

    Stability constants of the complexes formed between the natural trihydroxamic acids desferrioxamine B (DFB) and desferricoprogen (DFC) with Nd(III), Gd(III) and Yb(III) ions were determined using pH-potentiometry. The equilibrium in these systems can be described by models containing mononuclear protonated (Ln(HL), Ln(H2L) and Ln(H3L)), deprotonated (LnL) and ternary hydroxo Ln(H-1L) complexes, but for both ligands dinuclear complexes of low stability were also detected. The stability constants for the Ln(HDFB)(+) complexes are 11.95 (Nd(III)), 13.16 (Gd(III)) and 14.67 (Yb(III)), while these values of the Ln(DFC) complexes are considerably higher (14.42 (Nd(III)), 15.14 (Gd(III)) and 16.49 (Yb(III))). The stability constants of the complexes of DFB and DFC are much lower than those of the Ln(L)3 complexes formed with some aromatic hydroxamic acids indicating that the relatively long spacer between the hydroxamic acid moieties in DFB and DFC is unfavorable for Ln(III) complexation. The relaxometric study conducted for the Gd(HDFB)(+) species revealed an interesting pH dependence of the relaxivity associated with a large hydration number (bishydrated complex) and fast water exchange (kex=(29.9±0.4)×10(6)s(-1)), which would be favorable for CA use. However the dissociation of Gd(HDFB)(+) is fairly fast (<2ms) under all conditions employed in the present work thus the kinetically labile Gd(HDFB)(+) is not suitable for in vivo CA applications. Some low stability ternary complexes were also detected with K(Gd(HDFB)(HCO3))=17.5±1.9 and K(Gd(HDFB)(Lactate))=8.4±3.2 but in the presence of citrate and phosphate ions the Gd(HDFB)(+) complex was found to dissociate.

  3. Highly sensitive determination of lanthanides by capillary electrophoresis with direct visible detection after precapillary complexation with aromatic polyaminocarboxylate and additionally applying dynamic ternary complexation with nitrilotriacetic acid.

    PubMed

    Saito, Shingo; Danzaka, Naoki; Hoshi, Suwaru

    2006-08-01

    A newly synthesized aromatic polyaminocarboxylate (NBD-ABEDTA, H(4)L) was applied to precapillary derivatizing capillary electrophoresis as a chelating reagent for lanthanide ions (Ln(3+)). The Ln-L complexes provide both kinetic stability on dissociation due to their methyl-EDTA coordinating structure, and high light absorptivity (epsilon(max) = 2.4 x 10(4) cm(-1) mol(-1) dm(3)) in the visible region at 469 nm thanks to their nitrobenzofurazan moiety. A ligand was employed for capillary zone electrophoresis based on a unique concept: both precapillary and dynamic on-capillary complexation were carried out on one center-metal ion to achieve high resolution. As a ternary complex-formation agent, iminodiacetate (IDA), bound to the mother complex (Ln-L), was added to the carrier buffer solution. The carrier buffer solution of 9.5 mmol.dm(-3) (pH 9.45) borate and 33.5 mmol.dm(-3) IDA, drastically improved the resolution among Ln(3+) ions. Each of the Ln complexes was effectively separated, except for Pr-Sm. Furthermore, the absence of L from the carrier solution, which stabilizes the baseline fluctuation, provided low LOD (typically 4.2 x 10(-7) mol.dm(-3)). This strongly suggests that Ln-L complexes are kinetically stable even with a large excess of IDA. Quite unexpectedly, the order of migration differs from that of the atomic number, inverting at Nd. This is due to the effect of the cavity size of the residual coordination sites on the ternary complexation and the electronic density of Ln(3+).

  4. Synthesis, Potentiometry, and NMR Studies of Two New 1,7-Disubstituted Tetraazacyclododecanes and Their Complexes Formed with Lanthanide, Alkaline Earth Metal, Mn(2+), and Zn(2+) Ions.

    PubMed

    Burai, Laszlo; Ren, Jimin; Kovacs, Zoltan; Brücher, Erno; Sherry, A. Dean

    1998-01-12

    Two new 1,7-disubstituted-1,4,7,10-tetraazacyclododecane ligands, DO2P and DO2PME, and their complexes with Mg(2+), Ca(2+), Sr(2+), Mn(2+), Zn(2+) and Ln(3+) were prepared and characterized by pH potentiometry. The pH titration data showed that DO2P and DO2PME both form 1:1 M:L complexes with all divalent and trivalent metal ions. Protonated complexes did not appear to form with the bis(phosphonate ester) ligand, DO2PME, but were evident for all of the metal ion-DO2P complexes. The alkaline earth metal ion-DO2P complexes formed both ML and MHL complexes while the lanthanide ion (Ln(3+)), Zn(2+), and Mn(2+) complexes of DO2P formed ML, MHL, and MH(2)L species. Zn(2+) formed the most stable complex with both ligands. The stability (beta(101)) of the LnDO2PME(+) complexes increased by about 2 orders of magnitude along the lanthanide series (La(3+) to Lu(3+)) while the stability of the LnDO2P(-) complexes over this same series increased by over 3 orders of magnitude. The bis(phosphonate) ligand, DO2P, and some of its complexes formed with Ln(3+) ions were further examined by NMR spectroscopy. (1)H and (31)P spectra of DO2P collected as a function of pH provided evidence that the first two protonations on the ligand take place largely at the tertiary nitrogens. The similarity of the (31)P chemical shifts of EuDO2P(-) and EuDOTP(5)(-) indicate that DO2P forms an "in-cage" complex with Eu(3+) using all four macrocyclic ring nitrogens and the two phosphonate sidearms as ligands. (17)O NMR shifts of the water signal indicated that the DyDO2P(-) complex has two inner-sphere coordinated water molecules. In the presence of excess of DO2P, a 1:2 metal:ligand, LnDO2P(HDO2P)(4)(-), complex forms with the second ligand interacting only weakly with the coordination sites left vacant by the first DO2P. Both water proton relaxivity data for GdDO2P(-) and (31)P NMR spectra of EuDO2P(-) provide evidence for formation of an "out-of-cage" LnH(2)DO2P(+) complex at low pH values (<6.5) in

  5. 3,4,3-LI(1,2-HOPO): In Vitro Formation of Highly Stable Lanthanide Complexes Translates into Efficacious In Vivo Europium Decorporation

    SciTech Connect

    Sturzbecher-Hoehne, Manuel; Ng Pak Leung, Clara; Daleo, Anthony; Kullgren, Birgitta; Prigent, Anne-Laure; Shuh, David K.; Raymond, Kenneth N.; Abergel, Rebecca J.

    2011-07-13

    The spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) was investigated for its ability to act as an antennae that sensitizes the emission of Sm{sup III}, Eu{sup III}, and Tb{sup III} in the Visible range (Φ{sub tot} = 0.2 - 7%) and the emission of Pr{sup III}, Nd{sup III}, Sm{sup III}, and Yb{sup III} in the Near Infra-Red range, with decay times varying from 1.78 μs to 805 μs at room temperature. The particular luminescence spectroscopic properties of these lanthanide complexes formed with 3,4,3-LI(1,2-HOPO) were used to characterize their respective solution thermodynamic stabilities as well as those of the corresponding La{sup III}, Gd{sup III}, Dy{sup III}, Ho{sup III}, Er{sup III}, Tm{sup III}, and Lu{sup III} complexes. The remarkably high affinity of 3,4,3-LI(1,2-HOPO) for lanthanide metal ions and the resulting high complex stabilities (pM values ranging from 17.2 for La{sup III} to 23.1 for Yb{sup III}) constitute a necessary but not sufficient criteria to consider this octadentate ligand an optimal candidate for in vivo metal decorporation. The in vivo lanthanide complex stability and decorporation capacity of the ligand were assessed, using the radioactive isotope {sup 152}Eu as a tracer in a rodent model, which provided a direct comparison with the in vitro thermodynamic results and demonstrated the great potential of 3,4,3-LI(1,2-HOPO) as a therapeutic metal chelating agent.

  6. Monopropionate analogues of DOTA4- and DTPA5-: kinetics of formation and dissociation of their lanthanide(III) complexes.

    PubMed

    Balogh, Edina; Tripier, Raphaël; Fousková, Petra; Reviriego, Felipe; Handel, Henri; Tóth, Eva

    2007-08-28

    The replacement of an acetate function of the macrocyclic DOTA4-(DO3A-Nprop4-) or the acyclic DTPA5- in terminal position (DTTA-Nprop5-) has been recently shown to result in a significant increase of the water exchange rate on the Gd3+ complexes, which makes these chelates potential contrast agents for MRI applications. Here, two novel and straightforward synthetic routes to H4DO3A-Nprop are described. Protonation constants of DO3A-Nprop4- and stability constants with several alkaline earth and transition metal ions have been determined by potentiometry. For each metal, the thermodynamic stability constant is decreased in comparison to the DOTA chelates. The formation reaction of LnDO3A-Nprop- complexes (Ln=Ce, Gd and Yb) proceeds via the rapid formation of a diprotonated intermediate and its subsequent deprotonation and rearrangement in a slow, OH- catalyzed process. The stability of the LnH2DO3A-Nprop* intermediates is similar to those reported for the corresponding DOTA analogues. The rate constants of the OH- catalyzed deprotonation step increase with decreasing lanthanide ion size, and are slightly higher than for DOTA complexes. The kinetic inertness of GdDTTA-Nprop2- was characterized by the rates of its exchange reactions with Zn2+ and Eu3+. The rate of the reaction between GdDTTA-Nprop2- and Zn2+ increases with Zn2+ concentration, while it is independent of pH, implying that the exchange takes place predominantly via direct attack of the metal ion on the complex. In the Eu3+ exchange, the rate decreases with increasing concentration of the exchanging ion which is accounted for by the transitional formation of a dinuclear GdDTTA-NpropEu+ species. The kinetic inertness of the monopropionate GdDTTA-Nprop2- is decreased in comparison to GdDTPA2-: all rate constants, characterizing the dissociation reaction via either proton- or metal-catalyzed pathways being higher by 1-2 orders of magnitude. Similarly, a study of the acid-catalyzed dissociation of the

  7. Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol.

    PubMed

    Kostova, Irena; Manolov, Ilia; Radulova, Maritza

    2004-06-01

    A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.

  8. Enantioselective cleavage of supercoiled plasmid DNA catalyzed by chiral macrocyclic lanthanide(III) complexes.

    PubMed

    Krężel, Artur; Lisowski, Jerzy

    2012-02-01

    The enantiomers of the Sm (III), Eu (III) and Yb (III) complexes [LnL(NO(3))(2)](NO(3)) of a chiral hexaazamacrocycle were tested as catalysts for the hydrolytic cleavage of supercoiled plasmid DNA. The catalytic activity was remarkably enantioselective; while the [LnL(SSSS)(NO(3))(2)](NO(3)) enantiomers promoted the cleavage of plasmid pBR322 from the supercoiled form (SC) to the nicked form (NC), the [LnL(RRRR)(NO(3))(2)](NO(3)) enantiomers were inactive. Kinetics of plasmid DNA hydrolysis was also investigated by agarose electrophoresis and it indicated typical single-exponential cleavage reaction. The hydrolytic mechanism of DNA cleavage was confirmed by the successful ligation of hydrolysis product by T4 ligase. The NMR study of the solutions of the complexes in various buffers indicated that the complexes exist as monomeric cationic complexes [LnL(H(2)O)(3)](3+) in slightly acidic solutions and as dimeric cationic complexes [Ln(2)L(2)(μ-OH)(2)(H(2)O)(2)](4+) in slightly basic 8mM solutions, with the latter form being a possible catalyst for hydrolysis of phosphodiester bonds.

  9. Synthesis, structure and luminescence property of 2D lanthanide complexes with 3-fluorophthalate and oxalate

    SciTech Connect

    Cha, Yu-E; Li, Xia; Song, Shuang

    2012-12-15

    Complexes [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (Ln=Sm 1, Eu 2, Tb 3 and Dy 4; fpht=3-fluorophthalate and ox=oxalate) have been synthesized and structurally characterized by single crystal X-ray diffraction. The four complexes possess similar 2D framework structures constructed from Ln-fpht double-stranded helices and ox linkages. Complexes 2 and 3 display the characteristic emission {sup 5}D{sub 0}{yields}{sup 7}F{sub J} (J=0-4) transitions of Eu(III) ion and {sup 5}D{sub 4}{yields}{sup 7}F{sub J} (J=6-3) transitions of Tb(III) ion, respectively. The emission decay curves reveal a monoexponential behavior yielding the lifetime values of 0.266{+-}0.002 ms for 2 and 0.733{+-}0.002 ms for 3. The emission spectrum of 1 shows three weak bands corresponding to the characteristic emission {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 5/2}, {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 7/2} and {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 9/2} transitions of Sm(III) ion. The emission spectrum of 4 displays a broad band centered at 438 nm, which comes from the {pi}{sup Low-Asterisk }-{pi} transition of the ligand. - Graphical abstract: Complexes [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (fpht=3-fluorophthalate, ox=oxalate) possess 2D structures. Sm(III), Eu(III) and Tb(III) complexes show the characteristic fluorescent emission of the Ln(III). Dy(III) complex displays ligand-based luminescent behavior. Highlights: Black-Right-Pointing-Pointer [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (fpht=3-fluorophthalate; ox=oxalate) show 2D structures. Black-Right-Pointing-Pointer The 2D structures are constructed from Ln-fpht double-stranded helices and ox linkage. Black-Right-Pointing-Pointer The Sm(III), Eu(III) and Tb(III) complexes show the characteristic emission of the Ln(III) ions. Black-Right-Pointing-Pointer Dy(III) complex displays ligand-based luminescent behavior.

  10. Efficient Layers of Emitting Ternary Lanthanide Complexes for Fabricating Red, Green, and Yellow OLEDs.

    PubMed

    Ahmed, Zubair; Iftikhar, Khalid

    2015-12-07

    A series of novel nona- and octacoordinate highly volatile and luminescent complexes, [Eu(hfaa)3(indazole)3] and [Ln(hfaa)3(indazole)2] (Ln = Tb, Dy, and Lu), were synthesized using a monoanionic bidentate hexafluoroacetylacetone (hfaa(-)) and a neutral monodentate indazole ligand. The X-ray diffraction analyses of their single-crystals indicate that the complexes are mononuclear. The Eu complex is nonacoordinate and has a distorted monocapped square antiprismatic structure whereas the terbium and dysprosium complexes are octacoordinate and possess a trigonal bicapped prism geometry. The indazole units are involved in π-π stacking interaction and N-H···F hydrogen bonding with the fluorine atoms of hfaa(-). The photophysical studies of indazole and the complexes show that the triplet states are at the appropriate positions and make ligand-to-metal energy transfer process efficient. A strong protective shield is provided by the coordination of three hfaa(-) moieties (which have low frequency C-F vibrational oscillators), and two/three ancillary indazole ligands around these metal ions ascribe higher quantum yields and longer radiative life times (ΦEu = 69% ± 10, 989 ± 1 μs, ΦTb = 33% ± 10, 546 ± 1 μs, and ΦDy = 2.5% ± 10, 13.6 ± 1 μs) to these novel compounds. The emission from europium, terbium, and dysprosium are, respectively, red, green, and yellow. Finally, these compounds were used, as emitting layers, to fabricate electroluminescent devices of their respective colors. The best devices are found with the following structure: ITO/CuPc (15 nm)/[Eu complex]:CBP or [Tb complex]:CBP or [Dy complex]:CBP (80 nm)/BCP (25 nm)/AlQ (30 nm)/LiF (1 nm)/Al (100 nm), which indicates an improved EL performance for the Eu device over the Eu devices reported in the literature. The ligand, indazole, is a good sensitizer for trivalent europium, terbium, and dysprosium ions. It together with hfaa(-) plays an important role in fabricating OLEDs, especially

  11. Preparation of Lanthanide-Polymer Composite Material via Click Chemistry.

    PubMed

    Chen, Bin; Wen, Guian; Wu, Jiajie; Feng, Jiachun

    2015-10-01

    Covalently attaching lanthanide complexes to the polymer backbone can effectively reduce the clustering of lanthanides and thus become an important strategy to fully unleash their potential. In this Communication, a metal-free click reaction is used for the first time to link a lanthanide complex to the polymer matrix. A diene-bearing copolymer with anthracenylmethyl methacrylate as a monomer and a dienophile-bearing lanthanide complex with 5-maleimido-1,10-phenanthroline as the second ligand are synthesized and coupled together through a Diels-Alder cycloaddition (DA). A comparative investigation demonstrates that the composite material prepared by DA click reaction shows the highest quantum yields in the same lanthanide concentration as compared to materials prepared by widely used "directly doping" and "in situ coordinating lanthanide ions with macromolecular ligand" approaches. This work suggests that the "metal-free" DA click reaction can be a promising tool in the synthesis of high efficient lanthanide functionalized polymeric materials.

  12. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    PubMed

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-05

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts.

  13. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives

    NASA Astrophysics Data System (ADS)

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L = cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF = N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.

  14. Physicochemical Properties of Near-Linear Lanthanide(II) Bis(silylamide) Complexes (Ln = Sm, Eu, Tm, Yb).

    PubMed

    Goodwin, Conrad A P; Chilton, Nicholas F; Vettese, Gianni F; Moreno Pineda, Eufemio; Crowe, Iain F; Ziller, Joseph W; Winpenny, Richard E P; Evans, William J; Mills, David P

    2016-10-17

    Following our report of the first near-linear lanthanide (Ln) complex, [Sm(N(††))2] (1), herein we present the synthesis of [Ln(N(††))2] [N(††) = {N(Si(i)Pr3)2}; Ln = Eu (2), Tm (3), Yb (4)], thus achieving approximate uniaxial geometries for a series of "traditional" Ln(II) ions. Experimental evidence, together with calculations performed on a model of 4, indicates that dispersion forces are important for stabilization of the near-linear geometries of 1-4. The isolation of 3 under a dinitrogen atmosphere is noteworthy, given that "[Tm(N″)(μ-N″)]2" (N″ = {N(SiMe3)2}) has not previously been structurally authenticated and reacts rapidly with N2(g) to give [{Tm(N″)2}2(μ-η(2):η(2)-N2)]. Complexes 1-4 have been characterized as appropriate by single-crystal X-ray diffraction, magnetic measurements, electrochemistry, multinuclear NMR, electron paramagnetic resonance (EPR), and electronic spectroscopy, along with computational methods for 3 and 4. The remarkable geometries of monomeric 1-4 lead to interesting physical properties, which complement and contrast with comparatively well understood dimeric [Ln(N″)(μ-N″)]2 complexes. EPR spectroscopy of 3 shows that the near-linear geometry stabilizes mJ states with oblate spheroid electron density distributions, validating our previous suggestions. Cyclic voltammetry experiments carried out on 1-4 did not yield Ln(II) reduction potentials, so a reactivity study of 1 was performed with selected substrates in order to benchmark the Sm(III) → Sm(II) couple. The separate reactions of 1 with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), azobenzene, and benzophenone gave crystals of [Sm(N(††))2(TEMPO)] (5), [Sm(N(††))2(N2Ph2)] (6), and [Sm(N(††)){μ-OPhC(C6H5)CPh2O-κO,O'}]2 (7), respectively. The isolation of 5-7 shows that the Sm(II) center in 1 is still accessible despite having two bulky N(††) moieties and that the N-donor atoms are able to deviate further from linearity or ligand

  15. Covalent lanthanide(III) macrocyclic complexes: the bonding nature and optical properties of a promising single antenna molecule.

    PubMed

    Rabanal-León, Walter A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2014-12-21

    The present work is focused on the elucidation of the electronic structure, bonding nature and optical properties of a series of low symmetry (C2) coordination compounds of type [Ln(III)HAM](3+), where "Ln(III)" are the trivalent lanthanide ions: La(3+), Ce(3+), Eu(3+) and Lu(3+), while "HAM" is the neutral six-nitrogen donor macrocyclic ligand [C22N6H26]. This systematic study has been performed in the framework of the Relativistic Density Functional Theory (R-DFT) and also using a multi-reference approach via the Complete Active Space (CAS) wavefunction treatment with the aim of analyzing their ground state and excited state electronic structures as well as electronic correlation. Furthermore, the use of the energy decomposition scheme proposed by Morokuma-Ziegler and the electron localization function (ELF) allows us to characterize the bonding between the lanthanide ions and the macrocyclic ligand, obtaining as a result a dative-covalent interaction. Due to a great deal of lanthanide optical properties and their technological applications, the absorption spectra of this set of coordination compounds were calculated using the time-dependent density functional theory (TD-DFT), where the presence of the intense Ligand to Metal Charge Transfer (LMCT) bands in the ultraviolet and visible region and the inherent f-f electronic transitions in the Near-Infra Red (NIR) region for some lanthanide ions allow us to propose these systems as "single antenna molecules" with potential applications in NIR technologies.

  16. Syntheses, structure, magnetic and thermodynamics property of novel lanthanide complexes with nitronyl nitroxide radical

    NASA Astrophysics Data System (ADS)

    Song, Mei-Ying; Hou, Yi-Fang; Wen, Long-Mei; Wang, Shu-Ping; Yang, Shu-Tao; Zhang, Jian-Jun; Geng, Li-Na; Shi, Shi-Kao

    2016-03-01

    Four new nitronyl nitroxide radical-Ln(III) complexes, Ln(hfac)3(NITPhSCF3)2 (Ln(III) = Sm(1), Gd(2), Tb(3), Dy(4); NITPhSCF3 = 2-(4-trifluoromethylthiophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl- 3-oxide; hfac = hexafluoroacetylacetonate), have been synthesized and characterized. They are isostructural, which show mononuclear tri-spin structures. The central Ln(III) ion is eight-coordinated by three hfac anions and two NITPhSCF3 molecules. Direct-current magnetic study shows that there exist ferromagnetic interactions between Gd(III) ion and radicals (NITPhSCF3) with JGd-Rad = 1.61 cm-1, and antiferromagnetic interactions between radicals with JRad-Rad = -2.83 cm-1 in complex 2. The magnetic analysis with the rough approximate model show that a ferromagnetic coupling exists between Tb(III) and radical in 3, while a antiferromagnetic coupling between Dy(III) and radical in 4. The thermodynamics properties of four complexes were studied with differential scanning calorimetry (DSC), such as heat capacity, thermodynamic functions (HT-H298.15K), (ST-S298.15K), and (GT-G298.15K).

  17. Features of the complexation of octadecane-2,4-dione and lanthanide ions in Langmuir monolayers

    NASA Astrophysics Data System (ADS)

    Sokolov, M. E.; Repina, I. N.; Raitman, O. A.; Kolokolov, F. A.; Panyushkin, V. T.

    2016-05-01

    Monolayers of octadecane-2,4-dione on the surfaces of EuCl3 and TbCl3 solutions in the concentration range of 1 × 10-4 to 5 × 10-3 M at pH 5.8 are studied. It is found that the limiting area of octadecane-2,4-dione molecule in a monolayer dependence on Eu3+ and Tb3+ concentration is of extreme nature. The formation of complex compounds in the ligand monolayer is postulated, and structures are proposed for these compounds at different concentrations of metal ions.

  18. Induced circularly polarized luminescence arising from anion or protein binding to racemic emissive lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Carr, Rachel; Puckrin, Robert; McMahon, Brian K.; Pal, Robert; Parker, David; Pålsson, Lars-Olof

    2014-06-01

    A circularly polarized luminescence (CPL) spectrometer has been built and used to study the binding interaction of lactate and four different proteins with racemic EuIII and TbIII complexes in aqueous solution. Lactate binding gives rise to strong induced CPL spectra, and the observed emission dissymmetry factors vary linearly with enantiomeric composition. Particularly strong induced TbIII CPL also characterizes the binding interaction of alpha-1-acid glycoprotein with a dissociation constant, Kd, of 2.5 μM.

  19. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    DOE PAGES

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox.more » Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent actinides and early lanthanides to ionic strength of 6.60 m in low temperature environments in the presence of Ox. Furthermore, the work is also applicable to the accurate modeling transport of rare earth elements in various environments under the surface conditions.« less

  20. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters

    NASA Astrophysics Data System (ADS)

    Wang, Xinyi; Wang, Na; Yuan, Lan; Li, Na; Wang, Junxia; Yang, Xiaoda

    2016-08-01

    Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway. We propose a double fluorescence probe strategy, the combination of a proven paracellular indicator (europium complex) with fluorescent gold nanoclusters. We calculate changes of structural parameters in tight junctions based on determination of the diffusion coefficients of the probes. Two different types of tight junction openers are used to validate our strategy. Results show that EDTA disrupts tight junction structures and induces large and smooth paracellular pore paths with an average radius of 17 nm, but vanadyl complexes induce paths with the radius of 6 nm. The work suggests that the double fluorescence probe strategy is a useful and convenient approach for in vitro investigation of tight junction structural alternations caused by pharmacological or pathological events.

  1. Sunlight activated lanthanide complex for luminescent solar collector applications: effect of waveguide matrix

    NASA Astrophysics Data System (ADS)

    Shahi, Praveen Kumar; Singh, Priyam; Bahadur Rai, Shyam

    2017-02-01

    The performance of Eu(DBM)3Phen complex (EDP) dispersed in PMMA poly-(methyl methacrylate) polymer matrix, as simple planner luminescent solar collectors (LSCs) is demonstrated using spectroscopic and photovoltaic (PV) measurements. The organic ligands absorb ultra-violet-blue (UV-blue) radiation (220–450 nm) very efficiently and transfer its energy to the Eu3+ ion, which gives an intense red emission even in sunlight exposure. The excellent optical properties of EDP in PMMA permit its coating on the front surface of c-Si solar cell (10  ×  10 cm2) for PV measurements. The PV characterizations reveal the improvement in the short circuit current density (J sc) of PV cell and maximum improvement is found to be 4.6% for 2.5 wt% EDP concentration in PMMA matrix. The efficiency of solar cell increases from 17.22% to 18.33% for bare and 2.5% EDP in PMMA. At a higher concentration of EDP, the thin film starts losing its transparency and hence PV efficiency decreases. These results illustrate that a EDP complex combined with a PV cell could work as a prototype of a new generation solar cell.

  2. A homologous heterospin series of mononuclear lanthanide/TCNQF(4) organic radical complexes.

    PubMed

    Lopez, Nazario; Zhao, Hanhua; Prosvirin, Andrey V; Wernsdorfer, Wolfgang; Dunbar, Kim R

    2010-05-14

    Reactions between trivalent rare earth ions (M(III) = La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er and Yb) and the radical anion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF(4)) produce a family of mononuclear complexes {M[(TCNQF(4))](2)[H(2)O](x)}.(TCNQF(4))(3H(2)O), x = 6, 7. The cationic complex {M(III)([TCNQF(4)](-) )(2)[H(2)O](x)}(+) cocrystallizes with one [TCNQF(4)](-) radical anion and three water molecules. One of the coordinated [TCNQF(4)](-) radicals is involved in pi-pi stacking interactions with the uncoordinated [TCNQF(4)](-) radicals which leads to the antiferromagnetic coupling for these ((TCNQF(4))(2))(2-)pi-dimers. The second coordinated [TCNQF(4)](-) remains as a radical ligand and is not involved in pi-pi interactions. Magnetic studies indicate that the Sm compound magnetically orders at 4.4 K and that a fraction of the Gd and Dy samples undergo magnetic ordering at 3.7 K and 4.3 K respectively due to partial dehydration (loss of interstitial water molecules). Diamagnetic metal ions were used to generate magnetically dilute Gd, and Dy compounds that do not exhibit any signs of magnetic ordering.

  3. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters

    PubMed Central

    Wang, Xinyi; Wang, Na; Yuan, Lan; Li, Na; Wang, Junxia; Yang, Xiaoda

    2016-01-01

    Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway. We propose a double fluorescence probe strategy, the combination of a proven paracellular indicator (europium complex) with fluorescent gold nanoclusters. We calculate changes of structural parameters in tight junctions based on determination of the diffusion coefficients of the probes. Two different types of tight junction openers are used to validate our strategy. Results show that EDTA disrupts tight junction structures and induces large and smooth paracellular pore paths with an average radius of 17 nm, but vanadyl complexes induce paths with the radius of 6 nm. The work suggests that the double fluorescence probe strategy is a useful and convenient approach for in vitro investigation of tight junction structural alternations caused by pharmacological or pathological events. PMID:27574102

  4. Synthesis and design of organic light-emitting devices containing lanthanide-cored complexes

    NASA Astrophysics Data System (ADS)

    Phelan, Gregory D.; Carlson, Brenden; Lawson, Rhys; Rowe, Daniel; Allen, Kolby; Dalton, Larry; Jiang, Xuezhong; Kim, Joo H.; Jen, Alex K.

    2004-02-01

    There is a considerable interest in the use of metal centered materials as a light source in the growing field of organic light emitting devices (OLED's). In these devices, a polymeric host matrix containing either a carbazole type polymer or polyfluorene derivatives is used to help facilitate energy transfer to the luminophore. We have shown that by using a gadolinium complex that consist of three equivalents of a chelated dibenzoylmethane b-diketone ligand and one equivalent of a phenanthroline type ligand as a component in the host matrix, the performance of a double layer type OLED is improved. We have studied OLED systems that contain tris chelated europium compounds that contain three equivalents of partially fluorinated β-diketone type ligands and an equivalent of a phenanthroline type ligand. In these devices, the external efficiency has shown a 30-fold increase. We have also shown there is an increase for Osmium based OLED's that use the gadolinium complex as part of the polymer matrix. In these devices, the maximum quantum efficiency increased from 2.1% to a value of 3.8%.

  5. Ga(3+)/Ln(3+) Metallacrowns: A Promising Family of Highly Luminescent Lanthanide Complexes That Covers Visible and Near-Infrared Domains.

    PubMed

    Chow, Chun Y; Eliseeva, Svetlana V; Trivedi, Evan R; Nguyen, Tu N; Kampf, Jeff W; Petoud, Stéphane; Pecoraro, Vincent L

    2016-04-20

    Luminescent lanthanide(III)-based molecular scaffolds hold great promises for materials science and for biological applications. Their fascinating photophysical properties enable spectral discrimination of emission bands that range from the visible to the near-infrared (NIR) regions. In addition, their strong resistance to photobleaching makes them suitable for long duration or repeated biological experiments using a broad range of sources of excitation including intense and focalized systems such as lasers (e.g., confocal microscopy). A main challenge in the creation of luminescent lanthanide(III) complexes lies in the design of a ligand framework that combines two main features: (i) it must include a chromophoric moiety that possesses a large molar absorptivity and is able to sensitize several different lanthanide(III) ions emitting in the visible and/or in the near-infrared, and (ii) it must protect the Ln(3+) cation by minimizing nonradiative deactivation pathways due to the presence of -OH, -NH and -CH vibrations. Herein, a new family of luminescent Ga(3+)/Ln(3+) metallacrown (MC) complexes is reported. The MCs with the general composition [LnGa4(shi)4(C6H5CO2)4(C5H5N) (CH3OH)] (Ln-1, Ln = Sm(3+)-Yb(3+)) were synthesized in a one pot reaction using salicylhydroxamic acid (H3shi) with Ga(3+) and Ln(3+) nitrates as reagents. The molecular structure of [DyGa4(shi)4(C6H5CO2)4(C5H5N) (CH3OH)] was obtained by X-ray analysis of single crystals and shows that the complex is formed as a [12-MCGa(III)shi-4] core with four benzoate molecules bridging the central Dy(3+) ion to the Ga(3+) ring metals. The powder X-ray diffraction analysis demonstrates that all other isolated complexes are isostructural. The extended analysis of the luminescence properties of these complexes, excited by the electronic states of the chromophoric ligands, showed the presence of characteristic, sharp f-f transitions that can be generated not only in the NIR (Sm, Dy, Ho, Er, Yb) but also in the

  6. Lanthanide dinuclear complexes constructed from mixed oxygen-donor ligands: the effect of substituent positions of the neutral ligand on the magnetic dynamics in Dy analogues.

    PubMed

    Zhu, Wen-Hua; Li, Shan; Gao, Chen; Xiong, Xia; Zhang, Yan; Liu, Li; Powell, Annie K; Gao, Song

    2016-03-21

    Two series of lanthanide dinuclear complexes with the general formulae, [Ln(n-PNO)(Bza)3(H2O)] {Bza = benzoic acid; n = 3, n-PNO = 3-picoline N-oxide, Dy(1) and Er(2); and n = 4, n-PNO = 4-picoline N-oxide, Nd(3), Eu(4), Gd(5), Tb(6), Dy(7), Er(8) and Y(9)} have been successfully synthesized by the hydrothermal method. Single-crystal X-ray diffraction experiments illustrate that the two series of compounds possess similar carboxylic ligand-bridged dinuclear structure and coordination geometry around the lanthanide ions despite the different methyl-substituent positions on the neutral ligand. Comparative studies of the Dy analogues in the static-field measurements reveal only a little difference with a small butterfly-shaped opening for complex 1 and a close hysteresis loop for 7 at 2.0 K. However, systematic investigations of the alternating-current (ac) measurements indicate that the different substituent positions of the picoline N-oxide ligand have a significant effect on the magnetic relaxation dynamics. A more substantial suppression of the quantum tunnelling of magnetization (QTM) effect and pronounced slow magnetic relaxation were observed in complex 7 as compared to 1 under both zero and a 1 kOe static field.

  7. Synthesis, structure, and reactivity of lanthanide complexes incorporating indolyl ligands in novel hapticities.

    PubMed

    Feng, Zhijun; Zhu, Xiancui; Wang, Shaoyin; Wang, Shaowu; Zhou, Shuangliu; Wei, Yun; Zhang, Guangchao; Deng, Baojia; Mu, Xiaolong

    2013-08-19

    The chemistry of interactions of 2-(2,6-diisopropylphenylaminomethylene)indole ligand (1) with europium and ytterbium amides is described. Reaction of 2-(2,6-diisopropylphenylaminomethylene)indole 2-(2,6-i-Pr2C6H3NHCH2)C8H5NH (1) with europium amide [(Me3Si)2N]3Eu(III)(μ-Cl)Li(THF)3 afforded a novel europium(II) complex formulated as {[μ-η(6):η(1):η(1)-2-(2,6-i-Pr2C6H3N═CH)C8H5N]Eu[2-(2,6-i-Pr2C6H3N═CH)C8H5N]}2 (2), having a bridged indolyl ligand in the novel μ-η(6):η(1):η(1) hapticities with the reduction of europium(III) to europium(II) and the oxidation of amino to imino group. Reaction of 2-(2,6-diisopropylphenylaminomethylene)indole 2-(2,6-i-Pr2C6H3NHCH2)C8H5NH (1) with ytterbium(III) amide [(Me3Si)2N]3Yb(III)(μ-Cl)Li(THF)3 produced the only deprotonated ytterbium(III) complex formulated as [2-(2,6-i-Pr2C6H3NCH2)C8H5N]Yb[N(SiMe3)2](THF)2 (3), having an η(1) hapticity indolyl ligand. Reaction of 2 with formamidine [(2,6-Me2C6H3)NCHNH(C6H3Me2-2,6)] produced {[μ-η(3):η(1):η(1)-2-(2,6-i-Pr2C6H3N═CH)C8H5N]Eu[(2,6-Me2C6H3)NCHN(C6H3Me2-2,6)](THF)}2 (4), which has a bridged indolyl ligand in the novel μ-η(3):η(1):η(1) hapticities, whereas the reaction of 2 with the more sterically bulky formamidine [(2,6-i-Pr2C6H3)NCHNH(C6H3i-Pr2-2,6)] afforded complex {[μ-η(2):η(1):η(1)-2-(2,6-i-Pr2C6H3N═CH)C8H5N]Eu[(2,6-i-Pr2C6H3)N═CHN(C6H3i-Pr2-2,6)](THF)}2 (5), having the indolyl ligand in the novel μ-η(2):η(1):η(1) hapticities. The results represent the first example of organometallic complexes having indolyl ligands in the novel μ-η(6):η(1):η(1), μ-η(3):η(1):η(1), and μ-η(2):η(1):η(1) bonding modes with metal.

  8. Assessment of Density Functionals for Computing Thermodynamic Properties of Lanthanide Complexes.

    PubMed

    Jaoul, Arnaud; Nocton, Grégory; Clavaguéra, Carine

    2017-07-13

    The equilibrium between the radical phenanthroline complex Cp*2 Sm(phen) and the coupling product (Cp*2 Sm(phen))2 has been investigated based on quantum chemistry calculations. Topological analyses pointed out that the C-C bond created has a partial covalent character, explaining why both the monomeric and the dimeric forms exist in equilibrium. A large variety of density functionals have been tested to reproduce experimental thermodynamic data for this equilibrium. Finally, the PBE0-D3 and M06-2X functionals lead to a good evaluation of the energies and enable a correct description of the ligand to metal charge transfer, both in the 4f and 5d metal orbitals. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide] Ligand That Complexes and Sensitizes Lanthanide(III) Ions

    PubMed Central

    D'Aléo, Anthony; Xu, Jide; Do, King; Muller, Gilles; Raymond, Kenneth N.

    2009-01-01

    The synthesis of the cyclen derivative H4L1·2 HBr containing four 2-hydroxybenzamide groups is described. The spectroscopic properties of the LnIII conplexes of L1 (Ln=Gd, Tb, Yb, and Eu) reveal changes of the UV/VIS-absorption, circular-dichroism-absorption, luminescence, and circularly polarized luminescence spectra. It is shown that at least two metal-complex species are present in solution, whose relative amounts are pH dependent. At pH > 8.0, an intense long-lived emission is observed (for [TbL1] and [YbL1]), while at pH < 8.0, a weaker, shorter-lived species predominates. Unconventional LnIII emitters (Pr, Nd, Sm, Dy, and Tm) were sensitized in basic solution, both in the VIS and in the near-IR, to measure the emission of these ions. PMID:20161476

  10. Method bacterial endospore quantification using lanthanide dipicolinate luminescence

    NASA Technical Reports Server (NTRS)

    Ponce, Adrian (Inventor); Venkateswaran, Kasthuri J. (Inventor); Kirby, James Patrick (Inventor)

    2007-01-01

    A lanthanide is combined with a medium to be tested for endospores. The dipicolinic acid released from the endospores binds the lanthanides, which have distinctive emission (i.e., luminescence) spectra, and are detected using photoluminescence. The concentration of spores is determined by preparing a calibration curve generated from photoluminescence spectra of lanthanide complex mixed with spores of a known concentration. A lanthanide complex is used as the analysis reagent, and is comprised of lanthanide ions bound to multidentate ligands that increase the dipicolinic acid binding constant through a cooperative binding effect with respect to lanthanide chloride. The resulting combined effect of increasing the binding constant and eliminating coordinated water and multiple equilibria increase the sensitivity of the endospore assay by an estimated three to four orders of magnitude over prior art of endospore detection based on lanthanide luminescence.

  11. The comparison of crystal structures of lanthanide complexes with 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioic acid (H 4egta)

    NASA Astrophysics Data System (ADS)

    Inomata, Y.; Okamura, D.; Morita, K.; Yukawa, Y.; Howell, F. S.

    2003-10-01

    Nine lanthanide complexes with 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioic acid (H 4egta): [M'(H 2O) n][M(egta)(H 2O)] 2· nH 2O (M': Ca, Sr; M: La, Ce, Pr, Dy, Ho, Er) have been prepared and characterized by using their infrared absorption and Raman spectra, magnetic susceptibility and thermal analyses. The results of Raman spectra (600-200 cm -1) suggest that these complexes are of two types: the first includes La, Ce, and Pr complexes, and the second Dy, Ho and Er complexes. The crystal and molecular structures of [Ca(H 2O) 2][La(egta)(H 2O)] 2·8H 2O ( 1), [Ca(H 2O) 2][Ce(egta)(H 2O)] 2·6H 2O ( 2), [Sr(H 2O) 3][Dy(egta)(H 2O)] 2·7H 2O ( 3), and [Sr(H 2O) 3][Ho(egta)(H 2O)] 2·7H 2O ( 4) have been determined by a single-crystal X-ray diffraction method. The crystals of complexes ( 1) and ( 2) are iso-morphous to each other: monoclinic, space group P2 1/ c, Z=2. The central lanthanide metal atom is 10-coordinated, in a distorted bicapped square antiprism geometry, to two nitrogen and six oxygen atoms of egta 4-, a water molecule, and a carboxyl oxygen atom from an adjacent complex ion. The Ca 2+ is at the center of the octahedral geometry and ligated by four carboxyl oxygen atoms and two water molecules. Complexes ( 3) and ( 4) are iso-morphous to each other: monoclinic, space group P2 1/ n, Z=4. The central lanthanide metal atom is nine-coordinated, in a distorted tricapped trigonal prism geometry, to two nitrogen and six oxygen atoms of egta 4-, and to a water molecule which bridges to the Sr 2+ ion. Two carboxyl groups of [M(egta)(H 2O)] - (M: Dy, Ho) complex ion bridge to the single Sr 2+ ion. In addition, the Sr 2+ is coordinated by three non-bridged water molecules, and then the Sr 2+ is coordinated by nine atoms. A relationship has been found between the average M-N, M-O(ether) and M-O(carboxylate) bond lengths and Shannon's metal crystal radii for a series of complexes shown as [M'(H 2O) n][M(egta)(H 2O)] 2· nH 2O (M': Ca, Sr; M: La

  12. Lanthanide complexes of chiral 3 + 3 macrocycles derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol.

    PubMed

    Paluch, Marta; Lisowski, Jerzy; Lis, Tadeusz

    2006-01-14

    The enantiopure amine macrocycle H(3)L, as well as the parent macrocyclic Schiff base H(3)L1, the 3 + 3 condensation product of (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol, are able to form mononuclear complexes with lanthanide(III) ions. The lanthanide(III) complexes of H(3)L have been studied in solution using NMR spectroscopy and electrospray mass spectrometry. The NMR spectra indicate the presence of complexes of low C(1) and C(2) symmetry. The (1)H and (13)C NMR signals of the Lu(III) complex obtained from H(3)L have been assigned on the basis of COSY, TOCSY, NOESY, ROESY and HMQC spectra. The NMR data reveal unsymmetrical binding of lanthanide(III) ion and the presence of a dynamic process corresponding to rotation of Lu(III) within the macrocycle. The [Ln(H(4)L)(NO(3))(2)](NO(3))(2)(Ln = Sm(III), Eu(III), Dy(III), Yb(III) and Lu(III)) complexes of the cationic ligand H(4)L(+) have been isolated in pure form. The X-ray analysis of the [Eu(H(4)L)(NO(3))(2)](NO(3))(2) complex confirms the coordination mode of the macrocycle determined on the basis of NMR results. In this complex the europium(III) ion is bound to three phenolate oxygen atoms and two amine nitrogen atoms of the monoprotonated macrocycle H(4)L(+), as well as to two axial bidendate nitrate anions. In the presence of a base, mononuclear La(III), Ce(III) and Pr(III) complexes of the deprotonated form of the ligand L(3-) can be obtained. When 2 equivalents of Pr(III) are used in this synthesis Na(3)[Pr(2)L(NO(3))(2)(OH)(2)](2)NO(3).5H(2)O is obtained. The NMR, ES MS and an X-ray crystal model of this complex show coordination of two Pr(III) ions by the macrocycle L. The X-ray crystal structure of the free macrocycle H(3)L1 has also been determined. In contrast to macrocyclic amine H(3)L, the Schiff base H(3)L1 adopts a cone-type conformation resembling calixarenes.

  13. Electronic structures of organometallic complexes of f elements. Part 45. Comparison of phenomenological and calculated crystal field parameters of lanthanide organyls estimated on the basis of simple models

    NASA Astrophysics Data System (ADS)

    Jank, S.; Reddmann, H.; Amberger, H.-D.

    1998-09-01

    The crystal field (CF) parameters of Nd[N(SiMe 3) 2] 3, (THF) 3Li( μ-Cl)Nd[N(SiMe 3) 2] 3 and Nd[N(SiMe 3) 2] 3(CNC 6H 11) 2 (which are considered as model compounds for the corresponding σ-bonded organometallic complexes with [CH(SiMe 3) 2] - ligands), as well as those of organometallic π complexes of the types (Me 3SiC 5H 4) 3Pr and (C 8H 8)Pr[HB(3,5-Me 2pz) 3], were estimated on the basis of simple model calculations (point charge electrostatic model, simple overlap model, angular overlap model) and were compared with the results of CF calculations adopting the phenomenological model. The comparison suggests that these straightforward model calculations may provide satisfactory CF parameters for σ complexes but give poor results for π complexes of the lanthanides.

  14. Syntheses, characterization, biological activity and fluorescence properties of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand and its lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Taha, Ziyad A.; Ajlouni, Abdulaziz M.; Al-Hassan, Khader A.; Hijazi, Ahmed K.; Faiq, Ari B.

    2011-10-01

    Eight new lanthanide metal complexes [Ln L(NO 3) 2]NO 3 {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand} were prepared. These complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), molar conductivity measurements and spectral studies ( 1H NMR, FT-IR, UV-vis, and luminescence). The Schiff base ligand coordinates to Ln(III) ion in a tetra-dentate manner through the phenolic oxygen and azomethine nitrogen atoms. The coordination number of eight is achieved by involving two bi-dentate nitrate groups in the coordination sphere. Sm, Tb and Dy complexes exhibit the characteristic luminescence emissions of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of the complexes exhibit antibacterial activity against a number of pathogenic bacteria.

  15. ITP of lanthanides in microfluidic PMMA chip.

    PubMed

    Cong, Yongzheng; Bottenus, Danny; Liu, Bingwen; Clark, Sue B; Ivory, Cornelius F

    2014-03-01

    An ITP separation of eight lanthanides on a serpentine PMMA microchip with a tee junction and a 230-mm-long serpentine channel is described. The cover of the PMMA chip is 175 μm thick so that a C(4) D in microchip mode can be used to detect the lanthanides as they migrate through the microchannel. Acetate and α-hydroxyisobutyric acid are used as complexing agents to increase the electrophoretic mobility difference between the lanthanides. Eight lanthanides are concentrated within ∼ 6 min by ITP in the microchip using 10 mM ammonium acetate at pH 4.5 as the leading electrolyte and 10 mM acetic acid at ∼ pH 3.0 as the terminating electrolyte. In addition, a 2D numerical simulation of the lanthanides undergoing ITP in the microchip is compared with experimental results using COMSOL Multiphysics v4.3a.

  16. Gold nanoparticle assemblies stabilized by bis(phthalocyaninato)lanthanide(III) complexes through van der Waals interactions

    NASA Astrophysics Data System (ADS)

    Noda, Yuki; Noro, Shin-Ichiro; Akutagawa, Tomoyuki; Nakamura, Takayoshi

    2014-01-01

    Gold nanoparticle assemblies possess diverse application potential, ranging from industrial nanotechnology to medical biotechnology. Because the structures and properties of assemblies are directly affected by the stabilization mechanism between the organic molecules serving as protecting ligands and the gold nanoparticle surface, it is crucial to find and investigate new stabilization mechanisms. Here, we report that π-conjugated phthalocyanine rings can serve as stabilizing ligands for gold nanoparticles. Bis(phthalocyaninato)lutetium(III) (LuPc2) or bis(phthalocyaninato)terbium(III) (TbPc2), even though complex, do not have specific binding units and stabilize gold nanoparticles through van der Waals interaction between parallel adsorbed phthalocyanine ligands and the gold nanoparticle surface. AC magnetic measurements and the electron-transport properties of the assemblies give direct evidence that the phthalocyanines are isolated from each other. Each nanoparticle shows weak electronic coupling despite the short internanoparticle distance (~1 nm), suggesting Efros-Shklovskii-type variable-range hopping and collective single-electron tunnelling behaviours.

  17. Gold nanoparticle assemblies stabilized by bis(phthalocyaninato)lanthanide(III) complexes through van der Waals interactions

    PubMed Central

    Noda, Yuki; Noro, Shin-ichiro; Akutagawa, Tomoyuki; Nakamura, Takayoshi

    2014-01-01

    Gold nanoparticle assemblies possess diverse application potential, ranging from industrial nanotechnology to medical biotechnology. Because the structures and properties of assemblies are directly affected by the stabilization mechanism between the organic molecules serving as protecting ligands and the gold nanoparticle surface, it is crucial to find and investigate new stabilization mechanisms. Here, we report that π-conjugated phthalocyanine rings can serve as stabilizing ligands for gold nanoparticles. Bis(phthalocyaninato)lutetium(III) (LuPc2) or bis(phthalocyaninato)terbium(III) (TbPc2), even though complex, do not have specific binding units and stabilize gold nanoparticles through van der Waals interaction between parallel adsorbed phthalocyanine ligands and the gold nanoparticle surface. AC magnetic measurements and the electron-transport properties of the assemblies give direct evidence that the phthalocyanines are isolated from each other. Each nanoparticle shows weak electronic coupling despite the short internanoparticle distance (~1 nm), suggesting Efros–Shklovskii-type variable-range hopping and collective single-electron tunnelling behaviours. PMID:24441566

  18. Crystallization of the pneumococcal autolysin LytC: in-house phasing using novel lanthanide complexes

    PubMed Central

    Pérez-Dorado, Inmaculada; Sanles, Reyes; González, Ana; García, Pedro; García, José L.; Martínez-Ripoll, Martín; Hermoso, Juan A.

    2010-01-01

    LytC, one of the major autolysins from the human pathogen Streptococcus pneumoniae, has been crystallized as needles by the hanging-drop technique using 10%(w/v) PEG 3350 as precipitant and 10 mM HEPES pH 7.5. LytC crystals were quickly soaked in mother liquor containing 2 mM of the complex Gd-HPDO3A to produce derivatized crystals (LytCGd-HPDO3A). Both native LytC and isomorphous LytCGd-HPDO3A crystals were flash-cooled in a nitrogen flow at 120 K prior to X-ray data collection using an in-house Enraf–Nonius rotating-anode generator (λ = 1.5418 Å) and a MAR345 imaging-plate detector. In both cases, good-quality diffraction patterns were obtained at high resolution. LytCGd-HPDO3A crystals allowed the collection of a SAD X-ray data set to 2.6 Å resolution indexed in terms of a P21 monoclinic unit cell with parameters a = 59.37, b = 67.16, c = 78.85 Å, β = 105.69°. The anomalous Patterson map allowed the identification of one heavy-atom binding site, which was sufficient for the calculation of an interpretable anomalous map at 2.6 Å resolution. PMID:20383019

  19. Decreased overall basicity of a series of new N,N'-bis(carboxymethyl) macrocylcic ether-bis(lactone) ligands derived from EDTA and the ring size effect on the stability constants of their lanthanide complexes

    SciTech Connect

    Chang, C.A.; Chang, P.H.L.; Qin, S.Y.

    1988-03-09

    In order to examine the effects of positions of the nitrogen donor atoms and the relative coordination sites of the two carboxylate groups on lanthanide complexation in the study of the characteristics of both open-chain and macrocyclic ligands for the preparation of novel metal-ion selective reagents, a series of N, N'-bis(carboxymethyl)macrocyclic ether-bis(lactone)ligands derived from ethylenediaminetetraacetic acid have been prepared and characterized. The ligand protonation constants and the lanthanide complex formation constants have been determined and are reported here. 14 references, 2 figures, 2 tables.

  20. Failure of ESI Spectra to Represent Metal-Complex Solution Composition: A Study of Lanthanide-Carboxylate Complexes

    SciTech Connect

    McDonald, Luther W.; Campbell, James A.; Clark, Sue B.

    2014-01-21

    Electrospray ionization - mass spectrometry (ESI-MS) was used for the characterization of uranyl complexed to tributyl phosphate (TBP) and dibutyl phosphate (DBP). The stoichiometry of uranyl with TBP and DBP was determined, and the gas phase speciation was found to be dependent on the cone voltage applied to induce fragmentation on the gas phase complexes. To quantitatively compare the gas phase distribution of species to solution, apparent stability constants were calculated. With a cone voltage of 80V, the apparent stability constants for the complexes UO2(NO3)2•2TBP, UO2(NO3)2(H2O)•2TBP, and UO2(DBP)+ were determined. With a lower cone voltage applied, larger complexes were observed and stability constants for the complexes UO2(NO3)2•3TBP and UO2(DBP)42- were determined.

  1. Luminescence dynamics and {sup 13}C NMR characteristics of dinuclear complexes exhibiting coupled lanthanide(III) cation pairs

    SciTech Connect

    Matthews, K.D.; Bailey-Folkes, S.A.; Kahwa, I.A.

    1992-08-20

    Luminescence and cross-polarization magic angle spinning (CP-MAS) {sup 13}C NMR properties of lanthanide dinuclear macrocyclic complexes of a compartmental Schiff base chelate (1) derived from the condensation of 2,6-diformyl-p-cresol and 3,6-dioxa-1,8-octanediamine are reported. The Schiff base chromophore in 1 is a strong light absorber and an efficient sensitizer for intense Tb{sup 3+}({sup 5}D{sub 4}) and Eu{sup 3+}({sup 5}D{sub 0})(T < 110 K ) emission which does not exhibit self-quenching effects. Emission from Tb{sup 3+} is sensitized by the ligand singlet state; in striking contrast, Eu{sup 3+} emission is sensitized by the triplet state and reveals an unusual nonradiative quenching process at T > 110 K with a thermal barrier of {approx} 2300 cm{sup {minus}1}. Weak emission is observed from Dy{sup 3+}({sup 4}F{sub 9/2}), Sm{sup 3+}({sup 4}G{sub 5/2}), and Pr{sup 3+}({sup 1}D{sub 2}) diluted in Gd{sup 3+} (i.e., from Gd{sup 3+}-Ln{sup 3+} heteropairs, Ln = Pr, Sm, Dy). Intramolecular metal-metal (Ln-Ln = 4 {Angstrom}) interactions account for the greatly quenched emission from Sm{sup 3+}-Sm{sup 3+} and Dy{sup 3+}-Dy{sup 3+} homopairs compared to Gd{sup 3+}-Ln heteropairs (Ln = Sm, Dy). Gd{sup 3+}-Ln{sup 3+} emission lifetimes at 77 K are 1610 (Tb{sup 3+}), 890 (Eu{sup 3+}), 14 (Dy{sup 3+}) and {approx} 13 {mu}s (Sm{sup 3+}). Nonradiative relaxation processes at 77 K in dilute Ln{sup 3+}:Gd{sub 2}1(NO{sub 3}){sub 4}{center_dot}H{sub 2}O, being temperature independent for Sm{sup 3+} and Eu{sup 3+} but temperature dependent for Tb{sup 3+}, follow the energy gap law with {alpha} {approx} - 10{sup {minus}3} cm and B {approx} 2 x 10{sup 8} s{sup {minus}1}. CP-MAS data show paramagnetic broadening of {sup 13}C resonances which increases with the magnetic moment of Ln{sup 3+}. Surprisingly, no significant shifts in resonance positions corresponding to the changing nature of paramagnetic Ln{sup 3+} ions are observed. 43 refs., 8 figs., 2 tabs.

  2. Luminescent hybrid materials based on zeolite L crystals and lanthanide complexes: host-guest assembly and ultraviolet-visible excitation.

    PubMed

    Chen, Lei; Yan, Bing

    2014-10-15

    Several kinds of host-guest hybrid materials have been synthesized employing a ship in a bottle method by loading 9-hydroxy-2-methylphenalenone (MHPO) or 9-hydroxyphenalen (HPNP) from gas phase into the nanochannels of Ln(3+)-exchanged zeolite L (ZL) crystals (Ln=Gd or Eu). The resulting hybrids without lanthanide ions, MHPO-ZL, HPNP-ZL and the hybrids with lanthanide ions Ln-MHPO-ZL and Ln-HPNP-ZL are characterized with FT-IR, UV-vis DRS and photoluminescence spectroscopy. The photoluminescence properties of these hybrid materials have been analyzed and discussed, exhibiting the luminescence of Eu(3+) and ligands under the excitation at ultraviolet-visible region. These results provide useful data and can be expected to have potential application in the practical fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Multifunctional nanomesoporous materials with upconversion (in vivo) and downconversion (in vitro) luminescence imaging based on mesoporous capping UCNPs and linking lanthanide complexes.

    PubMed

    Sun, Lining; Ge, Xiaoqian; Liu, Jinliang; Qiu, Yannan; Wei, Zuwu; Tian, Bo; Shi, Liyi

    2014-11-07

    A series of new multifunctional nanomesoporous materials based on upconversion nanophosphors NaYF4:Yb,Tm@NaGdF4 (UCNPs) and lanthanide complexes were designed and synthesized through mesoporous capping UCNPs nanophosphors and linking lanthanide (Ln) complexes. The obtained UCNPs@mSiO2-Ln(dbm)4 (Ln = Eu, Sm, Er, Nd, Yb) materials can achieve downconversion and upconversion luminescence to show multicolor emission (covering the spectral region from 450 nm to 1700 nm) under visible-light excitation and 980 nm excitation, respectively. In addition, low cytotoxicity and good biocompatibility was found as determined by methyl thiazolyl tetrazolium assay, and the nanomesoporous materials were successfully applied to cell imaging in vitro based on Eu(3+) luminescence (under 405 nm excitation) and small animal imaging based on Tm(3+) luminescence (under 980 nm excitation). The doped Gd(3+) ion endows the nanomesoporous materials UCNPs@mSiO2-Ln(dbm)4 with effective T1 signal enhancement, which affords them as potential magnetic resonance imaging (MRI) contrast agents. Therefore, our results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications.

  4. Muffin-like lanthanide complexes with an N5O2-donor macrocyclic ligand showing field-induced single-molecule magnet behaviour.

    PubMed

    Antal, Peter; Drahoš, Bohuslav; Herchel, Radovan; Trávníček, Zdeněk

    2016-09-27

    Three mononuclear lanthanide complexes of a 2-pyridylmethyl pendant-armed 15-membered ligand {(3,12-bis(2-pyridylmethyl)-3,12,18-triaza-6,9-dioxabicyclo-[12.3.1]octadeca-1,14,16-triene); L} with general formula [Ln(L)(H2O)(NO3)](NO3)2 (Ln = Tb (1), Dy (2), and Er (3)) are reported. Based on X-ray diffraction analysis of 1 and 2, the central lanthanide atoms are nine-coordinated with the N5O4 donor set originating from the ligand L and one coordinated water molecule and one monodentate-bonded nitrato ligand. The coordination geometry of the [LnN5O4] cores can be described as a muffin-like shape. Magnetic measurements revealed that all three compounds show field-induced single-molecule magnet behaviour, with estimated energy barriers U ≈ 44-82 K. The experimental study was complemented by CASSCF calculations showing a trend of an increasing first excited energy gap (Tb → Dy → Er) within the muffin-like geometry with the lowest magnetization tunnelling probability for the Dy(III) complex 2.

  5. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with (pyrazol-1-yl)acetic acid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Scott, Brian L; Janicke, Michael T; Runde, Wolfgang

    2013-03-18

    As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (1-3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV-vis-NIR diffuse reflectance spectra with solution state UV-vis-NIR spectra suggests a different species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.

  6. Lanthanide Enhanced Luminescence (LEL) with One and Two Photon Excitation of Quantum Dyes(copyright) Lanthanide(III)-Macrocycles

    DTIC Science & Technology

    2004-01-01

    Quagliano, and L. M. Vallarino, The Addition of a Second Lanthanide Ion to Increase the Luminescence of Europium(IIl) Macrocyclic Complexes ...Increasing the Luminescence of Lanthanide (III) Macrocyclic Complexes , 2002, and United States Patent Application 20020132992, September 19, 2002. 3. J...R. Quagliano, R. C. Leif, L. M. Vallarino, and S. A. Williams, Methods to Increase the Luminescence of Lanthanide (III) Macrocyclic Complexes , Optical

  7. Lanthanide(III) complexes with a tetrapyridine pendant-armed macrocyclic ligand: 1H NMR structural determination in solution, X-ray diffraction, and density-functional theory calculations.

    PubMed

    Del C Fernandez-Fernandez, M; Bastida, R; Macías, A; Pérez-Lourido, P; Platas-Iglesias, C; Valencia, L

    2006-05-29

    Complexes between the tetrapyridyl pendant-armed macrocyclic ligand (L) and the trivalent lanthanide ions have been synthesized, and structural studies have been made both in the solid state and in aqueous solution. The crystal structures of the La, Ce, Pr, Gd, Tb, Er, and Tm complexes have been determined by single-crystal X-ray crystallography. In the solid state, all the cation complexes show a 10-coordinated geometry close to a distorted bicapped antiprism, with the pyridine pendants situated alternatively above and below the main plane of the macrocycle. The conformations of the two five-membered chelate rings present in the complexes change along the lanthanide series. The La(III) and Ce(III) complexes show a lambdadelta (or deltalambda) conformation, while the complexes of the heavier lanthanide ions present lambdalambda (or deltadelta) conformation. The cationic [Ln(L)]3+ complexes (Ln = La, Pr, Eu, Tb, and Tm) were also characterized by theoretical calculations at the density-functional theory (DFT) B3LYP level. The theoretical calculations predict a stabilization of the lambdalambda (or deltadelta) conformation on decreasing the ionic radius of the Ln(III) ion, in agreement with the experimental evidence. The solution structures show a good agreement with the calculated ones, as demonstrated by paramagnetic NMR measurements (lanthanide induced shifts and relaxation rate enhancements). The 1H NMR spectra indicate an effective D2 symmetry of the complexes in D2O solution. The 1H lanthanide induced shifts (LIS) observed for the Ce(III), Tm(III), and Yb(III) complexes can be fit to a theoretical model assuming that dipolar contributions are dominant for all protons. The resulting calculated values are consistent with highly rhombic magnetic susceptibility tensors with the magnetic axes being coincident with the symmetry axes of the molecule. In contrast with the solid-state structure, the analysis of the LIS data indicates that the Ce(III) complexes present a

  8. Macrocyclic lanthanide complexes as artificial nucleases and ribonucleases: effects of pH, metal ionic radii, number of coordinated water molecules, charge, and concentrations of the metal complexes.

    PubMed

    Chang, C Allen; Wu, Bo Hong; Kuan, Bu Yuan

    2005-09-19

    We have been interested in the design, synthesis, and characterization of artificial nucleases and ribonucleases by employing macrocyclic lanthanide complexes because their high thermodynamic stability, low kinetic lability, high coordination number, and charge density (Lewis acidity) allow more design flexibility and stability. In this paper, we report the study of the use of the europium(III) complex, EuDO2A+ (DO2A is 1,7-dicarboxymethyl-1,4,7,10-tetraazacyclododecane) and other lanthanide complexes (i.e., LaDO2A+, YbDO2A+, EuK21DA+, EuEDDA+, and EuHEDTA where K21DA is 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N'-diacetic acid, EDDA is ethylenediamine-N,N'-diacetic acid, and HEDTA is N-hydroxyethyl-ethylenediamine-N,N',N'-triacetic acid), as potential catalysts for the hydrolysis of the phosphodiester bond of BNPP (sodium bis(4-nitrophenyl)-phosphate). For the pH range 7.0-11.0 studied, EuDO2A+ promotes BNPP hydrolysis with the quickest rates among LaDO2A+, EuDO2A+, and YbDO2A+. This indicates that charge density is not the only factor affecting the reaction rates. Among the four complexes, EuDO2A+, EuK21DA+, EuEDDA+, and EuHEDTA, with their respective number of inner-sphere coordinated water molecules three, two, five, and three, EuEDDA+, with the greatest number of inner-sphere coordinated water molecules and a positive charge, promotes BNPP hydrolysis more efficiently at pH below 8.4, and the observed rate trend is EuEDDA+ > EuDO2A+ > EuK21DA+ > EuHEDTA. At pH > 8.4, the EuEDDA+ solution becomes misty and precipitates form. At pH 11.0, the hydrolysis rate of BNPP in the presence of EuDO2A+ is 100 times faster than that of EuHEDTA, presumably because the positively charged EuDO2A+ is more favorable for binding with the negatively charged phosphodiester compounds. The logarithmic hydrolysis constants (pKh) were determined, and are reported in the parentheses, by fitting the kinetic k(obs) data vs pH for EuDO2A+ (8.4), LaDO2A+ (8.4), YbDO2A+ (9.4), EuK21DA+ (7

  9. Biological and Clinical Aspects of Lanthanide Coordination Compounds

    PubMed Central

    Misra, Sudhindra N.; M., Indira Devi; Shukla, Ram S.

    2004-01-01

    The coordinating chemistry of lanthanides, relevant to the biological, biochemical and medical aspects, makes a significant contribution to understanding the basis of application of lanthanides, particularly in biological and medical systems. The importance of the applications of lanthanides, as an excellent diagnostic and prognostic probe in clinical diagnostics, and an anticancer material, is remarkably increasing. Lanthanide complexes based X-ray contrast imaging and lanthanide chelates based contrast enhancing agents for magnetic resonance imaging (MRI) are being excessively used in radiological analysis in our body systems. The most important property of the chelating agents, in lanthanide chelate complex, is its ability to alter the behaviour of lanthanide ion with which it binds in biological systems, and the chelation markedly modifies the biodistribution and excretion profile of the lanthanide ions. The chelating agents, especially aminopoly carboxylic acids, being hydrophilic, increase the proportion of their complex excreted from complexed lanthanide ion form biological systems. Lanthanide polyamino carboxylate-chelate complexes are used as contrast enhancing agents for Magnetic Resonance Imaging. Conjugation of antibodies and other tissue specific molecules to lanthanide chelates has led to a new type of specific MRI contrast agents and their conjugated MRI contrast agents with improved relaxivity, functioning in the body similar to drugs. Many specific features of contrast agent assisted MRI make it particularly effective for musculoskeletal and cerebrospinal imaging. Lanthanide-chelate contrast agents are effectively used in clinical diagnostic investigations involving cerebrospinal diseases and in evaluation of central nervous system. Chelated lanthanide complexes shift reagent aided 23Na NMR spectroscopic analysis is used in cellular, tissue and whole organ systems. PMID:18365075

  10. Coordination Complexes of Decamethylytterbocene with4,4'-Disubstituted Bipyridines: An Experimental Study of Spin Coupling inLanthanide Complexes

    SciTech Connect

    Walter, Marc D.; Berg, David J.; Andersen, Richard A.

    2005-12-08

    The paramagnetic 1:1 coordination complexes of (C5Me5)2Ybwith a series of 4,4'-disubstituted bipyridines, bipy-X, where X is Me,tert-Bu, OMe, Ph, CO2Me, and CO2Et have been prepared. All of thecomplexes are paramagnetic and the values of the magnetic susceptibilityas a function of temperature show that these values are less thanexpected for the cation, [(C5Me5)2Yb(III)(bipy-X)]+, which have beenisolated as the cation-anion ion-pairs[(C5Me5)2Yb(III)(bipy-X)]+[(C5Me5)2YbI2]f fnfn where X is CO2Et, OMe andMe. The 1H NMR chemical shifts (293 K) for the methine resonances locatedat the 6,6' site in the bipy-X ring show a linear relationship with thevalues of chiT (300 K) for the neutral complexes which illustrates thatthe molecular behavior does not depend upon the phase with one exception,viz., (C5Me5)2Yb(bipy-Me). Single crystals of the 4,4'-dimethylbipyridinecomplex undergo an irreversible, abrupt first order phase change at 228 Kthat shatters the single crystals. The magnetic susceptibility,represented in a delta vs. T plot, on this complex, in polycrystallineform undergoes reversible abrupt changes in the temperature regime 205 -212 K, which is suggested to be due to the way the individual molec ularunits pack in the unit cell. A qualitative model is proposed thataccounts for the sub-normal magnetic moments in theseytterbocene-bipyridine complexes.

  11. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    SciTech Connect

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox. Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent

  12. Complexation behavior of trivalent actinides and lanthanides with 1,10-phenanthroline-2,9-dicarboxylic acid based ligands: insight from density functional theory.

    PubMed

    Manna, Debashree; Ghanty, Tapan K

    2012-08-21

    We have investigated the complexation behavior of preorganized 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) based ligands with trivalent lanthanides and actinides using density functional theory with various GGA type exchange-correlation functionals and different basis sets. New ligands have been designed from PDA through functionalization with soft donor atoms such as sulfur, resulting in mono-thio-dicarboxylic acids (TCA/TCA1) and di-thio-dicarboxylic acid (THIO). It has been found that selectivity in terms of complexation energy of actinides over lanthanides is the maximum with TCA1 where the metal-ligand binding is through the O atoms. This unusual feature where a softer actinide metal ion is bonded strongly with hard donor oxygen atoms has been explained using the popular chemical concepts, viz., Pearson's Hard-Soft-Acid-Base (HSAB) principle and the frontier orbital theory of chemical reactivity as proposed by Fukui. Detailed analysis within the framework of the HSAB principle indicates that the presence of softer nitrogen atoms in the phenanthroline moiety (which also act as donors to the metal ion) has a profound influence in changing the soft nature of the actinide ion, which in turn binds with the hard oxygen atoms in a stronger way as compared to the valence isoelectronic lanthanide ion. Also, the trends in the variation of calculated values of the metal-ligand bond distances and the corresponding complex formation energies have been rationalized using the Fukui reactivity indices corresponding to the metal ions and the donor sites. All the calculations have also been done in the presence of solvent. The "intra-ligand synergistic effect" demonstrated here for PDA or TCA1 with soft and hard donor centers might be very important in designing new ligands for selective extraction of various metal ions in a competitive environment. However, for TCA and THIO ligands with only soft donor centers, "intra-ligand synergism" may not be very efficient although

  13. Lanthanide-containing polyimides

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, Anne K.

    1987-01-01

    The preparation of a variety of lanthanide-containing polyimide films is described, and results of their characterization are presented. The properties investigated include the glass transition temperature, thermooxidative stability, magnetic susceptibility, and electrical conductivity of the polymer. Films containing lanthanide chlorides, fluorides, and sulfides are flexible, but those containing lanthanide nitrates are extremely brittle. The addition of lanthanide acetates and acetylacetonates caused immediate gelation of two of the synthesis-mixture ingredients. It was found that, in general, the addition of lanthanide to the polyimide increases the density and glass transition temperature of the polymer but slightly decreases the thermooxidative stability.

  14. Lanthanide-containing polyimides

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, Anne K.

    1987-01-01

    The preparation of a variety of lanthanide-containing polyimide films is described, and results of their characterization are presented. The properties investigated include the glass transition temperature, thermooxidative stability, magnetic susceptibility, and electrical conductivity of the polymer. Films containing lanthanide chlorides, fluorides, and sulfides are flexible, but those containing lanthanide nitrates are extremely brittle. The addition of lanthanide acetates and acetylacetonates caused immediate gelation of two of the synthesis-mixture ingredients. It was found that, in general, the addition of lanthanide to the polyimide increases the density and glass transition temperature of the polymer but slightly decreases the thermooxidative stability.

  15. Novel near-IR absorbing phenyl-substituted phthalo- and naphthalocyanine complexes of lanthanide(III): synthesis and spectral and electrochemical properties.

    PubMed

    Dubinina, Tatiana V; Paramonova, Kseniya V; Trashin, Stanislav A; Borisova, Nataliya E; Tomilova, Larisa G; Zefirov, Nikolay S

    2014-02-21

    A series of novel phenyl-substituted planar and sandwich-type complexes of Eu, Er and Lu with phthalo and naphthalocyanine ligands was obtained. A successful synthesis of dinaphthalocyanines from the ligand is described. A selective synthetic approach to the phenyl-substituted triphthalocyanine complexes from the ligand and acetylacetonate salts of lanthanides was developed. Correlations between the ionic radii of the central metal and absorption maxima were obtained for sandwich-type complexes. It was found that intervalence (IV) bands for dinaphthalocyanine complexes were red-shifted about 200 nm in comparison with corresponding diphthalocyanines, reaching 1797 nm for the Eu complex. The electrochemical behaviour of planar and sandwich-type Lu complexes was investigated. For the first time a spectroelectrochemical study of multistep reduction and oxidation processes for a triple-decker complex was carried out using the example of the triphthalocyanine of Lu. The structures of the compounds obtained were determined by (1)H NMR and high resolution MALDI TOF/TOF. The first single-crystal structure for an aryl-substituted double-decker complex was described using the example of the diphthalocyanine of Lu, showing the presence of intramolecular π-π interactions between phenyl groups.

  16. Luminescent lanthanide chelates and methods of use

    DOEpatents

    Selvin, Paul R.; Hearst, John

    1997-01-01

    The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

  17. Complexation of lanthanides(III), americium(III), and uranium(VI) with bitopic N,O ligands: an experimental and theoretical study.

    PubMed

    Marie, Cécile; Miguirditchian, Manuel; Guillaumont, Dominique; Tosseng, Arnaud; Berthon, Claude; Guilbaud, Philippe; Duvail, Magali; Bisson, Julia; Guillaneux, Denis; Pipelier, Muriel; Dubreuil, Didier

    2011-07-18

    New functionalized terpyridine-diamide ligands were recently developed for the group actinide separation by solvent extraction. In order to acquire a better understanding of their coordination mode in solution, protonation and complexation of lanthanides(III), americium(III), and uranium(VI) with these bitopic N,O-bearing ligands were studied in homogeneous methanol/water conditions by experimental and theoretical approaches. UV-visible spectrophotometry was used to determine the protonation and stability constants of te-tpyda and dedp-tpyda. The conformations of free and protonated forms of te-tpyda were investigated using NMR and theoretical calculations. The introduction of amide functional groups on the terpyridine moiety improved the extracting properties of these new ligands by lowering their basicity and enhancing the stability of the corresponding 1:1 complexes with lanthanides(III). Coordination of these ligands was studied by density functional theory and molecular dynamics calculations, especially to evaluate potential participation of hard oxygen and soft nitrogen atoms in actinide coordination and to correlate with their affinity and selectivity. Two predominant inner-sphere coordination modes were found from the calculations: one mode where the cation is coordinated by the nitrogen atoms of the cavity and by the amide oxygen atoms and the other mode where the cation is only coordinated by the two amide oxygen atoms and by solvent molecules. Further simulations and analysis of UV-visible spectra using both coordination modes indicate that inner-sphere coordination with direct complexation of the three nitrogen and two oxygen atoms to the cation leads to the most likely species in a methanol/water solution.

  18. Two-photon sensitized visible and near-IR luminescence of lanthanide complexes using a fluorene-based donor-π-acceptor diketonate.

    PubMed

    Woodward, Adam W; Frazer, Andrew; Morales, Alma R; Yu, Jin; Moore, Anthony F; Campiglia, Andres D; Jucov, Evgheni V; Timofeeva, Tatiana V; Belfield, Kevin D

    2014-11-28

    A fluorene-based donor-acceptor ligand was successfully employed to sensitize visible and near-IR emitting lanthanide centers. The ligand construct is based on a donor-π-acceptor architecture with diphenylamino acting as the donor and a fluorenyl π bridge derivatized with a trifluoroacetonate moiety acting as both a strong acceptor and the classic bidentate scaffold for complexing metals. (1)H NMR analysis in the polar solvents THF and CDCl3 revealed the enolic form of the diketone dominant in solution equilibria at room temperature. This preferred cis-enol form binds strongly to the lanthanide(III) ions (Ln = Eu, Sm, Dy, Tb, Yb, Nd, Er, and Gd) in the presence of phenanthroline affording the resulting ternary tris(diketonates) complexes with 1,10-phenanthroline. Detailed characterization of these complexes was conducted, with particular emphasis on linear and nonlinear photophysical properties. Steady-state and time-resolved emission spectroscopy and overall photoluminescence quantum yield (PLQY) measurements were performed on all the complexes. Sizeable visible and near-IR efficiency for europium (room temperature, visible), samarium (low temperature, visible) and ytterbium, neodymium and erbium (room temperature, near-IR) was displayed, with long luminescent lifetimes for the europium and samarium complexes of 85 and 70 μs, respectively Measurement of the luminescence decay for the Yb complex at 976 nm, Nd complex at 874 nm, and Er complex at 1335 nm yielded mono-exponential decay curves, with lifetimes of ~13 μs, ~1.6 μs, and ~2.5 μs, respectively, inferring that the emission was generated by a single species. In addition, fluorescence anisotropy and two-photon absorption (2PA) spectra (via Z-scan) were obtained for the ligand and europium complex, revealing a maximum 2PA cross section of 340 GM for the latter upon excitation at 760 nm. A quadratic relationship was found by varying laser excitation power vs. luminescence intensity of the europium complex

  19. Enantioselective outer-sphere complexation of lanthanide(III) tris (pyridine-2,6-dicarboxylate) chelates with vitamin B 12 derivatives. An NMR and CD study

    NASA Astrophysics Data System (ADS)

    Meskers, Stefan C. J.; Dekkers, Harry P. J. M.

    1999-08-01

    The binding of three corrinoids, cyanocobalarnin (vitamin B 12, CNCbl), aquacobalamin (vitamin B 12a, H 2OCbl +) and dicyanocobinamide ((CN) 2Cbi), collectively denoted by Q, to the Δ- and Λ-enantiomer of Ln(DPA) 33- complexes (Ln=lanthanide, DPA=2,6-pyridine dicarboxylate) in aqueous solution at room temperature is investigated by NMR and Circular Dichroism (CD) spectroscopy. Tb(DPA) 33- induces shifts of the 1H-NMR resonances of Q. A formula, describing the dipolar interaction between the proton spin and the paramagnetic moment of the lanthanide complex, is fitted to the lanthanide induced shifts, yielding the position of Tb(DPA) 33- and the orientation of its magnetic axis with respect to the corrinoid. The magnitude of the shifts provide the value of Kavg, an average of the association constants of the two diastereomeric complexes {Δ-Tb(DPA) 33-Q) and {Λ-Tb(DPA) 33-Q}. We find Kavg=4±0.5 (B 12) and 0.8±0.2 M -1 ((CN) 2Cbi). The value for H 2OCbl + depends strongly on the solution's ionic strength I: Kavg=(7±1)×10 1, 22±5 and 16±7 M -1 at I=0.007, 0.12 and 0.22 M, respectively. The addition of the corrinoids to a (racemic) solution of Nd(DPA) 33-, induces CD in the electronic Nd(III) transitions in the 700-800 nm region (ICD). This Pfeiffer effect is attributed to an excess of Λ-Nd(DPA) 33- in the enantioselective, outer-sphere association with the corrinoids. From the magnitude of the ICD as a function of [Q], in conjunction with the (indirectly) determined CD effect of Λ-Nd(DPA) 33-, values are determined for KΔ- KΛ. We find KΔ- KΛ=-24±2 M -1 for H 2OCbl + at pH 6.7 and I=0.12 M and -12±2 M -1 at I=0.22 M; -4.4±0.5 M -1 for CNCbl and -0.9±0.3 M -1 for (CN) 2Cbi. Adopting the view that in the lanthanide series Ln(DPA) 33- chelates are isostructural, the results of the NMR and CD experiments are combined to estimate the enantioselectivity in the binding Eb, defined as ( KΔ- KΛ)/2 Kavg. We find Eb=-0.5±0.2 for H 2OCbl +, -0.7±0.2 for CNCbl

  20. Multifunctional nanomesoporous materials with upconversion (in vivo) and downconversion (in vitro) luminescence imaging based on mesoporous capping UCNPs and linking lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Sun, Lining; Ge, Xiaoqian; Liu, Jinliang; Qiu, Yannan; Wei, Zuwu; Tian, Bo; Shi, Liyi

    2014-10-01

    A series of new multifunctional nanomesoporous materials based on upconversion nanophosphors NaYF4:Yb,Tm@NaGdF4 (UCNPs) and lanthanide complexes were designed and synthesized through mesoporous capping UCNPs nanophosphors and linking lanthanide (Ln) complexes. The obtained UCNPs@mSiO2-Ln(dbm)4 (Ln = Eu, Sm, Er, Nd, Yb) materials can achieve downconversion and upconversion luminescence to show multicolor emission (covering the spectral region from 450 nm to 1700 nm) under visible-light excitation and 980 nm excitation, respectively. In addition, low cytotoxicity and good biocompatibility was found as determined by methyl thiazolyl tetrazolium assay, and the nanomesoporous materials were successfully applied to cell imaging in vitro based on Eu3+ luminescence (under 405 nm excitation) and small animal imaging based on Tm3+ luminescence (under 980 nm excitation). The doped Gd3+ ion endows the nanomesoporous materials UCNPs@mSiO2-Ln(dbm)4 with effective T1 signal enhancement, which affords them as potential magnetic resonance imaging (MRI) contrast agents. Therefore, our results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications.A series of new multifunctional nanomesoporous materials based on upconversion nanophosphors NaYF4:Yb,Tm@NaGdF4 (UCNPs) and lanthanide complexes were designed and synthesized through mesoporous capping UCNPs nanophosphors and linking lanthanide (Ln) complexes. The obtained UCNPs@mSiO2-Ln(dbm)4 (Ln = Eu, Sm, Er, Nd, Yb) materials can achieve downconversion and upconversion luminescence to show multicolor emission (covering the spectral region from 450 nm to 1700 nm) under visible-light excitation and 980 nm excitation, respectively. In addition, low cytotoxicity and good biocompatibility was found as determined by methyl thiazolyl tetrazolium assay, and the nanomesoporous materials were successfully applied to cell imaging in vitro based on Eu3+ luminescence (under 405 nm excitation) and small

  1. Five novel lanthanide complexes with 2-chloroquinoline-4-carboxylic acid and 1,10-phenanthroline: Crystal structures, molecular spectra, thermal properties and bacteriostatic activities

    NASA Astrophysics Data System (ADS)

    Wang, Ye; Jin, Cheng-Wei; He, Shu-Mei; Ren, Ning; Zhang, Jian-Jun

    2016-12-01

    Five novel lanthanide complexes [Ln2(2-ClQL)6(phen)2(H2O)2]·2H2O (Ln = Pr(1), Sm(2), Eu(3), Ho(4), Er(5)); 2-ClQL: 2-chloroquinoline-4-carboxylate; phen: 1,10-phenanthroline; were synthesized by conventional solution method at room temperature and characterized via elemental analysis, powder x-ray diffraction, Infrared spectroscopy and Raman spectrometry. The results indicate that complexes 1-5 are isostructural, and each Ln3+ ion is eight-coordinated adopting a distorted square antiprismatic molecular geometry. Binuclear complex 1 are stitched together via hydrogen bonding interactions to form 1D chains, and further to form 2D sheets by the π-π interactions. Luminescence investigation reveals that complex 3 displays strong red emission. TG/DTG-FTIR, reveal the thermal decomposition processes and products of title complexes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli, and Staphylococcus aureus.

  2. Preparation and luminescent properties of lanthanide (Eu3+ and Tb3+) complexes grafted to 3-aminopropyltriethoxysilane by covalent bonds

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjun; Wang, Haiyan

    2015-12-01

    A novel precursor PMA-Si was synthesized by modifying 1,2,4,5-benzene-tetracarboxylic acid (PMA) with 3-aminopropyltriethoxysilane (APTES). Then the hybrids were prepared by PMA-Si coordinating to lanthanide ions (Eu3+ and Tb3+) in sol-gel process. In order to improve luminescent efficiency, 1,10-Phenanthroline (Phen) was introduced to the system as the second ligand. As-prepared compounds in sol condition were coated on quartz plates to form a layer of thin film, which was different from other similar hybrids. The properties of the hybrids were characterized by FT-IR, fluorescence spectra, TG and SEM. The results showed that the obtained materials enhanced thermal stability, mechanical resistances, waterproofness as well as machining properties.

  3. Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

    SciTech Connect

    Moore, Evan G.; Xu, Jide; Dodani, Sheel; Jocher, Christoph; D'Aleo, Anthony; Seitz, Michael; Raymond, Kenneth

    2009-11-10

    The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution ({Phi}{sub tot}{sup Yb} {approx} 0.09-0.22%). Furthermore, the complexes demonstrate very high stability (pYb {approx} 18.8-21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a model Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding TD-DFT calculations at the B3LYP/6-311G{sup ++}(d,p) level of theory for a simplified model monovalent sodium complex.

  4. Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

    PubMed Central

    Moore, Evan G.; Xu, Jide; Dodani, Sheel C.; Jocher, Christoph J.; D'Aléo, Anthony; Seitz, Michael; Raymond, Kenneth N.

    2011-01-01

    The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution (ΦtotYb~0.09−0.22%). Furthermore, the complexes demonstrate very high stability (pYb ~ 18.8 – 21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a model Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding TD-DFT calculations at the B3LYP/6-311G++(d,p) level of theory for a simplified model monovalent sodium complex. PMID:20364838

  5. Chirality sensing and size recognition of N-Boc-amino acids by cage-type dimeric lanthanide complexes: chirality detection of N-Boc-aspartate anions via luminescence colour change.

    PubMed

    Ito, Hiroshi; Shinoda, Satoshi

    2015-03-04

    Chiral luminescent lanthanide complexes, characterized by covalently-linked face-to-face octadentate cyclen (tetraaza-12-crown-4) ligands, specifically bound a chiral N-Boc-aspartate among various N-Boc amino acid anions to enhance Eu(III) luminescence intensity at 615 nm. The combination of Tb(III) and Eu(III) complexes enabled naked-eye discrimination of N-Boc-D- and L-aspartates via the luminescence colour change.

  6. Investigation of the extraction complexes of light lanthanides(III) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid by EXAFS, IR, and MS in comparison with the americium(III) complex.

    PubMed

    Guoxin, Tian; Yongjun, Zhu; Jingming, Xu; Ping, Zhang; Tiandou, Hu; Yaning, Xie; Jing, Zhang

    2003-02-10

    The structure of the extraction complexes of light lanthanides (La(III), Nd(III), Eu(III)) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HBTMPDTP) have been characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), IR, and MS; the IR spectrum of the extraction complex of (241)Am with HBTMPDTP has been studied too. The molecular formula of the extraction complexes of lanthanides is deduced to be HML(4).H(2)O (M = La, Nd, Eu; L = anion of HBTMPDTP). The coordination number of Ln(III) in the complexes is 8; the coordinated donor atoms are 7 sulfur atoms from 4 HBTMDTP molecules and 1 O atom from a hydrated water molecule. With the increase of the atomic number of Ln, the coordination bond lengths of Ln-O and Ln-S decrease in the complexes. For La(III), Nd(III), and Eu(III), the coordination bond lengths of Ln-O are 2.70, 2.56, and 2.50, respectively, the coordination bond lengths of Ln-S are 3.01, 2.91, and 2.84, respectively, and the average distances between Ln and P atoms are 3.60, 3.53, and 3.46, respectively. The structure of the extraction complexes of Ln(III) with HBTMDTP is different from that of the Am(III) extraction complex. The results of IR show that there is no water coordinated with Am in the extraction complex. The molecular formula of the complex of Am(III) is deduced as being HAmL(4), and there are 8 S atoms from 4 HBTMPDTP molecules coordinated with Am. Composition and structure differences of the extraction complexes may be one of the most most important factors affecting the excellent selectivity of HBTMPDTP for Am(III) over Ln(III).

  7. Sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by a charge-transfer process.

    PubMed

    Kim, Yong Hee; Baek, Nam Seob; Kim, Hwan Kyu

    2006-01-16

    The photophysical properties of 4-naphthalen-1-yl-benzoic acid ligands and their Eu(III)-cored complexes were systematically investigated to elucidate the effective energy-transfer pathway in luminescent lanthanide complexes. A series of 4-naphthalen-1-yl-benzoic acid ligands, such as 4-naphthalen-1-yl-benzoic acid (NA-1), 4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzoic acid (NA-2), and 4-{4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzyloxy}-benzoic acid (NA-3), were synthesized and utilized for the synthesis of their Eu(III)-cored complexes, corresponding to NAC-1, NAC-2, and NAC-3. The fluorescence spectra of NA-1 and NA-2 show large Stokes shifts with increasing solvent polarity. These large Stokes shifts might be dominantly due to the formation of an intramolecular charge transfer (ICT) complex in the excited state. Also, the intensive luminescence of the Eu(III) ions by the photoexcitation of the ligand in NAC-1 and NAC-2 in polar solvents supports that the energy transfer from the ligand to the Eu(III) ion takes place efficiently. In the case of NA-3, which has a -CH2OPh- group that acts as a blocking group, there is no dependence of the fluorescence spectrum on the solvent nature and no luminescence of the Eu(III) ions by the photoexcitation of the ligand, indicating no formation of the ICT state. This can be due to the fact that the formation of the ICT state in NA-3 was prevented because the -OCH2- group acts as a blocking group by interrupting the pi-conjugation between the benzoic acid and the naphthalene unit. From these photophysical studies, we suggest that the ICT state plays a very important role in the energy-transfer pathway from the ligand to the Eu(III) ion. To our best knowledge, this is the first demonstration of sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by the charge-transfer process.

  8. One-dimensional simulation of lanthanide isotachophoresis using COMSOL.

    PubMed

    Dixon, Derek R; Clark, Sue B; Ivory, Cornelius F

    2012-03-01

    Electrokinetic separations can be used to quickly separate rare earth metals to determine their forensic signature. In this work, we simulate the concentration and separation of trivalent lanthanide cations by isotachophoresis. A one-dimensional simulation is developed using COMSOL v4.0a, a commercial finite element simulator, to represent the isotachophoretic separation of three lanthanides: lanthanum, terbium, and lutetium. The binding ligand chosen for complexation with the lanthanides is α-hydroxyisobutyric acid (HIBA) and the buffer system includes acetate, which also complexes with the lanthanides. The complexes formed between the three lanthanides, HIBA, and acetate are all considered in the simulation. We observe that the presence of only lanthanide:HIBA complexes in a buffer system with 10 mM HIBA causes the slowest lanthanide peak (lutetium) to split from the other analytes. The addition of lanthanide:acetate complexes into the simulation of the same buffer system eliminates this splitting. Decreasing the concentration of HIBA in the buffer to 7 mM causes the analyte stack to migrate faster through the capillary.

  9. Open-Shell Lanthanide(II+) or -(III+) Complexes Bearing σ-Silyl and Silylene Ligands: Synthesis, Structure, and Bonding Analysis

    PubMed Central

    2015-01-01

    Complexes featuring lanthanide (Ln)–Si bonds represent a highly neglected research area. Herein, we report a series of open-shell LnII+ and LnIII+ complexes bearing σ-bonded silyl and base-stabilized N-heterocyclic silylene (NHSi) ligands. The reactions of the LnIII+ complexes Cp3Ln (Ln = Tm, Ho, Tb, Gd; Cp = cyclopentadienide) with the 18-crown-6 (18-cr-6)-stabilized 1,4-oligosilanyl dianion [(18-cr-6)KSi(SiMe3)2SiMe2SiMe2Si(SiMe3)2K(18-cr-6)] (1) selectively afford the corresponding metallacyclopentasilane salts [Cp2Ln({Si(SiMe3)2SiMe2}2)]−[K2(18-cr-6)2Cp]+ [Ln = Tm (2a), Ho (2b), Tb (2c), Gd (2d)]. Complexes 2a–2d represent the first examples of structurally characterized Tm, Ho, Tb, and Gd complexes featuring Ln–Si bonds. Strikingly, the analogous reaction of 1 with the lighter element analogue Cp3Ce affords the acyclic product [Cp3CeSi(SiMe3)2SiMe2SiMe2Si(SiMe3)2-Cp3Ce]2–2[K(18-cr-6)]+ (3) as the first example of a complex featuring a Ce–Si bond. In an alternative synthetic approach, the aryloxy-functionalized benzamidinato NHSi ligand Si(OC6H4-2-tBu){(NtBu)2CPh} (4a) and the alkoxy analogue Si(OtBu){(NtBu)2CPh} (4b) were reacted with Cp*2Sm(OEt2), affording, by OEt2 elimination, the corresponding silylene complexes, both featuring SmII+ centers: Cp*2Sm ← :Si(O–C6H4-2-tBu){(NtBu)2CPh} (6) and Cp*2Sm ← :Si(OtBu){(NtBu)2CPh} (5). Complexes 5 and 6 are the first four-coordinate silylene complexes of any f-block element to date. All complexes were fully characterized by spectroscopic means and by single-crystal X-ray diffraction analysis. In the series 2a–2d, a linear correlation was observed between the Ln–Si bond lengths and the covalent radii of the corresponding Ln metals. Moreover, in complexes 5 and 6, notably long Sm–Si bonds are observed, in accordance with a donor–acceptor interaction between Si and Sm [5, 3.4396(15) Å; 6, 3.3142(18) Å]. Density functional theory calculations were carried out for complexes 2a–2d, 5, and 6 to

  10. The energetic and structural effects of steric crowding in phosphate and dithiophosphinate complexes of lanthanide cations M3+: a computational study.

    PubMed

    Boehme, C; Wipff, G

    2001-04-01

    Metal-ligand binding strength and selectivity result from antagonistic metal-ligand M-L attractions and ligand-ligand L-L repulsions. On the basis of quantum-mechanical (QM) calculations on lanthanide complexes, we show that this interplay determines the binding affinities in the gas phase. In the series of [ML3] complexes (M = La, Eu, and Yb) with negatively charged phosphoryl ligands L- = (MeO)2PO2- and Me2PS2-, the binding energies follow the order Yb3+ > Eu3+ > La3- for a given ligand, and (MeO)2PO2- > Me2PS2- for a given cation. However, adding a neutral LH ligand to [ML3] changes the order to Eu3+ > Yb3+ > La3+ for the oxygen ligand and La3+ > Eu3- > Yb3+ for the sulfur ligand, indicating that steric strain in the first coordination sphere is largest for the smallest cation and for sulfur binding sites. We investigated the question of additional hydration of the [ML3LH] complexes in aqueous solution by molecular dynamics (MD) simulations, using two sets of atomic charges. It was found that pairwise additive potentials overestimate the coordination and hydration numbers of the cations, while adding polarization energy terms for the ligands yields better agreement between QM and MD results and supports the concept of steric strain in the first coordination sphere.

  11. Homo dinuclear lanthanide(III) complexes of a mesogenic Schiff-base, N,N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane: synthesis and characterization.

    PubMed

    Shakya, Pawan Raj; Singh, Angad Kumar; Rao, T R

    2011-09-01

    A mesogenic Schiff-base, N,N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane, H2ddsdh (abbreviated as H2L2) that exhibits smectic-B (SmB) mesophase, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR & IR spectral techniques. The Schiff-base, H2L2, upon condensation with hydrated lanthanide(III) nitrates, yields LnIII complexes of the general composition [Ln2(L2H2)3(NO3)4](NO3)2, where Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L2H2) to the LnIII ions through two phenolate oxygens. The POM and DSC studies reveal that none of the LnIII complexes exhibits mesomorphism. Fluorescence studies show that the TbIII complex displays characteristic metal-centered fluorescence (solution state). Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Solid state and solution properties of lanthanide(III) complexes of a tetraiminodiphenolate macrocyclic ligand. X-ray structure, 1H NMR and luminescence spectral studies

    NASA Astrophysics Data System (ADS)

    Bag, Pradip; Dutta, Supriya; Flörke, Ulrich; Nag, Kamalaksha

    2008-11-01

    The lanthanide(III) complexes of composition [Ln(LH 2)(H 2O) 3Cl]Cl 2 (Ln = La-Lu and Y, 1- 15) derived from the tetraiminodiphenolate macrocyclic ligand L 2- have been prepared and characterized. In these compounds, the two uncoordinated imine nitrogens of the macrocycle are protonated and hydrogen-bonded with the metal-bound phenolate oxygens and thereby provide a zwitterionic structure to the ligand. The X-ray crystal structure of the compounds of La and Nd have been determined and they are found to be isostructural. The coordination polyhedra for the eight-coordinated metal centre in the complex cation [Ln(N 2O 2)(O 3Cl)] 2+ can be described as distorted square antiprism. Intermolecular hydrogen-bondings involving the three coordinated water molecules and the two uncoordinated chloride ions give rise to the 2-D network in which the chlorides are triply hydrogen-bridged and the water molecules are doubly hydrogen-bridged. Moreover, the aromatic rings in this network are involved in π-π interaction in two different ways. 1H NMR spectra of the complexes in (CD 3) 2SO have been studied. The spectral assignments for the paramagnetic complexes of Ce-Eu have been made from { 1H- 1H} COSY spectra and longitudinal relaxation time ( T1) measurements. It is inferred that the complex species [Ln(LH 2){(CD 3) 2SO} 4] 3+ that exist in solution are isostructural for the compounds of La-Eu. The contact and pseudo-contact contribution to the isotropic paramagnetic shifts in the complexes of Ce-Eu have been estimated. The luminescence spectra of the complexes of La, Sm, Eu and Tb have been studied in methanol-ethanol (1:4) glassy matrix and in the solid state at 77 K, and the quantum yields have been estimated.

  13. The addition of a second lanthanide ion to increase the luminescence of europium(III) macrocyclic complexes

    SciTech Connect

    Bromm, A.J. Jr.; Vallarino, L.M.; Leif, R.C.; Quagliano, J.R.

    1998-12-29

    At present, the microscopic visualization of luminescent labels containing lanthanide(III) ions, primarily europium(III), as light-emitting centers is best performed with time-gated instrumentation, which by virtually eliminating the background fluorescence results in an improved signal to noise ratio. However, the use of the europium(III) macrocycle, Quantum Dye{trademark}, in conjunction with the strong luminescence enhancing effect (cofluorescence) of yttrium(III) or gadolinium(III), can eliminate the need for such specialized instrumentation. In the presence of Gd(III), the luminescence of the Eu(III)-macrocycles can be conveniently observed with conventional fluorescence instrumentation at previously unattainable low levels. The Eu(III) {sup 5}D{sub 0} {r_arrow} {sup 7}F{sub 2} emission of the Eu(III)-macrocycles was observed as an extremely sharp band with a maximum at 619 nm and a clearly resolved characteristic pattern. At very low Eu(III)-macrocycle concentrations, another sharp emission was detected at 614 nm, arising from traces of Eu(III) present in even the purest commercially available gadolinium products. Discrimination of the resolved emissions of the Eu(III)-macrocycle and Eu(III) contaminant should provide a means to further lower the limit of detection of the Eu(III)-macrocycle.

  14. Optimizing the luminescence of lanthanide(III) macrocyclic complexes for the detection of anti-5BrdU

    NASA Astrophysics Data System (ADS)

    Leif, Robert C.; Becker, Margie C.; Bromm, Alfred J., Jr.; Vallarino, Lidia M.; Williams, John; Williams, Steven A.; Yang, Sean

    2002-05-01

    A Eu(III)-macrocycle-mono-isothiocyanate, Quantum Dye®, has been coupled to a monoclonal antibody against 5BrdU. Since Quantum Dyes do not undergo concentration quenching, the coupling conditions were optimized to achieve the maximum number of Eu(III) macrocycles bound to the antiBrdU, without decrease in solubility or loss of antigen-binding ability. In order to optimize the coupling conditions, a colorimetric method for the quantitation of the Eu(III)- macrocycle-mono-isothio-cyanate has been developed. A simple mixture composed of an ethanolic solution and a Gd(III)- containing aqueous solution is now used to provide lanthanide enhanced luminescence, LEL. Under LEL conditions, the specific binding of Eu(III) macrocycles to apoptotic cells has been observed in both aqueous and mounted slide preparations. A comparison between measurements of the same LEL model system, obtained in both time-gated luminescence and standard fluorescence modes, has demonstrated that time- gating significantly improves the signal to noise ratio.

  15. Lanthanide-based luminescence biolabelling.

    PubMed

    Sy, Mohamadou; Nonat, Aline; Hildebrandt, Niko; Charbonnière, Loïc J

    2016-04-14

    Luminescent lanthanide complexes display unrivalled spectroscopic properties, which place them in a special category in the luminescent toolbox. Their long-lived line-like emission spectra are the cornerstones of numerous analytical applications ranging from ultrasensitive homogeneous fluoroimmunoassays to the study of molecular interactions in living cells with multiplexed microscopy. However, achieving such minor miracles is a result of years of synthetic efforts and spectroscopic studies to understand and gather all the necessary requirements for the labels to be efficient. This feature article intends to survey these criteria and to discuss some of the most important examples reported in the literature, before explaining in detail some of the applications of luminescent lanthanide labels to bioanalysis and luminescence microscopy. Finally, the emphasis will be put on some recent applications that hold great potential for future biosensing.

  16. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  17. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  18. Multinuclear magnetic resonance study on the structure and dynamics of lanthanide(III) complexes of cyclic DTPA derivatives in aqueous solution

    SciTech Connect

    Bovens, E.; Hoefnagel, M.A.; Boers, E.

    1996-12-18

    The lanthanide coordination of the macrocyclic ligands cy(DTPA-EN) and cy (DTPA-EN-DTPA-EN) was studied in aqueous solution. {sup 17}O NMR measurements on the Dy{sup III} complexes showed that, in both complexes, the first coordination sphere of the Ln{sup III} ion contains one water molecule, leaving eight coordination sites for the ligand molecule. {sup 89}Y and {sup 139}La NMR analysis confirmed that the coordination mode of cy(DTPA-EN-DTPA-EN) is similar to that of the acyclic DTPA-bis(amide) derivatives. However, as a result of the cyclic nature of the similar to that of the acyclic DTPA-bis(amide) derivatives. However, as a result of the cyclic nature of the ligands considered the number of isomers in solution is lower than for the acyclic compounds. From variable-temperature {sup 1}H and {sup 13}C NMR data, the authors conclude that, in the respective Ln{sup III} complexes in solution, the cy(DTPA-EN) ligand is present in two rapidly interconverting isomers, whereas the cy(DTPA-EN-DTPA-EN) ligand exists in four isomeric forms. Two types of exchange processes are observed for the cy(DTPA-EN-DTPA-EN) complexes; one is fast on the NMR time scale and does not require decoordination of the ligand, and the second is relatively slow and decoordination is necessary to realize the interconversion. The complexes of cy(DTPA-EN) and the lighter Ln{sup III} ions (Ln = La {yields} Eu) precipitated, probably due to the formation of binuclear complexes. Comparisons are made with the previously studied acyclic DTPA-bis (amides).

  19. Series of isostructural planar lanthanide complexes [Ln(III)4(mu3-OH)2(mdeaH)2(piv)8] with single molecule magnet behavior for the Dy4 analogue.

    PubMed

    Abbas, Ghulam; Lan, Yanhua; Kostakis, George E; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

    2010-09-06

    A series of five isostructural tetranuclear lanthanide complexes of formula [Ln(4)(mu(3)-OH)(2)(mdeaH)(2)(piv)(8)], (mdeaH(2) = N-methyldiethanolamine; piv = pivalate; Ln = Tb (1), Dy (2), Ho (3), Er (4), and Tm (5)) have been synthesized and characterized. These clusters have a planar "butterfly" Ln(4) core. Magnetically, the Ln(III) ions are weakly coupled in all cases; the Dy(4) compound 2 shows Single Molecule Magnet (SMM) behavior.

  20. 17O NMR and density functional theory study of the dynamics of the carboxylate groups in DOTA complexes of lanthanides in aqueous solution.

    PubMed

    Mayer, Florian; Platas-Iglesias, Carlos; Helm, Lothar; Peters, Joop A; Djanashvili, Kristina

    2012-01-02

    The rotation of the carboxylate groups in DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate) complexes of several lanthanide ions and Sc(3+) was investigated with density functional theory (DFT) calculations and with variable temperature (17)O NMR studies at 4.7-18.8 T. The data obtained show that the rotation is much slower than the other dynamic processes taking place in these complexes. The exchange between the bound and unbound carboxylate oxygen atoms for the largest Ln(3+) ions (La(3+)→Sm(3+)) follows a pathway via a transition state in which both oxygens of the carboxylate group are bound to the Ln(3+) ion, whereas for the smaller metal ions (Tm(3+), Lu(3+), Sc(3+)) the transition state has a fully decoordinated carboxylate group. The activation free energies show a steady increase from about 75 to 125-135 kJ·mol(-1) going from La(3+) to Lu(3+). This computed trend is consistent with the results of the (17)O NMR measurements. Fast exchange between bound and unbound carboxylate oxygen atoms was observed for the diamagnetic La-DOTA, whereas for Pr-, Sm-, Lu-, and Sc-DOTA the exchange was slow on the NMR time scale. The trends in the linewidths for the various metal ions as a function of the temperature agree with trends in the rates as predicted by the DFT calculations.

  1. Responsive, di-metallic lanthanide complexes of a piperazine-bridged bis-macrocyclic ligand: modulation of visible luminescence and proton relaxivity.

    PubMed

    Andrews, Michael; Amoroso, Angelo J; Harding, Lindsay P; Pope, Simon J A

    2010-04-14

    The synthesis of a new functionalised bis-macrocyclic ligand (L1) is described together with the corresponding Ln(III) complexes, Ln(2)- (Ln = Gd(III), Eu(III)). Phosphorescence measurements on Gd(2)- at 77 K allowed the ligand-centred triplet state ((3)pi-pi*) to be estimated at ca. 28500 cm(-1). Steady state and time-resolved measurements confirmed emission from the f-centred excited state ((5)D(0)) for Eu(2)-. (1)H NMRD profiles revealed the longitudinal proton relaxivity (r(1)) of Gd(2)- to be 8.3 mM(-1)s(-1)(30 MHz, 25 degrees C). The interaction of Cu(II) and Hg(II) with the lanthanide complexes was probed using luminescence and relaxivity measurements. Addition of Cu(II) (10 eq.) resulted in quenching of the Eu(III) emission, but no increase in r(1) of the Gd(III) dimer. Addition of Hg(II) (10 eq.) caused changes to the hypersensitive emission bands of Eu(III) together with an increase in r(1) of Gd(2)- to be 10.3 mM(-1)s(-1)(30 MHz, 25 degrees C) suggesting a net increase in hydration at the Gd(III) centres.

  2. Anisotropic optical trapping as a manifestation of the complex electronic structure of ultracold lanthanide atoms: The example of holmium

    NASA Astrophysics Data System (ADS)

    Li, Hui; Wyart, Jean-François; Dulieu, Olivier; Lepers, Maxence

    2017-06-01

    The efficiency of optical trapping is determined by the atomic dynamic dipole polarizability, whose real and imaginary parts are associated with the potential energy and photon-scattering rate, respectively. In this article we develop a formalism to calculate analytically the real and imaginary parts of the scalar, vector, and tensor polarizabilities of lanthanide atoms. We assume that the sum-over-state formula comprises only transitions involving electrons in the valence orbitals like 6 s ,5 d ,6 p , and 7 s , while transitions involving 4 f core electrons are neglected. Applying this formalism to the ground level of configuration 4 fq6 s2 , we restrict the sum to transitions implying the 4 fq6 s 6 p configuration, which yields polarizabilities depending on two parameters: an effective transition energy and an effective transition dipole moment. Then, by introducing configuration-interaction mixing between 4 fq6 s 6 p and other configurations, we demonstrate that the imaginary part of the scalar, vector, and tensor polarizabilities is very sensitive to configuration-interaction coefficients, whereas the real part is not. The magnitude and anisotropy of the photon-scattering rate are thus strongly related to the details of the atomic electronic structure. Those analytical results agree with our detailed electronic-structure calculations of the energy levels, Landé g factors, transition probabilities, polarizabilities, and van der Waals C6 coefficients, previously performed on erbium and dysprosium and presently performed on holmium. Our results show that, although the density of states decreases with increasing q , the configuration interaction between 4 fq6 s 6 p ,4 fq -15 d 6 s2 , and 4 fq -15 d26 s is surprisingly stronger in erbium (q =12 ) than in holmium (q =11 ), itself stronger than in dysprosium (q =10 ).

  3. Brucella Control of Dendritic Cell Maturation Is Dependent on the TIR-Containing Protein Btp1

    PubMed Central

    Salcedo, Suzana P; Marchesini, María Ines; Lelouard, Hugues; Fugier, Emilie; Jolly, Gilles; Balor, Stephanie; Muller, Alexandre; Lapaque, Nicolas; Demaria, Olivier; Alexopoulou, Lena; Comerci, Diego J; Ugalde, Rodolfo A; Pierre, Philippe; Gorvel, Jean-Pierre

    2008-01-01

    Brucella is an intracellular pathogen able to persist for long periods of time within the host and establish a chronic disease. We show that soon after Brucella inoculation in intestinal loops, dendritic cells from ileal Peyer's patches become infected and constitute a cell target for this pathogen. In vitro, we found that Brucella replicates within dendritic cells and hinders their functional activation. In addition, we identified a new Brucella protein Btp1, which down-modulates maturation of infected dendritic cells by interfering with the TLR2 signaling pathway. These results show that intracellular Brucella is able to control dendritic cell function, which may have important consequences in the development of chronic brucellosis. PMID:18266466

  4. Titanium, aluminum and zinc complexes containing diamine-bis(benzotriazole phenolate) ligands: Synthesis, structural characterization and catalytic studies for ring-opening polymerization of ε-caprolactone

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Tang; Li, Chen-Yu; Chen, Jhy-Der; Liu, Wan-Ling; Tsai, Chen-Yen; Ko, Bao-Tsan

    2017-04-01

    Structurally diverse metal complexes bearing diamine-bis(benzotriazole phenolate) (DiBTP) ligands have been synthesized and fully characterized by single crystal X-ray crystallography. The reaction of Ti(OiPr)4 with C8MEADiBTP-H2 or C8BEADiBTP-H2 (1.0 mol equiv.) generated the monomeric titanium alkoxy complexes [(C8MEADiBTP)Ti(OiPr)2] (1) and [(C8BEADiBTP)Ti(OiPr)2] (2), respectively. Moreover, C8BEADiBTP-H2 reacted with 2.0 molar equiv. of AlMe3 to give the tetra-coordinated di-aluminum complex [(C8BEADiBTP)Al2Me4] (3). Zinc complex [(C8BEADiBTP)Zn2Et2] (4) could be obtained by the alkane elimination of ZnEt2 (2.0 equiv.) with C8BEADiBTP-H2 as the pro-ligand under similar synthetic methods in good yield. Single-crystal X-ray diffraction indicates that 3 is a bimetallic aluminum dimethyl complex with a tetradentate C8BEADiBTP moiety chelating two metal atoms, whereas complex 4 displays the dinuclear feature containing both tetra- and penta-coordinated zinc atoms bonded by one ONNON-pentadentate C8BEADiBTP ligand. Catalytic studies for ring-opening polymerization of ε-caprolactone of complex 1-4 were systematic explored; the comparative studies of such polymerization were also discussed.

  5. Sorption of trivalent lanthanides and actinides onto montmorillonite: Macroscopic, thermodynamic and structural evidence for ternary hydroxo and carbonato surface complexes on multiple sorption sites.

    PubMed

    Fernandes, M Marques; Scheinost, A C; Baeyens, B

    2016-08-01

    The credibility of long-term safety assessments of radioactive waste repositories may be greatly enhanced by a molecular level understanding of the sorption processes onto individual minerals present in the near- and far-fields. In this study we couple macroscopic sorption experiments to surface complexation modelling and spectroscopic investigations, including extended X-ray absorption fine structure (EXAFS) and time-resolved laser fluorescence spectroscopies (TRLFS), to elucidate the uptake mechanism of trivalent lanthanides and actinides (Ln/An(III)) by montmorillonite in the absence and presence of dissolved carbonate. Based on the experimental sorption isotherms for the carbonate-free system, the previously developed 2 site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) model needed to be complemented with an additional surface complexation reaction onto weak sites. The fitting of sorption isotherms in the presence of carbonate required refinement of the previously published model by reducing the strong site capacity and by adding the formation of Ln/An(III)-carbonato complexes both on strong and weak sites. EXAFS spectra of selected Am samples and TRLFS spectra of selected Cm samples corroborate the model assumptions by showing the existence of different surface complexation sites and evidencing the formation of Ln/An(III) carbonate surface complexes. In the absence of carbonate and at low loadings, Ln/An(III) form strong inner-sphere complexes through binding to three Al(O,OH)6 octahedra, most likely by occupying vacant sites in the octahedral layers of montmorillonite, which are exposed on {010} and {110} edge faces. At higher loadings, Ln/An(III) binds to only one Al octahedron, forming a weaker, edge-sharing surface complex. In the presence of carbonate, we identified a ternary mono- or dicarbonato Ln/An(III) complex binding directly to one Al(O,OH)6 octahedron, revealing that type-A ternary complexes form with the one

  6. The formation stability, hydrolytic behavior, mass spectrometry, DFT study, and luminescence properties of trivalent lanthanide complexes of H2ODO2A.

    PubMed

    Chang, C Allen; Wang, I-Fan; Lee, Hwa-Yu; Meng, Ching-Ning; Liu, Kuan-Yu; Chen, Ya-Fen; Yang, Tsai-Hua; Wang, Yun-Ming; Tsay, Yeou-Guang

    2012-12-28

    The trivalent lanthanide complex formation constants (log K(f)) of the macrocyclic ligand H(2)ODO2A (4,10-dicarboxymethyl-1-oxa-4,7,10-triazacyclododecane) have been determined by pH titration techniques to be in the range 10.84-12.62 which increase with increasing lanthanide atomic number, and are smaller than those of the corresponding H(2)DO2A (1,7-dicarboxylmethyl-1,4,7,10-tetraazacyclododecane) complexes. The equilibrium formation of the dinuclear hydrolysis species, e.g. Ln(2)(ODO2A)(2)(μ-OH)(+) and Ln(2)(ODO2A)(2)(μ-OH)(2), dominates over the mononuclear species, e.g. LnODO2A(OH) and LnODO2A(OH)(2)(-). Mass spectrometry confirmed the presence of [Eu(ODO2A)](+), [Eu(ODO2A)(OH)+H](+), [Eu(2)(ODO2A)(2)(OH(2))(2)+H](+), [Eu(ODO2A)(OH)(2)](-) and [Eu(2)(ODO2A)(2)(OH(2))(3)](-) species at pH > 7. Density function theory (DFT) calculated structures of the EuODO2A(H(2)O)(3)(+) and EuDO2A(H(2)O)(3)(+) complexes indicate that three inner-sphere coordinated water molecules are arranged in a meridional configuration, i.e. the 3 water molecules are on the same plane perpendicular to that of the basal N(3)O or N(4) atoms. However, luminescence lifetime studies reveal that the EuODO2A(+) and TbODO2A(+) complexes have 4.1 and 2.9 inner-sphere coordinated water molecules, respectively, indicating that other equilibrium species are also present for the EuODO2A(+) complex. The respective emission spectral intensities and lifetimes at 615 nm (λ(ex) = 395 nm) and 544 nm (λ(ex) = 369 nm) of the EuODO2A(+) and TbODO2A(+) complexes increase with increasing pH, consistent with the formation of μ-OH-bridged dinuclear species at higher pH. Additional DFT calculations show that each Y(iii) ion is 8-coordinated in the three possible cis-[Y(2)(ODO2A)(2)(μ-OH)(H(2)O)(2)](+), trans-[Y(2)(ODO2A)(2)(μ-OH)(H(2)O)(2)](+) and [Y(2)(ODO2A)(2)(μ-OH)(2)] dinuclear complex structures. The first and the second include 6-coordination by the ligand ODO2A(2-), one by the bridged μ-OH ion and

  7. Structural requirements for the inhibition of calcium mobilization and mast cell activation by the pyrazole derivative BTP2.

    PubMed

    Law, Mankit; Morales, J Luis; Mottram, Laurie F; Iyer, Archana; Peterson, Blake R; August, Avery

    2011-08-01

    Mast cells play a critical role in the development of the allergic response. Upon activation by allergens and IgE via the high affinity receptor for IgE (FcɛRI), these cells release histamine and other functional mediators that initiate and propagate immediate hypersensitivity reactions. Mast cells also secrete cytokines that can regulate immune activity. These processes are controlled, in whole or part, by increases in intracellular Ca(2+) induced by the FcɛRI. We show here that N-(4-(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)phenyl)-4-methyl-1,2,3-thiadiazole-5-carboxamide (BTP2), a pyrazole derivative, inhibits activation-induced Ca(2+) influx in the rat basophil cell line RBL-2H3 and in bone marrow-derived mast cells (BMMCs), without affecting global tyrosine phosphorylation of cellular proteins or phosphorylation of the mitogen-activated protein kinases Erk1/2, JNK and p38. BTP2 also inhibits activation-induced degranulation and secretion of interleukin (IL)-2, IL-3, IL-4, IL-6, IL-13, tumor necrosis factor (TNF)-α, and granulocyte macrophage-colony stimulating factor (GM-CSF) by BMMCs, which correlates with the inhibition of Nuclear Factor of Activated T cells (NFAT) translocation. In vivo, BTP2 inhibits antigen-induced histamine release. Structure-activity relationship analysis indicates that substitution at the C3 or C5 position of the pyrazole moiety on BTP2 (5-trifluoromethyl-3-methyl-pyrazole or 3-trifluoromethyl-5-methyl-pyrazole, respectively) affected its activity, with the trifluoromethyl group at the C3 position being critical to its activity. We conclude that BTP2 and related compounds may be potent modulators of mast cell responses and potentially useful for the treatment of symptoms of allergic inflammation.

  8. A family of 13 tetranuclear zinc(II)-lanthanide(III) complexes of a [3+3] Schiff-base macrocycle derived from 1,4-diformyl-2,3-dihydroxybenzene.

    PubMed

    Feltham, Humphrey L C; Klöwer, Frederik; Cameron, Scott A; Larsen, David S; Lan, Yanhua; Tropiano, Manuel; Faulkner, Stephen; Powell, Annie K; Brooker, Sally

    2011-11-21

    A family of thirteen tetranuclear heterometallic zinc(II)-lanthanide(III) complexes of the hexa-imine macrocycle (L(Pr))(6-), with general formula Zn(II)(3)Ln(III)(L(Pr))(NO(3))(3)·xsolvents (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), were prepared in a one-pot synthesis using a 3:1:3:3 reaction of zinc(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H(2)L(1)) and 1,3-diaminopropane. A hexanuclear homometallic zinc(II) macrocyclic complex [Zn(6)(L(Pr))(OAc)(5)(OH)(H(2)O)]·3H(2)O was obtained using a 2:0:1:1 ratio of the same reagents. A control experiment using a 1:0:1:1 ratio failed to generate the lanthanide-free [Zn(3)(L(Pr))] macrocyclic complex. The reaction of H(2)L(1) and zinc(II) acetate in a 1:1 ratio yielded the pentanuclear homometallic complex of the dialdehyde H(2)L(1), [Zn(5)(L(1))(5)(H(2)O)(6)]·3H(2)O. An X-ray crystal structure determination revealed [Zn(3)(II)Pr(III)(L(Pr))(NO(3))(2)(DMF)(3)](NO(3))·0.9DMF has the large ten-coordinate lanthanide(III) ion bound in the central O(6) site with two bidentate nitrate anions completing the O(10) coordination sphere. The three square pyramidal zinc(II) ions are in the outer N(2)O(2) sites with a fifth donor from DMF. Measurement of the magnetic properties of [Zn(II)(3)Dy(III)(L(Pr))(NO(3))(3)(MeOH)(3)]·4H(2)O with a weak external dc field showed that it has a frequency-dependent out-of-phase component of ac susceptibility, indicative of slow relaxation of the magnetization (SMM behaviour). Likewise, the Er and Yb analogues are field-induced SMMs; the latter is only the second example of a Yb-based SMM. The neodymium, ytterbium and erbium complexes are luminescent in the solid phase, but only the ytterbium and neodymium complexes show strong lanthanide-centred luminescence in DMF solution.

  9. Understanding the complexation of Eu(3+) with potential ligands used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle: A luminescence investigation.

    PubMed

    Sengupta, Arijit; Kadam, R M

    2017-02-15

    A systematic photoluminescence based investigation was carried out to understand the complexation of Eu(3+) with different ligands (TBP: tri-n-butyl phosphate, DHOA: di-n-hexyl octanamide, Cyanex 923: tri-n-alkyl phosphine oxide and Cyanex 272: Bis (2,4,4 trimethyl) pentyl phosphinic acid) used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle. In case of TBP and DHOA complexes, 3 ligand molecules coordinated in monodentate fashion and 3 nitrate ion in bidentate fashion to Eu(3+) to satisfy the 9 coordination of Eu. In case of Cyanex 923 and Cyanex 272 complexes, 3 ligand molecules, 3 nitrate ion and 3 water molecules coordinated to Eu(3+) in monodentate fashion. The Eu complexes of TBP and DHOA were found to have D3h local symmetry while that for Cyanex 923 and Cyanex 272 were C3h. Judd-Ofelt analysis of these systems revealed that the covalency of EuO bond followed the trend DHOA>TBP>Cyanex 272>Cyanex 923. Different photophysical properties like radiative and non-radiative life time, branching ratio for different transitions, magnetic and electric dipole moment transition probabilities and quantum efficiency were also evaluated and compared for these systems. The magnetic dipole transition probability was found to be almost independent of ligand field perturbation while electric dipole transition probability for (5)D0-(7)F2 transition was found to be hypersensitive with ligand field with a trend DHOA>TBP>Cyanex 272>Cyanex 923. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Understanding the complexation of Eu3 + with potential ligands used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle: A luminescence investigation

    NASA Astrophysics Data System (ADS)

    Sengupta, Arijit; Kadam, R. M.

    2017-02-01

    A systematic photoluminescence based investigation was carried out to understand the complexation of Eu3 + with different ligands (TBP: tri-n-butyl phosphate, DHOA: di-n-hexyl octanamide, Cyanex 923: tri-n-alkyl phosphine oxide and Cyanex 272: Bis (2,4,4 trimethyl) pentyl phosphinic acid) used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle. In case of TBP and DHOA complexes, 3 ligand molecules coordinated in monodentate fashion and 3 nitrate ion in bidentate fashion to Eu3 + to satisfy the 9 coordination of Eu. In case of Cyanex 923 and Cyanex 272 complexes, 3 ligand molecules, 3 nitrate ion and 3 water molecules coordinated to Eu3 + in monodentate fashion. The Eu complexes of TBP and DHOA were found to have D3h local symmetry while that for Cyanex 923 and Cyanex 272 were C3h. Judd-Ofelt analysis of these systems revealed that the covalency of Eusbnd O bond followed the trend DHOA > TBP > Cyanex 272 > Cyanex 923. Different photophysical properties like radiative and non-radiative life time, branching ratio for different transitions, magnetic and electric dipole moment transition probabilities and quantum efficiency were also evaluated and compared for these systems. The magnetic dipole transition probability was found to be almost independent of ligand field perturbation while electric dipole transition probability for 5D0-7F2 transition was found to be hypersensitive with ligand field with a trend DHOA > TBP > Cyanex 272 > Cyanex 923. Supplementary Table 2: Determination of inner sphere water molecules from the different empirical formulae reported in the literature.

  11. Design principles and theory of paramagnetic fluorine-labelled lanthanide complexes as probes for (19)F magnetic resonance: a proof-of-concept study.

    PubMed

    Chalmers, Kirsten H; De Luca, Elena; Hogg, Naomi H M; Kenwright, Alan M; Kuprov, Ilya; Parker, David; Botta, Mauro; Wilson, J Ian; Blamire, Andrew M

    2010-01-04

    The synthesis and spectroscopic properties of a series of CF(3)-labelled lanthanide(III) complexes (Ln=Gd, Tb, Dy, Ho, Er, Tm) with amide-substituted ligands based on 1,4,7,10-tetraazacyclododecane are described. The theoretical contributions of the (19)F magnetic relaxation processes in these systems are critically assessed and selected volumetric plots are presented. These plots allow an accurate estimation of the increase in the rates of longitudinal and transverse relaxation as a function of the distance between the Ln(III) ion and the fluorine nucleus, the applied magnetic field, and the re-rotational correlation time of the complex, for a given Ln(III) ion. Selected complexes exhibit pH-dependent chemical shift behaviour, and a pK(a) of 7.0 was determined in one example based on the holmium complex of an ortho-cyano DO3A-monoamide ligand, which allowed the pH to be assessed by measuring the difference in chemical shift (varying by over 14 ppm) between two (19)F resonances. Relaxation analyses of variable-temperature and variable-field (19)F, (17)O and (1)H NMR spectroscopy experiments are reported, aided by identification of salient low-energy conformers by using density functional theory. The study of fluorine relaxation rates, over a field range of 4.7 to 16.5 T allowed precise computation of the distance between the Ln(III) ion and the CF(3) reporter group by using global fitting methods. The sensitivity benefits of using such paramagnetic fluorinated probes in (19)F NMR spectroscopic studies are quantified in preliminary spectroscopic and imaging experiments with respect to a diamagnetic yttrium(III) analogue.

  12. Upconverting rare-earth nanoparticles with a paramagnetic lanthanide complex shell for upconversion fluorescent and magnetic resonance dual-modality imaging

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Ji, Lei; Zhang, Bingbo; Yin, Peihao; Qiu, Yanyan; Song, Daqian; Zhou, Juying; Li, Qi

    2013-05-01

    Multi-modal imaging based on multifunctional nanoparticles is a promising alternative approach to improve the sensitivity of early cancer diagnosis. In this study, highly upconverting fluorescence and strong relaxivity rare-earth nanoparticles coated with paramagnetic lanthanide complex shells and polyethylene glycol (PEGylated UCNPs@DTPA-Gd3+) are synthesized as dual-modality imaging contrast agents (CAs) for upconverting fluorescent and magnetic resonance dual-modality imaging. PEGylated UCNPs@DTPA-Gd3+ with sizes in the range of 32-86 nm are colloidally stable. They exhibit higher longitudinal relaxivity and transverse relaxivity in water (r1 and r2 values are 7.4 and 27.8 s-1 per mM Gd3+, respectively) than does commercial Gd-DTPA (r1 and r2 values of 3.7 and 4.6 s-1 per mM Gd3+, respectively). They are found to be biocompatible. In vitro cancer cell imaging shows good imaging contrast of PEGylated UCNPs@DTPA-Gd3+. In vivo upconversion fluorescent imaging and T1-weighted MRI show excellent enhancement of both fluorescent and MR signals in the livers of mice administered PEGylated UCNPs@DTPA-Gd3+. All the experimental results indicate that the synthesized PEGylated UCNPs@DTPA-Gd3+ present great potential for biomedical upconversion of fluorescent and magnetic resonance dual-modality imaging applications.

  13. Tuning the decay time of lanthanide-based near infrared luminescence from micro- to milliseconds through d-->f energy transfer in discrete heterobimetallic complexes.

    PubMed

    Torelli, Stéphane; Imbert, Daniel; Cantuel, Martine; Bernardinelli, Gérald; Delahaye, Sandra; Hauser, Andreas; Bünzli, Jean-Claude G; Piguet, Claude

    2005-05-20

    Inert and optically active pseudo-octahedral Cr(III)N6 and Ru(II)N6 chromophores have been incorporated by self-assembly into heterobimetallic triple-stranded helicates HHH-[CrLnL3]6+ and HHH-[RuLnL3]5+. The crystal structures of [CrLnL(3)](CF(3)SO(3))(6) (Ln=Nd, Eu, Yb, Lu) and [RuLnL3](CF3SO3)5 (Ln=Eu, Lu) demonstrate that the helical structure can accommodate metal ions of different sizes, without sizeable change in the intermetallic MLn distances. These systems are ideally suited for unravelling the molecular factors affecting the intermetallic nd-->4f communication. Visible irradiation of the Cr(III)N6 and Ru(II)N6 chromophores in HHH-[MLnL3]5/6+ (Ln=Nd, Yb, Er; M=Cr, Ru) eventually produces lanthanide-based near infrared (NIR) emission, after directional energy migration within the complexes. Depending on the kinetic regime associated with each specific d-f pair, the NIR luminescence decay times can be tuned from micro- to milliseconds. The origin of this effect, together with its rational control for programming optical functions in discrete heterobimetallic entities, are discussed.

  14. Multifunctional nanocomposites of lanthanide (Eu3+, Tb3+) complexes functionalized magnetic mesoporous silica nanospheres covalently bonded with polymer modified ZnO.

    PubMed

    Yan, Bing; Shao, Yan-Fei

    2013-07-14

    Methacrylic-group-modified ZnO nanoparticles (designated ZnO-MAA) prepared through the sol-gel process are copolymerized with 2-hydroxyethyl methacrylate (HEMA) to form ZnO-MAA-PHEMA hybrid system. ZnO-MAA-PHEMA unit is functionalized with 3-(triethoxysilyl)-propyl isocyanate (TEPIC) to form ZnO-MAA-PHEMA-Si hybrids, and then is incorporated with oleic acid-modified Fe3O4 nanoparticles by co-condensation of tetraethoxysilane (TEOS) and ZnO-MAA-PHEMA-Si. Subsequently, ZnO-polymer covalently bonded mesoporous silica nanospheres are assembled using cetyltrimethylammonium bromide (CTAB) surfactant as template. Furthermore, lanthanide (Eu(3+), Tb(3+)) complexes with nicotinic acid (NTA), isonicotinic acid (INTA) and 2-chloronicotinic (CNTA) are introduced by coordination bonds, resulting in the final multifunctional nanocomposites. The detailed physical characterization of these hybrids is discussed in detail. It reveals that they possess both magnetic and luminescent properties. Especially Eu(ZnO-MMS)(CNTA)3 and Tb(ZnO-MMS)(NTA)3 present high quantum yield values of 32.2% and 68.5%, respectively. The results will lay the foundation for further application in biomedical and biopharmaceutical fields.

  15. Lanthanide complexes containing 5-methyl-1,2,4-triazolo[1,5-a] pyrimidin-7(4H)-one and their therapeutic potential to fight leishmaniasis and Chagas disease.

    PubMed

    Caballero, Ana B; Rodríguez-Diéguez, Antonio; Salas, Juan M; Sánchez-Moreno, Manuel; Marín, Clotilde; Ramírez-Macías, Inmaculada; Santamaría-Díaz, Noelia; Gutiérrez-Sánchez, Ramón

    2014-09-01

    In the last years, numerous and significant advances in lanthanide coordination chemistry have been achieved. The unique chemical nature of these metal ions which is conferred by their f-electrons has led to a wide range of coordination compounds with interesting structural, physical and also biological properties. Consequently, lanthanide complexes have found applications mainly in catalysis, gas adsorption, photochemistry and as diagnostic tools. However, research on their therapeutic potential and the understanding of their mechanism of action is still taking its first steps, and there is a distinct lack of research in the parasitology field. In the present work, we describe the synthesis and physical properties of seven new lanthanide complexes with the anionic form of the bioactive ligand 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO), namely [Ln(mtpO)3(H2O)6]·9H2O (Ln=La(III), Nd(III), Eu(III), Gd(III), Tb(III), Dy(III) and Er(III)). In addition, results on the in vitro antiproliferative activity against Leishmania spp. and Trypanosoma cruzi are described. The high activity of the new compounds against parasite proliferation and their low cytotoxicity against reference host cell lines show a great potential of this type of compounds to become a new generation of highly effective and non-toxic antiparasitic agents to fight the so considered neglected diseases leishmaniasis and Chagas disease.

  16. Semiempirical quantum chemistry model for the lanthanides: RM1 (Recife Model 1) parameters for dysprosium, holmium and erbium.

    PubMed

    Filho, Manoel A M; Dutra, José Diogo L; Rocha, Gerd B; Simas, Alfredo M; Freire, Ricardo O

    2014-01-01

    Complexes of dysprosium, holmium, and erbium find many applications as single-molecule magnets, as contrast agents for magnetic resonance imaging, as anti-cancer agents, in optical telecommunications, etc. Therefore, the development of tools that can be proven helpful to complex design is presently an active area of research. In this article, we advance a major improvement to the semiempirical description of lanthanide complexes: the Recife Model 1, RM1, model for the lanthanides, parameterized for the trications of Dy, Ho, and Er. By representing such lanthanide in the RM1 calculation as a three-electron atom with a set of 5 d, 6 s, and 6 p semiempirical orbitals, the accuracy of the previous sparkle models, mainly concentrated on lanthanide-oxygen and lanthanide-nitrogen distances, is extended to other types of bonds in the trication complexes' coordination polyhedra, such as lanthanide-carbon, lanthanide-chlorine, etc. This is even more important as, for example, lanthanide-carbon atom distances in the coordination polyhedra of the complexes comprise about 30% of all distances for all complexes of Dy, Ho, and Er considered. Our results indicate that the average unsigned mean error for the lanthanide-carbon distances dropped from an average of 0.30 Å, for the sparkle models, to 0.04 Å for the RM1 model for the lanthanides; for a total of 509 such distances for the set of all Dy, Ho, and Er complexes considered. A similar behavior took place for the other distances as well, such as lanthanide-chlorine, lanthanide-bromine, lanthanide, phosphorus and lanthanide-sulfur. Thus, the RM1 model for the lanthanides, being advanced in this article, broadens the range of application of semiempirical models to lanthanide complexes by including comprehensively many other types of bonds not adequately described by the previous models.

  17. A lanthanide complex with dual biosensing properties: CEST (chemical exchange saturation transfer) and BIRDS (biosensor imaging of redundant deviation in shifts) with europium DOTA-tetraglycinate.

    PubMed

    Coman, Daniel; Kiefer, Garry E; Rothman, Douglas L; Sherry, A Dean; Hyder, Fahmeed

    2011-12-01

    Responsive contrast agents (RCAs) composed of lanthanide(III) ion (Ln3R) complexes with a variety of1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA4S) derivatives have shown great potential as molecular imaging agents for MR. A variety of LnDOTA–tetraamide complexes have been demonstrated as RCAs for molecular imaging using chemical exchange saturation transfer (CEST). The CEST method detects proton exchange between bulk water and any exchangeable sites on the ligand itself or an inner sphere of bound water that is shifted by a paramagnetic Ln3R ion bound in the core of the macrocycle. It has also been shown that molecular imaging is possible when the RCA itself is observed (i.e. not its effect on bulk water) using a method called biosensor imaging of redundant deviation in shifts (BIRDS). The BIRDS method utilizes redundant information stored in the nonexchangeable proton resonances emanating from the paramagnetic RCA for ambient factors such as temperature and/or pH.Thus, CEST and BIRDS rely on exchangeable and nonexchangeable protons, respectively, for biosensing. We posited that it would be feasible to combine these two biosensing features into the same RCA (i.e. dual CEST and BIRDS properties). A complex between europium(III) ion (Eu3R) and DOTA–tetraglycinate [DOTA–(gly)S4] was used to demonstrate that its CEST characteristics are preserved, while its BIRDS properties are also detectable. The in vitro temperature sensitivity of EuDOTA–(gly)S4 was used to show that qualitative MR contrast with CEST can be calibrated using quantitative MR mapping with BIRDS, thereby enabling quantitative molecular imaging at high spatial resolution.

  18. Semiempirical Quantum Chemistry Model for the Lanthanides: RM1 (Recife Model 1) Parameters for Dysprosium, Holmium and Erbium

    PubMed Central

    Filho, Manoel A. M.; Dutra, José Diogo L.; Rocha, Gerd B.; Simas, Alfredo M.; Freire, Ricardo O.

    2014-01-01

    Complexes of dysprosium, holmium, and erbium find many applications as single-molecule magnets, as contrast agents for magnetic resonance imaging, as anti-cancer agents, in optical telecommunications, etc. Therefore, the development of tools that can be proven helpful to complex design is presently an active area of research. In this article, we advance a major improvement to the semiempirical description of lanthanide complexes: the Recife Model 1, RM1, model for the lanthanides, parameterized for the trications of Dy, Ho, and Er. By representing such lanthanide in the RM1 calculation as a three-electron atom with a set of 5 d, 6 s, and 6 p semiempirical orbitals, the accuracy of the previous sparkle models, mainly concentrated on lanthanide-oxygen and lanthanide-nitrogen distances, is extended to other types of bonds in the trication complexes’ coordination polyhedra, such as lanthanide-carbon, lanthanide-chlorine, etc. This is even more important as, for example, lanthanide-carbon atom distances in the coordination polyhedra of the complexes comprise about 30% of all distances for all complexes of Dy, Ho, and Er considered. Our results indicate that the average unsigned mean error for the lanthanide-carbon distances dropped from an average of 0.30 Å, for the sparkle models, to 0.04 Å for the RM1 model for the lanthanides; for a total of 509 such distances for the set of all Dy, Ho, and Er complexes considered. A similar behavior took place for the other distances as well, such as lanthanide-chlorine, lanthanide-bromine, lanthanide, phosphorus and lanthanide-sulfur. Thus, the RM1 model for the lanthanides, being advanced in this article, broadens the range of application of semiempirical models to lanthanide complexes by including comprehensively many other types of bonds not adequately described by the previous models. PMID:24497945

  19. Complete stereocontrol in the synthesis of macrocyclic lanthanide complexes: direct formation of enantiopure systems for circularly polarised luminescence applications.

    PubMed

    Evans, Nicholas H; Carr, Rachel; Delbianco, Martina; Pal, Robert; Yufit, Dmitry S; Parker, David

    2013-11-28

    Mono-C-substitution of the 1,4,7-triazacyclononane ring induces formation of single enantiomers of Eu(III) complexes with nonadentate N6O3 ligands. The absolute configuration of each complex is determined by the stereogenicity of the C-substituent, revealed by comparison of the sign and sequence of CPL transitions for a series of complexes.

  20. Dual lanthanide-doped complexes: the development of a time-resolved ratiometric fluorescent probe for anthrax biomarker and a paper-based visual sensor.

    PubMed

    Wang, Qi-Xian; Xue, Shi-Fan; Chen, Zi-Han; Ma, Shi-Hui; Zhang, Shengqiang; Shi, Guoyue; Zhang, Min

    2017-03-16

    In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO2-Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO2-Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties.

  1. Hydrolytic synthesis of novel lanthanide(III) complexes with pyridine-2,6-dicarboxylic acid: Characterization of the structure and the physical properties

    NASA Astrophysics Data System (ADS)

    Hojnik, Nuša; Kristl, Matjaž; Golobič, Amalija; Jagličić, Zvonko; Drofenik, Miha

    2015-01-01

    The coordination compounds of pyridine-2,6-dicarboxylic acid and two lanthanide(III) ions, Ho3+ and Dy3+, were hydrolytically synthesized in aqueous solutions at a slightly basic pH, and then characterized by thermogravimetric analysis, IR spectroscopy, magnetic measurements as well as X-ray powder and single-crystal diffraction analysis. The elemental analyses were performed to check the purity of the compounds. The formula for these compounds is identified as Na3[Ln(Pydc)3]ṡ14H2O (Ln = Ho, 1; Ln = Dy, 2) in agreement with the X-ray structural analysis and all the other experimental data. The absence of the 1709 cm-1 band corresponding to ν(C dbnd O) in the IR spectra of the compounds evidences the deprotonating of the carboxyl group. The very strong inductive effect of the metal ion that is readily coordinated by the carboxylate group of the zwitterionic ligand is responsible for the formation of the product. The single-crystal X-ray structural analysis revealed that compounds 1 and 2 are isostructural. Their structure can be described as interchanging layers of complex anions [Ln(Pydc)3]3 (Ln = Ho and Dy for 1 and 2, respectively) and layers of hydrated sodium cations. In complex anions the holmium and dysprosium atoms are coordinated by three crystallographically independent pyridinedicarboxylate ligands in tridentate-chelate mode, via one O atom of both carboxylate groups and the ring N atom. The coordination number is nine and the coordination polyhedron is a tricapped trigonal prism with O atoms at the corners.

  2. Luminescent sensor for carbonate ion based on lanthanide(III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A).

    PubMed

    Vaněk, Jakub; Lubal, Přemysl; Hermann, Petr; Anzenbacher, Pavel

    2013-01-01

    Lanthanide(III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H(3)DO3A) are suggested as sensors for sensitive luminescence-based determination of a carbonate anion. Thermodynamic study of association of [Eu(H(2)O)(2)(DO3A)] with bidentate anionic ligands using luminescence spectroscopy reveals an affinity order CO(3)(2-) > oxalate(2-) > picolinate(-) > phthalate(2-) ≈ citrate(3-); presumably as a consequence of an increasing chelate ring size. The ternary [Eu(DO3A)(picolinate)](-) and [Tb(DO3A)(picolinate)](-) complexes show improved photophysical properties due to the antenna effect of the picolinate anion. High quenching effect of carbonate anion and, to a lesser extent also oxalate, enables construction of a linear calibration plot utilizing optimized experimental conditions (e.g. c(LnL) = 0.1 mM, c(picolinate) = 2-5 mM, pH = 7.4, λ(exc) = 286 nm, etc.) for carbonate determination in solution. Both sensors show a comparable sensitivity and the detection limit of about 0.4 mM. In order to improve the photophysical properties of Ln(III) sensor by shift of excitation wavelength about 40 nm to VIS range, the isoquinoline-3-carboxylic acid (IQCA) as antenna ligand was employed instead of picolinic acid. The analysis of commercial samples of European mineral waters was carried out and they were compared to the results obtained by capillary isotachophoresis to confirm there is no inherent (systematic) error to the present analysis. The Ln(III) sensor with IQCA is recommended since it has a better robustness than that with picolinate. The present analytical method is simple and rapid, and it is useful for sensitive determination of bicarbonate/carbonate concentration in water samples under aerobic conditions.

  3. Investigations of the effect of the non-manganese metal in heterometallic-oxido cluster models of the oxygen evolving complex of photosystem II: lanthanides as substitutes for calcium.

    PubMed

    Lin, Po-Heng; Takase, Michael K; Agapie, Theodor

    2015-01-05

    We report the syntheses and electrochemical properties of nine new clusters ([LLnMn(IV)3O4(OAc)3(DMF)n](+) (Ln = La(3+), Ce(3+), Nd(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Yb(3+), and Lu(3+), n = 2 or 3)) supported by a ligand (L(3-)) based on a 1,3,5-triarylbenzene motif appended with alkoxide and pyridine donors. All complexes were obtained by metal substitution of Ca(2+) with lanthanides upon treatment of previously reported LMn3CaO4(OAc)3(THF) with Ln(OTf)3. Structural characterization confirmed that the clusters contain the [LnMn3O4] cubane motif. The effect of the redox-inactive centers on the electronic properties of the Mn3O4 cores was investigated by cyclic voltammetry. A linear correlation between the redox potential of the cluster and the ionic radii or pKa of the lanthanide metal ion was observed. Chemical reduction of the LMn(IV)3GdO4(OAc)3(DMF)2 cluster with decamethylferrocene, resulted in the formation of LGdMn(IV)2Mn(III)O4(OAc)3(DMF)2, a rare example of mixed-valence [MMn3O4] cubane. The lanthanide-coordinated ligands can be substituted with other donors, including water, the biological substrate.

  4. Chiroptical spectra of a series of tetrakis((+)–3–heptafluorobutylyrylcamphorato)lanthanide(III) with an encapsulated alkali metal ion: circularly polarized luminescence and absolute chiral structures for the Eu(III) and Sm(III) complexes

    PubMed Central

    Lunkley, Jamie L.; Shirotani, Dai; Yamanari, Kazuaki; Kaizaki, Sumio; Muller, Gilles

    2011-01-01

    The luminescence and circularly polarized luminescence (CPL) spectra of MI[Eu((+)–hfbc)4] show a similar behavior to the exciton CD in the intraligand π–π* transitions when the alkali metal ions and solvents are manipulated. There is a difference in susceptibility in solvation toward the alkali metal ions but not toward the Eu(III) ion, as in the case of axially symmetric DOTA–type compounds. The remarkable CPL in the 4f–4f transitions provide much more information on stereospecific formation of chiral Eu(III) complexes, since CPL spectroscopy is limited to luminescent species and reflects selectively toward helicity of the local structural environment around the lanthanide(III). While in comparison, exciton CD reveals the chiral structural information from the helical arrangement of the four bladed chelates. Of special importance, the observation of the highest CPL activities measured to date for lanthanide(III)–containing compounds (i.e. Eu and Sm) in solution supports that the chirality of Lanthanide(III) in the excited state corresponds to that in the ground state, which was derived from the exciton CD. PMID:22074461

  5. Curvature of the Lanthanide Contraction: An Explanation

    SciTech Connect

    Raymond, Kenneth; Wellman, Daniel; Sgarlata, Carmelo; Hill, Aru

    2009-12-21

    A number of studies have shown that for isostructural series of the lanthanides (elements La through Lu), a plot of equivalent metal-ligand bond lengths versus atomic number differs significantly from linearity and can be better fit as a quadratic equation. However, for hydrogen type wave functions, it is the inverse of the average distance of the electron from the nucleus (an estimate of size) that varies linearly with effective nuclear charge. This generates an apparent quadratic dependence of radius with atomic number. Plotting the inverse of lanthanide ion radii (the observed distance minus the ligand size) as a function of effective nuclear charge gives very good linear fits for a variety of lanthanide complexes and materials. Parameters obtained from this fit are in excellent agreement with the calculated Slater shielding constant, k.

  6. Solution and solid-state characterization of highly rigid, eight-coordinate lanthanide(III) complexes of a macrocyclic tetrabenzylphosphinate

    SciTech Connect

    Aime, S.; Botta, M.; Howard, J.A.K.

    1994-10-12

    Structural characterization of rare earth tetrabenzylphosphinate complexes was performed using NMR, luminescence spectroscopy, and X-ray crystallography. The coordination structure of these complexes including an evaluation of stereorigidity is reported and uses as potential NMR tumor imaging agents are discussed.

  7. Experimental and theoretical study of lanthanide complexes based on linear and macrocyclic polyaminopolycarboxylic acids containing pyrazolylethyl arms.

    PubMed

    Pérez-Mayoral, Elena; Soriano, Elena; Cerdán, Sebastián; Ballesteros, Paloma

    2006-05-17

    We report the synthesis of two novel Gd(III)-complexes derived from linear and macrocyclic polyaminopolycarboxylic acids 1 and 2, which contain a 3,5- dimethylpyrazolyl-ethyl arm, and a study of their relaxivity properties. The relationships between the experimental and theoretical results have provided interesting information about the kinetic and thermodynamic stability of these complexes.

  8. Synthesis, spectroscopic characterization and antibacterial studies of lanthanide(III) Schiff base complexes containing N, O donor atoms

    NASA Astrophysics Data System (ADS)

    Lekha, L.; Raja, K. Kanmani; Rajagopal, G.; Easwaramoorthy, D.

    2014-01-01

    A series of six Ln(III) Schiff base complexes, Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III), were synthesized using sodium salt of Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-3-hydroxy-propionic acid, derived from L-serine and 5-bromosalicylaldehyde. These complexes having general formula [Ln(L)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, conductivity measurements, UV-Vis, FT-IR, mass spectrometry and fluorescence studies. Elemental analysis and conductivity measurements suggest the complexes have a 1:1 stoichiometry. From the spectral studies it has been concluded that Ln(III) complexes display eight coordination. The Schiff base and its Ln(III) metal complexes have also been screened for their antibacterial activities by Agar diffusion method.

  9. Comparative Study of f-Element Electronic Structure across a Series of Multimetallic Actinide, Lanthanide-Actinide and Lanthanum-Actinide Complexes Possessing Redox-Active Bridging Ligands

    SciTech Connect

    Schelter, Eric J.; Wu, Ruilian; Veauthier, Jacqueline M.; Bauer, Eric D.; Booth, Corwin H.; Thomson, Robert K.; Graves, Christopher R.; John, Kevin D.; Scott, Brian L.; Thompson, Joe D.; Morris, David E.; Kiplinger, Jaqueline L.

    2010-02-24

    A comparative examination of the electronic interactions across a series of trimetallic actinide and mixed lanthanide-actinide and lanthanum-actinide complexes is presented. Using reduced, radical terpyridyl ligands as conduits in a bridging framework to promote intramolecular metal-metal communication, studies containing structural, electrochemical, and X-ray absorption spectroscopy are presented for (C{sub 5}Me{sub 5}){sub 2}An[-N=C(Bn)(tpy-M{l_brace}C{sub 5}Me4R{r_brace}{sub 2})]{sub 2} (where An = Th{sup IV}, U{sup IV}; Bn = CH{sub 2}C{sub 6}H{sub 5}; M = La{sup III}, Sm{sup III}, Yb{sup III}, U{sup III}; R = H, Me, Et) to reveal effects dependent on the identities of the metal ions and R-groups. The electrochemical results show differences in redox energetics at the peripheral 'M' site between complexes and significant wave splitting of the metal- and ligand-based processes indicating substantial electronic interactions between multiple redox sites across the actinide-containing bridge. Most striking is the appearance of strong electronic coupling for the trimetallic Yb{sup III}-U{sup IV}-Yb{sup III}, Sm{sup III}-U{sup IV}-Sm{sup III}, and La{sup III}-U{sup IV}-La{sup III} complexes, [8]{sup -}, [9b]{sup -} and [10b]{sup -}, respectively, whose calculated comproportionation constant K{sub c} is slightly larger than that reported for the benchmark Creutz-Taube ion. X-ray absorption studies for monometallic metallocene complexes of U{sup III}, U{sup IV}, and U{sup V} reveal small but detectable energy differences in the 'white-line' feature of the uranium L{sub III}-edges consistent with these variations in nominal oxidation state. The sum of this data provides evidence of 5f/6d-orbital participation in bonding and electronic delocalization in these multimetallic f-element complexes. An improved, high-yielding synthesis of 4{prime}-cyano-2,2{prime}:6{prime},2{double_prime}-terpyridine is also reported.

  10. Synthesis and luminescence properties of two novel lanthanide (III) perchlorate complexes with bis(benzoylmethyl) sulfoxide and benzoic acid.

    PubMed

    Li, Wen-Xian; Chai, Wen-Juan; Sun, Xiao-Jun; Ren, Tie; Shi, Xiao-Yan

    2010-07-01

    Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L') had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, (1)HNMR and UV spectra. The results indicated that the composition of these complexes was REL(5)L'(ClO(4))(2) x nH(2)O (RE = Tb(III), Dy(III); L = C(6)H(5)COCH(2)SOCH(2)COC(6)H(5), L' = C(6)H(5)COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL(5) x (ClO(4))(3) x 2 H(2)O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL(5)L'(ClO(4))(2) x nH(2)O (RE = Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.

  11. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    SciTech Connect

    Song, Xue-Qin Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-15

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.

  12. Characterization of a lanthanide complex encapsulated with MRI contrast agents into liposomes for biosensor imaging of redundant deviation in shifts (BIRDS)

    PubMed Central

    Maritim, Samuel; Huang, Yuegao; Coman, Daniel; Hyder, Fahmeed

    2014-01-01

    Purposely-designed magnetic resonance imaging (MRI) probes encapsulated in liposomes, which alter contrast by their paramagnetic effect on longitudinal (T1) and transverse (T2) relaxation times of tissue water, hold promise for molecular imaging. However a challenge with liposomal MRI probes that are solely dependent on enhancement of water relaxation is lack of specific molecular readouts, especially in strong paramagnetic environments, thereby reducing the potential for monitoring disease treatment (e.g., cancer) beyond the generated MRI contrast. Previously it has been shown that molecular imaging with magnetic resonance is also possible by detecting the signal of non-exchangeable protons emanating from paramagnetic lanthanide complexes themselves (e.g., TmDOTP5−, which is a Tm3+-containing biosensor based on a macrocyclic chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate), DOTP5−) with a method called Biosensor Imaging of Redundant Deviation in Shifts (BIRDS). Here we show that BIRDS is useful for molecular imaging with probes like TmDOTP5− even when they are encapsulated inside liposomes with ultra-strong T1 and T2 contrast agents (e.g., Magnevist and Molday ION, respectively). We demonstrate that molecular readouts like pH and temperature determined from probes like TmDOTP5− are resilient, because sensitivity of the chemical shifts to the probe’s environment is not compromised by presence of other paramagnetic agents contained within the same nanocarrier milieu. Because high liposomal encapsulation efficiency allows for robust MRI contrast and signal amplification for BIRDS, nanoengineered liposomal probes containing both monomers like TmDOTP5− and paramagnetic contrast agents could allow high spatial resolution imaging of disease diagnosis (with MRI) and status monitoring (with BIRDS). PMID:25304046

  13. Characterization of a lanthanide complex encapsulated with MRI contrast agents into liposomes for biosensor imaging of redundant deviation in shifts (BIRDS).

    PubMed

    Maritim, Samuel; Huang, Yuegao; Coman, Daniel; Hyder, Fahmeed

    2014-12-01

    Purposely designed magnetic resonance imaging (MRI) probes encapsulated in liposomes, which alter contrast by their paramagnetic effect on longitudinal (T₁) and transverse (T₂) relaxation times of tissue water, hold promise for molecular imaging. However, a challenge with liposomal MRI probes that are solely dependent on enhancement of water relaxation is lack of specific molecular readouts, especially in strong paramagnetic environments, thereby reducing the potential for monitoring disease treatment (e.g., cancer) beyond the generated MRI contrast. Previously, it has been shown that molecular imaging with magnetic resonance is also possible by detecting the signal of non-exchangeable protons emanating from paramagnetic lanthanide complexes themselves [e.g., TmDOTP⁵⁻, which is a Tm³⁺ -containing biosensor based on a macrocyclic chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate), DOTP⁵⁻] with a method called biosensor imaging of redundant deviation in shifts (BIRDS). Here, we show that BIRDS is useful for molecular imaging with probes like TmDOTP⁵⁻ even when they are encapsulated inside liposomes with ultrastrong T₁and T₂contrast agents (e.g., Magnevist and Molday ION, respectively). We demonstrate that molecular readouts such as pH and temperature determined from probes like TmDOTP⁵⁻ are resilient, because the sensitivity of the chemical shifts to the probe's environment is not compromised by the presence of other paramagnetic agents contained within the same nanocarrier milieu. Because high liposomal encapsulation efficiency allows for robust MRI contrast and signal amplification for BIRDS, nanoengineered liposomal probes containing both monomers, TmDOTP⁵⁻ and paramagnetic contrast agents, could allow high spatial resolution imaging of disease diagnosis (with MRI) and status monitoring (with BIRDS).

  14. Five different types of η(8)-cyclooctatetraenyl-lanthanide half-sandwich complexes from one ligand set, including a "giant neodymium wheel".

    PubMed

    Sroor, Farid M; Hrib, Cristian G; Liebing, Phil; Hilfert, Liane; Busse, Sabine; Edelmann, Frank T

    2016-09-14

    The lithium-cyclopropylethynylamidinates Li[c-C3H5-C[triple bond, length as m-dash]C-C(NR)2] (1a: R = (i)Pr, 1b: R = cyclohexyl (Cy)) have been used as precursors for the preparation of five new series of half-sandwich complexes. These complexes contain the large flat cyclooctatetraenyl ligand (C8H8(2-), commonly abbreviated as COT), and were isolated as solvated, unsolvated and inverse sandwich complexes. Treatment of the halide precursors [(COT)Pr(μ-Cl)(THF)2]2 with 1b and [(COT)Nd(μ-Cl)(THF)2]2 with 1a and 1b in THF in a 1 : 2 molar ratio, respectively, afforded (COT)Ln[μ-c-C3H5-C[triple bond, length as m-dash]C-C(NR)2]2Li(L) (2: Ln = Pr, R = Cy, L = Et2O; 3: Ln = Nd, R = (i)Pr, L = THF; 4: Ln = Nd, R = Cy, L = THF). Treatment of the dimeric cerium(iii) bis(cyclopropylethynylamidinate) complexes [{c-C3H5-C[triple bond, length as m-dash]C-C(NR)2}2Ce(μ-Cl)(THF)]2 (5: R = (i)Pr; 6: R = Cy) in situ with K2C8H8 in a 1 : 1 molar ratio in THF at room temperature afforded the inverse-sandwich complexes (μ-η(8):η(8)-COT)[Ce{c-C3H5-C[triple bond, length as m-dash]C-C(NR)2}2]2 (7: R = (i)Pr; 8: R = Cy). This reaction represents a new method for encapsulation of a planar (C8H8)(2-) ring in lanthanide complexes containing amidinate ligands in the outer decks. Novel unsolvated dinuclear lanthanide half-sandwich complexes were prepared by using the precursors 1a, 1b and COT(2-). Unlike the complexes 2-4, the reaction of [(COT)Pr(μ-Cl)(THF)2]2 with 1a afforded the unsolvated centrosymmetric complex [(COT)Pr(μ-c-C3H5-C[triple bond, length as m-dash]C-C(N(i)Pr)2)]2 (9). These dimeric structures could be also accessed by reaction of LnCl3 (Ln = Ce or Nd) with 1a or 1b and K2COT in a 1 : 1 : 1 molar ratio as a one-pot reaction to give novel [(COT)Ln(μ-c-C3H5-C[triple bond, length as m-dash]C-C(NR)2)]2 complexes (10: Ln = Ce, R = (i)Pr; 11: Ln = Ce, R = Cy; 12: Ln = Nd, R = (i)Pr). Similar treatment of HoCl3 with 1a or 1b and K2COT as three

  15. Influence of metal loading and humic acid functional groups on the complexation behavior of trivalent lanthanides analyzed by CE-ICP-MS.

    PubMed

    Kautenburger, Ralf; Hein, Christina; Sander, Jonas M; Beck, Horst P

    2014-03-13

    The complexation behavior of Aldrich humic acid (AHA) and a modified humic acid (AHA-PB) with blocked phenolic hydroxyl groups for trivalent lanthanides (Ln) is compared, and their influence on the mobility of Ln(III) in an aquifer is analyzed. As speciation technique, capillary electrophoresis (CE) was hyphenated with inductively coupled plasma mass spectrometry (ICP-MS). For metal loading experiments 25 mg L(-1) of AHA and different concentrations (cLn(Eu+Gd)=100-6000 μg L(-1)) of Eu(III) and Gd(III) in 10mM NaClO4 at pH 5 were applied. By CE-ICP-MS, three Ln-fractions, assumed to be uncomplexed, weakly and strongly AHA-complexed metal can be detected. For the used Ln/AHA-ratios conservative complex stability constants log βLnAHA decrease from 6.33 (100 μg L(-1) Ln(3+)) to 4.31 (6000 μg L(-1) Ln(3+)) with growing Ln-content. In order to verify the postulated weaker and stronger humic acid binding sites for trivalent Eu and Gd, a modified AHA with blocked functional groups was used. For these experiments 500 μg L(-1) Eu and 25 mg L(-1) AHA and AHA-PB in 10mM NaClO4 at pH-values ranging from 3 to 10 have been applied. With AHA-PB, where 84% of the phenolic OH-groups and 40% of the COOH-groups were blocked, Eu complexation was significantly lower, especially at the strong binding sites. The log β-values decrease from 6.11 (pH 10) to 5.61 at pH 3 (AHA) and for AHA-PB from 6.01 (pH 7) to 3.94 at pH 3. As a potential consequence, particularly humic acids with a high amount of strong binding sites (e.g. phenolic OH- and COOH-groups) can be responsible for a higher metal mobility in the aquifer due to the formation of dissolved negatively charged metal-humate species. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Two Series of Homodinuclear Lanthanide Complexes: Greatly Enhancing the Energy Barriers through Tuning the Terminal Solvent Ligands in Dy2 Single-Molecule Magnets.

    PubMed

    Li, Yahong; Qin, Yaru; Zhang, Haifeng; Sun, Hao; Pan, Yangdan; Ge, Yu; Zhang, Yiquan

    2017-08-24

    The utilization of 2-ethoxy-6-(((2-hydroxy-3-methoxy benzyl)imino)methyl)phenol (H2L) as a chelating ligand, in combination with the employment of alcohols (EtOH and MeOH) as auxiliary ligands, in the 4f-metal chemistry afforded two series of dinuclear lanthanide complexes of compositions [Ln2L2(NO3)2 (EtOH)2] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7)) and [Ln2L2(NO3)2(MeOH)2] (Ln = Sm (8), Eu (9), Gd (10), Tb (11), Dy (12), Ho (13), Er (14)). Complexes 1-7 are isomorphous. The two LnIII ions in 1-7 are doubly bridged by two deprotonated aminophenoxide oxygen atoms of two μ2: η0:η1:η2:η1:η1:η0 L2- ligands. One nitrogen atom, two oxygen atoms of NO3- anion, two methoxide oxygen atoms of two ligand sets, and one oxygen atom of the terminal-coordinated EtOH molecule complete the distorted dodecahedron geometry of each LnIII ion. Compounds 8-14 are isomophous and their structures are similar to those of 1-7. The slight difference between 1-7 and 8-14 stems from purposefully replacing the EtOH ligands in 1-7 with MeOH in 8-14. Dc magnetic susceptibility studies in the 2-300 K range reveal probably weak antiferromagnetic interactions for 3, 4, 7, 10, 11, and 14, and ferromagnetic interactions at low temperature for 5, 6, 12, and 13. Complexes 5 and 12 exhibit SMM behavior with energy barriers of 131.3 K for 5 and 198.8 K for 12, respectively. Namely, the energy barrier is significantly enhanced by dexterously regulating the terminal ligands. To rationalize the observed difference in the magnetic behavior, complete-active-space self-consistent field (CASSCF) calculations were performed on two Dy2 complexes. Subtle variation in the angle θ between the magnetic axes and the vector connecting two DyIII ions results in the weaker influence on the tunneling gap of individual DyIII ions by the dipolar field in 12. This work proposes an efficient strategy for synthesizing Dy2 SMMs with high energy barriers. © 2017 WILEY-VCH Verlag GmbH & Co. KGa

  17. Antimicrobial Study of Newly Synthesized Lanthanide(III) Complexes of 2-[2-hydroxy-3-methoxyphenyl]-3-[2-hydroxy-3-methoxybenzylamino]-1,2-dihydroquinazolin-4(3H)-one

    PubMed Central

    Gudasi, Kalagouda B.; Havanur, Vidyadhar C.; Patil, Siddappa A.; Patil, Basavaraj R.

    2007-01-01

    New lanthanide(III) complexes with 2-[2-hydroxy-3-methoxyphenyl]-3-[hydroxyl-3-methoxybenzylamino]-1,2-dihydroquin- azoline-4(3H)-one (Hmpbaq) have been synthesized and characterized by elemental analysis, conductance measurements, magnetic susceptibilities, spectroscopic (IR, NMR, UV, EPR), and thermal studies. Molar conductance studies indicate 1 : 1 electrolytic behavior for these complexes. IR spectra indicate that Hmpbaq acts as a tridentate ligand coordinating through carbonyl oxygen, benzyl amine nitrogen, and deprotonated phenolic oxygen. TG and DTA studies of La(III) and Pr(III) complexes indicate the presence of two coordinated water molecules. Based on these studies, the complexes have been formulated as [La(mpbaq)2(H2O)2]·NO3, where Ln = La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Th(III), Dy(III), and Y(III). The ligand, lanthanide(III) salts, and the corresponding complexes have been simultaneously screened for their antibacterial and antifungal activities and compared with the drugs in use. PMID:18309372

  18. Synthesis, characterization of the luminescent lanthanide complexes with ( Z)-4-(4-methoxyphenoxy)-4-oxobut-2-enoic acid

    NASA Astrophysics Data System (ADS)

    Duan, Guo-Jian; Yang, Ying; Liu, Tong-Huan; Gao, Ya-Ping

    2008-02-01

    ( Z)-4-(4-Methoxyphenoxy)-4-oxobut-2-enoic acid and its solid rare earth complexes LnL 3·2H 2O (Ln = La, Eu, Tb) were synthesized and characterized by means of MS, elemental analysis, FTIR, 13C NMR and TG-DTA. The IR and 13C NMR results show that the carboxylic groups in the complexes coordinated to the rare earth ions in the form of a bidentate ligand, but the ester carboxylic groups have not taken part in the coordination. The luminescence spectra of Eu(III) and Tb(III) complexes in solid state were also studied. The strong luminescence emitting peaks at 616 nm for Eu(III) and 547 nm for Tb(III) can be observed, which could be attributed to the ligand has an enhanced effect to the luminescence intensity of the Eu and Tb.

  19. Kinetically Stable Lanthanide Complexes Displaying Exceptionally High Quantum Yields upon Long-Wavelength Excitation: Synthesis, Photophysical Properties, and Solution Speciation.

    PubMed

    Routledge, Jack D; Jones, Michael W; Faulkner, Stephen; Tropiano, Manuel

    2015-04-06

    We demonstrate how highly emissive, kinetically stable complexes can be prepared using the macrocyclic scaffold of DO3A bearing coordinating aryl ketones as highly effective sensitizing chromophores. In the europium complexes, high quantum yields (up to 18% in water) can be combined with long-wavelength excitation (370 nm). The behavior in solution upon variation of pH, studied by means of UV-vis absorption, emission, and NMR spectroscopies, reveals that the nature of the chromophore can give rise to pH-dependent behavior as a consequence of deprotonation adjacent to the carbonyl group. Knowledge of the molecular speciation in solution is therefore critical when assessing the luminescence properties of such complexes.

  20. Direct evidence of energy transfer from a singlet ligand level to lanthanide ions in their diketonate complexes

    NASA Astrophysics Data System (ADS)

    Mironov, L. Yu.; Sveshnikova, E. B.; Ermolaev, V. L.

    2015-07-01

    We have compared the fluorescence intensity of 2-naphthoyltrifluoroacetonate (NTA) in nanoparticles from Gd(NTA)3phen complexes with the fluorescence intensities of this compound in nanoparticles from similar complexes of Pr, Nd, Sm, Eu, Tb, Dy, Er, Ho, and Tm, which absorb in the NTA fluorescence range. We have proven that there is energy transfer from the S 1 level of NTA ligands to Ln(III) ions, which occurs with rates k tr ˜ 1011-1012 s-1. We have also studied the competition between two processes: energy transfer from Ln(NTA)3phen to Ln(III) ions and energy transfer to Nile blue molecules incorporated into nanoparticles from complexes of these ions. It has been shown that, in nanoparticles from complexes of Nd(III), Tb(III), Dy(III), and Tm(III) ions, which are incapable of sensitizing the fluorescence of Nile blue, the values of k tr2 for the energy transfer from NTA to Ln(III) ions, which were obtained from the data on the change in the intensity of the sensitized fluorescence of Nile blue, completely coincide with the values of k tr1 determined from the fluorescence quenching of NTA in these nanoparticles. We have found that, in nanoparticles from Pr, Sm, Eu, Er, and Ho complexes, the efficiency of the sensitized fluorescence of Nile blue is higher than that predicted from the fluorescence quenching of NTA by these ions in their complexes, which indicates that all these ions participate as mediators in the energy transfer from ligands to the dye.

  1. Relaxometry, luminescence measurements, electrophoresis, and animal biodistribution of lanthanide(III) complexes of some polyaza macrocyclic acetates containing pyridine

    SciTech Connect

    Kim, W.D.; Sherry, A.D.; Kiefer, G.E.; McMillan, K.; Maton, F.; Muller, R.N.

    1995-04-12

    Four Gd{sup 3+} complexes [Gd(BP2A){sup +}, Gd(PC2A){sup +}, Gd(PCTA){sup 0}, and Gd(BPO4A){sup {minus}}] with polyazamacrocyclic ligands that contain a pyridine moiety were prepared and examined for possible use as MRI contrast enhancement agents. The authors estimated the number of inner sphere water molecules (q{sub Gd}) for the Gd{sup 3+} complexes from the values of q found for the Tb{sup 3+} and/or Eu{sup 3+} complexes by luminescence lifetime measurements. It was estimated that q{sub Gd} = 3.5, 3.3, 2.4, and 0.2 for Gd(BP2A){sup +}, Gd(PC2A){sup +}, Gd(PCTA){sup 0}, and Gd(BPO4A){sup {minus}}, respectively. The inner sphere relaxivities (r{sub 1,inner}) of these tetraaza macrocyclic complexes were higher than that of Gd(DOTA){sup {minus}} [i.e. 6.79 for Gd(BP2A){sup +}, 6.21 for Gd(PC2A){sup +}, and 4.60 for Gd(PCTA){sup 0} mM{sup {minus}1}s{sup {minus}1} at 40 MHz and 25{degrees}C], but the normalized relaxivities per q{sub Gd} (1.94, 1.88, and 1.92 mM{sup {minus}1}s{sup {minus}1}, respectively) were comparable to that of Gd(DOTA){sup {minus}}. A quantitative treatment of the NMRD profiles based on Solomon-Bloembergen-Morgan theory, using the NMRD profile of Gd(BPO4A){sup {minus}} to correct for an outer sphere contribution, showed that the complexes exhibit characteristics similar to that of Gd(DOTA){sup {minus}} but with shorter electronic relaxation times. Tissue biodistribution results using radioactive {sup 153}Sm and {sup 159}Gd complexes in rats indicate that the cationic [{sup 153}Sm-(BP2A){sup +} and {sup 153}Sm(PC2A){sup +}] complexes accumulate preferably in the bone tissue while the neutral [{sup 153}Sm-(PCTA){sup 0}] and anionic [{sup 153}Sm(BPO4A){sup {minus}}] complexes appear to have renal clearances similar to those of other low molecular weight contrast agents [i.e. Gd(DTPA){sup 2{minus}} and Gd(DOTA){sup {minus}}].

  2. Dual Emissive-Reflective Display Materials with Large Emission Switching Using Highly Luminescent Lanthanide(III) Complex and Electrochromic Material

    NASA Astrophysics Data System (ADS)

    Kanazawa, Kenji; Nakamura, Kazuki; Kobayashi, Norihisa

    2013-05-01

    Electroswitching of emission and coloration was achieved by a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV2+), in order to utilize them as novel display devices with dual emissive-reflective modes. The coloration was associated with the HV2+ electrochromism. Emission control was also achieved by the HV2+ electrochromism via intermolecular energy transfer from the excited state of the Eu(III) ion to the HV+. In order to improve ON-OFF contrast in emission, the emission quantum yield of Eu(III) complex were considerably improved using low vibrational phosphine oxide ligands, resulting in the large control of emission switching.

  3. Nuclear Magnetic Resonance Shift Reagents: Abnormal 13C Shifts Produced by Complexation of Lanthanide Chelates with Saturated Amines and n-Butyl Isocyanide

    PubMed Central

    Marzin, Claude; Leibfritz, Dieter; Hawkes, Geoffrey E.; Roberts, John D.

    1973-01-01

    Lanthanide-induced shfits of 13C nuclear magnetic resonances are reported for several amines and n-butyl isocyanide. Contact contributions to such shifts, especially of β carbons, are clearly important for the chelates of Eu+3 and Pr+3. The importance of contact terms is shown to change in a rather predictable manner with the structure of the amine. PMID:16592062

  4. A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions

    SciTech Connect

    D'Aleo, Anthony; Xu, Jide; Do, King; Muller, Gilles; Raymond, Kenneth N.

    2009-04-30

    The synthesis of a cyclen derivative containing four isophthalamide groups (L{sup 1}) is described. The spectroscopic properties of the Ln(III) complexes of L{sup 1} (Ln = Gd, Tb, Yb, Eu) reveal changes of the UV/visible absorption, circular dichroism absorption, luminescence and circularly polarized luminescence properties. It is shown that at least two metal complex species are present in solution, whose relative amounts are pH dependent. When at pH > 8.0, an intense long lived emission is observed (for [L{sup 1}Tb] and [L{sup 1}Yb]) while at pH < 8.0, a weaker, shorter-lived species predominates. Unconventional Ln(III) emitters (Pr, Nd, Sm, Dy and Tm) were sensitized in basic solution, both in the visible and in the near infra-red, to measure the emission of these ions.

  5. Synthesis and characterisation of dimeric eight-coordinate lanthanide(III) complexes of a macrocyclic tribenzylphosphinate ligand.

    PubMed

    Senanayake, Kanthi; Thompson, Amber L; Howard, Judith A K; Botta, Mauro; Parker, David

    2006-12-07

    The macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7-triyl(methylenebenzyl-phosphinic acid) H3L3, has been prepared and its complexes with Eu, Gd and Tb(III) studied by NMR, relaxometry, luminescence and single crystal X-ray crystallography. In solution and in the crystal, the complexes have eight-coordinate metal centres with bridging phosphinate groups linking the two twisted square antiprismatic coordination polyhedra. A single stereoisomer crystallises from solution with an RRR and SSS configuration at the P centres in each sub-unit. The relaxivity of [GdL3]2 is low (1.9 mM-1 s-1, 298 K, 20 MHz), consistent with the absence of any proximate water molecules. The terbium dimer possesses a relatively long excited state lifetime (2.47 ms, 298 K).

  6. Thin films of metal oxides grown by chemical vapor deposition from volatile transition metal and lanthanide metal complexes

    NASA Astrophysics Data System (ADS)

    Pollard, Kimberly Dona

    1998-08-01

    This thesis describes the synthesis and characterization of novel volatile metal-organic complexes for the chemical vapor deposition (CVD) of metal oxides. Monomeric tantalum complexes, lbrack Ta(OEt)sb4(beta-diketonate)) are prepared by the acid-base reaction of lbrack Tasb2(OEt)sb{10}rbrack with a beta-diketone, (RC(O)CHsb2C(O)Rsp' for R = CHsb3, Rsp' = CFsb3; R = Rsp'=C(CHsb3)sb3; R = Csb3Fsb7,\\ Rsp'=C(CHsb3)sb3;\\ R=Rsp'=CFsb3; and R = Rsp' = CHsb3). The products are characterized spectroscopically. Thermal CVD using these complexes as precursors gave good quality Tasb2Osb5 thin films which are characterized by XPS, SEM, electrical measurements, and XRD. Factors affecting the film deposition such as the type of carrier gas and the temperature of the substrate were considered. Catalyst-enhanced CVD reactions with each of the precursors and a palladium catalyst, ((2-methylallyl)Pd(acac)), were studied as a lower temperature route to good quality Tasb2Osb5 films. The decomposition mechanism at the hot substrate surface was studied. Precursors for the formation of yttria by CVD were examined. New complexes of the form (Y(hfac)sb3(glyme)), (hfac = \\{CFsb3C(O)CHC(O)CFsb3\\}sp-,\\ glyme=CHsb3O(CHsb2CHsb2O)sb{n}CHsb3 for n = 1-4) were synthesized and characterized spectroscopically. X-ray structural determinations of three new complexes were obtained. CVD reaction conditions were determined which give YOF films and, with catalyst-enhanced CVD, reaction conditions which give selective formation of Ysb2Osb3, YOF, or YFsb3. The films were studied by XPS, SEM, and XRD. Decomposition mechanisms which lead to film formation, together with a possible route for fluorine atom transfer from the ligand to the metal resulting in fluorine incorporation, were studied by analysis of exhaust products using GC-MS. Novel precursors of the form lbrack Ce(hfac)sb3(glyme)rbrack,\\ (hfac=\\{CFsb3C(O)CHC(O)CFsb3\\}sp-,\\ glyme=CHsb3O(CHsb2CHsb2O)sb{n}CHsb3, n = 1-4) for CVD of ceria were

  7. Pentanuclear [2.2] spirocyclic lanthanide(III) complexes: slow magnetic relaxation of the Dy(III) analogue.

    PubMed

    Biswas, Sourav; Das, Sourav; van Leusen, Jan; Kögerler, Paul; Chandrasekhar, Vadapalli

    2015-11-28

    The reaction of LnCl3·6H2O (Ln = Dy(3+), Tb(3+) and Ho(3+)) with the multisite coordinating ligand N'-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylidene)acetohydrazide (LH3) in the presence of pivalic acid (PivH) leads to the formation of three isostructural homometallic pentanuclear complexes, [Dy5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·9·5H2O·5MeOH (1), [Tb5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·10.5H2O·2MeOH·2CHCl3 (2) and [Ho5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·14.5H2O·2CHCl3 (3). 1-3 are monocationic and are comprised of four doubly deprotonated [LH](2-) ligands along with six pivalate ions. These complexes possess a [2.2] spirocyclic topology formed by the fusion of two triangles of Ln(III) ions at a common vertex. The magneto chemical analysis reveals the presence of antiferromagnetic exchange interactions at low temperature, and the Dy(III) complex 1 gives an out-of-phase signal with a small curvature in alternating current (ac) magnetic susceptibility measurement. Application of a 3000 G static field during ac measurement intensifies the signals, revealing a second slow relaxation process in the Dy(III) analogue.

  8. Determination of solubility products of complex compounds of certain lanthanide and actinide diiodies with 18-crown-6 in tetrahydrofuran

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Kulyukhin, S.A.

    1988-09-01

    The existence of divalent americium in a tetrahydrofuran (THF) solution was proved for the first time. The values of the solubility products (SP) of the complex compounds with the composition of MeI{sub 2}{centered dot}18-crown-6 (Me = Sm, Eu, Yb, Am, Cf, Es, Fm) in the THF solutions were determined by the cocrystallization method. The SP values obtained are within (5.9-7.9){centered dot}10{sup {minus}12} and are close to the SP value for SrI{sub 2}{centered dot}10{sup {minus}12}, which indicates a similarity in the properties of these elements.

  9. Dissociation kinetics of macrocyclic trivalent lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (DO2A).

    PubMed

    Lin, Chih-Cheng; Chen, Chia-Ling; Liu, Kuan-Yu; Chang, C Allen

    2011-06-21

    The [H(+)]-catalyzed dissociation rate constants of several trivalent lanthanide (Ln) complexes of 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (LnDO2A(+), Ln = La, Pr, Eu, Er and Lu) have been determined in two pH ranges: 3.73-5.11 and 1.75-2.65 at four different temperatures (19-41.0 °C) in aqueous media at a constant ionic strength of 0.1 mol dm(-3) (LiClO(4)). For the study in the higher pH range, i.e. pH 3.73-5.11, copper(II) ion was used as the scavenger for the free ligand DO2A in acetate/acetic acid buffer medium. The rates of Ln(III) complex dissociation have been found to be independent of [Cu(2+)] and all the Ln(III) complexes studied show [H(+)]-dependence at low acid concentrations but become [H(+)]-independent at high acid concentrations. Influence of the acetate ion content in the buffer on the dissociation rate has also been investigated and all the complexes exhibit a first-order dependence on [Acetate]. The dissociation reactions follow the rate law: k(obs) = k(Ac)[Acetate] + K'k(lim)[H(+)]/(1 + K'[H(+)]) where k(AC) is the dissociation rate constant for the [Acetate]-dependent pathway, k(lim) is the limiting rate constant, and K' is the equilibrium constant for the reaction LnDO2A(+) + H(+) ⇔ LnDO2AH(2+). In the lower pH range, i.e. pH 1.75-2.65, the dye indicator, cresol red, was used to monitor the dissociation rate, and all the Ln(III) complexes also show [H(+)]-dependence dissociation pathways but without the rate saturation observed at higher pH range. The dissociation reactions follow the simple rate law: k(obs) = k(H)[H(+)], where k(H) is the dissociation rate constant for the pathway involving monoprotonated species. The absence of an [H(+)]-independent pathway in both pH ranges indicates that LnDO2A(+) complexes are kinetically rather inert. The obtained k(AC) values follow the order: LaDO2A(+) > PrDO2A(+) > EuDO2A(+) > ErDO2A(+) > LuDO2A(+), whereas the k(lim) and k(H) values follow the order: LaDO2A(+) > PrDO2A(+) > ErDO2A

  10. Syntheses, structures, and sensitized lanthanide luminescence by Pt --> Ln (Ln = Eu, Nd, Yb) energy transfer for heteronuclear PtLn2 and Pt2Ln4 complexes with a terpyridyl-functionalized alkynyl ligand.

    PubMed

    Li, Xiu-Ling; Shi, Lin-Xi; Zhang, Li-Yi; Wen, Hui-Min; Chen, Zhong-Ning

    2007-12-10

    Reaction of Pt(dppm-P,P')Cl2 (dppm = 1,2-bis(diphenylphosphino)methane) with HCCPhtpy (HCCPhtpy = 4'-(4-ethynylphenyl)-2,2':6',2"-terpyridine) in the presence of copper(I) iodide and diisopropylamine induced isolation of mononuclear complex cis-Pt(dppm-P,P')(C[triple bond]CPhtpy)2 (1), which can be converted into face-to-face diplatinum(II) species Pt2(mu-dppm)2(C[triple bond]CPhtpy)4 (5) when equivalent dppm is added. Incorporating 1 or 5 to Ln(hfac)3(H2O)2 (Hhfac = hexafluoroacetylacetone) gave PtLn2 (Ln = Nd (2), Eu (3), Yb (4)) or Pt2Ln4 (Ln = Nd (6), Eu (7), Gd (8), Yb (9)) adducts with the lanthanide centers chelated by terdentate terpyridyl in the bridging C[triple bond]CPhtpy. The structures of 1, 6, 7, and 9 were determined by X-ray crystallography. Upon excitation at lambdaex = 360-450 nm (2-4) or 360-500 nm (6-9), where the PtII alkynyl antenna chromophores absorb strongly but the model complexes Ln(hfac)3(HC[triple bond]CPhtpy) lack obvious absorption in this region, these PtLn2 and Pt2Ln4 (Ln = Nd, Eu, Yb) species exhibit band-like lanthanide luminescence that is typical of the corresponding Ln3+ ions, demonstrating unambiguously that efficient Pt --> Ln energy transfer occurs indeed from the PtII alkynyl antenna chromophores to the lanthanide centers across the bridging CCPhtpy with intramolecular Pt...Ln distances being ca. 14.2 A. The Pt --> Ln energy transfer rate (kET) is 6.07 x 10(7) s(-1) for Pt2Nd4 (6) and 2.12 x 10(5) s(-1) for Pt2Yb4 (9) species.

  11. Preparation, crystal structure and luminescent properties of the (6,3) type network supramolecular lanthanide picrate complexes with 2,2'-[(1,2-naphthalene)bis(oxy)]bis[N-(phenylmethyl)]acetamide

    SciTech Connect

    Wang Qin; Tang Kuanzhen; Liu Weisheng; Tang Yu; Tan Minyu

    2009-11-15

    Solid complexes of lanthanide picrates with a new podand-type ligand, 2,2'-[(1,2-naphthalene)bis(oxy)]bis[N-(phenylmethyl)]acetamide (L) have been prepared and characterized by elemental analysis, conductivity measurements, IR and electronic spectroscopies. The crystal and molecular structures of the coordination polymer {l_brace}[Eu{sub 2}L{sub 3}(Pic){sub 6}].(CHCl{sub 3}){sub 3}.(H{sub 2}O){sub 0.5}{r_brace}{sub n} have been determined by single-crystal X-ray diffraction, and the structure displays a two-dimensional honeycomb-like framework in the ab plane, which can be regarded as a (6,3) topological network with europium atoms acting as 'three-connected' centers. Furthermore, the coordination layers are linked by the intermolecular hydrogen bonds to form a three-dimensional (3-D) netlike supermolecule. Under excitation, Eu complex exhibited characteristic emissions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion. - Graphical abstract: The (6,3) type network supramolecular luminescent lanthanide picrate complexes {l_brace}Ln{sub 2}L{sub 3}(Pic){sub 6}{r_brace}{sub n} (L=2,2'-[(1,2-naphthalene)bis(oxy)]bis[N-(phenylmethyl)]acetamide) displaying a two-dimensional honeycomb-like framework have been designed and prepared.

  12. Complex magnetism of lanthanide intermetallics and the role of their valence electrons: Ab Initio theory and experiment

    DOE PAGES

    Petit, L.; Paudyal, D.; Mudryk, Y.; ...

    2015-11-09

    We explain a profound complexity of magnetic interactions of some technologically relevant gadolinium intermetallics using an ab initio electronic structure theory which includes disordered local moments and strong f-electron correlations. The theory correctly finds GdZn and GdCd to be simple ferromagnets and predicts a remarkably large increase of Curie temperature with a pressure of +1.5 K kbar–1 for GdCd confirmed by our experimental measurements of +1.6 K kbar–1. Moreover, we find the origin of a ferromagnetic-antiferromagnetic competition in GdMg manifested by noncollinear, canted magnetic order at low temperatures. As a result, replacing 35% of the Mg atoms with Zn removesmore » this transition, in excellent agreement with long-standing experimental data.« less

  13. Spectral studies of Lanthanide interactions with membrane surfaces

    SciTech Connect

    Karukstis, K.K.; Kao, M.Y.; Savin, D.A.; Bittker, R.A.; Kaphengst, K.J.; Emetarom, C.M.; Naito, N.R.; Takamoto, D.Y.

    1995-03-23

    We have monitored the interactions of the series of trivalent lanthanide cations with the thylakoid membrane surface of spinach chloroplasts using two complementary spectral techniques. Measurements of the fluorescence emission of the extrinsic probe 2-p-toluidinonaphthalene-6-sulfonate (TNS) and the absorbance of the intrinsic chromophore chlorophyll provide two sensitive means of characterizing the dependence of the cation-membrane interaction on the nature of the cation. In these systems, added lanthanide cations adsorb onto the membrane surface to neutralize exposed segments of membrane-embedded protein complexes. The lanthanide-induced charge neutralization increases the proximity of added TNS anion to the membrane surface as evidenced by variations in the TNS fluorescence level and wavelength of maximum emission. Our results reveal a strong dependence of TNS fluorescence parameters on both lanthanide size and total orbital angular momentum L value. Lanthanides with greater charge density (small size and/or low L value) enhance the TNS fluorescence level to a greater extent. A possible origin for the lanthanide-dependent TNS fluorescence levels is suggested in terms of a heterogeneity in the number and type of TNS binding sites. The data are consistent with the proposal that larger lanthanides with smaller enthalpies of hydration induce more significant membrane appression. 59 refs., 9 figs., 2 tabs.

  14. Kinetics of formation for lanthanide (III) complexes of DTPA-(Me-Trp)2 used as imaging agent.

    PubMed

    Tiwari, Anjani K; Sinha, Deepa; Datta, Anupama; Kakkar, Dipti; Mishra, Anil K

    2011-05-01

    Diethlenetriamine-N,N,N'N''N''-pentaacetic acid (DTPA)-bis (amide) analogs have been synthesized and evaluated as a potential biomedical imaging agents. Imaging and biodistribution studies were performed in mice that showed a significant accumulation of DTPA analogs in brain. The stability and protonation constants of the complexes formed between the ligand [DTPA-(Me-Trp)(2)] and Gd(3+), Eu(3+), and Cu(2+) have been determined by pH potentiometry (Gd(3+), Eu(3+)) and spectrophotometry (Cu(2+)) at 25 °C and at constant ionic strength maintained by 0.10 M KCl. The kinetic inertness of Gd [DTPA-(Me-Trp)(2)] was characterized by the rates of exchange reactions with Zn(2+) and Eu(3+). In the Eu(3+) exchange, a second-order [H(+)] dependence was found for the pseudo-first-order rate constant [k(0) = (4.5 ± 1.2) × 10(-6)/s; k(1) = 0.58 ± 0.1 /M/s, k(2) = (6.6 ± 0.2) × 10(4) /M(2)/s, k(3) = (4.8 ± 0.8) × 10(-4) /M/s]. In the Eu(3+) exchange, at pH <5.0, the rate decreases with increasing concentration of the exchanging ion. At physiological pH, the kinetic inertness of [DTPA-(Me-Trp)(2)] is more inert than GdDTPA(2-), the most commonly used MRI contrast agent (t(1/2) = 127 h). High kinetic stability is an important requirement for the Gd complexes used as contrast enhancement agents in magnetic resonance imaging. © 2011 John Wiley & Sons A/S.

  15. A Pyridine-Based Ligand with Two Hydrazine Functions for Lanthanide Chelation: Remarkable Kinetic Inertness for a Linear, Bishydrated Complex.

    PubMed

    Bonnet, Célia S; Laine, Sophie; Buron, Frédéric; Tircsó, Gyula; Pallier, Agnès; Helm, Lothar; Suzenet, Franck; Tóth, Éva

    2015-06-15

    To study the influence of hydrazine functions in the ligand skeleton, we designed the heptadentate HYD ligand (2,2',2″,2‴-(2,2'-(pyridine-2,6-diyl)bis(2-methylhydrazine-2,1,1-triyl)) tetraacetic acid) and compared the thermodynamic, kinetic, and relaxation properties of its Ln(3+) complexes to those of the parent pyridine (Py) analogues without hydrazine (Py = 2,6-pyridinebis(methanamine)-N,N,N',N'-tetraacetic acid). The protonation constants of HYD were determined by pH-potentiometric measurements, and assigned by a combination of UV-visible and NMR spectroscopies. The protonation sequence is rather unusual and illustrates that small structural changes can strongly influence ligand basicity. The first protonation step occurs on the pyridine nitrogen in the basic region, followed by two hydrazine nitrogens and the carboxylate groups at acidic pH. Contrary to Py, HYD self-aggregates through a pH-dependent process (from pH ca. 4). Thermodynamic stability constants have been obtained by pH-potentiometry and UV-visible spectrophotometry for various Ln(3+) and physiological cations (Zn(2+), Ca(2+), Cu(2+)). LnHYD stability constants show the same trend as those of LnDTPA complexes along the Ln(3+) series, with log K = 18.33 for Gd(3+), comparable to the Py analogue. CuHYD has a particularly high stability (log K > 19) preventing its determination from pH-potentiometric measurements. The stability constant of CuPy was also revisited and found to be underestimated in previous studies, highlighting that UV-visible spectrophotometry is often indispensable to obtain reliable stability constants for Cu(2+) chelates. The dissociation of GdL, assessed by studying the Cu(2+)-exchange reaction, occurs mainly via an acid-catalyzed process, with limited contribution from direct Cu(2+) attack. The kinetic inertness of GdHYD is remarkable for a linear bishydrated chelate; the 25-fold increase in the dissociation half-life with respect to the monohydrated commercial contrast agent

  16. Solvent extraction and lanthanide complexation studies with new terdentate ligands containing two 1,3,5-triazine moieties.

    PubMed

    Drew, Michael G B; Hill, Clement; Hudson, Michael J; Iveson, Peter B; Madic, Charles; Youngs, Tristan G A

    2004-01-21

    The extracting agent 2,6-bis(4,6-di-pivaloylamino-1,3,5-triazin-2-yl)-pyridine (L(5)) in n-octanol was found, in synergy with 2-bromodecanoic acid, to give D(Am)/D(Eu) separation factors (SFs) between 2.4 and 3.7 when used to extract the metal ions from 0.02-0.12 M HNO(3). Slightly higher SFs (4-6) were obtained in the absence of the synergist when the ligand was used to extract Am(III) and Eu(III) from 0.98 M HNO(3). In order to investigate the possible nature of the extracted species crystal structures of L(5) and the complex formed between Yb(III) with 2,6-bis(4,6-di-amino-1,3,5-triazin-2-yl)-pyridine (L(4)) were also determined. The structure of L(5) shows 3 methanol solvent molecules all of which form 2 or 3 hydrogen bonds with triazine nitrogen atoms, amide nitrogen or oxygen atoms, or pyridine nitrogen atoms. However, L(5) is relatively unstable in metal complexation reactions and loses amide groups to form the parent tetramine L(4). The crystal structure of Yb(L(4))(NO(3))(3) shows ytterbium in a 9-coordinate environment being bonded to three donor atoms of the ligand and three bidentate nitrate ions. The solvent extraction properties of L(4) and L(5) are far inferior to those found for the 2,6-bis-(1,2,4-triazin-3-yl)-pyridines (L(1)) which have SF values of ca. 140 and theoretical calculations have been made to compare the electronic properties of the ligands. The electronic charge distribution in L(4) and L(5) is similar to that found in other terdentate ligands such as terpyridine which have equally poor extraction properties and suggests that the unique properties of L(1) evolve from the presence of two adjacent nitrogen atoms in the triazine rings.

  17. Lanthanide(III)/actinide(III) differentiation in coordination of azine molecules to tris(cyclopentadienyl) complexes of cerium and uranium.

    PubMed

    Mehdoui, Thouraya; Berthet, Jean-Claude; Thuéry, Pierre; Ephritikhine, Michel

    2004-02-21

    Reaction of azine molecules L with the trivalent metallocenes [M(C5H4R)3](M = Ce, U; R = But, SiMe3) in toluene gave the Lewis base adducts [M(C5H4R)3(L)](L = pyridine, 3-picoline, 3,5-lutidine, 3-chloropyridine, pyridazine, pyrimidine, pyrazine, 3,5-dimethylpyrazine and s-triazine), except in the cases of M = U and L = 3-chloropyridine, pyridazine, pyrazine and s-triazine where oxidation of U(III) was found to occur. In the pairs of analogous compounds of Ce(III) and U(III), i.e.[M(C5H4But)3(L)](L = pyridine, picoline) and [M(C5H4SiMe3)3(L)](L = pyridine, lutidine, pyrimidine and dimethylpyrazine), the M-N and average M-C distances are longer for M = Ce than for M = U; however, within a series of azine adducts of the same metallocene, no significant variation is noted in the M-N and average M-C distances. The equilibria between [M(C5H4R)3], L and [M(C5H4R)3(L)] were studied by 1H NMR spectroscopy. The stability constants of the uranium complexes, KUL, are greater than those of the cerium counterparts, KCeL. The values of KML are much greater for R = SiMe3 than for R = But and a linear correlation is found between the logarithms of KML and the hydrogen-bond basicity pKHB scale of the azines. Thermodynamic parameters indicate that the enthalpy-entropy compensation effect holds for these complexation reactions. Competition reactions of [Ce(C5H4R)3] and [U(C5H4R)3] with L show that the selectivity of L in favour of U(III) increases with the [small pi] donor character of the metallocene and is proportional to the pi accepting ability of the azine molecule, measured by its reduction potential.

  18. Ionic liquids as a novel solvent for lanthanide extraction.

    PubMed

    Nakashima, Kazunori; Kubota, Fukiko; Maruyama, Tatsuo; Goto, Masahiro

    2003-08-01

    Octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) dissolved in an ionic liquids, 1-butyl-3-methyl-imidazolium hexafluorophosphate, greatly enhances extractability and selectivity of lanthanide cations compared to that dissolved in conventional organic solvents; further, the recovery of lanthanides extracted into ionic liquids can be accomplished using several stripping solutions containing complexing agents. The possibility of utilizing ionic liquids as novel separation media in an industrial liquid-liquid extraction process was demonstrated.

  19. Characterization of the Prophage Repertoire of African Salmonella Typhimurium ST313 Reveals High Levels of Spontaneous Induction of Novel Phage BTP1

    PubMed Central

    Owen, Siân V.; Wenner, Nicolas; Canals, Rocío; Makumi, Angela; Hammarlöf, Disa L.; Gordon, Melita A.; Aertsen, Abram; Feasey, Nicholas A.; Hinton, Jay C. D.

    2017-01-01

    In the past 30 years, Salmonella bloodstream infections have become a significant health problem in sub-Saharan Africa and are responsible for the deaths of an estimated 390,000 people each year. The disease is predominantly caused by a recently described sequence type of Salmonella Typhimurium: ST313, which has a distinctive set of prophage sequences. We have thoroughly characterized the ST313-associated prophages both genetically and experimentally. ST313 representative strain D23580 contains five full-length prophages: BTP1, Gifsy-2D23580, ST64BD23580, Gifsy-1D23580, and BTP5. We show that common S. Typhimurium prophages Gifsy-2, Gifsy-1, and ST64B are inactivated in ST313 by mutations. Prophage BTP1 was found to be a functional novel phage, and the first isolate of the proposed new species “Salmonella virus BTP1”, belonging to the P22virus genus. Surprisingly, ∼109 BTP1 virus particles per ml were detected in the supernatant of non-induced, stationary-phase cultures of strain D23580, representing the highest spontaneously induced phage titer so far reported for a bacterial prophage. High spontaneous induction is shown to be an intrinsic property of prophage BTP1, and indicates the phage-mediated lysis of around 0.2% of the lysogenic population. The fact that BTP1 is highly conserved in ST313 poses interesting questions about the potential fitness costs and benefits of novel prophages in epidemic S. Typhimurium ST313. PMID:28280485

  20. Characterization of the Prophage Repertoire of African Salmonella Typhimurium ST313 Reveals High Levels of Spontaneous Induction of Novel Phage BTP1.

    PubMed

    Owen, Siân V; Wenner, Nicolas; Canals, Rocío; Makumi, Angela; Hammarlöf, Disa L; Gordon, Melita A; Aertsen, Abram; Feasey, Nicholas A; Hinton, Jay C D

    2017-01-01

    In the past 30 years, Salmonella bloodstream infections have become a significant health problem in sub-Saharan Africa and are responsible for the deaths of an estimated 390,000 people each year. The disease is predominantly caused by a recently described sequence type of Salmonella Typhimurium: ST313, which has a distinctive set of prophage sequences. We have thoroughly characterized the ST313-associated prophages both genetically and experimentally. ST313 representative strain D23580 contains five full-length prophages: BTP1, Gifsy-2(D23580), ST64B(D23580), Gifsy-1(D23580), and BTP5. We show that common S. Typhimurium prophages Gifsy-2, Gifsy-1, and ST64B are inactivated in ST313 by mutations. Prophage BTP1 was found to be a functional novel phage, and the first isolate of the proposed new species "Salmonella virus BTP1", belonging to the P22virus genus. Surprisingly, ∼10(9) BTP1 virus particles per ml were detected in the supernatant of non-induced, stationary-phase cultures of strain D23580, representing the highest spontaneously induced phage titer so far reported for a bacterial prophage. High spontaneous induction is shown to be an intrinsic property of prophage BTP1, and indicates the phage-mediated lysis of around 0.2% of the lysogenic population. The fact that BTP1 is highly conserved in ST313 poses interesting questions about the potential fitness costs and benefits of novel prophages in epidemic S. Typhimurium ST313.

  1. Luminescence and single-molecule magnet behavior in lanthanide complexes involving a tetrathiafulvalene-fused dipyridophenazine ligand.

    PubMed

    Pointillart, Fabrice; Jung, Julie; Berraud-Pache, Romain; Le Guennic, Boris; Dorcet, Vincent; Golhen, Stéphane; Cador, Olivier; Maury, Olivier; Guyot, Yannick; Decurtins, Silvio; Liu, Shi-Xia; Ouahab, Lahcène

    2015-06-01

    The reaction between the TTF-fused dipyrido[3,2-a:2',3'-c]phenazine (dppz) ligand (L) and 1 equiv of Ln(hfac)3·2H2O (hfac(-) = 1,1,1,5,5,5-hexafluoroacetyacetonate) or 1 equiv of Ln(tta)3·2H2O (tta(-) = 2-thenoyltrifluoroacetonate) (Ln(III) = Dy(III) or Yb(III)) metallic precursors leads to four mononuclear complexes of formula [Ln(hfac)3(L)]·C6H14 (Ln(III) = Dy(III) (1), Yb(III) (2)) and [Ln(tta)3(L)]·C6H14 (Ln(III) = Dy(III) (3), Yb(III) (4)), respectively. Their X-ray structures reveal that the Ln(III) ion is coordinated to the bischelating nitrogenated coordination site and adopts a D4d coordination environment. The dynamic magnetic measurements show a slow relaxation of the Dy(III) magnetization for 1 and 3 with parameters highlighting a slower relaxation for 3 than for 1 (τ0 = 4.14(±1.36) × 10(-6) and 1.32(±0.07) × 10(-6) s with Δ = 39(±3) and 63.7(±0.7) K). This behavior as well as the orientation of the associated magnetic anisotropy axes have been rationalized on the basis of both crystal field splitting parameters and ab initio SA-CASSCF/RASSI-SO calculations. Irradiation of the lowest-energy HOMO → LUMO ILCT absorption band induces a (2)F5/2 → (2)F7/2 Yb-centered emission for 2 and 4. For these Yb(III) compounds, Stevens operators method has been used to fit the thermal variation of the magnetic susceptibilities, and the resulting MJ splittings have been correlated with the emission lines.

  2. Complexation of metal ions, including alkali-earth and lanthanide(III) ions, in aqueous solution by the ligand 2,2',6',2''-terpyridyl.

    PubMed

    Hamilton, Joanna M; Anhorn, Michael J; Oscarson, Karen A; Reibenspies, Joseph H; Hancock, Robert D

    2011-04-04

    Some metal-ion-complexing properties of the ligand 2,2',6',2''-terpyridyl (terpy) in aqueous solution are determined by following the π-π* transitions of 2 × 10(-5) M terpy by UV-visible spectroscopy. It is found that terpy forms precipitates when present as the neutral ligand above pH ∼5, in the presence of electrolytes such as NaClO(4) or NaCl added to control the ionic strength, as evidenced by large light-scattering peaks. The protonation constants of terpy are thus determined at the ionic strength (μ) = 0 to avoid precipitation and found to be 4.32(3) and 3.27(3). The log K(1) values were determined for terpy with alkali-earth metal ions Mg(II), Ca(II), Sr(II), and Ba(II) and Ln(III) (Ln = lanthanide) ions La(III), Gd(III), and Lu(III) by titration of 2 × 10(-5) M free terpy at pH >5.0 with solutions of the metal ion. Log K(1)(terpy) was determined for Zn(II), Cd(II), and Pb(II) by following the competition between the metal ions and protons as a function of the pH. Complex formation for all of these metal ions was accompanied by marked sharpening of the broad π-π* transitions of free terpy, which was attributed to complex formation affecting ligand vibrations, which in the free ligand are coupled to the π-π* transitions and thus broaden them. It is shown that log K(1)(terpy) for a wide variety of metal ions correlates well with log K(1)(NH(3)) values for the metal ions. The latter include both experimental log K(1)(NH(3)) values and log K(1)(NH(3)) values predicted previously by density functional theory calculation. The structure of [Ni(terpy)(2)][Ni(CN)(4)]·CH(3)CH(2)OH·H(2)O (1) is reported as follows: triclinic, P1, a = 8.644(3) Å, b = 9.840(3) Å, c = 20.162(6) Å, α = 97.355(5)°, β = 97.100(5)°, γ = 98.606(5)°, V = 1663.8(9) Å(3), Z = 4, and final R = 0.0319. The two Ni-N bonds to the central N donors of the terpy ligands in 1 average 1.990(2) Å, while the four peripheral Ni-N bonds average 2.107(10) Å. This difference in the M

  3. Group IV complexes containing the benzotriazole phenoxide ligand as catalysts for the ring-opening polymerization of lactides, epoxides and as precatalysts for the polymerization of ethylene.

    PubMed

    Pappuru, Sreenath; Chokkapu, Eswara Rao; Chakraborty, Debashis; Ramkumar, Venkatachalam

    2013-12-14

    A series of Ti(IV), Zr(IV) and Hf(IV) benzotriazole phenoxide (BTP) complexes were synthesized and characterized by various spectroscopic techniques, elemental analysis and X-ray crystallography. The monosubstituted Zr(IV) BTP complexes [(μ-L)Zr(O(i)Pr)3]2 1-3 [L = (C1)BTP-H (1), (TCl)BTP-H (2), (pent)BTP-H (3)] and tetrasubstituted Zr(IV), Hf(IV) complexes ZrL4 4-6 [L = (C1)BTP-H (4), (TCl)BTP-H (5), (pent)BTP-H (6)] and HfL4 7-9 [L = (C1)BTP-H (7), (TCl)BTP-H (8), (pent)BTP-H (9)] were prepared by the reaction of Zr(O(i)Pr)4·((i)PrOH) and Hf(O(t)Bu)4 in toluene with the respective ligands in different stoichiometric proportions. The reaction between BTP and TiCl4 and ZrCl4 and HfCl4 in a 2 : 1 stoichiometric reaction resulted in the formation of disubstituted group IV chloride complexes L2MCl2 10-12 [L = (C1)BTP-H, M = Ti, Zr and Hf]. The molecular structures of complexes 1, 4, 7, 10, 11, and 12 were determined by single-crystal X-ray studies. The X-ray structure of 1 reveals a dimeric Zr(IV) complex containing a Zr2O2 core bridged through the oxygen atoms of the phenoxide groups. Each Zr atom is distorted from an octahedral symmetry. These complexes were found to be active towards the ring-opening polymerization (ROP) of L-lactide (L-LA) and rac-lactide (rac-LA). Complex 1 produced highly heterotactic poly(lactic acid) (PLA) from rac-LA under melt conditions with narrow molecular weight distributions (MWDs) and well controlled number average molecular weights (M(n)). Additionally, epoxide polymerizations using rac-cyclohexene oxide (CHO), rac-propylene oxide (PO), and rac-styrene oxide (SO) were also carried out with these complexes. The yield and molecular weight of the polymer was found to increase with the extension of reaction time. Compounds 1-12 were activated by methylaluminoxane (MAO) and show good activity for ethylene polymerization and produced high molecular weight polyethylene.

  4. Two-Color Three-State Luminescent Lanthanide Core-Shell Crystals.

    PubMed

    Balogh, Cristina M; Veyre, Laurent; Pilet, Guillaume; Charles, Cyril; Viriot, Laurent; Andraud, Chantal; Thieuleux, Chloé; Riobé, François; Maury, Olivier

    2017-02-03

    Luminescent core-shell crystals based on lanthanide tris-dipicolinate complexes were obtained from the successive growing of two different lanthanide complex layers. Selective or simultaneous emission of each part of the crystal can be achieved by a careful choice of the excitation wavelength.

  5. Lanthanide complexes based on a 1,7-diaza-12-crown-4 platform containing picolinate pendants: a new structural entry for the design of magnetic resonance imaging contrast agents.

    PubMed

    Mato-Iglesias, Marta; Roca-Sabio, Adrián; Pálinkás, Zoltán; Esteban-Gómez, David; Platas-Iglesias, Carlos; Tóth, Eva; de Blas, Andrés; Rodríguez-Blas, Teresa

    2008-09-01

    We have synthesized a new macrocyclic ligand, N,N'-Bis[(6-carboxy-2-pyridyl)methyl]-1,7-diaza-12-crown-4 (H 2bp12c4), designed for complexation of lanthanide ions in aqueous solution. The X-ray crystal structure of the Gd (III) complex shows that the metal ion is directly bound to the eight donor atoms of the bp12c4 ligand, the ninth coordination site being occupied by an oxygen atom of a carboxylate group of a neighboring [Gd(bp12c4)] (+) unit, while the structure of the Lu (III) analogue shows the metal ion being only eight-coordinate. The hydration numbers obtained from luminescence lifetime measurements in aqueous solution of the Eu (III) and Tb (III) complexes suggest an equilibrium in aqueous solution between a dihydrated ( q = 2), ten-coordinate and a monohydrated ( q = 1), nine-coordinate species. This has been confirmed by a variable temperature UV-vis spectrophotometric study on the Eu (III) complex. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by theoretical calculations performed at the DFT (B3LYP) level. The results indicate that the change in hydration number occurring around the middle of the lanthanide series is accompanied by a change in the conformation adopted by the complexes in solution [Delta(lambdalambdalambdalambda) for q = 2 and Lambda(deltalambdadeltalambda) for q = 1]. The structure calculated for the Yb (III) complex (Lambda(deltalambdadeltalambda)) is in good agreement with the experimental structure in solution, as demonstrated by the analysis of the Yb (III)-induced paramagnetic (1)H shifts.

  6. Stability, water exchange, and anion binding studies on lanthanide(III) complexes with a macrocyclic ligand based on 1,7-diaza-12-crown-4: extremely fast water exchange on the Gd3+ complex.

    PubMed

    Pálinkás, Zoltán; Roca-Sabio, Adrián; Mato-Iglesias, Marta; Esteban-Gómez, David; Platas-Iglesias, Carlos; de Blas, Andrés; Rodríguez-Blas, Teresa; Tóth, Eva

    2009-09-21

    The picolinate-derivative ligand based on the 1,7-diaza-12-crown-4 platform (bp12c4(2-)) forms stable Ln(3+) complexes with stability constants increasing from the early to the middle lanthanides, then being relatively constant for the rest of the series (logK(LnL) = 16.81(0.06), 18.82(0.01), and 18.08(0.05) for Ln = La, Gd, and Yb, respectively). The complex formation is fast, allowing for direct potentiometric titrations to assess the stability constants. In the presence of Zn(2+), the dissociation of [Gd(bp12c4)](+) proceeds both via proton- and metal-assisted pathways, and in this respect, this system is intermediate between DTPA-type and macrocyclic, DOTA-type chelates, for which the dissociation is predominated by metal- or proton-assisted pathways, respectively. The Cu(2+) exchange shows an unexpected pH dependency, with the observed rate constants decreasing with increasing proton concentration. The rate of water exchange, assessed by (17)O NMR, is extremely high on the [Gd(bp12c4)(H(2)O)(q)](+) complex (k(ex)(298) = (2.20 +/- 0.15) x 10(8) s(-1)), and is in the same order of magnitude as for the Gd(3+) aqua ion (k(ex)(298) = 8.0 x 10(8) s(-1)). In aqueous solution, the [Gd(bp12c4)(H(2)O)(q)](+) complex is present in hydration equilibrium between nine-coordinate, monohydrated, and ten-coordinate, bishydrated species. We attribute the fast exchange to the hydration equilibrium and to the flexible nature of the inner coordination sphere. The large negative value of the activation entropy (DeltaS = -35 +/- 8 J mol(-1) K(-1)) points to an associative character for the water exchange and suggests that water exchange on the nine-coordinate, monohydrated species is predominant in the overall exchange. Relaxometric and luminescence measurements on the Gd(3+) and Eu(3+) analogues, respectively, indicate strong binding of endogenous anions such as citrate, hydrogencarbonate, or phosphate to [Ln(bp12c4)](+) complexes (K(aff) = 280 +/- 20 M(-1), 630 +/- 50 M(-1), and

  7. Giant exchange interaction in mixed lanthanides

    PubMed Central

    Vieru, Veacheslav; Iwahara, Naoya; Ungur, Liviu; Chibotaru, Liviu F.

    2016-01-01

    Combining strong magnetic anisotropy with strong exchange interaction is a long standing goal in the design of quantum magnets. The lanthanide complexes, while exhibiting a very strong ionic anisotropy, usually display a weak exchange coupling, amounting to only a few wavenumbers. Recently, an isostructural series of mixed (Ln = Gd, Tb, Dy, Ho, Er) have been reported, in which the exchange splitting is estimated to reach hundreds wavenumbers. The microscopic mechanism governing the unusual exchange interaction in these compounds is revealed here by combining detailed modeling with density-functional theory and ab initio calculations. We find it to be basically kinetic and highly complex, involving non-negligible contributions up to seventh power of total angular momentum of each lanthanide site. The performed analysis also elucidates the origin of magnetization blocking in these compounds. Contrary to general expectations the latter is not always favored by strong exchange interaction. PMID:27087470

  8. Spectrally resolved confocal microscopy using lanthanide centred near-IR emission.

    PubMed

    Liao, Zhiyu; Tropiano, Manuel; Mantulnikovs, Konstantins; Faulkner, Stephen; Vosch, Tom; Sørensen, Thomas Just

    2015-02-11

    The narrow, near infrared (NIR) emission from lanthanide ions has attracted great interest, particularly with regard to developing tools for bioimaging, where the long lifetimes of lanthanide excited states can be exploited to address problems arising from autofluorescence and sample transparency. Despite the promise of lanthanide-based probes for near-IR imaging, few reports on their use are present in the literature. Here, we demonstrate that images can be recorded by monitoring NIR emission from lanthanide complexes using detectors, optical elements and a microscope that were primarily designed for the visible part of the spectrum.

  9. Rapid fluorophosphate nerve agent detection with lanthanides.

    PubMed

    Menzel, E Roland; Menzel, Laird W; Schwierking, Jake R

    2005-08-15

    We explore the detection of vapors of diisopropylfluorophosphate, a model compound for nerve agents such as Sarin, by means of photoluminescence quenching of filter paper impregnated with sensitized complexes of lanthanides, involving thenoyltrifluoroacetone and 1,10-phenanthroline as sensitizing ligands. We find that the presence of the fluorophosphate vapor is detectable in as little as 2s, by simple visual observation under illumination with a hand-held low intensity ultraviolet lamp.

  10. Luminescent 1-hydroxy-2-pyridinone chelates of lanthanides

    DOEpatents

    Raymond, Kenneth N.; Xu, Jide; Moore, Evan G.; Werner, Eric J.

    2013-10-15

    The present invention provides luminescent complexes between a lanthanide ion and an organic ligand which contains 1,2-hydroxypyridinone units. The complexes of the invention are stable in aqueous solutions and are useful as molecular probes, for example in medical diagnostics and bioanalytical assay systems. The invention also provides methods of using the complexes of the invention.

  11. Luminescent 1-hydroxy-2-pyridinone chelates of lanthanides

    DOEpatents

    Raymond, Kenneth N.; Xu, Jide; Moore, Evan G.; Werner, Eric J.

    2017-01-31

    The present invention provides luminescent complexes between a lanthanide ion and an organic ligand which contains 1,2-hydroxypyridinone units. The complexes of the invention are stable in aqueous solutions and are useful as molecular probes, for example in medical diagnostics and bioanalytical assay systems. The invention also provides methods of using the complexes of the invention.

  12. Lanthanide ion (III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate for dual biosensing of pH with chemical exchange saturation transfer (CEST) and biosensor imaging of redundant deviation in shifts (BIRDS).

    PubMed

    Huang, Yuegao; Coman, Daniel; Ali, Meser M; Hyder, Fahmeed

    2015-01-01

    Relaxivity-based magnetic resonance of phosphonated ligands chelated with gadolinium (Gd(3+)) shows promise for pH imaging. However instead of monitoring the paramagnetic effect of lanthanide complexes on the relaxivity of water protons, biosensor (or molecular) imaging with magnetic resonance is also possible by detecting either the nonexchangeable or the exchangeable protons on the lanthanide complexes themselves. The nonexchangeable protons (e.g. -CHx, where 3 ≥ x ≥ 1) are detected using a three-dimensional chemical shift imaging method called biosensor imaging of redundant deviation in shifts (BIRDS), whereas the exchangeable protons (e.g. -OH or -NHy , where 2 ≥ y ≥ 1) are measured with chemical exchange saturation transfer (CEST) contrast. Here we tested the feasibility of BIRDS and CEST for pH imaging of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminophosphonate (DOTA-4AmP(8-)) chelated with thulium (Tm(3+) ) and ytterbium (Yb(3+)). BIRDS and CEST experiments show that both complexes are responsive to pH and temperature changes. Higher pH and temperature sensitivities are obtained with BIRDS for either complex when using the chemical shift difference between two proton resonances vs using the chemical shift of a single proton resonance, thereby eliminating the need to use water resonance as reference. While CEST contrast for both agents is linearly dependent on pH within a relatively large range (i.e. 6.3-7.9), much stronger CEST contrast is obtained with YbDOTA-4AmP(5-) than with TmDOTA-4AmP(5-). In addition, we demonstrate the prospect of using BIRDS to calibrate CEST as new platform for quantitative pH imaging.

  13. Allosteric effects in coiled-coil proteins folding and lanthanide-ion binding.

    PubMed

    Samiappan, Manickasundaram; Alasibi, Samaa; Cohen-Luria, Rivka; Shanzer, Abraham; Ashkenasy, Gonen

    2012-10-07

    Peptide sequences modified with lanthanide-chelating groups at their N-termini, or at their lysine side chains, were synthesized, and new Ln(III) complexes were characterized. We show that partial folding of the conjugates to form trimer coiled coil structures induces coordination of lanthanides to the ligand, which in turn further stabilizes the 3D structure.

  14. Lanthanide-halide based humidity indicators

    DOEpatents

    Beitz, James V.; Williams, Clayton W.

    2008-01-01

    The present invention discloses a lanthanide-halide based humidity indicator and method of producing such indicator. The color of the present invention indicates the humidity of an atmosphere to which it is exposed. For example, impregnating an adsorbent support such as silica gel with an aqueous solution of the europium-containing reagent solution described herein, and dehydrating the support to dryness forms a substance with a yellow color. When this substance is exposed to a humid atmosphere the water vapor from the air is adsorbed into the coating on the pore surface of the silica gel. As the water content of the coating increases, the visual color of the coated silica gel changes from yellow to white. The color change is due to the water combining with the lanthanide-halide complex on the pores of the gel.

  15. Photodetachment of Lanthanide Oxide Anions

    NASA Astrophysics Data System (ADS)

    Covington, A. M.; Emmons, E. D.; Kraus, R. G.; Thompson, J. S.; Calabrese, D.; Davis, V. T.

    2007-06-01

    Laser photodetached electron spectroscopy (LPES) has been used to study the structure and collision properties of lanthanide oxide anions including LaOn^- and CeOn^-. Preliminary photoelectron spectra from these anions will be presented along with ion beam production data from these and other lanthanide oxide anions.

  16. Lanthanide tris(β-diketonates) as useful probes for chirality determination of biological amino alcohols in vibrational circular dichroism: ligand to ligand chirality transfer in lanthanide coordination sphere.

    PubMed

    Miyake, Hiroyuki; Terada, Keiko; Tsukube, Hiroshi

    2014-06-01

    A series of lanthanide tris(β-diketonates) functioned as useful chirality probes in the vibrational circular dichroism (VCD) characterization of biological amino alcohols. Various chiral amino alcohols induced intense VCD signals upon ternary complexation with racemic lanthanide tris(β-diketonates). The VCD signals observed around 1500 cm(-1) (β-diketonate IR absorption region) correlated well with the stereochemistry and enantiomeric purity of the targeted amino alcohol, while the corresponding monoalcohol, monoamine, and diol substrates induced very weak VCD signals. The high-coordination number and dynamic property of the lanthanide complex offer an effective chirality VCD probing of biological substrates.

  17. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    SciTech Connect

    Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

    2015-01-15

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln{sub 2}(phen){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub n} (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]{sub n} (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO{sub 4}{sup 2−} anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic–inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature. - Graphical abstract: Lanthanide sulfates and lanthanide sulfonate-carboxylates have been hydrothermally synthesized. Interestingly, sulfate anions, 2-sulfobenzoate and benzoate ligands came from the in situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. - Highlights: • In situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. • The organic–inorganic hybrid lanthanide sulfates with one-dimensional column-like structure. • The dinuclear lanthanide sulfonate-carboxylates. • The emission spectra exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–4) of the Eu(III)

  18. Characterization and thermogravimetric analysis of lanthanide hexafluoroacetylacetone chelates.

    PubMed

    Shahbazi, Shayan; Stratz, S Adam; Auxier, John D; Hanson, Daniel E; Marsh, Matthew L; Hall, Howard L

    2017-01-01

    This work reports the thermodynamic characterizations of organometallic species as a vehicle for the rapid separation of volatile nuclear fission products via gas chromatography due to differences in adsorption enthalpy. Because adsorption and sublimation thermodynamics are linearly correlated, there is considerable motivation to determine sublimation enthalpies. A method of isothermal thermogravimetric analysis, TGA-MS and melting point analysis are employed on thirteen lanthanide 1,1,1,5,5,5-hexafluoroacetylacetone complexes to determine sublimation enthalpies. An empirical correlation is used to estimate adsorption enthalpies of lanthanide complexes on a quartz column from the sublimation data. Additionally, four chelates are characterized by SC-XRD, elemental analysis, FTIR and NMR.

  19. Extraction of lanthanide ions by 2-methyl-8-quinolinol

    SciTech Connect

    Taguchi, S.; Freiser, H.

    1985-01-01

    The equilibrium extraction behavior of a series of tervalent lanthanides (La, Pr, Eu, Ho, and Yb) with 2-methyl-8-quinolinol (HL) in chloroform has been studied. Although the sterically hindered extractant does not form neutral LnL/sub 3/ complexes, ion pair complexes of intermediate chelates with either perchlorate or thiocyanate ions are extractable. The extraction constants of such species are smaller than those of other 8-quinolinols and closer together because the adverse steric influence of the 2-methyl group is greater on the heavier lanthanide ions. 12 refs., 3 figs., 1 tab.

  20. Yttrium and lanthanide complexes of β-dialdehydes: synthesis, characterization and luminescence of coordination compounds with the conjugate base of nitromalonaldehyde.

    PubMed

    Bortoluzzi, Marco; Bianchin, Elena; Roppa, Stefania; Bertolasi, Valerio; Enrichi, Francesco

    2014-07-14

    Coordination compounds having formulae [AsPh4][Ln(NMA)4] (1(Ln)), Ln(NMA)3(tppo)2 (2(Ln)), Ln(NMA)3(bipyO2) (3(Ln)), Ln(NMA)3(phen) (4(Ln)) and Ln(NMA)3(terpy) (5(Ln)) (Ln = Y and some lanthanides; NMA = conjugate base of nitromalonaldehyde; tppo = triphenylphosphine oxide; bipyO2 = 2,2'-bipyridine-N,N'-dioxide; phen = 1,10-phenanthroline; terpy = 2,2':6',2''-terpyridine) were synthesized and characterized and X-ray diffraction data were collected for [AsPh4][Y(NMA)4] (1(Y)). The neutral europium derivatives showed appreciable luminescence in the solid state upon excitation with UV light and photoluminescence measurements were carried out. These compounds were used as dopants for the preparation of luminescent poly(methyl methacrylate). Luminescent polyvinylpyrrolidone samples were obtained by reacting the pure polymer with water solutions containing NMA and trivalent europium ions.

  1. 1-Methyl-3-hydroxy-pyridin-2-one complexes of near infra-red emitting lanthanides: efficient sensitization of Yb(III) and Nd(III) in aqueous solution.

    PubMed

    Moore, Evan G; Xu, Jide; Dodani, Sheel C; Jocher, Christoph J; D'Aléo, Anthony; Seitz, Michael; Raymond, Kenneth N

    2010-05-03

    The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution (Phi(tot)(Yb) approximately 0.09-0.22%).Furthermore, the complexes demonstrate very high stability (pYb approximately 18.8-21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a model Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding time-dependent density functional theory (TD-DFT) calculations at the B3LYP/6-311G++(d,p) level of theory for a simplified model monovalent sodium complex.

  2. Stability vs. reactivity: understanding the adsorption properties of Ni3(BTP)2 by experimental and computational methods.

    PubMed

    Shearer, Greig C; Colombo, Valentina; Chavan, Sachin; Albanese, Elisa; Civalleri, Bartolomeo; Maspero, Angelo; Bordiga, Silvia

    2013-05-14

    FTIR spectroscopy and ab initio molecular modelling have been employed to probe the interaction between CO and Ni3(BTP)2, a thermally and chemically stable MOF. A combination of low pressure adsorption isotherms and FTIR spectroscopy has been utilised to study the material for its interaction with CO2 and H2. The experimental results indicate that despite an abundance of Ni(2+) coordination vacancies in the activated sample, the molecular probes considered in this study do not interact with them. These findings are in alignment with the data obtained by molecular modelling, in which it is shown that the unreactive diamagnetic, low spin state is more stable. Due to the strong N-donor character of the pyrazolate ligands on this material, the electrostatic potential map of the optimized low spin structure does not show any evidence of a region of positive potential typical of open metal sites.

  3. Lanthanide(III) complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p) in solution and in the solid state: structural studies along the series.

    PubMed

    Campello, M Paula C; Lacerda, Sara; Santos, Isabel C; Pereira, Giovannia A; Geraldes, Carlos F G C; Kotek, Jan; Hermann, Petr; Vanek, Jakub; Lubal, Premysl; Kubícek, Vojtech; Tóth, Eva; Santos, Isabel

    2010-07-26

    Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H(6)do2a2p, H(6)L) with transition metal and lanthanide(III) ions were investigated. The stability constant values of the divalent and trivalent metal-ion complexes are between the corresponding values of H(4)dota and H(8)dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were determined by X-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nona-coordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated water molecule. In the series of Sm, Eu, Tb, Dy, Er, Yb, the complexes are octa-coordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissociation of several Ln(III)-H(6)L complexes were investigated at different temperatures and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H(2)O)](3-) complex is the most kinetically inert among complexes of the investigated lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate-acetate dota analogues, kinetic inertness of the cerium(III) complexes is increased with a higher number of phosphonate arms in the ligand, whereas the opposite is true for europium(III) complexes. According to the (1)H NMR spectroscopic pseudo-contact shifts for the Ce-Eu and Tb-Yb series, the solution structures of the complexes reflect the structures of the [Ce(HL)(H(2)O)](2-) and [Yb(HL)](2-) anions, respectively, found in the solid state. However, these solution NMR spectroscopic studies showed that there is no unambiguous relation between (31)P/(1)H lanthanide-induced shift (LIS) values and coordination of water in the complexes; the values rather express a relative position of the central ions between the N(4

  4. Fluorescence and Ir studies on the hydration state of lanthanides(III) and curium(III) in the complexes extracted with purified Cyanex301, Cyanex302 and Cyanex272

    SciTech Connect

    Tian, Guoxin; Kimura, Takaumi; Yoshida, Zenko; Zhu, Yongjun; Rao, Linfeng

    2004-03-22

    The hydration number of lanthanides, Ln(III) (Ln = Sm, Eu, Tb, Dy), and Cm(III) in the extracted complexes with purified Cyanex301, Cyanex302 and Cyanex272 was investigated using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and FT-IR spectroscopy. The results, in conjunction with the previous results on the Ln(III) and Am(III) complexes, provide insight into the composition of the extracted complexes. No difference has been observed in the hydration number or the composition between the Ln(III) and Cm(III) complexes with Cyanex302 or Cyanex272. The extracted complexes of Ln(III) and Cm(III) with Cyanex302 have the formula, ML(HL2)2 cdot nH2O, where L stands for the anion of Cyanex302 and n = 3 - 5. No water molecules are found in the first coordination shell of Ln(III) or Cm(III) complexes with Cyanex272. In contrast to the extraction with Cyanex302 or Cyanex272, the composition of the Ln(III) complexes is different from that of the Cm(III) complex in the extraction wi th Cyanex301. The Ln(III) complex with Cyanex301 has one or two H2O molecules with a molecular formula of LnL3 cdot 2H2O or HLnL4 cdot H2O, where L stands for the anion of Cyanex301. However, the Cm(III) complex with Cyanex301 does not contain H2O with the molecular formula of HCmL4, in which only the 8 sulfur atoms from Cyanex301 coordinate to Cm(III). The results for Cm(III) agree with the previous data for Am(III) from EXAFS and IR measurements.

  5. Early Transcriptional Responses of Bovine Chorioallantoic Membrane Explants to Wild Type, ΔvirB2 or ΔbtpB Brucella abortus Infection

    PubMed Central

    Mol, Juliana P. S.; Costa, Erica A.; Carvalho, Alex F.; Sun, Yao-Hui; Tsolis, Reneé M.; Paixão, Tatiane A.; Santos, Renato L.

    2014-01-01

    The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM) explants inoculated with wild type (strain 2308), ΔvirB2 or ΔbtpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05) were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ΔvirB2 or the ΔbtpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ΔvirB and ΔbtpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion. PMID:25259715

  6. A Ratiometric Luminescent Thermometer Co-doped with Lanthanide and Transition Metals.

    PubMed

    Li, Zhiqiang; Hou, Zhaohui; Ha, Denghui; Li, Huanrong

    2015-12-01

    Herein, we report the fabrication of a sensitive ratiometric and colorimetric luminescent thermometer with a wide operating-temperature range, from cryogenic temperatures up to high temperatures, through the combination of lanthanide and transition metal complexes. Benefiting from the transition metal complex as a self-reference, the lanthanide content in the mixed-coordination complex, Eu0.05(Mebip-mim bromine)0.15Zn0.95(Mebip-mim bromine)1.9, was lowered to 5%.

  7. Purely heterometallic lanthanide(III) macrocycles through controlled assembly of disulfide bonds for dual color emission.

    PubMed

    Lewis, David J; Glover, Peter B; Solomons, Melissa C; Pikramenou, Zoe

    2011-02-02

    Lanthanide complexes based on bis(amides) of diethylenetriaminepentaacetic acid with thiol functionalities are modified with 2,2'-dipyridyl disulfide to give activated complexes that can selectively react with thiol-functionalized complexes to form heterometallic lanthanide macrocycles. The preparation and full characterization of the polyaminocarboxylate ligands N,N''-bis[p-thiophenyl(aminocarbonyl)]diethylenetriamine-N,N',N''-triacetic acid (H(3)L(x)) and the activated N,N''-bis[p-(pyridyldithio)[phenyl(aminocarbonyl)

  8. Understanding stability trends along the lanthanide series.

    PubMed

    Regueiro-Figueroa, Martín; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos

    2014-04-01

    The stability trends across the lanthanide series of complexes with the polyaminocarboxylate ligands TETA(4-) (H4TETA=2,2',2'',2'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetraacetic acid), BCAED(4-) (H4BCAED=2,2',2'',2'''-{[(1,4-diazepane-1,4-diyl)bis(ethane-2,1-diyl)]bis(azanetriyl)}tetraacetic acid), and BP18C6(2-) (H2BP18C6=6,6'-[(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene)]dipicolinic acid) were investigated using DFT calculations. Geometry optimizations performed at the TPSSh/6-31G(d,p) level, and using a 46+4f(n) ECP for lanthanides, provide bond lengths of the metal coordination environments in good agreement with the experimental values observed in the X-ray structures. The contractions of the Ln(3+) coordination spheres follow quadratic trends, as observed previously for different isostructural series of complexes. We show here that the parameters obtained from the quantitative analysis of these data can be used to rationalize the observed stability trends across the 4f period. The stability trends along the lanthanide series were also evaluated by calculating the free energy for the reaction [La(L)](n+/-)(sol)+Ln(3+)(sol)→[Ln(L)](n+/-)(sol)+La(3+)(sol). A parameterization of the Ln(3+) radii was performed by minimizing the differences between experimental and calculated standard hydration free energies. The calculated stability trends are in good agreement with the experimental stability constants, which increase markedly across the series for BCAED(4-) complexes, increase smoothly for the TETA(4-) analogues, and decrease in the case of BP18C6(2-) complexes. The resulting stability trend is the result of a subtle balance between the increased binding energies of the ligand across the lanthanide series, which contribute to an increasing complex stability, and the increase in the absolute values of hydration energies along the 4f period.

  9. A computational approach to predicting ligand selectivity for the size-based separation of trivalent lanthanides

    DOE PAGES

    Ivanov, Alexander S.; Bryantsev, Vyacheslav S.

    2016-06-20

    An accurate description of solvation effects for trivalent lanthanide ions is a main stumbling block to the qualitative prediction of selectivity trends along the lanthanide series. In this work, we propose a simple model to describe the differential effect of solvation in the competitive binding of a ligand by lanthanide ions by including weakly co-ordinated counterions in the complexes of more than a +1 charge. The success of the approach to quantitatively reproduce selectivities obtained from aqueous phase complexation studies demonstrates its potential for the design and screening of new ligands for efficient size-based separation.

  10. A computational approach to predicting ligand selectivity for the size-based separation of trivalent lanthanides

    SciTech Connect

    Ivanov, Alexander S.; Bryantsev, Vyacheslav S.

    2016-06-20

    An accurate description of solvation effects for trivalent lanthanide ions is a main stumbling block to the qualitative prediction of selectivity trends along the lanthanide series. In this work, we propose a simple model to describe the differential effect of solvation in the competitive binding of a ligand by lanthanide ions by including weakly co-ordinated counterions in the complexes of more than a +1 charge. The success of the approach to quantitatively reproduce selectivities obtained from aqueous phase complexation studies demonstrates its potential for the design and screening of new ligands for efficient size-based separation.

  11. Tri- and tetra-substituted cyclen based lanthanide(III) ion complexes as ribonuclease mimics: a study into the effect of log Ka, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP).

    PubMed

    Fanning, Ann-Marie; Plush, Sally E; Gunnlaugsson, Thorfinnur

    2015-05-28

    A series of tetra-substituted 'pseudo' dipeptide ligands of cyclen (1,4,7,10,-tetraazacyclododecane) and a tri-substituted 3'-pyridine ligand of cyclen, and the corresponding lanthanide(III) complexes were synthesised and characterised as metallo-ribonuclease mimics. All complexes were shown to promote hydrolysis of the phosphodiester bond of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP, τ1/2 = 5.87 × 10(3) h), a well known RNA mimic. The La(III) and Eu(III) tri-substituted 3'-pyridine lanthanide(III) complexes being the most efficient in promoting such hydrolysis at pH 7.4 and at 37 °C; with τ1/2 = 1.67 h for La(III) and 1.74 h for Eu(III). The series was developed to provide the opportunity to investigate the consequences of altering the lanthanide(III) ion, coordination ability and hydrophobicity of a metallo-cavity on the rate of hydrolysis using the model phosphodiester, HPNP, at 37 °C. To further provide information on the role that the log Ka of the metal bound water plays in phosphodiester hydrolysis the protonation constants and the metal ion stability constants of both a tri and tetra-substituted 3'pyridine complex were determined. Our results highlighted several key features for the design of lanthanide(III) ribonucelase mimics; the presence of two metal bound water molecules are vital for pH dependent rate constants for Eu(III) complexes, optimal pH activity approximating physiological pH (∼7.4) may be achieved if the log Ka values for both MLOH and ML(OH)2 species occur in this region, small changes to hydrophobicity within the metallo cavity influence the rate of hydrolysis greatly and an amide adjacent to the metal ion capable of forming hydrogen bonds with the substrate is required for achieving fast hydrolysis.

  12. Lanthanides in molecular magnetism: so fascinating, so challenging.

    PubMed

    Luzon, Javier; Sessoli, Roberta

    2012-11-28

    Due to their usual large magnetic moments and large magnetic anisotropy lanthanide ions are investigated for the search of Single Molecule Magnets with high blocking temperature. However, the low symmetry crystal environment, the complexity of the electronic states or the non-collinearity of the magnetic anisotropy easy-axes in polynuclear systems make the rationalization of the magnetic behaviour of lanthanide based molecular systems difficult. In this perspective article we expose a methodology in which the use of additional characterization techniques, like single crystal magnetic measurements or luminescence experiments, complemented by relativistic ab initio calculations and a suitable choice of spin Hamiltonian models, can be of great help in order to overcome such difficulties, representing an essential step for the rational design of lanthanide based Single Molecule Magnets with enhanced physical properties.

  13. Lanthanide template synthesis of a molecular trefoil knot.

    PubMed

    Ayme, Jean-François; Gil-Ramírez, Guzmán; Leigh, David A; Lemonnier, Jean-François; Markevicius, Augustinas; Muryn, Christopher A; Zhang, Gen

    2014-09-24

    We report on a complex featuring three 2,6-pyridinedicarboxamide ligands entwined around a lanthanide (Ln(3+)) ion. The ligand strands can be cyclized by ring-closing olefin metathesis to form a molecular trefoil knot in 58% yield. Demetalation with tetraethylammonium fluoride quantitatively generates the wholly organic 81-atom-loop trefoil knot.

  14. Noncovalent ligand-to-ligand interactions alter sense of optical chirality in luminescent tris(β-diketonate) lanthanide(III) complexes containing a chiral bis(oxazolinyl) pyridine ligand.

    PubMed

    Yuasa, Junpei; Ohno, Tomoko; Miyata, Kohei; Tsumatori, Hiroyuki; Hasegawa, Yasuchika; Kawai, Tsuyoshi

    2011-06-29

    Highly luminescent tris[β-diketonate (HFA, 1,1,1,5,5,5-hexafluoropentane-2,4-dione)] europium(III) complexes containing a chiral bis(oxazolinyl) pyridine (pybox) ligand--[(Eu(III)(R)-Ph-pybox)(HFA)(3)], [(Eu(III)(R)-i-Pr-pybox)(HFA)(3)], and [(Eu(III)(R)-Me-Ph-pybox)(HFA)(3)])--exhibit strong circularly polarized luminescence (CPL) at the magnetic-dipole ((5)D(0) → (7)F(1)) transition, where the [(Eu(III)(R)-Ph-pybox)(HFA)(3)] complexes show virtually opposite CPL spectra as compared to those with the same chirality of [(Eu(III)(R)-i-Pr-pybox)(HFA)(3)] and [(Eu(III)(R)-Me-Ph-pybox)(HFA)(3)]. Similarly, the [(Tb(III)(R)-Ph-pybox)(HFA)(3)] complexes were found to exhibit CPL signals almost opposite to those of [(Tb(III)(R)-i-Pr-pybox)(HFA)(3)] and [(Tb(III)(R)-Me-Ph-pybox)(HFA)(3)] complexes with the same pybox chirality. Single-crystal X-ray structural analysis revealed ligand-ligand interactions between the pybox ligand and the HFA ligand in each lanthanide(III) complex: π-π stacking interactions in the Eu(III) and Tb(III) complexes with the Ph-pybox ligand, CH/F interactions in those with the i-Pr-pybox ligand, and CH/π interactions in those with the Me-Ph-pybox ligand. The ligand-ligand interactions between the achiral HFA ligands and the chiral pybox results in an asymmetric arrangement of three HFA ligands around the metal center. The metal center geometry varies depending on the types of ligand-ligand interaction.

  15. Density functional theory investigations of the homoleptic tris(dithiolene) complexes [M(dddt)(3)](-q) (q = 3, 2 ; M = Nd(3+) and U(3+/4+)) related to lanthanide(III)/actinide(III) differentiation.

    PubMed

    Meskaldji, Samir; Belkhiri, Lotfi; Arliguie, Thérèse; Fourmigué, Marc; Ephritikhine, Michel; Boucekkine, Abdou

    2010-04-05

    The structures of the homoleptic lanthanide and actinide tris(dithiolene) complexes [M(dddt)(3)](q-) (q = 3, M = Nd(3+) and q = 3 or 2, M = U(3+/4+)) have been investigated using relativistic Density Functional Theory (DFT) computations including spin-orbit corrections coupled with the COnductor-like Screening Model (COSMO) for a realistic solvation approach. The dithiolene ligands are known to be very efficient at stabilizing metal high oxidation states. The aim of the work is to explain the peculiar symmetric folding of the three Mdddt metallacycles in these complexes, some of them existing under a polymeric form, in relation with the Ln(III)/An(III) differentiation. In the [M(dddt)(3)(py)](q-) species, where an additional pyridine ligand is linked to the metal center, the Mdddt moieties appear to be almost planar. The study brings to light the occurrence of a M...C=C interaction explaining the Mdddt folding of the [U(dddt)(3)](q-) uranium species, the metal 5f electrons playing a driving role. No such interaction appears in the case of the Nd(III) complex, and the folding of the rather flexible dddt ligands in the polymeric structure of this species should be mainly due to steric effects. Moreover, the analysis of the normal modes of vibration shows that the U(III) complex [U(dddt)(3)](3-), which has not yet been isolated, is thermodynamically stable. It appears that the X-ray characterized U(IV) complex [U(dddt)(3)](2-) should be less stable than the calculated U(III) complex in a polar solvent.

  16. Complexations of Ln(III) with SnS4H and Sn2S6: Solvothermal syntheses and characterizations of lanthanide coordination polymers with thiostannate and polyamine mixed ligands

    NASA Astrophysics Data System (ADS)

    Tang, Chunying; Lu, Jialin; Han, Jingyu; Liu, Yun; Shen, Yali; Jia, Dingxian

    2015-10-01

    Polymeric lanthanide complexes with thiostannate and polyamine mixed ligands, [Ln(peha)(μ-SnS4H)]n [Ln=La (1a), Nd (1b)] and [{Ln(tepa)(μ-OH)}2(μ-Sn2S6)]nnH2O [Ln=Nd (2a), Sm (2b), Gd (2c), Dy (2d)] (peha=pentaethylenehexamine, tepa=tetraethylenepentamine) were respectively prepared in peha and tepa coordinative solvents by the solvothermal methods. In 1a and 1b, the Ln3+ ions are coordinated by a hexadentate peha ligand forming [Ln(peha)]3+ units. The [SnS4H]3- anion chelates a [Ln(peha)]3+ unit via two S atoms and coordinates to another [Ln(peha)]3+ unit via the third S atom. As a result, the [Ln(peha)]3+ units are connected into coordination polymers [Ln(peha)(μ-SnS4H)]n by an unprecedented tridentate μ-η1,η2-SnS4H bridging ligands. In 2a-2d, the Ln3+ ions are coordinated by a pentadentate tepa ligand, and two [Ln(tepa)]3+ units are joined by two μ-OH bridges to form a binuclear [{Ln(tepa)(μ-OH)}2]4+ unit. Behaving as a bidentate μ-η1, η1-Sn2S6 bridging ligand, the Sn2S6 unit connects [{Ln(tepa)(μ-OH)}2]4+ units into a neutral coordination polymer [{Ln(tepa)(μ-OH)}2(μ-Sn2S6)]n via the trans S atoms. The Ln3+ ions are in distorted monocapped square antiprismatic and bicapped trigonal prismatic environments in [{Ln(peha)(μ-SnS4H)]n and [{Ln(tepa)(μ-OH)}2(μ-Sn2S6)]n, respectively. The denticities of ethylene polyamine play an important role on the formation and complexation of the thiostannate in the presence of lanthanide ions. Compounds 1a-2d show well-defined absorption edges with band gaps between 2.81 and 3.15 eV.

  17. Ab Initio Crystal Field for Lanthanides.

    PubMed

    Ungur, Liviu; Chibotaru, Liviu F

    2017-03-13

    An ab initio methodology for the first-principle derivation of crystal-field (CF) parameters for lanthanides is described. The methodology is applied to the analysis of CF parameters in [Tb(Pc)2 ](-) (Pc=phthalocyanine) and Dy4 K2 ([Dy(4) K(2) O(OtBu)(12) ]) complexes, and compared with often used approximate and model descriptions. It is found that the application of geometry symmetrization, and the use of electrostatic point-charge and phenomenological CF models, lead to unacceptably large deviations from predictions based on ab initio calculations for experimental geometry. It is shown how the predictions of standard CASSCF (Complete Active Space Self-Consistent Field) calculations (with 4f orbitals in the active space) can be systematically improved by including effects of dynamical electronic correlation (CASPT2 step) and by admixing electronic configurations of the 5d shell. This is exemplified for the well-studied Er-trensal complex (H3 trensal=2,2',2"-tris(salicylideneimido)trimethylamine). The electrostatic contributions to CF parameters in this complex, calculated with true charge distributions in the ligands, yield less than half of the total CF splitting, thus pointing to the dominant role of covalent effects. This analysis allows the conclusion that ab initio crystal field is an essential tool for the decent description of lanthanides.

  18. The Lanthanide Contraction beyond Coordination Chemistry.

    PubMed

    Ferru, Geoffroy; Reinhart, Benjamin; Bera, Mrinal K; Olvera de la Cruz, Monica; Qiao, Baofu; Ellis, Ross J

    2016-05-10

    The lanthanide contraction is conceptualized traditionally through coordination chemistry. Here we break this mold in a structural study of lanthanide ions dissolved in an amphiphilic liquid. The lanthanide contraction perturbs the weak interactions between molecular aggregates that drive mesoscale assembly and emergent behavior. The weak interactions correlate with lanthanide ion transport properties, suggesting new strategies for rare-earth separation that exploit forces outside of the coordination sphere. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Rapid hydrolytic cleavage of the mRNA model compound HPNP by glycine based macrocyclic lanthanide ribonuclease mimics.

    PubMed

    Gunnlaugsson, Thorfinnur; Davies, R Jeremy H; Nieuwenhuyzen, Mark; Stevenson, Clarke S; Viguier, Romain; Mulready, Sinead

    2002-09-21

    The lanthanide ion based macrocyclic complexes 1.Ln mimic the hydrophobic nature of ribonucleases, where the lanthanide ions induce the formation of a hydrophobic cavity for 1, giving rise to a large order of magnitude enhancement in the hydrolytic cleavage of HPNP.

  20. Structural variations in (CuL)2Ln complexes of a series of lanthanide ions with a salen-type unsymmetrical Schiff base(H2L): Dy and Tb derivatives as potential single-molecule magnets.

    PubMed

    Mahapatra, Prithwish; Ghosh, Soumavo; Koizumi, Naoki; Kanetomo, Takuya; Ishida, Takayuki; Drew, Michael G B; Ghosh, Ashutosh

    2017-09-28

    A new series of heterometallic trinuclear Cu2Ln complexes [lanthanide ions Ln = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5)] has been synthesized using a Cu(ii)-metalloligand derived from a N2O2 donor unsymmetrical Schiff base, H2L (where H2L = N-α-methylsalicylidene-N'-salicylidene-1,3-propanediamine), and structurally characterized. Among these complexes, [(CuL)2Gd(NO3)3(CH3CN)2] (1), [(CuL)2Tb(NO3)3(CH3CN)2] (2) and [(CuL)2Dy(NO3)3(CH3CN)2] (3) are isomorphic and isostructural. In these complexes two metalloligands coordinate to the central Ln(iii) (Ln = Gd, Tb and Dy respectively) ion in a transoid fashion viaμ2-phenoxido oxygen atoms. The Ln(iii) ions are deca-coordinated with a distorted tetradecahedron geometry. The two terminal Cu(ii) ions of the complexes possess a hexa-coordinated distorted octahedral geometry. In contrast, in complexes [(CuL)2Ho(NO3)3(CH3CN)], (4) and [(CuL)2Er(NO3)3(CH3CN)]·0.5(CH3CN) (5), the two metalloligands coordinated to the Ln(iii) ions in a cisoid fashion. The Ho(iii) ion in 4 is nona-coordinated with a distorted tricapped trigonal prismatic geometry and the Er(iii) ion in 5 is octa-coordinated with a distorted square antiprismatic geometry. The two terminal Cu(ii) ions in complexes 4 and 5 are penta-coordinated with a distorted square-pyramidal geometry. The dc magnetic susceptibilities and field dependent magnetization measurement of complex 1 reveal the occurrence of ferromagnetic interactions between Cu(ii) and Gd(iii) ions as well as intermolecular antiferromagnetic interactions. Both complexes 2 and 3 show ferromagnetic interactions between Cu(ii) and Ln(iii) ions. The ac magnetic susceptibilities of all the complexes were also recorded and it was found that only complexes 2 and 3 exhibit slow relaxation of magnetization reorientation below 10 K at 2000 Oe applied dc field, this being characteristic of single molecule magnets.

  1. The separation of lanthanides and actinides in supercritical fluid carbon dioxide

    DOE PAGES

    Mincher, Bruce J.; Wai, Chien M.; Fox, Robert V.; ...

    2015-10-28

    Supercritical fluid carbon dioxide presents an attractive alternative to conventional solvents for recovery of the actinides and lanthanides. Carbon dioxide is a good solvent for fluorine and phosphate-containing ligands, including the traditional tributylphosphate ligand used in process-scale uranium separations. Actinide and lanthanide oxides may even be directly dissolved in carbon dioxide containing the complexes formed between these ligands and mineral acids, obviating the need for large volumes of acids for leaching and dissolution, and the corresponding organic liquid–liquid solvent extraction solutions. As a result, examples of the application of this novel technology for actinide and lanthanide separations are presented.

  2. Features of the reaction of heterocyclic analogs of chalcone with lanthanide shift reagents

    SciTech Connect

    Turov, A.V.; Khilya, V.P.

    1994-10-01

    The PMR spectra of heterocyclic analogs of 2-hydroxychalcone containing thiazole, benzofuran, triazole, imidazole, benzodioxane, or pyridine rings in the presence of lanthanide shift reagents are studied. It is found that the most effective reagent for modifying the spectra of these compounds is Yb(fod)3. The broadening of the spectra of 2-hydroxy chalcones in the presence of lanthanide shift reagents is explained by the dynamic effects of complex formation. An example is given of the determination of the conformation of molecules of 2-hydroxychalcone by the simultaneous use of lanthanide shift reagents and the homonuclear Overhauser effect. 9 refs., 1 fig., 1 tab.

  3. Lanthanides: New life metals?

    PubMed

    Chistoserdova, Ludmila

    2016-08-01

    Lanthanides (Ln(3+)) that are Rare Earth Elements, until recently thought to be biologically inert, have recently emerged as essential metals for activity and expression of a special type of methanol dehydrogenase, XoxF. As XoxF enzyme homologs are encoded in a wide variety of microbes, including microbes active in important environmental processes such as methane and methanol metabolism, Ln(3+) may represent some of the key biogeochemical drivers in cycling of carbon and other elements. However, significant gaps in understanding the role of Ln(3+) in biological systems remain as the functions of most of the proteins potentially dependent of Ln(3+) and their roles in specific metabolic networks/respective biogeochemical cycles remain unknown. Moreover, enzymes dependent on Ln(3+) but not related to XoxF enzymes may exist, and these so far have not been recognized. Through connecting the recently uncovered genetic divergence and phylogenetic distribution of XoxF-like enzymes and through elucidation of their activities, metal and substrate specificities, along with the biological contexts of respective biochemical pathways, most parsimonious scenarios for their evolution could be uncovered. Generation of such data will firmly establish the role of Ln(3+) in the biochemistry of Life inhabiting this planet.

  4. Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with μ3-η2:η2:η2 bonding.

    PubMed

    Bag, Pradip; Dutta, Supriya; Biswas, Papu; Maji, Swarup Kumar; Flörke, Ulrich; Nag, Kamalaksha

    2012-03-28

    A series of mononuclear lanthanide(III) complexes [Ln(LH(2))(H(2)O)(3)Cl](ClO(4))(2) (Ln = La, Nd, Sm, Eu, Gd, Tb, Lu) of the tetraiminodiphenolate macrocyclic ligand (LH(2)) in 95 : 5 (v/v) methanol-water solution fix atmospheric carbon dioxide to produce the carbonato-bridged trinuclear complexes [{Ln(LH(2))(H(2)O)Cl}(3)(μ(3)-CO(3))](ClO(4))(4)·nH(2)O. Under similar conditions, the mononuclear Y(III) complex forms the dimeric compound [{Y(LH(2))(H(2)O)Cl}(μ(2)-CO(3)){Y(LH(2))(H(2)O)(2)}](ClO(4))(3)·4H(2)O. These complexes have been characterized by their IR and NMR ((1)H, (13)C) spectra. The X-ray crystal structures have been determined for the trinuclear carbonato-bridged compounds of Nd(III), Gd(III) and Tb(III) and the dinuclear compound of Y(III). In all cases, each of the metal centers are 8-coordinate involving two imine nitrogens and two phenolate oxygens of the macrocyclic ligand (LH(2)) whose two other imines are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The oxygen atoms of the carbonate anion in the trinuclear complexes are bonded to the metal ions in tris-bidentate μ(3)-η(2):η(2):η(2) fashion, while they are in bis-bidentate μ(2)-η(2):η(2) mode in the Y(III) complex. The magnetic properties of the Gd(III) complex have been studied over the temperature range 2 to 300 K and the magnetic susceptibility data indicate a very weak antiferromagnetic exchange interaction (J = -0.042 cm(-1)) between the Gd(III) centers (S = 7/2) in the metal triangle through the carbonate bridge. The luminescence spectral behaviors of the complexes of Sm(III), Eu(III), and Tb(III) have been studied. The ligand LH(2) acts as a sensitizer for the metal ions in an acetonitrile-toluene glassy matrix (at 77 K) and luminescence intensities of the complexes decrease in the order Eu(3+) > Sm(3+) > Tb(3+).

  5. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    NASA Astrophysics Data System (ADS)

    Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

    2015-01-01

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln2(phen)2(SO4)3(H2O)2]n (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]n (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO4 2 - anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic-inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.

  6. The lanthanide contraction beyond coordination chemistry

    DOE PAGES

    Ferru, Geoffroy; Reinhart, Benjamin; Bera, Mrinal K.; ...

    2016-04-06

    Lanthanide chemistry is dominated by the ‘lanthanide contraction’, which is conceptualized traditionally through coordination chemistry. Here we break this mold, presenting evidence that the lanthanide contraction manifests outside of the coordination sphere, influencing weak interactions between groups of molecules that drive mesoscale-assembly and emergent behavior in an amphiphile solution. Furthermore, changes in these weak interactions correlate with differences in lanthanide ion transport properties, suggesting new forces to leverage rare earth separation and refining. Our results show that the lanthanide contraction paradigm extends beyond the coordination sphere, influencing structure and properties usually associated with soft matter science.

  7. The lanthanide contraction beyond coordination chemistry

    SciTech Connect

    Ferru, Geoffroy; Reinhart, Benjamin; Bera, Mrinal K.; Olvera de la Cruz, Monica; Qiao, Baofu; Ellis, Ross J.

    2016-04-06

    Lanthanide chemistry is dominated by the ‘lanthanide contraction’, which is conceptualized traditionally through coordination chemistry. Here we break this mold, presenting evidence that the lanthanide contraction manifests outside of the coordination sphere, influencing weak interactions between groups of molecules that drive mesoscale-assembly and emergent behavior in an amphiphile solution. Furthermore, changes in these weak interactions correlate with differences in lanthanide ion transport properties, suggesting new forces to leverage rare earth separation and refining. Our results show that the lanthanide contraction paradigm extends beyond the coordination sphere, influencing structure and properties usually associated with soft matter science.

  8. Experimental and theoretical comparison of actinide and lanthanide bonding in M[N(EPR(2))(2)](3) complexes (M = U, Pu, La, Ce; E = S, Se, Te; R = Ph, iPr, H).

    PubMed

    Gaunt, Andrew J; Reilly, Sean D; Enriquez, Alejandro E; Scott, Brian L; Ibers, James A; Sekar, Perumal; Ingram, Kieran I M; Kaltsoyannis, Nikolas; Neu, Mary P

    2008-01-07

    Treatment of M[N(SiMe3)2]3 (M = U, Pu (An); La, Ce (Ln)) with NH(EPPh2)2 and NH(EPiPr2)2 (E = S, Se), afforded the neutral complexes M[N(EPR2)2]3 (R = Ph, iPr). Tellurium donor complexes were synthesized by treatment of MI3(sol)4 (M = U, Pu; sol = py and M = La, Ce; sol = thf) with Na(tmeda)[N(TePiPr2)2]. The complexes have been structurally and spectroscopically characterized with concomitant computational modeling through density functional theory (DFT) calculations. The An-E bond lengths are shorter than the Ln-E bond lengths for metal ions of similar ionic radii, consistent with an increase in covalent interactions in the actinide bonding relative to the lanthanide bonding. In addition, the magnitude of the differences in the bonding is slightly greater with increasing softness of the chalcogen donor atom. The DFT calculations for the model systems correlate well with experimentally determined metrical parameters. They indicate that the enhanced covalency in the M-E bond as group 16 is descended arises mostly from increased metal d-orbital participation. Conversely, an increase in f-orbital participation is responsible for the enhancement of covalency in An-E bonds compared to Ln-E bonds. The fundamental and practical importance of such studies of the role of the valence d and f orbitals in the bonding of the f elements is emphasized.

  9. Triplet state properties of the OLED emitter Ir(btp)2(acac): characterization by site-selective spectroscopy and application of high magnetic fields.

    PubMed

    Finkenzeller, Walter J; Hofbeck, Thomas; Thompson, Mark E; Yersin, Hartmut

    2007-06-11

    The well-known red emitting complex Ir(btp)2(acac) (bis(2-(2'-benzothienyl)-pyridinato-N,C3')iridium(acetylacetonate)), frequently used as emitter material in OLEDs, has been investigated in a polycrystalline CH2Cl2 matrix. The studies were carried out under variation of temperature down to 1.2 K and at magnetic fields up to B=10 T. Highly resolved emission and excitation spectra of several specific sites are obtained by site-selective spectroscopy. For the preferentially investigated site (I-->0 at 16268 cm-1), the three substates I, II, and III of the T1 triplet state are separated by DeltaEII-I=2.9 cm-1 and DeltaEIII-I=25.0 cm-1, respectively. DeltaEIII-I represents the total zero-field splitting (ZFS). The individual decay times of these substates are tauI=150 micros, tauII=58 micros, and tauIII=2 micros, respectively. The long decay time of the lowest substate I indicates its almost pure triplet character. The time for relaxation from state II to state I (spin-lattice relaxation, SLR) is as long as 22 micros at T=1.5 K, while the thermalization between the two lower lying substates and substate III is fast. Application of a magnetic field induces Zeeman mixing of the substates of T1, resulting in an increased splitting between the two lower lying substates from 2.9 cm-1 at zero field to, for example, 6.8 cm-1 at B=10 T. Further, the decay time of the B-field perturbed lowest substate IB decreases by a factor of about 7 up to 10 T. The magnetic field properties clearly show that the three investigated states belong to the same triplet parent term of one single site. Other sites show a similar behavior, though the values of ZFS vary between 15 and 27 cm-1. Since the amount of ZFS reflects the extent of MLCT (metal-to-ligand charge transfer) parentage, it can be concluded that the emitting state T1 is a 3LC (ligand centered) state with significant admixtures of 1,3MLCT (metal-to-ligand charge transfer) character. Interestingly, the results show that the MLCT

  10. The interactions between the sterically demanding trimesitylphosphine oxide and trimesityphosphine with scandium and selected lanthanide ions

    NASA Astrophysics Data System (ADS)

    Platt, Andrew W. G.; Singh, Kuldip

    2016-05-01

    The reactions between lanthanide nitrates, Ln(NO3)3 and scandium and lanthanide trifluoromethane sulfonates, Ln(Tf)3 with trimesitylphosphine oxide, Mes3PO show that coordination to the metal ions does not lead to crystalline complexes. Investigation of the reactions by 31-P NMR spectroscopy shows that weak complexes are formed in solution. The crystal structures of Mes3PO·0.5CH3CN (1) and [Mes3PO]3H3O·2CH3CN·Tf (2), formed in the reaction between ScTf3 and Mes3PO, are reported. Trimesitylphosphine, Mes3P, is protonated by scandium and lanthanide trifluoromethane sulfonates and lanthanide nitrates in CD3CN and the structure of [Mes3PH]Cl·HCl·2H2O (3) is reported.

  11. "Straining" to Separate the Rare Earths: How the Lanthanide Contraction Impacts Chelation by Diglycolamide Ligands.

    PubMed

    Ellis, Ross J; Brigham, Derek M; Delmau, Laetitia; Ivanov, Alexander S; Williams, Neil J; Vo, Minh Nguyen; Reinhart, Benjamin; Moyer, Bruce A; Bryantsev, Vyacheslav S

    2017-02-06

    The subtle energetic differences underpinning adjacent lanthanide discrimination are explored with diglycolamide ligands. Our approach converges liquid-liquid extraction experiments with solution-phase X-ray absorption spectroscopy (XAS) and density functional theory (DFT) simulations, spanning the lanthanide series. The homoleptic [(DGA)3Ln](3+) complex was confirmed in the organic extractive solution by XAS, and this was modeled using DFT. An interplay between steric strain and coordination energies apparently gives rise to a nonlinear trend in discriminatory lanthanide ion complexation across the series. Our results highlight the importance of optimizing chelate molecular geometry to account for both coordination interactions and strain energies when designing new ligands for efficient adjacent lanthanide separation for rare-earth refining.

  12. Synthesis and characterization of lanthanide(III) (La, Gd, Yb, Y) disalicylidene-1,2-phenylenediamine (H{sub 2}dsp) Schiff-base complexes

    SciTech Connect

    Chen, Huiyong; Archer, R.D.

    1994-11-09

    Novel rare earth (III) disalicylidene-1,2-phenylenediamine(H{sub 2}dsp) complexes with the formula M[Ln(dsp){sub 2}] (M = Li, Na, K, Cs) were prepared. UV-visible absorption and NMR were used to study the disproportionation equilibrium for these complexes in DMSO. Structures for these complexes are suggested.

  13. Novel materials based on DNA-CTMA and lanthanide (Ce(3+) , Pr(3+) ).

    PubMed

    Lazar, Cosmina Andreea; Kajzar, François; Mihaly, Maria; Rogozea, Adina Elena; Petcu, Adina Roxana; Olteanu, Nicoleta Liliana; Rau, Ileana

    2016-09-01

    New, deoxyribonucleic acid (DNA) based compounds, functionalized with hexadecyltrimethylammonium chloride (CTMA) and lanthanide hydroxide nanoparticles were synthesized. The spectral measurements suggest that between the DNA-CTMA complex and the lanthanide (III) ions a chemical interaction takes place. The obtained materials exhibit an improved fluorescence efficiency, showing a potential interest for application in photonics, and more particularly, in light emitting devices. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 613-617, 2016. © 2016 Wiley Periodicals, Inc.

  14. Enhancement of anion binding in lanthanide optical sensors.

    PubMed

    Cable, Morgan L; Kirby, James P; Gray, Harry B; Ponce, Adrian

    2013-11-19

    In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the "lock-and-key". Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability, and dynamics. In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, filled d shell. Luminescent lanthanides such as terbium, europium, dysprosium, and samarium display many photophysical properties that make them excellent candidates for molecular sensor applications. Complexes of lanthanide ions act as receptors that exhibit a detectable change in metal-based luminescence upon binding of an anion. In our work on sensors for detection of dipicolinate, the unique biomarker of bacterial spores, we discovered that the incorporation of an ancillary ligand (AL) can enhance binding constants of target anions to lanthanide ions by as much as two orders of magnitude. In this Account, we show that selected ALs in lanthanide/anion systems greatly improve sensor performance for medical, planetary science, and biodefense applications. We suggest that the observed anion binding enhancement could result from an AL-induced increase in positive charge at the lanthanide ion binding site. This effect depends on lanthanide polarizability, which can be

  15. Enhancement of Anion Binding in Lanthanide Optical Sensors

    PubMed Central

    Cable, Morgan L.; Kirby, James P.; Gray, Harry B.; Ponce, Adrian

    2013-01-01

    In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the ‘lock-and-key.’ Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability and dynamics. In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, filled d shell. Luminescent lanthanides such as terbium, europium, dysprosium and samarium display many photophysical properties that make them excellent candidates for molecular sensor applications. Complexes of lanthanide ions act as receptors that exhibit a detectable change in metal-based luminescence upon binding of an anion. In our work on sensors for detection of dipicolinate, the unique biomarker of bacterial spores, we discovered that the incorporation of an ancillary ligand (AL) can enhance binding constants of target anions to lanthanide ions by as much as two orders of magnitude. In this Account, we show that selected ALs in lanthanide/anion systems greatly improve sensor performance for medical, planetary science and biodefense applications. We suggest that the observed anion binding enhancement could result from an AL-induced increase in positive charge at the lanthanide ion binding site. This effect depends on lanthanide polarizability, which can

  16. The Partitioning of Americium and the Lanthanides Using Tetrabutyldiglycolamide (TBDGA) in Octanol and in Ionic Liquid Solution

    SciTech Connect

    M.E. Mincher; D.L. Quach; Y.J. Liao; B.J. Mincher; C.M. Wai

    2012-11-01

    Separations among the lanthanides and the separation of Am from the lanthanides remain challenging, and research in this area continues to expand. The separation of adjacent lanthanides is of interest to high-tech industries because individual lanthanides have specialized uses and are in short supply. In nuclear fuel cycle applications Am would be incorporated into fast reactor fuels, yet the lanthanides are not desired. In this work the diamide N,N,N',N'-tetrabutyldiglycolamide (TBDGA) was investigated as a ligand for lanthanide and Am solvent extraction in both molecular and room temperature ionic liquid (RTIL) diluents. The RTIL [C4MIM][Tf2N-] showed very high extraction efficiency for these trivalent metals from low nitric acid concentrations, while the molecular diluent 1-octanol showed high extraction efficiency at high acid concentrations. This was attributed to the extraction of ionic nitrate complexes by the RTIL, whereas 1-octanol extracted neutral nitrate complexes. TBDGA in RTIL did not provide adequate separation factors for Am/lanthanide partitioning, but 1-octanol did show reasonable separation possibilities. Lanthanide intergroup separations appeared to be feasible in both diluents, but with higher separation factors from 1-octanol.

  17. Acylpyrazolones: Synthesis, self-assembly and lanthanide metal ion separation

    NASA Astrophysics Data System (ADS)

    Yang, Jun

    The central hypothesis that nanoscale self-assemblies can provide excellent metal ion recognition has been substantiated by employing acylpyrazolones and trivalent lanthanide metal ions as model systems. Several novel acylpyrazolones and their amphiphilic analogs have been designed, synthesized, and characterized. Their lanthanide metal ion recognition efficacies have been demonstrated through baseline separations of a mixture of light, middle, and heavy lanthanide metal ions by employing them in the aqueous mobile phase of high performance liquid chromatography (HPLC) with octadecylsilanized silica (ODS) as the stationary phase. The complex separation mechanism is influenced by the structures of acylpyrazolone and amphiphilic moieties, and spontaneous self-assembly of the ligand in the aqueous and on the stationary phases. Transmission electron microscopy (TEM) studies of the ligand self-assemblies in the aqueous phase in the absence and presence of lanthanide metal ions reveal spherical, dendritic, and linear (nanofibers, nanorods, and nanotubes) nanoscale structures. Such structures have also been observed when chloromethylated acylpyrazolones are stimulated to self-assemble by a base in nonaqueous solvents and when silica nanoparticles derivatized with them spontaneously self-assemble in aqueous and nonaqueous solvents.

  18. Biological toxicity of lanthanide elements on algae.

    PubMed

    Tai, Peidong; Zhao, Qing; Su, Dan; Li, Peijun; Stagnitti, Frank

    2010-08-01

    The biological toxicity of lanthanides on marine monocellular algae was investigated. The specific objective of this research was to establish the relationship between the abundance in the seawater of lanthanides and their biological toxicities on marine monocellular algae. The results showed that all single lanthanides had similar toxic effects on Skeletonema costatum. High concentrations of lanthanides (29.04+/-0.61 micromol L(-1)) resulted in 50% reduction in growth of algae compared to the controls (0 micromol L(-1)) after 96 h (96 h-EC50). The biological toxicity of 13 lanthanides on marine monocellular algae was unrelated with the abundance of different lanthanide elements in nature, and the "Harkins rule" was not appropriate for the lanthanides. A mixed solution that contained equivalent concentrations of each lanthanide element had the same inhibition effect on algae cells as each individual lanthanide element at the same total concentration. This phenomenon is unique compared to the groups of other elements in the periodic table. Hence, we speculate that the monocellular organisms might not be able to sufficiently differentiate between the almost chemically identical lanthanide elements. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  19. Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides.

    PubMed

    Zhang, Qingnan; Hu, Shu-Xian; Qu, Hui; Su, Jing; Wang, Guanjun; Lu, Jun-Bo; Chen, Mohua; Zhou, Mingfei; Li, Jun

    2016-06-06

    The chemistry of lanthanides (Ln=La-Lu) is dominated by the low-valent +3 or +2 oxidation state because of the chemical inertness of the valence 4f electrons. The highest known oxidation state of the whole lanthanide series is +4 for Ce, Pr, Nd, Tb, and Dy. We report the formation of the lanthanide oxide species PrO4 and PrO2 (+) complexes in the gas phase and in a solid noble-gas matrix. Combined infrared spectroscopic and advanced quantum chemistry studies show that these species have the unprecedented Pr(V) oxidation state, thus demonstrating that the pentavalent state is viable for lanthanide elements in a suitable coordination environment.

  20. Trivalent actinide and lanthanide separations using tetraalkyldiglycolamides (TCnDGA) in molecular and ionic liquid diluents

    SciTech Connect

    Bruce J. Mincher; Robert V. Fox; Mary E. Mincher; Chien M. Wai

    2014-09-01

    The use of the diglycolamide, tetrabutyldiglycolamide was investigated for intergroup separations of the lanthanides, focusing especially on those lanthanides (Y, Ce, Eu, Tb, Dy, Er, and Yb) found in lighting phosphors. Tetrabutyldiglycolamide extraction efficiency for the lanthanides varied depending on whether the diluent was the conventional molecular diluent 1-octanol, the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide, or a mixture of the two. This was attributed to extraction of either neutral, cationic or anionic lanthanide metal complexes with nitrate ion. Based on the batch contact solvent extraction results measured here, a series of extractions providing product streams containing separated Y, Ce, Eu, Tb/Dy, and Er/Yb are proposed.

  1. Combined high resolution NMR and 1H and 17O relaxometric study sheds light on the solution structure and dynamics of the lanthanide(III) complexes of HPDO3A.

    PubMed

    Delli Castelli, Daniela; Caligara, Maria C; Botta, Mauro; Terreno, Enzo; Aime, Silvio

    2013-06-17

    GdHPDO3A is one of the most used MRI contrast agents (CAs) for clinical use. However, unlike most of the other commercially available Gd-based CAs, only limited information is available on its solution structure and dynamics. 600 MHz high resolution (1)H NMR spectra of nine LnHPDO3A complexes (Ln = Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, and Yb) have been recorded at 298 K and neutral pH. Because of the low symmetry of the Ln-chelates, each proton gives rise to a different peak. Despite the very crowded spectra, it is possible to detect the presence of two sets of resonances associated with different isomers in solution in slow exchange in the NMR time scale. In principle, the LnHPDO3A complexes may be present in solution as eight isomeric forms (four enantiomeric pairs) differing in the layout of the acetate arms (Δ or Λ), in the conformation of the macrocyclic ring (δδδδ or λλλλ) and in the configuration of the chiral center (R or S). 1D- and 2D proton NMR spectra were measured as a function of temperature across the Lanthanide ser