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Sample records for lanthanide btp complexes

  1. Assessing covalency in equatorial U-N bonds: density based measures of bonding in BTP and isoamethyrin complexes of uranyl.

    PubMed

    Di Pietro, Poppy; Kerridge, Andrew

    2016-06-22

    Calculations performed at the density functional level of theory have been used to investigate complexes of uranyl with the expanded porphyrin isoamethyrin and the bis-triazinyl-pyridine (BTP) ligands, the latter of which is well-known to be effective in the separation of trivalent lanthanides and actinides. Analysis has been performed using a range of density-based techniques, including the Quantum Theory of Atoms in Molecules (QTAIM), the Electron Localisation Function (ELF) and the reduced density gradient (RDG). The effects of peripheral alkyl substituents on UO2-isoamethyrin, known to be vital for proper replication of the experimental geometry, are considered. Evidence for comparable amounts of covalent character has been found in the largely ionic U-N bonds of UO2-isoamethyrin and [UO2(BTP)2](2+) and examination of the variation in the electronic characteristics of the uranyl unit upon complexation in both of these cases reveal striking similarities in the nature of the U-N bonding and the effect of this bonding on the U-Oyl interaction, as well as evidence of donation into the U-N bonding region from the uranyl unit itself. PMID:27279271

  2. 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.

  3. Luminescent macrocyclic lanthanide complexes

    DOEpatents

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

    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.

  4. Thermolysis of lanthanide dithiocarbamate complexes

    SciTech Connect

    Boncher, William L.; Regulacio, Michelle D.; Stoll, Sarah L.

    2010-01-15

    Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex. The synthesis temperatures are generally lower than standard solid state preparations, avoid toxic sulfurizing gases and provide a convenient route to prepare lanthanide chalcogenide nanoparticles. Depending on the reaction conditions and oxophilicity of the lanthanide, the sulfide material was formed with oxidized products including oxysulfides, oxysulfates and the oxide. - Graphical abstract: Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex.

  5. 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.

  6. A TRLFS study on the complexation of novel BTP type ligands with Cm(III).

    PubMed

    Beele, Björn B; Rüdiger, Elias; Schwörer, Felicitas; Müllich, Udo; Geist, Andreas; Panak, Petra J

    2013-09-14

    Two BTP-type N-donor ligands with different numbers of aromatic nitrogen atoms (2,6-bis(4-ethyl-pyridazin-1-yl)pyridine, Et-BDP and 2,6-bis(4-(n)propyl-2,3,5,6-tetrazine-1-yl)pyridine, (n)Pr-Tetrazine) have been synthesized and characterized by NMR and MS techniques. The complexation with Cm(III) in 2-propanol-water (1 : 1, vol.) is studied for both ligands using time resolved laser-induced fluorescence spectroscopy (TRLFS) and the complexation properties are compared to (n)Pr-BTP. With increasing the ligand concentration three different species, the 1 : 1-, 1 : 2- and 1 : 3-complex, were found. Log β3 values of 7.6 for the formation of Cm(Et-BDP)3 and 9.2 for the formation of Cm((n)Pr-Tetrazine)3 are determined. The complexation with (n)Pr-Tetrazine shows slow kinetics. Thermodynamic data of the complexation reactions are determined in a temperature range of 25 °C-60 °C. The complexation with Et-BDP is exothermic (ΔH = -16.3 ± 1.2 kJ mol(-1)) and exergonic (ΔG = -43.8 ± 2.6 kJ mol(-1)) whereas the complexation with (n)Pr-Tetrazine is endothermic (ΔH = 43.9 ± 3.1 kJ mol(-1)) and exergonic (ΔG = -51.7 ± 2.2 kJ mol(-1)). In the case of the latter the complexation is driven by a highly positive reaction entropy change (ΔS = 320.6 ± 15.4 J mol(-1) K(-1)). In comparison to (n)Pr-BTP, less negative ΔG values were found for the complexation of Cm(III) with both ligands. PMID:23552476

  7. Photoacoustic spectral studies on lanthanide amino acid complexes

    NASA Astrophysics Data System (ADS)

    Yang, Yue-tao; Zhao, Gui-wen; Zhang, Shu-yi

    2003-01-01

    Several kinds of lanthanide complexes with glycine, alanine, phenylalanine, and tryptophan were synthesized and their photoacoustic (PA) spectra were measured. For the complexes of weakly fluorescent lanthanide ions with amino acids, the PA spectra reflect the influences of the ligands on the energy levels of lanthanide ions, whereas for the complexes of fluorescent lanthanide ions with amino acids, the PA spectra can be used to study the energy transfer from aromatic amino acids to lanthanide ions. At last, separating the overlapping peaks of lanthanide complex with tryptophan using the PA phase resolved method is introduced.

  8. 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. PMID:26555573

  9. Non-classical divalent lanthanide complexes.

    PubMed

    Nief, François

    2010-08-01

    The synthesis of non-classical divalent lanthanide complexes, i.e. those not containing the classical samarium(II), europium(II) or ytterbium(II), was once thought impossible. Since 1997, when the first stable complex of thulium(II) was discovered, there has been many more examples of stable coordination and organometallic complexes of lanthanum(II), neodymium(II) and dysprosium(II) in addition to thulium(II), and the influence of the ligand system on the stability of the complexes is beginning to be understood. These non-classical divalent compounds show exceptional reactivity as some of them have been shown to activate dinitrogen at room temperature, together with related reduced divalent-like systems, and to undergo spontaneous intramolecular carbon-hydrogen bond activation. Many more examples of non-classical divalent compounds together with new aspects of their exciting reactivity should be discovered in the near future. PMID:20631944

  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. De Novo Designed Imaging Agents Based on Lanthanide Peptides Complexes.

    PubMed

    Peacock, A F A

    2016-01-01

    Herein are discussed a selection of lanthanide peptide/protein complexes in view of their potential applications as imaging agents, both in terms of luminescence detection and magnetic resonance imaging. Though this chapter covers a range of different peptides and protein, if focuses specifically on the opportunities afforded by the de novo design of coiled coils, miniature protein scaffolds, and the development on lanthanide-binding sites into these architectures. The requirements for lanthanide coordination and the challenges that need to be addressed when preparing lanthanide peptides with a view to their potential adoption as clinical imaging applications, will be highlighted. PMID:27586349

  12. Trivalent actinide and lanthanide complexation of 5,6-dialkyl-2,6-bis(1,2,4-triazin-3-yl)pyridine (RBTP; R = H, Me, Et) derivatives: a combined experimental and first-principles study.

    PubMed

    Bhattacharyya, Arunasis; Kim, Eunja; Weck, Philippe F; Forster, Paul M; Czerwinski, Kenneth R

    2013-01-18

    Complexations of lanthanide ions with 5,6-dialkyl-2,6-bis(1,2,4-triazin-3-yl)pyridine [RBTP; R = H (HBTP), methyl (MeBTP), ethyl (EtBTP)] derivatives have been studied in the acetonitrile medium by electrospray ionization mass spectrometry, time-resolved laser-induced fluorescence spectroscopy, and UV-vis spectrophotometric titration. These studies were carried out in the absence and presence of a nitrate ion in order to understand the effect of the nitrate ion on their complexation behavior, particularly in the poor solvating acetonitrile medium where strong nitrate complexation of hard lanthanide ions is expected. Consistent results from all three techniques undoubtedly show the formation of lower stoichiometric complexes in the presence of excess nitrate ion. This kind of nitrate ion effect on the speciation of Ln(3+) complexes of RBTP ligands has not so far been reported in the literature. Different Am(3+) and Ln(3+) complexes were observed with RBTP ligands in the presence of 0.01 M tetramethylammonium nitrate, and their stability constant values are determined using UV-vis spectrophotometric titrations. The formation of higher stoichiometric complexes and higher stability constants for Am(3+) compared to Ln(3+) ions indicates the selectivity of these classes of ligands. A single-crystal X-ray diffraction (XRD) study of europium(III) complexes shows the formation of a dimeric complex with HBTP and a monomeric complex with EtBTP, whereas MeBTP forms both the dimeric and monomeric complexes. Density functional theory calculations confirm the findings from single-crystal XRD and also predict the structures of Eu(3+) and Am(3+) complexes observed experimentally. PMID:23270453

  13. Salicylamide-lanthanide complexes for use as luminescent markers

    DOEpatents

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

    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.

  14. 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.

  15. 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.

  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.; 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.

  18. Phthalamide-lanthanide complexes for use as luminescent markers

    DOEpatents

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

    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.

  19. Calibration beads containing luminescent lanthanide ion complexes

    NASA Astrophysics Data System (ADS)

    Leif, Robert C.; Jin, Dayong; Piper, James; Vallarino, Lidia M.; Williams, John W.; Yang, Sean; Zucker, Robert M.

    2008-02-01

    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 microscopes. Methods: 0.5, 3, and 5 micron (µm) beads containing a luminescent europium-complex were manufactured and the luminescence distribution of the 5 µm beads was measured with a time-delayed luminescence flow cytometer and a timedelayed digital microscope. The distribution of the luminescence intensity from the europium-complex in individual beads was determined on optical sections by confocal microscopy. The emission spectra of the beads under UV excitation were determined with a PARISS® spectrophotometer. The kinetics of the luminescence bleaching caused by UV irradiation were measured under LED excitation with a fluorescence microscope. Results: The kinetics of UV bleaching were very similar for the 0.5, 3, and 5 µm beads. Emission peaks were found at 592, 616, and 685 nanometers (nm). The width of the principal peak at half-maximum (616 nm) was 9.9 nm. The luminescence lifetimes in water and in air were 340 and 460 microseconds (µs), respectively. The distribution of the europium- complex in the beads was homogeneous. Conclusions: The 5 µm beads can be used for spectral calibration of microscopes equipped with a spectrograph, as test particles for time-delayed luminescence flow cytometers, and possibly as labels for macromolecules and cells.

  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. Coordination of lanthanides by two polyamino polycarboxylic macrocycles: formation of highly stable lanthanide complexes

    SciTech Connect

    Loncin, M.F.; Desreux, J.F.; Merciny, E.

    1986-07-16

    The formation constants of a few lanthanide complexes with DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) and TETA (1,4,8,11-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid) have been measured by potentiometric and competition methods. The ligand DOTA forms the most stable lanthanide chelates known so far (log K/sub ML/ = 28.2-29.2) while the stability of the TETA compounds at 80 /sup 0/C (log K/sub ML/ = 14.5-16.5) is comparable to the stability of the EDTA complexes. A competition method with the oxalate anion as a probe had to be used for determining the formation constants of the DOTA lanthanide chelates because of the high stability of these compounds. The relative stability of the DOTA and TETA complexes in accounted for by steric factors with reference to known solution- and solid-state structures. 20 references, 2 tables.

  2. Photoacoustic Spectral Study of Lanthanide Complexes Doped in Silica Matrix

    NASA Astrophysics Data System (ADS)

    Yang, Y. T.; Gao, B.; Zhang, S. Y.; Liu, X. J.

    2015-06-01

    Lanthanide phenanthroline (phen) complexes and were incorporated into a silica matrix by an ultrasonic assisted sol-gel method. In the region of ligand absorption, the photoacoustic (PA) intensity for a lanthanide complex is the same as in wet gels. Upon heat treatment at 120C, however, the PA intensity of a O-doped sample is much larger than that of a O-doped sample. The characteristic emissions of complex-doped samples were used to interpret the stability of the complex in silica matrices. The luminescence spectra are consistent with the PA results. The study indicates that phen can only coordinate with lanthanide ions in a silica matrix after a suitable heat treatment. Moreover, the covalency parameters and PA bands of f-f transionts of have been used to study the formation of the complex in a silica matrix.

  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. 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

  6. Comparative investigation of N donor ligand-lanthanide complexes from the metal and ligand point of view

    NASA Astrophysics Data System (ADS)

    Prüßmann, T.; Denecke, M. A.; Geist, A.; Rothe, J.; Lindqvist-Reis, P.; Löble, M.; Breher, F.; Batchelor, D. R.; Apostolidis, C.; Walter, O.; Caliebe, W.; Kvashnina, K.; Jorissen, K.; Kas, J. J.; Rehr, J. J.; Vitova, T.

    2013-04-01

    N-donor ligands such as n-Pr-BTP (2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine) studied here preferentially bind An(III) over Ln(III) in liquid-liquid separation of trivalent ac-tinides from spent nuclear fuel. The chemical and physical processes responsible for this selectivity are not yet well understood. We present systematic comparative near-edge X-ray absorption structure (XANES) spectroscopy investigations at the Gd L3 edge of [GdBTP3](NO3)3, [Gd(BTP)3](OTf)3, Gd(NO3)3, Gd(OTf)3 and N K edge of [Gd(BTP)3](NO3)3, Gd(NO3)3 complexes. The pre-edge absorption resonance in Gd L3 edge high-energy resolution X-ray absorption near edge structure spectra (HR-XANES) is explained as arising from 2p3/2 → 4f/5d electronic transitions by calculations with the FEFF9.5 code. Experimental evidence is found for higher electronic density on Gd in [Gd(BTP)3](NO3)3 and [Gd(BTP)3](OTf)3 compared to Gd in Gd(NO3)3 and Gd(OTf)3, and on N in [Gd(BTP)3](NO3)3 compared to n-Pr-BTP. The origin of the pre-edge structure in the N K edge XANES is explained by density functional theory (DFT) with the ORCA code. Results at the N K edge suggest a change in ligand orbital occupancies and mixing upon complexation but further work is necessary to interpret observed spectral variations.

  7. 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.

  8. 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.

  9. Structural rearrangement through lanthanide contraction in dinuclear complexes.

    PubMed

    Hutchings, Amy-Jayne; Habib, Fatemah; Holmberg, Rebecca J; Korobkov, Ilia; Murugesu, Muralee

    2014-02-17

    A new series of lanthanide complexes was synthesized, and the geometry and preliminary magnetic measurements of the complexes were explored. The specific ligand used (N'-(2-hydroxy-3-methoxybenzylidene)benzhydrazide) (H2hmb) was synthesized using a Schiff-base approach and was employed due to the presence of a coordination pocket that is able to accommodate magnetically selective lanthanide ions. The series can be divided into two groups that are categorized by a drastic structural rearrangement. The first group, Type I, contains six analogous complexes with the formula [M(III)2(Hhmb)3(NCS)3]·2MeOH·py (M = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Ho 6), while the second group, Type II, contains two dinuclear complexes with formula [M(III)2(Hhmb)2(NCS)4(MeOH)2] (M = Er 7, and Yb 8). Single-crystal X-ray analysis revealed that all M(III) ions in Type I exhibit monocapped distorted square antiprismatic geometries, while those of Type II exhibit distorted dodecahedron geometry. The direct current and alternating current magnetic measurements were carried out on all complexes, with 5, 7, and 8 exhibiting slow relaxation of the magnetization under an applied optimum dc field. Furthermore, complex 8 is the first example of a dinuclear Yb-based single-molecule magnet showing field-dependent multiple relaxation processes. PMID:24499030

  10. Lanthanide humic substances complexation. I. Experimental evidence for a lanthanide contraction effect

    NASA Astrophysics Data System (ADS)

    Sonke, Jeroen E.; Salters, Vincent J. M.

    2006-03-01

    The interaction of the lanthanides (Ln) with humic substances (HS) was investigated with a novel chemical speciation tool, Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry (CE-ICP-MS). By using an EDTA-ligand competition method, a bi-modal species distribution of LnEDTA and LnHS is attained, separated by CE, and detected online by sector field ICP-MS. We quantified the binding of all 14 rare earth elements (REEs), Sc and Y with Suwannee river fulvic acid, Leonardite coal humic acid, and Elliot soil humic acid under environmental conditions (pH 6-9, 0.001-0.1 mol L -1 NaNO 3, 1-1000 nmol L -1 Ln, 10-20 mg L -1 HS). Conditional binding constants for REE-HS interaction ( Kc) ranged from 8.9 < log Kc < 16.5 under all experimental conditions, and display a lanthanide contraction effect, ΔLKc: a gradual increase in Kc from La to Lu by 2-3 orders of magnitude as a function of decreasing ionic radius. HS polyelectrolyte effects cause Kc to increase with increasing pH and decreasing ionic strength. ΔLKc increases significantly with increasing pH, and likely with decreasing ionic strength. Based on a strong correlation between ΔLKc values and denticity for organic acids, we suggest that HS form a range of tri- to tetra-dentate complexes under environmental conditions. These results confirm HS to be a strong complexing agent for Ln, and show rigorous experimental evidence for potential REE fractionation by HS complexation.

  11. 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

    2015-12-01

    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. PMID:26588004

  12. 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. PMID:23627284

  13. Radiolysis and Ageing of C2-BTP in Cinnamaldehyde/Hexanol Mixtures

    SciTech Connect

    Fermvik, Anna; Ekberg, Christian; Retegan, Teodora; Skarnemark, Gunnar

    2007-07-01

    The separation of actinides from lanthanides is an important step in the alternative methods for nuclear waste treatment currently under development. Polycyclic molecules containing nitrogen are synthesised and used for solvent extraction. A potential problem in the separation process is the degradation of the molecule due to irradiation or ageing. An addition of nitrobenzene has proved to have an inhibitory effect on degradation when added to a system containing C2-BTP in hexanol before irradiation. In this study, 2,6-di(5,6-diethyl-1,2,4-triazine-3-yl)pyridine (C2-BTP) was dissolved in different mixtures of cinnamaldehyde and hexanol and the effects on extraction after ageing and irradiation were investigated. Similar to nitrobenzene, cinnamaldehyde contains an aromatic ring which generally has a relatively high resistance towards radiolysis. Both C2-BTP in cinnamaldehyde and C2-BTP in hexanol seem to degrade with time. The system with C2-BTP in pure hexanol is relatively stable up to 17 days but then starts slowly to degrade. The solution with pure cinnamaldehyde as diluent started to degrade after only {approx}20 hours. The opposite is true for degradation caused by radiolysis; hexanol systems are more sensitive to radiolysis than cinnamaldehyde systems. Most of the radiolytic degradation took place during the first days of irradiation, up to a dose of 4 kGy. (authors)

  14. 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

  15. 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.

  16. 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. PMID:27320499

  17. 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. PMID:27167830

  18. 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

  19. 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.

  20. Estimation of free acid content in lanthanide salt solutions used for potentiometric determination of stability constant of lanthanide complexes with organic ligands

    SciTech Connect

    Zheltvai, T.I.; Tishchenko, M.A.

    1985-08-20

    This paper studies the possibility of alkalimetric titration of free acid after binding the metal ions by the disodium salt of ethylenediaminetetraacetic (complexone III). The proposed method of free acid determination in lanthanide salt solutions is very simple and helps to avoid gross methodical errors in works involving determination of stability constants of lanthanide complexes.

  1. 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)

  2. 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.

  3. 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

  4. 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

    2015-01-01

    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 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. PMID:26449199

  5. Molecular Design Guidelines for Large Magnetic Circular Dichroism Intensities in Lanthanide Complexes.

    PubMed

    Kitagawa, Yuichi; Wada, Satoshi; Yanagisawa, Kei; Nakanishi, Takayuki; Fushimi, Koji; Hasegawa, Yasuchika

    2016-03-16

    Magneto optical devices based on the Faraday effects of lanthanide ion have attracted much attention. Recently, large Faraday effects were found in nano-sized multinuclear lanthanide complexes. In this study, the Faraday rotation intensities were estimated for lanthanide nitrates [Ln(III) (NO3 )3 ⋅n H2 O: Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and Eu(III) complexes with β-diketone ligands, using magnetic circular dichroism. Eu ions exhibit the largest Faraday rotation intensity for (7) F0 →(5) D1 transitions, and high-symmetry fields around the Eu ions induce larger Faraday effects. The molecular design for the enhancement of Faraday effects in lanthanide complexes is discussed. PMID:26789658

  6. Molecular magnets based on homometallic hexanuclear lanthanide(III) complexes.

    PubMed

    Das, Sourav; Hossain, Sakiat; Dey, Atanu; Biswas, Sourav; Sutter, Jean-Pascal; Chandrasekhar, Vadapalli

    2014-05-19

    The reaction of lanthanide(III) chloride salts (Gd(III), Dy(III), Tb(III), and Ho(III)) with the hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl)picolinohydrazide (LH3) in the presence of triethylamine afforded the hexanuclear Ln(III) complexes [{Ln6(L)2(LH)2}(μ3-OH)4][MeOH]p[H2O]q[Cl]4·xH2O·yCH3OH (1, Ln = Gd(III), p = 4, q = 4, x = 8, y = 2; 2, Ln = Dy(III), p = 2, q = 6, x = 8, y = 4; 3, Ln = Tb(III), p = 2, q = 6, x = 10, y = 4; 4, Ln = Ho(III), p = 2, q = 6, x = 10, y = 2). X-ray diffraction studies revealed that these compounds possess a hexanuclear [Ln6(OH)4](14+) core consisting of four fused [Ln3(OH)](8+) subunits. Both static (dc) and dynamic (ac) magnetic properties of 1-4 have been studied. Single-molecule magnetic behavior has been observed in compound 2 with an effective energy barrier and relaxation time pre-exponential parameters of Δ/kB = 46.2 K and τ0 = 2.85 × 10(-7) s, respectively. PMID:24766539

  7. 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.

  8. Thermodynamics of lanthanide and uranyl complexes with tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA).

    SciTech Connect

    Morss, L. R.; Nash, K. L.; Tennessee Technological Univ.

    2000-01-01

    We present the results of an investigation of the thermochemistry of the complexation of La{sup 3+} Nd{sup 3+}, Eu{sup 3+}, Dy{sup 3+}, Tm{sup 3+}, and UO{sub 2}{sup 2+} by tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA). This predisposed structural analog to oxydiacetic acid (ODA) has been previously shown both to exhibit greater sensitivity to lanthanide cation radius than complexes with the unconstrained ODA and to form anomalously weak complexes with UO{sub 2}{sup 2+}. Our purpose is to interpret these observations in terms of the balance between enthalpy and entropy contributions to the overall complexation thermodynamics. Enthalpies have been calculated from titration calorimetry experiments both for the protonation of the free ligand and for the formation of selected 1:1 and 1:2 complexes in pH 2-3 acidic media (I = 0.1 M). The complexation entropies for the lanthanide complexes have been calculated using the previously reported stability constants for the MH{sub 2}L{sup +}, MHL, and M(H{sub 2}L){sup 2-}. The stability constants for the uranyl complexes have been determined by potentiometric titration and these values used to calculate the thermodynamic parameters. Complexation enthalpies for the 1:1 lanthanide-THFTCA complexes (MH{sub 2}L{sup +} species) are nearly identical to those of the lanthanide ODA complexes. Therefore, the size-selectivity observed in the lanthanide-THFTCA complexes arises from the complexation entropy. The comparative weakness of the uranyl complexes with THFTCA also is accounted for thermodynamically in the entropy term. Calculations based on an electrostatic model for complexation entropy and molecular mechanics modeling are used to help interpret the experimental results.

  9. Characterization of lanthanide(III) DOTP complexes: Thermodynamics, protonation, and coordination to alkali metal ions

    SciTech Connect

    Sherry, A.D.; Ren, J.; Huskens, J.

    1996-07-31

    The chemical and thermodynamic characterization of Lanthanide(III) DOTP complexes was performed. Spectrophotometry, potentiometry, osmometry, and NMR spectroscopy were used in this characterization. Stability constants, protonation equilibria, and interactions of the complexes with alkali metal ions were measured and summarized.

  10. Pyridine-based lanthanide complexes combining MRI and NIR luminescence activities.

    PubMed

    Bonnet, Célia S; Buron, Frédéric; Caillé, Fabien; Shade, Chad M; Drahoš, Bohuslav; Pellegatti, Laurent; Zhang, Jian; Villette, Sandrine; Helm, Lothar; Pichon, Chantal; Suzenet, Franck; Petoud, Stéphane; Tóth, Éva

    2012-01-27

    A series of novel triazole derivative pyridine-based polyamino-polycarboxylate ligands has been synthesized for lanthanide complexation. This versatile platform of chelating agents combines advantageous properties for both magnetic resonance (MR) and optical imaging applications of the corresponding Gd(3+) and near-infrared luminescent lanthanide complexes. The thermodynamic stability constants of the Ln(3+) complexes, as assessed by pH potentiometric measurements, are in the range log K(LnL)=17-19, with a high selectivity for lanthanides over Ca(2+), Cu(2+), and Zn(2+). The complexes are bishydrated, an important advantage to obtain high relaxivities for the Gd(3+) chelates. The water exchange of the Gd(3+) complexes (k(ex)(298)=7.7-9.3×10(6) s(-1)) is faster than that of clinically used magnetic resonance imaging (MRI) contrast agents and proceeds through a dissociatively activated mechanism, as evidenced by the positive activation volumes (ΔV(≠)=7.2-8.8 cm(3) mol(-1)). The new triazole ligands allow a considerable shift towards lower excitation energies of the luminescent lanthanide complexes as compared to the parent pyridinic complex, which is a significant advantage in the perspective of biological applications. In addition, they provide increased epsilon values resulting in a larger number of emitted photons and better detection sensitivity. The most conjugated system PheTPy, bearing a phenyl-triazole pendant on the pyridine ring, is particularly promising as it displays the lowest excitation and triplet-state energies associated with good quantum yields for both Nd(3+) and Yb(3+) complexes. Cellular and in vivo toxicity studies in mice evidenced the non-toxicity and the safe use of such bishydrated complexes in animal experiments. Overall, these pyridinic ligands constitute a highly versatile platform for the simultaneous optimization of both MRI and optical properties of the Gd(3+) and the luminescent lanthanide complexes, respectively. PMID:22213187

  11. A lanthanide complex for metal encapsulations and anion exchanges.

    PubMed

    Sun, Yan-Qiong; Wan, Fang; Li, Xin-Xiong; Lin, Jian; Wu, Tao; Zheng, Shou-Tian; Bu, Xianhui

    2016-08-01

    A cationic lanthanide metalloligand with 3 dangling carboxylate groups on its periphery co-assembles with nitrate into a porous thermochromic solid responsive to both external cations and anions, owing to the presence of exchangeable NO3(-) as well as cation cavities arising from cooperative orientation of free carboxylate groups. An especially interesting feature is the structural memory effect during crystallization exhibited by the metalloligand, even after dissolution and binding to secondary cations (Cu(2+), Cd(2+)…). Moreover, the porous solid can undergo ion-exchange with various anions, leading to tunable thermochromic temperature and color range. PMID:27463609

  12. Controlling energy transfer in ytterbium complexes: oxygen dependent lanthanide luminescence and singlet oxygen formation.

    PubMed

    Watkis, Andrew; Hueting, Rebekka; Sørensen, Thomas Just; Tropiano, Manuel; Faulkner, Stephen

    2015-11-01

    Pyrene-appended ytterbium complexes have been prepared using Ugi reactions to vary the chromophore-lanthanide separation. Formation of the ytterbium(iii) excited state is sensitised via both the singlet and triplet excited states of the chromophore. Energy transfer from the latter is relatively slow, and gives rise to oxygen-dependent luminescence. PMID:26346499

  13. Recognition of some lanthanides, actinides, and transition- and heavy-metal cations by N-donor ligands: thermodynamic and kinetic aspects.

    PubMed

    Hubscher-Bruder, Véronique; Haddaoui, Jaouad; Bouhroum, Saliha; Arnaud-Neu, Françoise

    2010-02-15

    The remarkable actinide(III) selectivity of the polyaromatic N-donors bis-triazine-pyridines (BTPs), hemi-bis-triazine-pyridines (hemi-BTPs) and bis-triazine-bipyridines (BTBPs) make these ligands the most promising candidates in partitioning and transmutation processes developed so far to better manage nuclear waste. The interactions of n-Pr-BTP, C(5)-hemi-BTP, and the two most extensively investigated BTBPs (C(5)-BTBP and CyMe(4)-BTBP) have been studied with some representative lanthanide(III), uranyl, thorium, and transition- and other heavy-metal cations in methanol. The formation of complexes of different stoichiometries, the stability of which depended on both the ligands and the cations, was shown using UV absorption spectrophotometry. Study of the complexation reactions of La(3+), Eu(3+) and Yb(3+) with these four ligands by stopped-flow spectrophotometry allowed determination of the rate constants and postulation of possible complexation mechanisms. PMID:20055507

  14. Structural and electronic analysis of lanthanide complexes: reactivity may not necessarily be independent of the identity of the lanthanide atom--a DFT study.

    PubMed

    Schinzel, Sandra; Bindl, Martin; Visseaux, Marc; Chermette, Henry

    2006-10-01

    Density functional theory calculations were used to study a given complex for the whole series of lanthanide cations: [Ln(C3H5)Cp(OMe)] (1) [Ln = La (Z = 57)-Lu (Z = 71)], the radioactive lanthanide promethium (Z = 61) excepted. Contrary to the common assumptions, the calculations suggested a significant, albeit indirect, contribution of f electrons to bonding. Relativistic effects were considered in the calculations of the bonding energies, as well as in geometry optimizations in both spin-restricted and unrestricted formalisms. The unrestricted orbitals were finally used for the analysis of the charges and the composition of the frontier orbitals. It was confirmed that the ionic character was more pronounced for complexes of the late lanthanides. PMID:17004742

  15. 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

    2015-10-01

    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. PMID:26482000

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

    PubMed

    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

  17. 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

  18. Smart Grafting of Lanthanides onto Silica via N,N-Dialkylcarbamato Complexes.

    PubMed

    Armelao, Lidia; Belli Dell'Amico, Daniela; Bellucci, Luca; Bottaro, Gregorio; Labella, Luca; Marchetti, Fabio; Samaritani, Simona

    2016-01-19

    The grafting and the postgrafting functionalization of lanthanide ions on commercial amorphous silica have been herein carried out by using as a precursor the terbium N,N-dibutylcarbamato derivative [Tb(O2CNBu2)3]. The reaction of the complex with the surface silanols involved only a fraction of the carbamato ligands. The following protolytic substitution of the residual carbamato ligands was carried out by exploiting the Brønsted's acidity of the β-diketone dibenzoylmethane (Hdbm), in view of the antenna effect of the β-diketonato groups, which are commonly used in lanthanide photoluminescence studies. The reaction proceeded at room temperature in a clean and easy way affording the introduction of the chosen functionality in the lanthanide coordination sphere. The same procedure has been followed by using as a precursor the X-ray characterized heterometallic N,N-dibutylcarbamato complex [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] (Ln = Eu, Tb, Tm). In both cases, X-ray photoelectron spectroscopy evidenced the chemical implantation of the lanthanide ions on the silica surface, and photoluminescence studies pointed out the potentiality of the proposed synthetic approach in the preparation of highly luminescent materials. PMID:26741027

  19. Optical properties of planar polymer waveguides doped with organo-lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Moynihan, S.; Van Deun, R.; Binnemans, K.; Redmond, G.

    2007-08-01

    Lanthanide complexes, Eu(dbm)3(Phen), [Et4N][Eu(nta)4] and Er(dbm)3(Phen), are employed as luminescent dopants within planar waveguides based on a UV-processable fluorinated polymer material. Thin films doped with each of the complexes are fabricated and their spectroscopic properties investigated in detail. The films act as low loss multi-mode planar waveguides capable of guiding visible and near infrared light emitted following optical excitation of the lanthanide dopants. Judd-Ofelt parameters are calculated for the europium complex dopants and effects of the polymer host environment on the photophysical properties of the chelates are identified. The radiative properties of the europium complexes are also determined viz. their potential for use in optical amplification applications.

  20. 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.

  1. Neutral "Cp-Free" Silyl-Lanthanide(II) Complexes: Synthesis, Structure, and Bonding Analysis.

    PubMed

    Zitz, Rainer; Hlina, Johann; Gatterer, Karl; Marschner, Christoph; Szilvási, Tibor; Baumgartner, Judith

    2015-07-20

    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

  2. Lanthanide--humic substances complexation. II. Calibration of humic ion-binding model V.

    PubMed

    Sonke, Jeroen E

    2006-12-15

    The experimental complexation of the lanthanides (Sc, Y, and rare earth elements) with Suwannee river fulvic acid, Leonardite coal humic acid, and Elliot soil humic acid is described with Humic Ion-Binding Model V. The fitted intrinsic equilibrium constants for metal-proton exchange, pKMHA, for Eu3+ are similar to previously published experimental fits, and linear free energy relationship (LFER) estimated values. The experimentally observed lanthanide contraction effect in REE-humic complex stability is reflected in the gradual decrease in pKMHA from La to Lu. In Model V, a decrease in pKMHA from La to Lu indicates an increase in complex stability. Fitted pKMHA values for heavy REE are lower than those estimated by LFERs. Consequently, REE fractionation by humic substances complexation could be more pronounced than previously thought. Recommended pKMHA values for lanthanide-fulvic and -humic acid complexation are derived by superimposing the fitted trends in pKMHA for all REE, i.e., the decrease in pKMHA from La to Lu, on the average Eu pKMHA value for all literature datasets. These results will allow modeling assessments of organic matter induced REE fractionation in aquatic environments, taking into account changes in pH, ionic strength, and ion competition. A simulation of dissolved REE speciation in an average world river suggests that organic matter outcompetes carbonate complexation, even under alkaline conditions. PMID:17256484

  3. 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

  4. EXAFS characterisation of metal bonding in highly luminescent, UV stable, water-soluble and biocompatible lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Kalyakina, A.; Utochnikova, V.; Trigub, A.; Zubavichus, Y.; Kuzmina, N.; Bräse, S.

    2016-05-01

    The combination of X-ray diffraction with EXAFS was employed to assess the coordination environment of lanthanide complexes in solutions. This method is based on the assumption that the local structure of lanthanide complexes in solution combines elements of the crystal structure of the complex in the solid state (single- or polycrystalline) and the elements of the local structure of a lanthanide salt, completely dissociated in the solvent (usually chlorides). The success of this approach is demonstrated with the lanthanide (III) 2,3,4,5,6-pentafluorobenzoate complexes, where the local structure in aqueous and methanol solutions were estimated. Moreover, the dissociation degree of the complexes in aqueous and methanol solutions was evaluated.

  5. Structural and photophysical properties of lanthanide complexes with N-(diphenylphosphoryl)-4-methylbenzenesulfonamide

    NASA Astrophysics Data System (ADS)

    Kasprzycka, E.; Trush, V. A.; Amirkhanov, V. M.; Jerzykiewicz, L.; Gawryszewska, P.

    2014-11-01

    Lanthanide complexes with N-(diphenylphosphoryl)-4-methylbenzenesulfonamide (HPMSP) as new sensitizers of visible luminescence were obtained. The series of stable lanthanide complexes Na[Ln(PMSP)4], where Ln = Eu3+, Gd3+, Tb3+ were characterized by X-ray diffraction, IR, absorption, emission, and excitation spectra at 295 and 77 K as well as luminescence decay times and intrinsic emission quantum yields. The Tb complex, exhibiting relatively efficient ligand-to-metal energy transfer and strong metal-centred emission, is a promising candidate for effective UV-to-visible energy converters. Temperature dependent quenching of sensitized 5D0 europium emission and presence of 5D1 emission are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  7. 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. PMID:25305620

  8. Physical characteristics of lanthanide complexes that act as magnetization transfer (MT) contrast agents

    NASA Astrophysics Data System (ADS)

    Zhang, Shanrong; Sherry, A. Dean

    2003-02-01

    Rapid water exchange is normally considered a prerequisite for efficient Gd 3+-based MRI contrast agents. Yet recent measures of exchange rates in some Gd 3+ complexes have shown that water exchange can become limiting when such complexes are attached to larger macromolecular structures. A new class of lanthanide complexes that display unusually slow water exchange (bound water lifetimes ( τM298) > 10 μs) has recently been reported. This apparent disadvantage may be taken advantage of by switching the metal ion from gadolinium(III) to a lanthanide that shifts the bound water resonance substantially away from bulk water. Given appropriate water exchange kinetics, one can then alter the intensity of the bulk water signal by selective presaturation of this highly shifted, Ln3+-bound water resonance. This provides the basis of a new method to alter MR image contrast in tissue. We have synthesized a variety of DOTA-tetra(amide) ligands to evaluate as potential magnetization transfer (MT) contrast agents and found that the bound water lifetimes in these complexes are sensitive to both ligand structure (a series of Eu 3+ complexes have τM298 values that range from 1 to 1300 μs) and the identity of the paramagnetic Ln3+ cation (from 3 to 800 μs for a single ligand). This demonstrates that it may be possible either to fine-tune the ligand structure or to select proper lanthanide cation to create an optimal MT agent for any clinical imaging field.

  9. Study of Lanthanide Complexes with BTFA in Silica Gels by Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, R. Y.; Zhang, H. X.; Yang, Y. T.; Zhang, S. Y.; Liu, X. J.

    2016-06-01

    In this work, lanthanide β -diketonate complexes Ln(btfa){}3 \\cdot 2H2O (Ln^{3+}: Eu^{3+}, Sm^{3+ }, and Tb^{3+}; btfa: 4,4,4-trifluoro-l-phenyl-1,3-butanedione) were incorporated into silica gels by a sol-gel method. Photoacoustic (PA) spectra of these complex-doped silica samples were measured and studied. The PA intensity of the β -diketonate ligand is nearly the same for lanthanide complexes in wet gels. After heat treatment at 150°C, however, the PA intensity of the ligand increases for Eu^{3+}, Sm^{3+}, and Tb^{3+} complexes in silica gels, respectively. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The luminescence result is consistent with the PA spectra. The result indicates that lanthanide β -diketonate complexes cannot be formed in silica gels without a suitable heat treatment. Moreover, the relaxation process model is proposed based on the PA and luminescence results.

  10. Reversible recruitment and emission of DO3A-derived lanthanide complexes at ligating molecular films on gold.

    PubMed

    Lehr, Joshua; Bennett, Jamie; Tropiano, Manuel; Sørensen, Thomas J; Faulkner, Stephen; Beer, Paul D; Davis, Jason J

    2013-02-01

    The recruitment of DO3A-derived lanthanide complexes by ligation to isophthalic acid and catechol-modified gold surfaces, and their resulting sensitization, is reported herein. Predictably pH-dependent surface recruitment is associated with the expected fingerprint europium and terbium emission characteristics. The intensity of the lanthanide luminescence scales exponentially with spacer length, indicating a strong quenching interaction between the lanthanide and the gold surface. The switchable catechol oxidation state provides a means of electrochemically triggering the release of prior ligated complexes. PMID:23320931

  11. Complexation of Lanthanides with Glutaroimide-dioxime: Binding Strength and Coordination Modes.

    PubMed

    Ansari, Seraj A; Yang, Yanqiu; Zhang, Zhicheng; Gagnon, Kevin J; Teat, Simon J; Luo, Shunzhong; Rao, Linfeng

    2016-02-01

    The complexation of lanthanides (Nd(3+) and Eu(3+)) with glutaroimide-dioxime (H2L), a cyclic imide dioxime ligand that has been found to form stable complexes with actinides (UO2(2+) and NpO2(+)) and transition metal ions (Fe(3+), Cu(2+), etc.), was studied by potentiometry, absorption spectrophotometry, luminescence spectroscopy, and microcalorimetry. Lanthanides form three successive complexes, M(HL)(2+), M(HL)L, and M(HL)2(+) (where M stands for Nd(3+)/Eu(3+) and HL(-) stands for the singly deprotonated ligand). The enthalpies of complexation, determined by microcalorimetry, show that the formation of these complexes is exothermic. The stability constants of Ln(3+)/H2L complexes are several orders of magnitude lower than that of the corresponding Fe(3+)/H2L complexes but are comparable with that of UO2(2+)/H2L complexes. A structure of Eu(3+)/H2L complex, identified by single-crystal X-ray diffractometry, shows that the ligand coordinates to Eu(3+) in a tridentate mode, via the two oxygen atoms of the oxime group and the nitrogen atom of the imide group. The relocation of protons of the oxime groups (-CH═N-OH) from the oxygen to the nitrogen atom, and the deprotonation of the imide group (-CH-NH-CH-) result in a conjugated system with delocalized electron density on the ligand (-O-N-C-N-C-N-O-) that forms strong complexes with the lanthanide ions. PMID:26765525

  12. Lanthanide complexes of cage-type ligands as luminescent labels in fluoroimmunoassays

    NASA Astrophysics Data System (ADS)

    Sabbatini, Nanda; Guardigli, Massimo; Manet, Ilse; Ziessel, Raymond; Ungaro, Rocco

    1995-05-01

    General aspects of immunological analyses are reported and the application of some lanthanide complexes in fluoroimmunoassays is discussed. The photophysical properties of the complexes of cage-type ligands, which, up to now, showed the most intense metal luminescence are reported. The luminescence intensity of these complexes is discussed considering the efficiency of the incident light/emitted light conversion, defined as the product of the absorption efficiency of the ligand and the metal luminescence quantum yield upon excitation in the ligand. It is illustrated how the luminescence intensity can be enhanced by adapting the ligands on basis of the previously obtained results.

  13. Organometallic compounds of the lanthanides. 42/sup 1/ bis(dimethyloxyethane)lithium bis(cyclopentadienyl)bis(trimethylsilyl)lanthanide complexes

    SciTech Connect

    Schumann, H.; Nickel, S.; Loebel, J.; Pickardt, J.

    1988-09-01

    The trichlorides of Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu react with NaC/sub 5/H/sub 5/ in tetrahydrofuran in the presence of dimethoxyethane (dme) with formation of bis(cyclopentadienyl)lanthanide chloride complexes of the types (C/sub 5/H/sub 5/)/sub 2/Ln(/mu/-Cl)/sub 2/Na(dme). The reactions of these organolanthanide halide complexes with (trimethylsilyl)lithium in dme yield compounds of the type (Li(dme)/sub 2/)((C/sub 5/H/sub 5/)/sub 2/Ln(SiMe/sub 3/)/sub 2/) (Ln = Sm, Dy, Ho, Er, Tm, Lu). C/sub 5/H/sub 5//sub 2/Sm(/mu/-Cl)/sub 2/Na(dme) reacts with (trimethylgermyl)lithium in dme/pentane with formation of (Li(dme)/sub 3/)((C/sub 5/H/sub 5/)/sub 3/SmClSm(C/sub 5/H/sub 5/)/sub 3/) (7a.). The new compounds have been characterized by elemental analyses and IR and NMR spectra. The structure of (Li(dme)/sub 3/)(C/sub 5/H/sub 5/)/sub 3/SmClSm(C/sub 5/H/sub 5/)/sub 3/ (7a) has been elucidated through complete X-ray analysis. The crystals are monoclinic with a = 14.00 (1) /angstrom/, b = 13.38 (2) /angstrom/, c = 23.49 (3) /angstrom/, /beta/ = 93.37 (9)/degree/, space group P2/sub 1//n,Z = 4, and R = 0.0411 for 4671 reflections. The (Cp/sub 3/SmClSmCp/sub 3/)/sup /minus// anion consists of two Cp/sub 3/Sm units bridged by a chlorine atom with Sm-Cl distances of 2.827 (2) and 2.798 (2) /angstrom/.

  14. 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.

  15. A caged lanthanide complex as a paramagnetic shift agent for protein NMR.

    PubMed

    Prudêncio, Miguel; Rohovec, Jan; Peters, Joop A; Tocheva, Elitza; Boulanger, Martin J; Murphy, Michael E P; Hupkes, Hermen-Jan; Kosters, Walter; Impagliazzo, Antonietta; Ubbink, Marcellus

    2004-07-01

    A lanthanide complex, named CLaNP (caged lanthanide NMR probe) has been developed for the characterisation of proteins by paramagnetic NMR spectroscopy. The probe consists of a lanthanide chelated by a derivative of DTPA (diethylenetriaminepentaacetic acid) with two thiol reactive functional groups. The CLaNP molecule is attached to a protein by two engineered, surface-exposed, Cys residues in a bidentate manner. This drastically limits the dynamics of the metal relative to the protein and enables measurements of pseudocontact shifts. NMR spectroscopy experiments on a diamagnetic control and the crystal structure of the probe-protein complex demonstrate that the protein structure is not affected by probe attachment. The probe is able to induce pseudocontact shifts to at least 40 A from the metal and causes residual dipolar couplings due to alignment at a high magnetic field. The molecule exists in several isomeric forms with different paramagnetic tensors; this provides a fast way to obtain long-range distance restraints. PMID:15224334

  16. 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. PMID:27044594

  17. New homotrinuclear lanthanide complexes: synthesis, characterization and spectroscopic study.

    PubMed

    Silva, Wagner E; Belian, Mônica Freire; Freire, Ricardo O; de Sá, Gilberto F; Alves, Severino

    2010-09-23

    This work presents the synthesis and spectroscopic study of new homotrinuclear (TRI) systems for photonics applications. The luminescence spectroscopy shows characteristics transitions of Eu(III) and Tb(III) ions. For the Gd(III) complexes, the triplets states were determined by phosphorescence measurement. The complexes’ coordination geometries were calculated using the Sparkle/AM1 model. For the europium systems, the Sparkle/AM1 geometries were used to calculate all details involved in the energy transfer process, and the theoretical quantum yields were determined. From an energy diagram, that estimates triplet levels, it was possible to understand some experimental phenomenon, such as weak luminescence for precursor complex (without heterocyclics ligands), and ligands emission in terbium complexes. Some of these observations can also be explained by the Jablonski diagrams that describe, based on theoretical calculations, all luminescent process. The synthesized complexes showed high values of quantum yield in ethanolic environment: 50% for EuTRIDipy, 26% EuTRITerpy, and 56% for EuTRIPhen complexes. PMID:20738128

  18. 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.

  19. 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. PMID:23016509

  20. 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.

  1. 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. PMID:24769618

  2. Preferential accumulation within tumors and in vivo imaging by functionalized luminescent dendrimer lanthanide complexes

    PubMed Central

    Alcala, Marco A.; Shade, Chad M.; Uh, Hyounsoo; Kwan, Shu Ying; Bischof, Matthias; Thompson, Zachary P.; Gogick, Kristy A.; Meier, Adam R.; Strein, Timothy G.; Bartlett, David L.; Modzelewski, Ruth A.; Lee, Yong J.; Petoud, Stéphane; Brown, Charles Komen

    2011-01-01

    We have created a dendrimer complex suitable for preferential accumulation within liver tumors and luminescence imaging by substituting thirty-two naphthalimide fluorophores on the surface of the dendrimer and incorporating eight europium cations within the branches. We demonstrate the utility and performance of this luminescent dendrimer complex to detect hepatic tumors generated via direct subcapsular implantation or via splenic injections of colorectal cancer cells (CC531) into WAG/RijHsd rats. Luminescence imaging of the tumors after injection of the dendrimer complex via hepatic arterial infusion revealed that the dendrimer complex can preferentially accumulate within liver tumors. Further investigation indicated that dendrimer luminescence in hepatic tumors persisted in vivo. Due to the incorporation of lanthanide cations, this luminescence agent presents a strong resistance against photobleaching. These studies show the dendrimer complex has great potential to serve as an innovative accumulation and imaging agent for the detection of metastatic tumors in our rat hepatic model. PMID:21925728

  3. 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.

  4. NMR temperature measurements using a paramagnetic lanthanide complex.

    PubMed

    Zuo, C S; Metz, K R; Sun, Y; Sherry, A D

    1998-07-01

    NMR thermometry has previously suffered from poor thermal resolution owing to the relatively weak dependence of chemical shift on temperature in diamagnetic molecules. In contrast, the shifts of nuclear spins near a paramagnetic center exhibit strong temperature dependencies. The chemical shifts of the thulium 1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate) complex (TmDOTP5-) have been studied as a function of temperature, pH, and Ca2+ concentration over ranges which may be encountered in vivo. The results demonstrate that the 1H and 31P shifts in TmDOTP5- are highly sensitive to temperature and may be used for NMR thermometry with excellent accuracy and resolution. A new technique is also described which permits simultaneous measurements of temperature and pH changes from the shifts of multiple TmDOTP5- spectral lines. PMID:9654468

  5. Characterization of metal complexation in multiligand systems with lanthanide luminescence

    SciTech Connect

    Martinez, G.A.; Traina, S.J.; Logan, T.J.

    1998-08-01

    The effectiveness of an Eu{sup 3+} luminescence technique to describe metal complexation reactions in humic substances was evaluated. The molecular uncertainties intrinsic to humic substances were circumvented by using polyacrylic acid (PAA) and polyvinylsulfonic acid (PVS) as probes. An adequate determination of the Eu{sup 3+}-citrate affinity constant suggested that this technique could potentially be used to characterize metal binding reactions in polyelectrolytes. Various mixtures of PAA and PVS were then evaluated. The commonly adopted assumption of a single metal binding environment in those systems proved ineffective and resulted in a misleading representation of the Eu-PAA binding isotherm. The evidence indicates that prior knowledge about the number of binding environments, as well as their relative contribution to the overall sorption, is needed to describe metal binding on humic substances appropriately through this approach. The effect of metal competition on Eu{sup 3+} binding by a mixed polymer system (1:1 PAA:PVS) was also ascertained. The affinity series obtained (Cu{sup 2+} > Pb{sup 2+} {much_gt} Cd{sup 2+} {ge} Co{sup 2+} {approx_equal} Mg{sup 2+} {approx_equal} Ni{sup 2+} > Ca{sup 2+}) was similar to that frequently observed in humic substances, which reinforces the utility of these polymers as their surrogates in metal sorption studies.

  6. 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.

  7. Lanthanide anilido complexes: synthesis, characterization, and use as highly efficient catalysts for hydrophosphonylation of aldehydes and unactivated ketones.

    PubMed

    Liu, Chengwei; Qian, Qinqin; Nie, Kun; Wang, Yaorong; Shen, Qi; Yuan, Dan; Yao, Yingming

    2014-06-14

    Lanthanide anilido complexes stabilized by the 2,6-diisopropylanilido ligand have been synthesized and characterized, and their catalytic activity for hydrophosphonylation reaction was explored. A reaction of anhydrous LnCl3 with 5 equivalents of LiNHPh-(I)Pr2-2,6 in THF generated the heterobimetallic lanthanide-lithium anilido complexes (2,6-(I)Pr2PhNH)5LnLi2(THF)2 [Ln = Sm(1), Nd(2), Y(3)] in good isolated yields. These complexes are well characterized by elemental analysis, IR, NMR (for complex ) and single-crystal structure determination. Complexes 1 - 3 are isostructural. In these complexes, the lanthanide metal ion is five-coordinated by five nitrogen atoms from five 2,6-diisopropylanilido ligands to form a distorted trigonal bipyramidal geometry. The lithium ion is coordinated by two nitrogen atoms from two 2,6-diisopropylanilido ligands, and one oxygen atom from a THF molecule. It was found that these simple lanthanide anilido complexes are highly efficient for catalyzing hydrophosphonylation reactions of various aldehydes and unactivated ketones to generate α-hydroxyphosphonates in good to excellent yields (up to 99%) within a short time (5 min for aldehydes, 20 min for ketones). Furthermore, the mechanism of hydrophosphonylation reactions has also been elucidated via(1)H NMR monitoring of reaction. PMID:24728525

  8. 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.

  9. Localizing Perturbations of the Racemic Equilibria Involving Dipicolinate-Derived Lanthanide(III) Complexes.

    PubMed

    Nguyen, Brian T; Ingram, Andrew J; Muller, Gilles

    2016-04-01

    Helical D3 tris(4-amino-2,6-pyridine-dicarboxylate)terbium(III) and europium(III) complexes, which form a racemic equilibrium in aqueous solution, were prepared to study their secondary coordination sphere interactions with chiral amino acids. These interactions were probed using a combination of circularly polarized luminescence (CPL) and 13C NMR spectroscopy. The results indicate that, regardless of the interaction between the chiral molecule and the complex, without an accessible hydrogen-bond donor on the associating molecule, perturbation of the racemic equilibrium cannot occur. A generalized conclusion is established that indicates that the mechanism of chiral recognition by tris(dipicolinate)lanthanide(III) complexes is similar across a variety of analogous ligands. PMID:26935003

  10. Acetato-bridged dinuclear lanthanide complexes with single molecule magnet behaviour for the Dy2 species.

    PubMed

    Zhang, Haixia; Lin, Shuang-Yan; Xue, Shufang; Wang, Chao; Tang, Jinkui

    2014-04-28

    Five dinuclear lanthanide complexes with formula [Ln2L2(OAc)4(MeOH)a(H2O)b] · cMeOH · dH2O (a = 2, b = 0, c = 2, d = 0, Ln = Sm (1), Gd (2), Dy (3); a = 0, b = 2, c = 4, d = 2, Ln = Tm (4)) and [Yb2L2(OAc)4(MeOH)2]·[Yb2L2(OAc)4(H2O)2] · 2H2O (5) (HL = (E)-N'-(2-hydroxybenzylidene)-2-mercaptonicotinohydrazide), have been synthesized and their crystal structures and magnetic properties are reported. All five complexes are centrosymmetric, showing a similar dinuclear core with two lanthanide ions in each complex being bridged by acetate groups in the η(1):η(2):μ2 mode. The various coordination modes of acetate groups result in two kinds of coordination geometries for Ln ions with the ones in complexes 1-4 and the Yb2 in 5 being nine-coordinated with a mono-capped square antiprism geometry, while the Yb1 ions in the other part of complex 5 are eight-coordinated with a triangular dodecahedron geometry. Magnetic susceptibility studies reveal that complex 3 shows single molecule magnet behaviour with an energy barrier of 39.1 K. In addition, comparison of the structural parameters among the similar Dy2 SMMs with a η(1):η(2):μ2 coordination mode of carboxylate groups reveals the significant role played by coordination geometry in modulating the relaxation dynamics of SMMs. PMID:24599563

  11. 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.

  12. 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.

  13. 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.

  14. Thermodynamic study of the complexation of trivalent actinide and lanthanide cations by ADPTZ, a tridentate N-donor ligand.

    PubMed

    Miguirditchian, Manuel; Guillaneux, Denis; Guillaumont, Dominique; Moisy, Philippe; Madic, Charles; Jensen, Mark P; Nash, Kenneth L

    2005-03-01

    To better understand the bonding in complexes of f-elements by polydentate N-donor ligands, the complexation of americium(III) and lanthanide(III) cations by 2-amino-4,6-di-(pyridin-2-yl)-1,3,5-triazine (ADPTZ) was studied using a thermodynamic approach. The stability constants of the 1:1 complexes in a methanol/water mixture (75/25 vol %) were determined by UV-visible spectrophotometry for every lanthanide(III) ion (except promethium), and yttrium(III) and americium(III) cations. The thermodynamic parameters (DeltaH degrees , DeltaS degrees) of complexation were determined from the temperature dependence of the stability constants and by microcalorimetry. The trends of the variations of DeltaG degrees , DeltaH degrees , and DeltaS degrees across the lanthanide series are compared with published results for other tridentate ligands and confirm strongly ionic bonding in the lanthanide-ADPTZ complexes. Comparison of the thermodynamic properties between the Am- and Ln-ADPTZ complexes highlights an increase in stability of the complexes by a factor of 20 in favor of the americium cation. This difference arises from a more exothermic reaction enthalpy in the case of Am, which is correlated with a greater degree of covalency in the americium-nitrogen bonds. Quantum chemistry calculations performed on a series of trivalent actinide and lanthanide-ADPTZ complexes support the experimental results, showing a slightly greater covalence in the actinide-ligand bonds that originates from a charge transfer from the ligand sigma orbitals to the 5f and 6d orbitals of the actinide ion. PMID:15732980

  15. 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

  16. Organo-lanthanide complexes as luminescent dopants in polymer waveguides fabricated by hot embossing

    NASA Astrophysics Data System (ADS)

    Moynihan, S.; Van Deun, R.; Binnemans, K.; Krueger, J.; von Papen, G.; Kewell, A.; Crean, G.; Redmond, G.

    2007-08-01

    Lanthanide complexes, Eu(dbm)3(Phen) and Er(dbm)3(Phen), are employed as luminescent dopants within polymer channel waveguide devices fabricated by hot embossing. Spectroscopic properties of the complexes as dopants in the waveguide core polymer are investigated in detail. Judd-Ofelt parameters are calculated for the europium chelate and radiative properties are determined viz. potential for optical amplification. Channel waveguides fabricated by single level embossing are shown to be capable of guiding visible and infrared light emitted following optical excitation of the dopants. Multi-level polymer micro-optical benches incorporating doped channel waveguides and passive locational features for self-alignment and integration of optical fibres are fabricated in a multi-level single-step embossing process and are shown to successfully out-couple the waveguided dopant emission.

  17. 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

  18. A study of in vitro antibacterial activity of lanthanides complexes with a tetradentate Schiff base ligand

    PubMed Central

    Al Momani, Waleed Mahmoud; Taha, Ziyad Ahmed; Ajlouni, Abdulaziz Mahmoud; Shaqra, Qasem Mohammad Abu; Al Zouby, Muaz

    2013-01-01

    Objective To establish the antibacterial activity of lanthanides complexes with a tetradentate Schiff base ligand L. Methods (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. The antimicrobial activity of the resultant Ln (III) complexes was investigated using agar well diffusion and micro-broth dilution techniques; the latter was used to establish the minimum inhibitory concentrations for each compound investigated. Results Most of Ln (III) complexes were found to exhibit antibacterial activities against a number of pathogenic bacteria with MICs ranging between 1.95-250.00 µg/mL. Staphylococcus aureus was the most susceptible bacterial species to [LaL(NO3)2(H2O)](NO3) complex while Shigella dysenteriae and Escherichia coli required a relatively higher MIC (250 µg/mL). The complexes La (III) and Pr (III) were effective inhibitors against Staphylococcus aureus, whereas Sm (III) complex was effective against Serratia marcescens. On the other hand, Gd (III), La (III) and Nd (III) were found to be more potent inhibitors against Pseudomonas aeruginosa than two of commonly used antibiotics. The remaining Ln (III) complexes showed no remarkable activity as compared to the two standard drugs used. Conclusions Tetradentate Schiff base ligand L and its complexes could be a potential antibacterial compounds after further investigation. PMID:23646299

  19. 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. PMID:25691149

  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. 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.

  2. 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

    2015-03-01

    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). PMID:25692564

  3. 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)

  4. 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.

  5. Insight into the dynamics of lanthanide-DTPA complexes as revealed by oxygen-17 NMR.

    PubMed

    Fusaro, Luca; Mocci, Francesca; Muller, Robert N; Luhmer, Michel

    2012-08-01

    DTPA chelates of various diamagnetic and paramagnetic lanthanide(III) metal ions, as well as the chemically similar DTPA chelate of Y(3+), were studied in aqueous solution by variable temperature (17)O NMR with the aim of characterizing their internal dynamics. As a consequence of poor chemical shift dispersion and fast quadrupole relaxation, no dynamic exchange process could be detected for the diamagnetic complexes nor for the Sm-DTPA complex. In contrast, the spectra recorded for the Eu-DTPA complex show chemical exchange due to the well-known racemization process and, at high temperature, feature signal broadening that reveals a fluxional process involving the interchange of the coordinated and noncoordinated oxygen atoms of the carboxylate groups. The spectra recorded for the Pr-DTPA complex feature coalescence events due to such a fluxional process, which is ascribable to the rotation of the carboxylate groups. The activation free energy barriers determined experimentally are remarkably lower than the calculated activation barriers recently reported for the rotation of the carboxylate groups of various Ln-DOTA complexes. Furthermore, the smallest activation free energy measured for the Pr-DTPA complex, about 45 kJ mol(-1), is significantly lower than the activation free energy characterizing the racemization process. The fluxional behavior of the carboxylate groups is, however, not expected to significantly affect the residence time of the water molecule coordinated to the metal ion. PMID:22817329

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

    PubMed

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

    2011-10-15

    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 [LnL(NO(3))(2)(H(2)O)(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 ((1)H 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(•) is concentration dependent and higher than that of the free ligand L. PMID:21764359

  7. Versatile lanthanide-azide complexes with azide/carboxylate/hydroxy mixed bridged chain exhibiting magnetic and luminescent properties

    SciTech Connect

    Wang Haichao; Xue Min; Guo Qian; Zhao Jiongpeng; Liu Fuchen; Ribas, Joan

    2012-03-15

    Two new lanthanide-azide complexes, [Ln{sub 2}(N{sub 3})(isonic){sub 2}(OH){sub 3}(Hisonic)(H{sub 2}O)]{sub n} (Ln=Yb for 1 and Tb for 2, isonic=isonicotinate), were obtained in hydrothermal condition. X-ray diffraction analysis indicated the two complexes are isomorphic chain structure in which the Ln{sup III} ions are mixed bridged by the azide anions, hydroxyl anions and carboxylate groups of the isonicotinate ligands. Further studies indicated weak antiferromagnetic interactions between the Ln{sup III} ions in 1 and 2, and complex 2 exhibit green sensitized Luminescent character of Tb{sup III} ion. - Graphical abstract: Two new 1D lanthanide-azide complexes, [Ln{sub 2}(N{sub 3})(isonic){sub 2}(OH){sub 3}(Hisonic)(H{sub 2}O)]{sub n} (Ln=Yb{sup III} for 1 and Tb{sup III} for 2, isonic=isonicotinate), were synthesized by hydrothermal reaction and exhibit interesting magnetism and fluorescence properties. Highlights: Black-Right-Pointing-Pointer The research provided a new method for synthesizing lanthanide-azide complexes. Black-Right-Pointing-Pointer The complexes have an interesting azide/hydroxyl/carboxylate mixed bridged1D chain structure. Black-Right-Pointing-Pointer The antiferromagnetic coupling between the complexes and 2 displays green luminescence.

  8. Anion Effects on Lanthanide(III) Tetrazole-1-acetate Dinuclear Complexes Showing Slow Magnetic Relaxation and Photofluorescent Emission.

    PubMed

    Lu, Ying-Bing; Jiang, Xiao-Ming; Zhu, Shui-Dong; Du, Zi-Yi; Liu, Cai-Ming; Xie, Yong-Rong; Liu, Liang-Xian

    2016-04-18

    Three types of lanthanide complexes based on the tetrazole-1-acetic acid ligand and the 2,2'-bipyridine coligand were prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses; the formulas of these complexes are [Ln2(1-tza)4(NO3)2(2,2'-bipy)2] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), [Dy2(1-tza)4Cl2(2,2'-bipy)2] (6), and [Yb2(1-tza)4(NO3)2(2,2'-bipy)2] (7) (1-tza = tetrazole-1-acetate and 2,2'-bipy = 2,2'-bipyridine). They are dinuclear complexes possessing similar structures but different lanthanide(III) ion coordination geometries because of the distinction of peripheral anions (such as NO3(-) and Cl(-)) and the effect of lanthanide contraction. The variable-temperature magnetic susceptibilities of 1-6 were measured. Both Dy(III) complexes (5 and 6) display field-induced single-molecule magnet behaviors. Ab initio calculations revealed that the Dy(III) complex 6 possesses a more anisotropic Dy(III) ion in comparison to that in 5. The room-temperature photoluminescence spectra of Sm(III) (1), Eu(III) (2), Tb(III) (4), and Dy(III) (5 and 6) complexes exhibit strong characteristic emissions in the visible region, whereas the Yb(III) (7) complex shows near-infrared (NIR) luminescence. PMID:27023680

  9. Near-IR luminescent lanthanide complexes with 1,8-diaminoanthraquinone-based chromophoric ligands.

    PubMed

    Stacey, Oliver J; Ward, Benjamin D; Amoroso, Angelo J; Pope, Simon J A

    2016-04-12

    Three new chromophoric anthraquinone-based multidentate ligands have been synthesised in a step-wise manner from 1,8-dichloroanthraquinone. The ligands each comprise two dipicolyl amine units and react with trivalent lanthanide ions to form monometallic complexes of the form [Ln(L)](OTf)3 as indicated by MS studies and elemental analyses. Supporting DFT studies show that the monometallic species are highly favoured (>1000 kJ mol(-1)) over the formation of a 2 : 2 dimetallic congener. Both ligands and complexes absorb light efficiently (ε ∼ 10(4) M(-1) cm(-1)) in the visible part of the spectrum, with λabsca. 535-550 nm through an intramolecular charge transfer (ICT) transition localised on the substituted anthraquinone unit. In all cases the complexes show a fluorescence band at ca. 675 nm due to the ICT emitting state. The corresponding Nd(iii), Yb(iii) and Er(iii) complexes also reveal sensitised near-IR emission characteristic of each ion following excitation of the ICT visible absorption band at 535 nm. PMID:26974664

  10. Tuning a Lanthanide Complex To Be Responsive to the Environment in Solution.

    PubMed

    Golkowski, Ryan T; Settineri, Nicholas S; Zhao, Xikang; McMillin, David R

    2015-12-01

    The f-f emissions of lanthanide-ion complexes have predictable emission energies and many practical applications, but the emitting states are generally impervious to the surroundings. This investigation explores ligand- and metal-centered emission processes for a series of mixed-ligand complexes of composition M(X-T)(NO3)3, where the metal ion is europium, gadolinium, terbium, or lutetium, and X-T denotes the tridentate ligand 2,2':6',2″-terpyridine (H-T), 4'-phenyl-2,2':6',2″-terpyridine (Ph-T), or 4'-pyrrolidin-N-yl-2,2':6',2″-terpyridine (pyrr-T). The presence of the pyrrolidinyl substituent imparts intraligand charge-transfer (ILCT) character to the ligand-based excited states and reduces the energy gap between the singlet and the triplet excited states. An enhanced rate of intersystem crossing results in a lutetium complex with a relatively small fluorescence quantum yield (0.15%) and a gadolinium complex with an impressive phosphorescence yield of 9.6% in deaerated solution. The Tb(pyrr-T)(NO3)3 system is unique because the relatively low-energy triplet ILCT state equilibrates with the emissive f-f state. The result is a truly remarkable f-f emission signal that is sensitive to the polarity of the local environment as well as the presence of dioxygen. PMID:26571330

  11. Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen-Type Lanthanide (III) Complexes.

    PubMed

    Berardozzi, Roberto; Pescitelli, Gennaro; Di Pietro, Sebastiano; Resta, Claudio; Ballistreri, Francesco P; Pappalardo, Andrea; Tomaselli, Gaetano A; Di Bari, Lorenzo

    2015-12-01

    The salen-type ligand prepared with (R,R) diphenylethan-1,2-diamine and salicylaldehyde provides stable and inert complexes KLnL2 upon simple reaction with lanthanide halides or pseudohalides LnX3 (Ln = Tb(3+) -Lu(3+) ; X = Cl(-) or TfO(-) ) of its potassium salt. All the complexes were completely characterized through nuclear magnetic resonance (NMR), electronic circular dichroism (ECD) in the UV and some (Er(3+) , Tm(3+) , Yb(3+) ) also with Near-IR ECD (NIR-ECD) and luminescence (Tb(3+) , Tm(3+) ). Careful analysis of the NMR shifts demonstrated that the complexes are isostructural in solution and afforded an accurate geometry. This was further confirmed by means of Density Functional Theory (DFT) optimization of the Lu(3+) complex, and by comparing the ligand-centered experimental and time-dependent TD-DFT computed UV-ECD spectra. As final validation, we used the NIR-ECD spectrum of the Yb(3+) derivative calculated by means of Richardson's equations. The excellent match between calculated and experimental ECD spectra confirm the quality of the NMR structure. PMID:26422601

  12. 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].

  13. 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.

  14. 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).

  15. Positron annihilation studies in binary solid solutions and mechanical mixtures of lanthanide dipivaloylmethanate complexes

    NASA Astrophysics Data System (ADS)

    Fulgêncio, F.; Oliveira, F. C.; Windmöller, D.; Araujo, M. H.; Marques-Netto, A.; Machado, J. C.; Magalhães, W. F.

    2015-11-01

    Measurements using positron annihilation lifetime (PALS) and Doppler broadening annihilation radiation lineshape (DBARLS) spectroscopies were performed in several lanthanide dipivaloylmethanate complexes, Ln(dpm)3 where Ln = Sm3+, Gd3+, Tb3+, Ho3+, Er3+, Yb3+ and dpm = 2,2,6,6-tetramethyl-3,5-pentanedionate, and also on their binary solid solutions and mechanical mixtures, biphasic systems, of the general formula Ln1-xEux(dpm)3. Expressive positronium formation was observed in all Ln(dpm)3 complexes, except in Eu(dpm)3 complex. The results indicate formation of solid solutions in the Sm3+, Gd3+and Tb3+ systems, where total inhibition of positronium formation was observed. A Stern-Volmer type equation, I30/I3 = 1 + kx, was used to fit the data, enabling the calculation of the inhibition constants, k. A mechanical mixture behavior, with linear variation of I3 between the I3 values of the pure complexes, was observed in systems containing Ho3+, Er3+ and Yb3+ complexes, where no effective solid solution formation occurred due to differences between the crystalline structures of these complexes and Eu(dpm)3. No positronium quenching reactions were observed in the solid solutions. DBARLS results confirmed those of PALS, evidencing that the positron annihilation spectroscopies are useful techniques to characterize the formation of solid solutions. PALS measurements at 80 K were performed in the Sm1-xEux(dpm)3 and Gd1-xEux(dpm)3 solid solutions. The results indicate that, despite a contraction in the crystalline structures, the solid solution structure remains intact at low temperatures. The temperature dependence of the inhibition constant do not seem to be understood from the positronium formation spur model and might be related to intra and intermolecular energy and charge transfer processes in the solid solutions, which is currently being studied.

  16. 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

    2015-01-01

    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. PMID:25369972

  17. Self-assembly of 2-aldehyde-8-hydroxyquinolinate-based lanthanide complexes and NIR luminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Meiqi; Li, Hongfeng; Chen, Peng; Sun, Wenbin; Zhang, Lei; Yan, Pengfei

    2015-02-01

    Self-assembly reaction of 2-aldehyde-8-hydroxyquinoline, tris(hydroxymethyl)aminomethane and LnCl3ṡ6H2O affords a series of mononuclear lanthanide complexes Ce(baho)2·Et2O (1) (H2baho = 2,8-bis(2-(8-hydroxylquinolinyl))-1-aza-5-hydroxymethyl-3,7-dioxabicyclo[3.3.0]octane), Dy(nhm)2Cl·0.5H2O (2) and Ln(nhm)2Cl·0.5C6H14 (Ln = Ho (3), Er (4), Yb (5) and Hnhm = N-(2-(8-hydroxylquinolinyl)methylene)(trishydroxymethyl)methylamine. The crystal structures have been determined by X-ray crystallographic analysis, and the tetravalence of Ce in 1 has been proven by XPS. Interestingly, the positive charge of Ce4+ ion in 1 is neutralized by two deprotonated baho2- ligands, while two deprotonated nhm- ligands and one Cl- compensate the positive charge of Ln3+ ions in 2-5. Complex 5 exhibit essential NIR luminescence of Yb3+ ion with lifetime of 17.64 μs in solid and 9.96 μs in CH3OH solution.

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

    PubMed Central

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

    2009-01-01

    The use of lanthanide-based contrast agents for magnetic resonance imaging (MRI) 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 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. In this paper we present a study of the kinetics of acid catalyzed dissociation, thermodynamic stability, serum stability and biodistribution of a series of DOTA-tetraamide complexes that have been substituted with peripheral hydroxyl groups. The data indicate that these non-traditional contrast agents exhibit in vivo stability comparable to agents with much higher log KML values demonstrating the important contribution of kinetic inertness. PMID:19083028

  19. 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%.

  20. 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.

  1. 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. PMID:26205500

  2. 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. PMID:24680836

  3. 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. PMID:25099883

  4. [DOTA-bis(amide)]lanthanide complexes: NMR evidence for differences in water-molecule exchange rates for coordination isomers.

    PubMed

    Zhang, S; Kovacs, Z; Burgess, S; Aime, S; Terreno, E; Sherry, A D

    2001-01-01

    Two derivatives of 1,4,7,10-tetraazacyclododecane with trans-acetate and trans-amide side-chain ligating groups have been prepared and their complexes with lanthanide cations examined by multinuclear NMR spectroscopy. These lanthanide complexes exist in aqueous solution as a mixture of slowly interconverting coordination isomers with 1H chemical shifts similar to those reported previously for the major (M) and minor (m) forms of the tetraacetate ([Ln(dota)]-) and tetraamide ([Ln(dtma)]3+) complexes. As in the [Ln(dota)]- and [Ln(dtma)]3+ complexes, the m/M ratio proved to be a sensitive function of lanthanide size and temperature. An analysis of 1H hyperfine shifts in spectra of the Yb3+ complexes revealed significant differences between the axial (D1) and non-axial (D2) components of the magnetic susceptibility tensor anisotropy in the m and M coordination isomers and the energetics of ring inversion and m <==> M isomerization as determined by two-dimensional exchange spectroscopy (EXSY). (17)O shift data for the Dy3+ complexes showed that both have one inner-sphere water molecule. A temperature-dependent (17)O NMR study of bulk water linewidths for solutions of the Gd3+ complexes provided direct evidence for differences in water exchange rates for the two coordination isomers. The bound-water lifetimes (tauM298) in the M and m isomers of the Gd3+ complexes ranged from 1.4-2.4 micros and 3-14 ns, respectively. This indicates that 1) the inner-sphere water lifetimes for the complexes with a single positive charge reported here are considerably shorter for both coordination isomers than the corresponding values for the [Gd(dtma)]3+ complex with three positive charges, and 2) the difference in water lifetimes for M and m isomers in these two series is magnified in the [Gd[dota-bis(amide)

  5. NOVEL APPROACH TO METAL-HUMIC COMPLEXATION STUDIES BY LANTHANID ION PROBE SPECTROSCOPY

    EPA Science Inventory

    Naturally occurring humic substances are known to be potentially strong binders of metals in the environment. ensitive spectroscopic technique, based on the unique luminescence properties of the tripositive lanthanide metal ions, has been developed to selectively probe metal bind...

  6. 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. PMID:26325624

  7. 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. PMID:25649522

  8. 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.

  9. Pentamethylcyclopentadienyl and bis(trimethylsilyl)amido complexes of the di- and trivalent lanthanides

    SciTech Connect

    Tilley, T.D.

    1982-03-01

    The reaction of the divalent iodides YbI/sub 2/ and EuI/sub 2/ with NaN(SiMe/sub 3/)/sub 2/ has provided pentane-soluble, monomeric derivatives of the divalent lanthanides. These compounds are isolated as the solvated species Eu(N(SiMe/sub 3/)/sub 2/)/sub 2/L/sub 2/ (L = thf or 1,2-dme), Yb(N(SiMe/sub 3/)/sub 2/)/sub 2/(thf)/sub 1/ /sub 5/ and Yb(N(SiMe/sub 3/)/sub 2/)/sub 2/L/sub 2/ (L = 1,2-dme or OEt/sub 2/), or as the sodium salts NaM(N(SiMe/sub 3/)/sub 2/)/sub 3/ (M = Eu or Yb). The pentamethylcyclopentadienyl ligand has been used to obtain trivalent derivatives of the type (C/sub 5/Me/sub 5/)/sub 2/MCl/sub 2/M'L/sub x/ (M = Nd, Sm or Yb; M' = Li or Na; L = OEt/sub 2/ or tmed) or (C/sub 5/Me/sub 5/)/sub 2/MCl(thf) (M = Nd or Yb). These compounds undergo metathesis reactions. The interaction of NaC/sub 5/Me/sub 5/ with EuCl/sub 3/ yields only the divalent (C/sub 5/Me/sub 5/)/sub 2/EuL (L = thf or OEt/sub 2/). Analogous compounds of ytterbium are obtained by reaction of YbI/sub 2/ with NaC/sub 5/Me/sub 5/ in thf or OEt/sub 2/. The ytterbium amine complexes are weakly paramagnetic, apparently due to charge transfer from ytterbium to the aromatic rings. The divalent phosphine complexes (C/sub 5/Me/sub 5/)/sub 2/ML (M = Eu or Yb; L = dmpe or dmpm) are also described. Crystallographic data are summarized.

  10. New crystal structural families of lanthanide chloride alcohol/water complexes

    SciTech Connect

    Chakoumakos, Bryan C; Custelcean, Radu; Ramey, Joanne Oxendine; Boatner, Lynn A

    2012-01-01

    The exploration of lanthanide chloride compounds as possible scintillation materials for gamma ray and neutron detection has led to the discovery of several new families of crystal structures with the general formula LnCl3(CH3OH)x(H2O)y. The specific crystal structure depends on the water/methanol content and lanthanide ion. The coordination of the light (large) lanthanides is the typical value of 8 and reduces to 7 for the heavier (small) lanthanides. The binding energy of water versus alcohol ligands is comparable, so that if water is present in the system, it is typically incorporated as a ligand in the crystal. In these crystals, the molecular adducts occur as monomers, dimers, and dichloro-bridged chains. These, in turn, form 3-D frameworks through H-bonds to the Cl atoms. Other distinct crystal structures are predicted, given the volume changes due to the lanthanide contraction, the water content of the crystal growth solutions, and the specific halide.

  11. Highly Emitting Near-Infrared Lanthanide “Encapsulated Sandwich” Metallacrown Complexes with Excitation Shifted Toward Lower Energy

    PubMed Central

    2015-01-01

    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-MCZn(II),quinHA-4]2[24-MCZn(II),quinHA-8] (Ln3+[Zn(II)MCquinHA]) 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)MCquinHA] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLnL = 2.88(2)%, τobs = 150.7(2) μs; Nd3+, QLnL = 1.35(1)%, τobs = 4.11(3) μs; Er3+, QLnL = 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. PMID:24432702

  12. 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.

  13. Strategies to enhance signal intensity with paramagnetic fluorine-labelled lanthanide complexes as probes for 19F magnetic resonance.

    PubMed

    Chalmers, Kirsten H; Botta, Mauro; Parker, David

    2011-01-28

    The synthesis and (19)F NMR spectroscopic properties are reported for three series of CF(3)-labelled lanthanide(III) complexes, based on mono- and diamide cyclen ligands. Analyses of variable temperature, pH and field (19)F, (17)O and (1)H NMR spectroscopic experiments are reported and the merits of a triphosphinate mono-amide complex defined by virtue of its favourable isomer distribution and attractive relaxation properties. These lead to an enhanced sensitivity of detection in (19)F magnetic resonance experiments versus a diamagnetic Y(III) analogue, paving the way for future shift and imaging studies. PMID:21127807

  14. 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

  15. 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.

  16. 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.

  17. Novel lanthanide(II) complexes supported by carbon-bridged biphenolate ligands: synthesis, structure and catalytic activity.

    PubMed

    Deng, Mingyu; Yao, Yingming; Shen, Qi; Zhang, Yong; Sun, Jin

    2004-03-21

    [Ln[N(SiMe3)2]2(THF)2](Ln = Sm, Yb) reacts with 1 equiv. of carbon-bridged biphenols, 2,2'-methylene-bis(6-tert-butyl-4-methylphenol)(L1H2) or 2,2'-ethylidene-bis(4,6-di-tert-butylphenol)(L2H2), in toluene to give the novel aryloxide lanthanide(II) complexes [[LnL1(THF)n]2](Ln = Sm, n = 3 (1); Ln = Yb, n = 2 (2)) and [[LnL2(THF)3]2](Ln = Sm (5); Ln = Yb (6)) in quantitative yield, respectively. Addition of 2 equiv. of hexamethylphosphoric triamide (HMPA) to a tetrahydrofuran (THF) solution of 1, 2 and 5 affords the corresponding HMPA-coordinated complexes, [[LnL1(THF)m(HMPA)n]2(THF)y](Ln = Sm, n = 2, m = 0, y = 2 (3); Ln = Yb, m = 1, n = 1, y = 6 (4)) and [[SmL2(HMPA)2]2](7) in excellent yields. The single-crystal structural analyses of 3, 4 and 7 revealed that these aryloxide lanthanide(II) complexes are dimeric with two Ln-O bridges. The coordination geometry of each lanthanide metal can be best described as a distorted trigonal bipyramid. Complexes 1-3, 5 and 7 can catalyze the ring-opening polymerization of epsilon-caprolactone (epsilon-CL), and 1-3, along with 5 show moderate activity for the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) and the copolymerization of epsilon-CL and DTC to give random copolymers with high molecular weights and relatively narrow molecular weight distributions.. PMID:15252483

  18. Novel one-dimensional lanthanide acrylic acid complexes: an alternative chain constructed by hydrogen bonding

    SciTech Connect

    Li Hui . E-mail: lihui@bit.edu.cn; Hu Changwen

    2004-12-01

    Novel one-dimensional (1D) chains of three lanthanide complexes La(L{sup 1}){sub 3}(CH{sub 3}OH)].CH{sub 3}OH (L{sup 1}=(E)-3-(2-hydroxyl-phenyl)-acrylic acid) 1, La(L{sup 2}){sub 3}(H{sub 2}O){sub 2}].2.75H{sub 2}O (L{sup 2}=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) 2, and La(L{sup 3}){sub 3}(CH{sub 3}OH){sub 2}(H{sub 2}O)].CH{sub 3}OH (L{sup 3}=(E)-3-(4-hydroxyl-phenyl)-acrylic acid) 3 are reported. The crystal structure data are as follows for 1: C{sub 29}H{sub 29}LaO{sub 11}, monoclinic, P2{sub 1}/n, a=15.4289(12)A, b=7.9585(6)A, c=23.041(2)A, {beta}=99.657(2){sup o}, Z=4, R{sub 1}=0.0637, wR{sub 2}=0.0919; for 2: C{sub 27}H{sub 30.50}LaO{sub 13.75}, triclinic, P-1, a=8.4719(17)A, b=13.719(3)A, c=14.570(3)A, {alpha}=62.19(3){sup o}, {beta}=99.657(2){sup o}, {gamma}=78.22(3){sup o}, Z=2, R{sub 1}=0.0384, wR{sub 2}=0.0820; and for 3: C{sub 30}H{sub 35}LaO{sub 13}, monoclinic, P2(1)/c, a=9.5667(6)A, b=24.3911(15)A, c=14.0448(9)A, {beta}=109.245(2){sup o}, Z=4, R{sub 1}=0.0374, wR{sub 2}=0.0630. All the three structure data were collected using graphite monochromated molybdenum K{alpha} radiation and refined using full-matrix least-squares techniques on F{sup 2}. These structures show that four kinds of the carboxylato bridge modes are included in these chains to link the La(III) ions. It is the first time that it has been found that the intra-chain hydrogen bonding can construct an alternative chain even, when the coordination bridge mode is the same along the chain (complex 2). There are 2D and 3D hydrogen bonding in the crystal lattices of complexes 1-3.

  19. An europium(III) diglycolamide complex: insights into the coordination chemistry of lanthanides in solvent extraction.

    PubMed

    Antonio, Mark R; McAlister, Daniel R; Horwitz, E Philip

    2015-01-14

    The synthesis, stoichiometry, and structural characterization of a homoleptic, cationic europium(III) complex with three neutral tetraalkyldiglycolamide ligands are reported. The tri(bismuth tetrachloride)tris(N,N,N',N'-tetra-n-octyldiglycolamide)Eu salt, [Eu(TODGA)3][(BiCl4)3] obtained from methanol was examined by Eu L3-edge X-ray absorption spectroscopy (XAS) to reveal an inner-sphere coordination of Eu(3+) that arises from 9 O atoms and two next-nearest coordination spheres that arise from 6 carbon atoms each. A structural model is proposed in which each TODGA ligand with its O=Ca-Cb-O-Cb-Ca=O backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu(3+). Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3](3+) with six 5-membered chelate rings, the six Eu-Ca and six Eu-Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4](-) anions are beyond the cationic [Eu(TODGA)3](3+) cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu(3+) coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln(3+)) complexes with tetraalkyldiglycolamide ligands (of the same 1:3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln(3+) ions in terms of the local structure of Eu(3+) in a solid state coordination complex with TODGA. PMID:25310364

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    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, 1H NMR, 13C 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.

  2. 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. PMID:26374465

  3. Selective recovery of minor trivalent actinides from high level liquid waste by R-BTP/SiO2-P adsorbents

    NASA Astrophysics Data System (ADS)

    Sano, Yuichi; Surugaya, Naoki; Yamamoto, Masahiko

    2010-03-01

    Concerning the selective recovery of minor trivalent actinides (MA(III) = Am(III) and Cm(III)) from high level liquid waste (HLLW) by extraction chromatography, adsorption and elution behaviours of MA(III) and fission products (FP) in a nitric acid media were studied using iHex-BTP/SiO2-P adsorbents, which is expected to show high adsorption affinity for MA(III) even in concentrated HNO3 solution, such as HLLW. In the batch experiments, Pd showed strong adsorption on iHex-BTP/SiO2-P adsorbents under any concentration of HNO3. The MA(III) and heavy Ln(III) (Sm(III), Eu(III) and Gd(III)) were also adsorbed at the condition of high HNO3 concentration, but they showed no adsorption under low HNO3concentration. The separation factor for MA(III)/heavy Ln(III) took the maximum value (over 100) at around 1mol/dm3 HNO3. It was difficult to elute MA(III) or heavy Ln(III) selectively by HNO3 from the iHex-BTP/SiO2-P adsorbents degradated by γ-ray irradiation. The chromatographic separation of real HLLW by an iHex-BTP/SiO2-P column showed that MA(III) could be recovered selectively by adjusting the acidity of the feed solution, i.e. HLLW, to 1mol/dm3 and using H2O as eluant. The adsorption of Pd(II) can be decreased by the addition of appropriate complexing reagents, e.g. DTPA, into HLLW without any effects on the MA(III) adsorption.

  4. Studies on complexation and solvent extraction of lanthanides in the presence of diaza-18-crown-6-di-isopropionic acid.

    PubMed

    Kim, J S; Lee, C H; Han, S H; Suh, M Y

    1997-12-19

    Stability constants of some lanthanides with K22DAP (diaza-18-crown-6-diisopropionic acid) were determined by potentiometric titration method. The logarithmic values of these constants for La(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III), and Lu(III) are 11.14, 11.43, 11.78, 11.74, 11.95, 12.09, 11.49, and 10.88, respectively. Solvent extraction studies were carried out on the K22DAP complexes of La(III), Nd(III) and Lu(III) using TTA (thenoyltrifluoroacetone) as an extractant in different diluents. It appears that nitrobenzene, a diluent with high dielectric constant, favors the extraction of the complexes. Extraction rates of the K22DAP complexes of lanthanides were investigated at pH 5.5 and 8.0 with TTA in chloroform. The rates of extraction are found to be dependent upon the nature of the extracted species. Competitive extractions were carried out to see if selective extractions could be achieved. PMID:18967024

  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

    2015-04-01

    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. PMID:25723709

  6. 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

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

    PubMed

    Ahmed, Zubair; Iftikhar, K

    2013-11-01

    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

  8. 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

  9. Squaring the cube: a family of octametallic lanthanide complexes including a Dy8 single-molecule magnet.

    PubMed

    Fang, Ming; Zhao, Hanhua; Prosvirin, Andrey V; Pinkowicz, Dawid; Zhao, Bin; Cheng, Peng; Wernsdorfer, Wolfgang; Brechin, Euan K; Dunbar, Kim R

    2013-10-01

    A series of isostructural octanuclear lanthanide complexes of general formula [Ln8(sao)4(μ3-OH)4(NO3)12(DMF)12] (Ln = Nd (), Sm (), Eu (), Gd (), Tb (), Dy (), Ho (), Er (); DMF = dimethylformamide) have been prepared via reactions of salicylaldoxime (saoH2), tetramethylammonium hydroxide (Me4NOH) with the appropriate lanthanide nitrate salt (Ln(NO3)3·6H2O). The metallic skeletons of the complexes describe [Ln4] tetrahedra encapsulated inside a [Ln4] square with the inner core stabilised through μ3-OH(-) ions and the periphery by μ4-sao(2-) ligands. The magnetic properties of compounds were investigated by dc and ac magnetometry. Temperature dependent ac magnetic susceptibility data reveal that the dysprosium analogue () displays an out-of-phase signal in the absence of an applied magnetic field indicative of slow relaxation of the magnetization typical of a Single-Molecule Magnet (SMM). Micro-SQUID measurements reveal temperature and sweep rate dependent hysteresis below 1.0 K. PMID:23943045

  10. 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

    2015-07-01

    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. PMID:26051749

  11. Lanthanide complexes assembled from two flexible amide-type tripodal ligands: terminal groups effect on photoluminescence behavior.

    PubMed

    Wang, Qin; Tang, Kuanzhen; Jin, Xiaojie; Huang, Xiaoguang; Liu, Weisheng; Yao, Xiaojun; Tang, Yu

    2012-03-28

    To explore the effect of terminal groups of tripodal ligands on the photoluminescence behaviors of the complexes, lanthanide (Eu(III), Tb(III)) nitrate complexes with two flexible amide-type tripodal ligands, 2,2',2''-nitrilotris-(N-phenylmethyl)-acetamide (L(I)) and 2,2',2''-nitrilotris-(N-naphthalenemethyl)-acetamide (L(II)) were synthesized and characterized. The general formulas of the complexes are [EuL(I)(2)(C(3)H(6)O)]·(NO(3))(3)·(HCCl(3))·(H(2)O)(4) (1), TbL(I)(2)(NO(3))(3)·2H(2)O (2), EuL(II)(NO(3))(3) (3), and TbL(II)(NO(3))(3) (4). Among them, 1, 3, and 4 were characterized by single-crystal X-ray diffraction. Complex 1 demonstrates a 1 : 2 (ML(2)) capsule type stoichiometry, and the complexes 3 and 4 confirm 1 : 1 (ML) type coordination structures. What is more, the triplet energy levels of L(I) and L(II) are 24,331 and 19,802 cm(-1), which were determined from the phosphorescence spectra of the Gd(III) complexes. Ligand modification by changing the terminal groups alters their triplet energy, and results in a different sensitizing ability towards lanthanide ions. The density functional theory (DFT) calculations of energy levels including HOMO, LUMO, singlet, and triplet energies tuned by the different terminal groups are also discussed in detail, and the trends are almost consistent with the experimental conclusions. PMID:22302199

  12. 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.

  13. 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. PMID:25408760

  14. 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. PMID:25001925

  15. Solution structure and dynamics, stability, and NIR emission properties of lanthanide complexes with a carboxylated bispyrazolylpyridyl ligand.

    PubMed

    Mato-Iglesias, Marta; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos; Starck, Matthieu; Kadjane, Pascal; Ziessel, Raymond; Charbonnière, Loïc

    2009-02-16

    The complexation behavior of the ligand 2,6-bis{3-[N,N-bis(carboxymethyl)aminomethyl]pyrazol-1-yl}-pyridine, L, toward lanthanide cations was investigated throughout the series. Potentiometric titration experiments on L (0.1 M KCl) revealed the presence of four protonation steps in the 2-12 pH domain, associated with the protonation of the two tertiary amine nitrogen atoms and with two of the four carboxylate functions. The stability constants for the formation of the [LnL](-) complexes (Ln = La, Nd, Eu, Ho, and Lu) were determined in water and evidenced a hill-shaped complexation trend along the series, with log K increasing from 14.56(9) (La) to 16.68(2) (Ho) and decreasing to 15.42(2) (Lu). Geometry optimizations showed the [LnL](-) complexes (Ln = La, Nd, Eu, Ho, Yb, and Lu) adopting a C(2) symmetry with the symmetry axis going through the metal atom and the nitrogen atom of the central pyridine ring, leading to the presence of Delta and Lambda helical enantiomers. Analysis of the calculated Ln-O and Ln-N bond lengths showed a marked deviation from the expected values at the end of the series, which accounts for the observed decreased complexation affinity. (1)H and (13)C NMR experiments in D(2)O (room temperature) showed the shortening of the bond distances in [LnL](-) complexes from La to Lu to be accompanied by a rigidification of the structure, leading to a decreased C(2) symmetry for the Lu complex compared to C(2v) for La. This decreased symmetry was attributed to a slow Delta <--> Lambda interconversion that was followed by variable-temperature (13)C NMR experiments on the Lu complex. The activation parameters determined by line broadening analysis for this interconversion process point to an associatively assisted interconversion process. The (1)H NMR spectrum of the paramagnetic [YbL](-) complex was investigated in D(2)O, and a lanthanide induced shift analysis showed good agreement between the observed paramagnetic chemical shifts and those calculated

  16. 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.

  17. {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.

  18. 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. PMID:25305612

  19. Homodinuclear lanthanide {Ln2} (Ln = Gd, Tb, Dy, Eu) complexes prepared from an o-vanillin based ligand: luminescence and single-molecule magnetism behavior.

    PubMed

    Bag, Prasenjit; Rastogi, Chandresh Kumar; Biswas, Sourav; Sivakumar, Sri; Mereacre, Valeriu; Chandrasekhar, Vadapalli

    2015-03-01

    Four dinuclear lanthanide complexes [Gd2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (1), [Tb2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (2), [Dy2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (3) and [Eu2 (H2L)2 (µ-piv)2 (piv)2]·2CHCl3 (4) were synthesized by the reaction of appropriate Ln(III) chloride salts and a multidentate ligand, 2,2'-(2-hydroxy-3-methoxy-5-methylbenzylazanediyl)diethanol (H3L) in the presence of pivalic acid. 1-4 are neutral and are held by two monoanionic, [H2L](-) ligands. The two lanthanide ions are doubly bridged to each other via two phenolate oxygen atoms. Both the lanthanide ions are nine coordinated and possess a distorted capped square antiprism geometry. Photophysical studies reveal that Tb(3+) (2) and Dy(3+) (3) complexes display strong ligand-sensitized lanthanide-characteristic emission. The Tb(3+) complex (2) shows a very high overall quantum yield of 76.2% with a lifetime of 1.752 ms. Magnetic studies reveal single-molecule magnet behavior for 3 which shows in its ac susceptibility studies a two-step slow relaxation yielding two effective relaxation energy barriers of ΔE = 8.96 K and 35.51 K. PMID:25641498

  20. 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

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

    DOE PAGESBeta

    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.

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

    PubMed

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

    2015-04-20

    Syntheses, structural, and spectroscopic characterization of multinuclear tris(amidate) lanthanide complexes is described. Addition of K3[N(o-PhNC(O)(t)Bu)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)(t)Bu)3)(DMF)]2(μ-DMF) (Ln = La (1), Ce (2), Nd(3)), in good yields. Syntheses of tetranuclear complexes, [Ln(N(o-PhNC(O)(t)Bu)3)]4 (Ln = Ce (4), Nd(5)), resulted from protonolysis of Ln[N(SiMe3)2]3 (Ln = Ce, Nd) with N(o-PhNCH(O)(t)Bu)3. 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. PMID:25843202

  3. 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. PMID:26561258

  4. 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.

  5. Structure variation and luminescence properties of lanthanide complexes with 1,9-bis [2-(2'-picolylaminoformyl)-1,4,7,9-tetraoxadecane

    SciTech Connect

    Song Xueqin; Zang Zhipeng; Liu Weisheng; Zhang Yujie

    2009-04-15

    Using 1,9-salicylamide bissubstituted oxadecane ligand, 1,9-bis [2-(2'-picolylaminoformyl)-1,4,7,9-tetraoxadecane (L), two novel lanthanide complexes have been prepared and well characterized by means of elemental analysis, IR spectroscopy, UV-vis spectroscopy, TGA analysis and single-crystal X-ray diffraction. {l_brace}[PrL(NO{sub 3}){sub 3}(H{sub 2}O){sub 2}].CH{sub 3}OH{r_brace}{sub n} is a 1D zigzag polymer with three-dimensional supramolecular structure formed by hydrogen bonds, while [EuL(NO{sub 3}){sub 3}(H{sub 2}O)]{sub n} is a linear coordination polymer and present an interesting supramolecular double chain, which are very different from the structure of terbium complex reported before. The result reported herein demonstrated that steric crowding associated with the decreasing lanthanide ion radius causes changes of the conformation of the ligand as well as structures. Luminescence studies for the Eu(III) complexes demonstrated that the salicylamide ligand also exhibits a good antennae effect for the Eu(III) ion due to efficient intersystem crossing and ligand-to-metal energy transfer and the Eu(III) ion is well shielded from the surrounding environment. - Graphical abstract: Structure variation and luminescence properties of lanthanide complexes with 1,9-bis [2-(2'-picolylaminoformyl)-1,4,7,9-tetraoxadecane.

  6. Tetranuclear lanthanide (III) complexes containing dimeric subunits: single-molecule magnet behavior for the Dy4 analogue.

    PubMed

    Chandrasekhar, Vadapalli; Das, Sourav; Dey, Atanu; Hossain, Sakiat; Sutter, Jean-Pascal

    2013-10-21

    The reaction of the lanthanide(III) salts [Dy(III), Tb(III), and Gd (III)] with a hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide (LH3) and pivalic acid (PivH) in the presence of tetra-n-butylammonium hydroxide (TBAH) afforded the tetranuclear Ln(III) coordination compounds, [Ln4(LH)2(LH2)2(μ2-η(1)η(1)Piv)2(η(1)Piv)4]·2CHCl3 [Ln = Dy(1), Tb(2), and Gd(3)]. The molecular structure of these complexes reveals that the tetranuclear derivatives are composed of two dinuclear subunits which are interconnected through the coordination action of the picolinoyl hydrazine ligand. Within each subunit two different types of Ln(III) ions are present. One of these is eight-coordinate in a distorted triangular dodecahedral geometry while the other is nine-coordinate in a distorted spherical capped square antiprism geometry. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent two step out-of-phase signals under 1kOe DC field which is characteristic of a single-molecule magnet (SMM) behavior. Analysis of the magnetic data afforded the anisotropic barriers and relaxation times: Δ/kB = 62.6 K, τ0 = 8.7 × 10(-7) s; Δ/kB = 26.3 K, τ0 = 1.26 × 10(-6) s for the slow and fast relaxations respectively. PMID:24111517

  7. 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. PMID:20449498

  8. Luminescent lanthanide coordination polymers

    SciTech Connect

    Ma, L.; Evans, O.R.; Foxman, B.M.; Lin, W.

    1999-12-13

    One-dimensional lanthanide coordination polymers with the formula Ln(isonicotinate){sub 3}(H{sub 2}O){sub 2} (Ln = Ce, Pr, Nd, Sm, Eu, Tb; 1a-f) were synthesized by treating nitrate or perchlorate salts of Ln(III) with 4-pyridinecarboxaldehyde under hydro(solvo)thermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. While Ce(III), Pr(III), and Nd(III) complexes adopt a chain structure with alternating Ln-(carboxylate){sub 2}-Ln and Ln-(carboxylate){sub 4}-Ln linkages, Sm(III), Eu(III), and Tb(III) complexes have a doubly carboxylate-bridged infinite-chain structure with one chelating carboxylate group on each metal center. In both structures, the lanthanide centers also bind to two water molecules to yield an eight-coordinate, square antiprismatic geometry. The pyridine nitrogen atoms of the isonicotinate groups do not coordinate to the metal centers in these lanthanide(III) complexes; instead, they direct the formation of Ln(III) coordination polymers via hydrogen bonding with coordinated water molecules. Photoluminescence measurements show that Tb(isonicotinate){sub 3}(H{sub 2}O){sub 2} is highly emissive at room temperature with a quantum yield of {approximately}90%. These results indicate that highly luminescent lanthanide coordination polymers can be assembled using a combination of coordination and hydrogen bonds. Crystal data for 1a: monoclinic space group P2{sub 1}/c, a = 9.712(2) {angstrom}, b = 19.833(4) {angstrom}, c = 11.616(2) {angstrom}, {beta} = 111.89(3){degree}, Z = 4. Crystal data for 1f: monoclinic space group C2/c, a = 20.253(4) {angstrom}, b = 11.584(2) {angstrom}, c = 9.839(2) {angstrom}, {beta} = 115.64(3){degree}, Z = 8.

  9. 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.

  10. A lanthanide complex with dual biosensing properties: CEST and BIRDS with EuDOTA-(gly)4−

    PubMed Central

    Coman, Daniel; Kiefer, Garry E.; Rothman, Douglas L.; Sherry, A. Dean; Hyder, Fahmeed

    2011-01-01

    Responsive contrast agents (RCAs) [R1.12] composed of lanthanide III ion (Ln3+) complexes with a variety of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA4−) derivatives have shown great potential as molecular imaging agents for magnetic resonance (MR). A variety of LnDOTA-tetraamide complexes have been demonstrated as RCAs for molecular imaging with 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 Ln3+ 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 affect on bulk water) using a method called biosensor imaging of redundant deviation in shifts (BIRDS). The BIRDS method utilizes redundant information stored in the non-exchangeable proton resonances emanating from the paramagnetic RCA for ambient factors like temperature and/or pH. Thus CEST and BIRDS rely on exchangeable and non-exchangeable protons, respectively, for biosensing. We posited that it is feasible to combine these two biosensing features into the same RCA (i.e., dual CEST and BIRDS properties). A complex between europium ion (Eu3+) and DOTA-tetra-glycinate (DOTA-(gly)44−) is used to demonstrate that its CEST characteristics are preserved while BIRDS properties are detected. In vitro temperature sensitivity of EuDOTA-(gly)4− is 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. PMID:22020775

  11. X-ray diffraction and (1)H NMR in solution: structural determination of lanthanide complexes of a Py(2)N(6)Ac(4) ligand.

    PubMed

    Valencia, L; Martinez, J; Macías, A; Bastida, R; Carvalho, R A; Geraldes, C F G C

    2002-10-01

    Complexes between the Py(2)N(6)Ac(4) (H(4)L) ligand containing four carboxylate pendant arms and trivalent lanthanide ions have been synthesized, and structural studies have been made both in the solid state and aqueous solution. The crystal structures of the La, Ce, Sm, Tb, Dy, Ho, Er, Tm, and Lu complexes, with chemical formulas [LaH(2)L](NO(3)).3H(2)O (1), [Ce(4)L(2)](NO(3))(4).30H(2)O (2), [SmHL].EtOH.3H(2)O (5), [TbHL].EtOH.3H(2)O (8), [DyHL].2EtOH.2H(2)O (9), [HoHL].3H(2)O (10), [ErHL].EtOH.3H(2)O (11) [TmHL].EtOH.3H(2)O (12), and [LuHL].3H(2)O (14), have been determined by single-crystal X-ray crystallography. In the solid state, the complexes of the lighter lanthanide ions La(3+)-Dy(3+) show a 10-coordinated geometry close to a distorted bicapped antiprism, where the carboxylate pendants are situated alternatively above and below the best plane that contains the nitrogen donor atoms. The complexes of the heavier ions, Ho(3+)-Lu(3+), have a 9-coordinated geometry close to distorted tricapped trigonal prism, with one of the pendant carboxylate groups uncoordinated. The ligand is in a "twist-fold" conformation, where the twisting of the pyridine units is accompanied by an overall folding of the major ring of the macrocycle so that the pyridine nitrogen atoms and the metal are far from linear. The aqueous solution structures of the complexes were thoroughly characterized, the diamagnetic ones (La(3+) and Lu(3+)) by their COSY NMR spectra, and the paramagnetic complexes using a linear least-squares fitting of the (1)H LIS (lanthanide-induced shift) and LIR (lanthanide-induced relaxation) data with rhombic magnetic susceptibility tensors. The solution structures obtained for the La(3+)-Dy(3+) complexes (10-coordinate) and for the Tm(3+)-Lu(3+) complexes (9-coordinate) are in very good agreement with the corresponding crystal structures. However, the 10-coordinate structure is still exclusive in solution for the Ho(3+) complex and predominant for the Er(3

  12. meso-Phenyltetrabenzotriazaporphyrin based double-decker lanthanide(III) complexes: synthesis, structure, spectral properties and electrochemistry.

    PubMed

    Pushkarev, Victor E; Kalashnikov, Valery V; Tolbin, Alexander Yu; Trashin, Stanislav A; Borisova, Nataliya E; Simonov, Sergey V; Rybakov, Victor B; Tomilova, Larisa G; Zefirov, Nikolay S

    2015-10-01

    A series of half-sandwich and sandwich-type lanthanide(III) complexes have been prepared using tetrabenzotriazaporphyrin ligands. Reaction of 27-phenyl-29H,31H-tetrabenzo[b,g,l,q][5,10,15]-triazaporphyrin (PhTBTAPH2, 1) with salts [LnX3]·nH2O (Ln = Eu (a), Lu (b); X = OAc, acac) afforded the single- and homoleptic double-deckers (PhTBTAP)LnOAc (2) and (PhTBTAP)2Ln (3) respectively. Heteroleptic double-decker compounds (PhTBTAP)LnPc (4a,b) were obtained upon interaction of 1 with the corresponding Ln mono(phthalocyaninates). An unexpected formation of partially and completely dephenylated co-products 5 and 6 has been detected in the synthesis of sandwich 3, while the possibility of the dearylation of the half-sandwich compound 2 has been demonstrated as well. A more predictable yet firstly observed formation of the triple-decker compound (PhTBTAP)3Eu2 (7) has also been found. Structural studies of 3 supported by 1H NMR spectra, XRD analysis and DFT theoretical calculations reveal that the Eu complex 3a is formed as a single isomer, while the lutetium compound 3b represents an inseparable mixture of two rotational isomers with virtually identical spectral characteristics. The double-decker compounds 3 and 4 reveal intrinsic UV-Vis/NIR absorption as well as peculiar electrochromic behavior. The heteroleptic derivatives 4 generally show intermediate spectral and electrochemical properties with respect to their homoleptic relatives. PMID:26332086

  13. Slow magnetic relaxation in lanthanide complexes with chelating nitronyl nitroxide radical.

    PubMed

    Wang, Xiao-Ling; Li, Li-Cun; Liao, Dai-Zheng

    2010-06-01

    Two rare-earth radical complexes [Ln(hfac)(3)NIT-2Py].0.5C(7)H(16) [Ln = Tb (1), Dy (2)] have been synthesized and characterized structurally as well as magnetically. Both complexes are isomorphous, in which the NIT-2Py radical is coordinated to the Ln(III) ion in a chelating manner. Magnetic studies reveal that complex 1 shows a frequency-dependent, alternating-current magnetic susceptibility typical of a single-molecule magnet, whereas slow magnetic relaxation is observed in 2 under an applied direct-current field. PMID:20438100

  14. 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.

  15. Computational study of organo-cesium complexes and the possibility of lanthanide/actinide ions substitution

    NASA Astrophysics Data System (ADS)

    Rabanal-León, Walter A.; Martinez-Ariza, Guillermo; Roberts, Sue A.; Hulme, Christopher; Arratia-Pérez, Ramiro

    2015-11-01

    Relativistic DFT calculations suggest that two organo-cesium complexes studied herein afford large HOMO-LUMO gaps of around 2.4 eV with the PBE xc-functional, which accounts for their stability. Energy decomposition studies suggest these two complexes are largely ionic with about 20% covalency. However, when the Cs+ ions are substituted by the isoelectronic La3+ and Th4+, their predicted ionicity decreases significantly. The significant increase in covalence indicates that employing Ugi reaction cascades that afford tetramic acid-based organo-cesium complexes may be extended to La3+ and Th4+ organometallics.

  16. 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.

  17. Comparison of Crystal Field Dependent and Independent Methods to Analyse Lanthanide Induced NMR Shifts in Axially Symmetric Complexes. Part II: Systems with a C4 Symmetry Axis

    PubMed Central

    Zhang, Shanrong; Sherry, A. Dean

    2003-01-01

    Analysis of the LIS data for several series of Ln3+ complexes of C4 symmetry in terms of structural changes, crystal-field effects and/or variation of hyperfine constants along the lanthanide series was undertaken using a combination of the two-nuclei and three-nuclei techniques together with the classical onenucleus technique. Isostructurality of whole series of complexes, with changes of the Fi, and B02 parameters, was clearly defined for the complexes of L by the combination of the two first methods. Small changes, involving the three Fi, Gi and B02 parameters, are observed for the series of complexes of L-L4, using the three data plotting methods. Some of the plots according to the two- and three-nuclei methods are accidentally linear, without necessarily implying isostructurality of the complexes, as they involve parameters, which may be insensitive to any small structural changes occurring in these systems. These parameter variations could result from a magnification, by the present graphical analysis, of the breaks expected from the gradual structural changes along the series due to the lanthanide contraction. The α and β parameters of the three-nuclei method are not diagnostic of the type of structures the complexes have in solution, due to their very indirect dependence on the geometric factors. PMID:18365039

  18. 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

    2015-09-01

    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. PMID:26347289

  19. Luminescent lanthanide complexes of a bis-bipyridine-phosphine-oxide ligand as tools for anion detection.

    PubMed

    Charbonnière, Loïc J; Ziessel, Raymond; Montalti, Marco; Prodi, Luca; Zaccheroni, Nelsi; Boehme, Christian; Wipff, Georges

    2002-07-01

    The Gd(3+), Tb(3+), and Eu(3+) complexes of a bis-bipyridine-phenylphosphine oxide ligand PhP(O)(bipy)(2) 1 (bipy for 6-methylene-6'-methyl-2,2'-bipyridine) have been synthesized. In acetonitrile solutions at room temperature, the Tb(3+) and Eu(3+) complexes show a metal-centered luminescence, indicative of an efficient energy transfer from the two bipy subunits to the Ln center. The photophysical properties drastically depend on the nature of the anions present in solution. In particular, addition of 2 equiv of nitrate anions to a solution containing the [Ln.1](OTf-)(3) leads to an 11-fold increase of the luminescence intensity for the Eu(3+) and a 7-fold increase for the Tb(3+) complexes. Similar effects are provided with Cl-, F-, and CH(3)COO- anions. UV-vis titration experiments were used to determine association constants for binding of, respectively, one, two, and three anions. Stepwise anion addition has also been investigated on the molecular level using quantum mechanical (QM) calculations for the Eu complexes. These calculations reproduce the experimental findings, especially if solvent molecule addition is taken into account. The X-ray crystal structure of the nitrate salt of the Tb complex, as well as QM calculation of a similar Eu complex, demonstrates the coordination of three nitrate anions in a bidentate mode and the step-by-step relegation of the bipy subunits in the second coordination sphere. These features give valuable insights into the mechanism of the overall light amplification process. PMID:12083932

  20. Luminescent lanthanide complexes with 4-acetamidobenzoate: Synthesis, supramolecular assembly via hydrogen bonds, crystal structures and photoluminescence

    SciTech Connect

    Yin Xia; Fan Jun; Wang Zhihong; Zheng Shengrun; Tan Jingbo; Zhang Weiguang

    2011-07-15

    Four new luminescent complexes, namely, [Eu(aba){sub 2}(NO{sub 3})(C{sub 2}H{sub 5}OH){sub 2}] (1), [Eu(aba){sub 3}(H{sub 2}O){sub 2}].0.5 (4, 4'-bpy).2H{sub 2}O (2), [Eu{sub 2}(aba){sub 4}(2, 2'-bpy){sub 2}(NO{sub 3}){sub 2}].4H{sub 2}O (3) and [Tb{sub 2}(aba){sub 4}(phen){sub 2}(NO{sub 3}){sub 2}].2C{sub 2}H{sub 5}OH (4) were obtained by treating Ln(NO{sub 3}){sub 3}.6H{sub 2}O and 4-acetamidobenzoic acid (Haba) with different coligands (4, 4'-bpy=4, 4'-bipyridine, 2, 2'-bpy=2, 2'-bipyridine, and phen=1, 10-phenanthroline). They exhibit 1D chains (1-2) and dimeric structures (3-4), respectively. This structural variation is mainly attributed to the change of coligands and various coordination modes of aba molecules. Moreover, the coordination units are further connected via hydrogen bonds to form 2D even 3D supramolecular networks. These complexes show characteristic emissions in the visible region at room temperature. In addition, thermal behaviors of four complexes have been investigated under air atmosphere. The relationship between the structures and physical properties has been discussed. - Graphical abstract: Structure variation of four complexes is attributed to the change of coligands and various coordination modes of aba molecules. Moreover, they show characteristic emissions in the visible region. Highlights: > Auxiliary ligands have played the crucial roles on the structures of the resulting complexes. > Isolated structure units are further assembled via H-bonds to form supramolecular networks. > These solid-state complexes exhibit strong, characteristic emissions in the visible region.

  1. 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.

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

    PubMed

    Ahmed, Zubair; Iftikhar, Khalid

    2015-12-01

    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

  3. Peculiarities of the structure of lanthanide chloride complexes with heterocyclic diimines and the efficiency of energy transfer processes

    NASA Astrophysics Data System (ADS)

    Puntus, Lada N.; Zhuravlev, Konstantin P.; Pekareva, Irina S.; Lyssenko, Konstantin A.; Zolin, Vladislav F.

    2008-01-01

    Two families of lanthanide chlorides LnCl 3L 2(H 2O) n and LnCl 3L(H 2O) m where L is 1,10-phenanthroline or 2,2'-bipyridine were synthesized. Their luminescence properties were investigated in the solid state and 1-dodecyl-3-methylimidazolium chloride solution. The structural peculiarities of lanthanide chlorides were elucidated by joint analysis of the X-ray, vibrational and luminescence data including the lifetime measurements. As a result the analysis of efficiency of energy transfer processes was performed and the correlation between the structure and the luminescence intensity was demonstrated in the systems studied.

  4. 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.

  5. 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

    2016-04-01

    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 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. PMID:26802538

  6. 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.

  7. Complexation of Sn{sub 2}Se{sub 6} with lanthanide(III) centers influenced by ethylene polyamines: Solvothermal syntheses, crystal structures, and optical properties of lanthanide selenidostannates

    SciTech Connect

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

    2013-08-15

    Lanthanide selenidostannates (H{sub 3}O){sub n}[Ce(tepa)(μ-1κ{sup 2}:2κ{sup 2}-Sn{sub 2}Se{sub 6})]{sub n} (1), [(Yb(tepa)(μ-OH)){sub 2}(μ-1κ:2κ-Sn{sub 2}Se{sub 6})]{sub n}·nH{sub 2}O (2), [Htrien]{sub 2}[(Ln(trien)(tren)){sub 2}(μ-1κ:2κ-Sn{sub 2}Se{sub 6})][Sn{sub 2}Se{sub 6}] (Ln=Ce(3), Nd(4)) and [(Yb(dien){sub 2}){sub 2}(μ-OH){sub 2}]Sn{sub 2}Se{sub 6} (5) were solvothermally prepared in different ethylene polyamines. The Sn{sub 2}Se{sub 6} unit connects [Ce(tepa)]{sup 3+} and [(Yb(tepa)(μ-OH)){sub 2}]{sup 4+} fragments with tetradentate μ-1κ{sup 2}Se{sup 1},Se{sup 2}:2κ{sup 2}Se{sup 5},Se{sup 6} and bidentate μ-1κSe{sup 1}:2κSe{sup 5} bridging coordination modes in tepa, to form polymers 1 and 2, respectively. It joins two [Ln(trien)(tren)]{sup 3+} fragments as a μ-1κSe{sup 1}:2κSe{sup 5} ligand to form binuclear complexes 3 and 4 in trien. Unlike the Sn{sub 2}Se{sub 6} units in 1–4 that bind with Ln(III) centers as Se-donor ligands, the Sn{sub 2}Se{sub 6} 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 Sn{sub 2}Se{sub 6} 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 Sn{sub 2}Se{sub 6} with Ln(III) centers. - Graphical abstract: New lanthanide complexes concerning the Sn{sub 2}Se{sub 6} ligand were solvothermally prepared, and the effect of ethylene polyamines on the complexation of Sn{sub 2}Se{sub 6} with Ln(III) centers are observed. Highlights: • Lanthanide complexes concerning the selenidostannates have been solvothermally prepared in different ethylene polyamines. • A tetradentate μ-1κ{sup 2}Se{sup 1},Se{sup 2}:2κ{sup 2}Se{sup 5},Se{sup 6} and a bidentate μ-1κSe{sup 1}:2κSe{sup 5} bridging coordination modes for the Sn{sub 2}Se{sub 6} ligand is obtained. • The complexation of the Sn{sub 2}Se{sub 6} ligand with Ln(III) centers are

  8. 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.

  9. 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.

  10. 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. PMID:25357209

  11. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters.

    PubMed

    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

  12. 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

  13. High-affinity recognition of lanthanide(III) chelate complexes by a reprogrammed human lipocalin 2.

    PubMed

    Kim, Hyun Jin; Eichinger, Andreas; Skerra, Arne

    2009-03-18

    Human lipocalin 2 (Lcn2), also known as neutrophil gelatinase-associated lipocalin (NGAL), which naturally scavenges bacterial ferric siderophores, has been engineered to specifically bind rare-earth and related metal ions as chelate complexes with [(R)-2-amino-3-(4-aminophenyl)propyl]-trans-(S,S)-cyclohexane-1,2-diaminepentaacetic acid (p-NH(2)-Bn-CHX-A''-DTPA). To this end, 12 amino acid residues in the ligand pocket of Lcn2, which is formed by four loops at the open end of an eight-stranded beta-barrel, were subjected to targeted random mutagenesis, and from the resulting library, variants with binding activity for the Me x DTPA group were selected using the method of bacterial phage display. One promising candidate was further developed in several cycles of in vitro affinity maturation using partial random mutagenesis and selection (via phage display and/or Escherichia coli colony screening) under conditions of increasing stringency. As result, an Lcn2 variant was obtained that binds Y x DTPA with a dissociation constant as low as 400 pM. The Lcn2 variant specifically recognizes the artificial ligand, as exemplified in (competitive) ELISA and real-time surface plasmon resonance analyses. DTPA-complexed Y(3+), Tb(3+), Gd(3+), and Lu(3+) are most tightly bound, comprising metal ions whose isotopes are in common use for radiotherapy and imaging. All of the Lcn2 variants are stably folded and can be functionally produced in high yield in E. coli. X-ray crystallographic analyses show that the new ligand is well-accommodated in the central cavity of the engineered lipocalin, whose fold is largely preserved, but that the mode of binding differs from the one seen with the natural ligand Fe x enterobactin. This structural study reveals analogies but also differences with respect to previously described antibody-metal chelate complexes. Notably, the functionalized side chain of DTPA protrudes from the ligand pocket of the lipocalin in such a way that its conjugates (with

  14. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    DOE PAGESBeta

    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

  15. 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

  16. 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

  17. Lanthanide complexes of new nonadentate imino-phosphonate ligands derived from 1,4,7-triazacyclononane: synthesis, structural characterisation and NMR studies.

    PubMed

    Tei, Lorenzo; Blake, Alexander J; Wilson, Claire; Schröder, Martin

    2004-07-01

    The polyamino ligand 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane (1) has been used to synthesise two new ligands by Schiff-base condensation with methyl sodium acetyl phosphonate to give ligand L and methyl sodium 4-methoxybenzoyl phosphonate to give ligand L1 in the presence of lanthanide ion as templating agent to form the complexes [Ln(L)] and [Ln(L1)](Ln = Y, La, Gd, Yb). Both ligands L and L1 have nine donor atoms comprising three amine and three imine N-donors and three phosphonate O-donors and form Ln(III) complexes in which the three pendant arms of the ligands wrap around the nine-coordinate Ln(III) centres. Complexes with Y(III), La(III), Gd(III) and Yb(III) have been synthesised and the complexes [Y(L)], [Gd(L)] and [Gd(L1)] have been structurally characterised. In all the complexes the coordination polyhedron about the lanthanide centre is slightly distorted tricapped trigonal prismatic with the two triangular faces of the prism formed by the macrocyclic N-donors and the phosphonate O-donors. Interestingly, given the three chiral phosphorus centres present in [Ln(L)] and [Ln(L1)] complexes, the three crystal structures reported show the presence of only one diastereomer of the four possible. 1H, 13C and 31P NMR spectroscopic studies on diamagnetic [Y(L)] and [La(L)] and on paramagnetic [Yb(L)] complexes indicate the presence in solution of all the four different diastereomers in varying proportions. The stability of complexes [Y(L)] and [Y(L1)] in D2O in both neutral and acidic media, and the relaxivity of the Gd(III) complexes, have also been investigated. PMID:15252581

  18. 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.

  19. 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

  20. Polymeric heterometallic Pb-Ag iodometallates, iodoplumbates and iodoargentates with lanthanide complex cations as templates.

    PubMed

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

    2013-11-14

    Heterometallic Pb-Ag iodometallates [Ln(DMF)8]2Pb3Ag10I22 [Ln = Ce(1), Pr(2)] were prepared by the reactions of PbI2, AgNO3 and KI in dimethylformamide (DMF) templated by [Ln(DMF)8](3+) complexes formed in situ by stirring LnCl3 in DMF. The same reactions in the absence of AgNO3 or PbI2 afforded iodoplumbate [Pr(DMF)9]2[Pr(DMF)8]Pb11I31 (3), and iodoargentates [Ln(DMF)8]Ag6I9 [Ln = Ce(4), Pr(5)], respectively. Compounds 1 and 2 contain a ternary one-dimensional polymeric [Pb3Ag10I22](6-) anion self-assembled from five AgI4, one PbI6 and one PbI4 primary units via edge- and face-sharing. Twelve PbI6 octahedra are interlinked via sharing of common faces to generate a 1D zigzag [Pb11I31(9-)]n chain in 3, which represents a new member of iodoplumbate aggregates. In 4 and 5, three AgI4 tetrahedra connect through common edges to form the [Ag6I12](6-) building block. The [Ag6I12](6-) blocks are further interlinked by sharing common edges, resulting in the 1D [Ag6I9(3-)]n chain. Optical absorption spectra showed that the synthesized Ag-iodoplumbate and iodoplumbate have potential for being used as semiconductors. Our results show that heterometallic halometallate properties can be tuned by combining structural units with different symmetries, enabling the synthesis of specific functional materials. PMID:24005846

  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. 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. PMID:26248311

  3. 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

  4. Chain-like and dinuclear coordination polymers in lanthanide (Nd, Eu) oxochloride complexes with 2,2':6',2''-terpyridine: synthesis, XRD structure and magnetic properties.

    PubMed

    Lhoste, Jérôme; Pérez-Campos, Ana; Henry, Natacha; Loiseau, Thierry; Rabu, Pierre; Abraham, Francis

    2011-09-28

    The solvothermal reactions (at 180 °C for 48 h) of a mixture of lanthanide chlorides (Nd, Eu) with the tridendate heterocyclic nitrogen ligand, 2,2':6',2''-terpyridine (terpy), in ethanol medium give rise to the formation of crystalline mixed chloro-hydroxo-aquo complex Ln(2)Cl(5)(OH)(H(2)O)(terpy). Its crystal structure consists of the connection of eight- and nine-fold coordinated lanthanide centers linked to each other via μ(2,3)-chloro and μ(3)-hydroxo species to form a tetranuclear unit, which are then further connected through chloro edges to generate infinite ribbons. Only one lanthanide cation in every two is chelated by terpy. Similar molar composition of the starting reactants led to the crystallization at room temperature of a second type of complex LnCl(3)(H(2)O)(terpy) (Ln = Nd, Eu). It is built up from the molecular assembly of dinuclear species containing two eight-fold coordinated lanthanide centers chelated by terpy and linked through a μ(2)-Cl edge. Luminescence spectra have been collected for the europium-based compound and indicates a strong red signal with the expected bands from the F-D transitions. The magnetic properties of the four compounds were investigated. Their behaviors correspond to that of the rare-earth ions present in the structure. The magnetic susceptibility of the neodymium-based compounds agrees with that of the Nd(III) ion with an (4)I(9/2) ground state split by crystal field. Concerning the Eu(III) derivatives, the term (7)F is split by spin-orbit coupling, the first excited states being thermally populated. Accordingly, the thermal dependence of the magnetic susceptibility was nicely reproduced by using appropriate analytical relations. The refined values of the spin-orbit coupling are consistent with the energies of the electronic levels deduced from the photoluminescence spectra. Unexpectedly, the magnetic susceptibility exhibits a hysteretic behavior in the range 45-75 K. PMID:21818485

  5. Low-voltage organic field-effect transistors based on novel high-κ organometallic lanthanide complex for gate insulating materials

    SciTech Connect

    Liu, Qi; Li, Yi; Zhang, Yang; Song, You E-mail: yli@nju.edu.cn Wang, Xizhang E-mail: yli@nju.edu.cn Hu, Zheng; Sun, Huabin; Li, Yun E-mail: yli@nju.edu.cn Shi, Yi

    2014-08-15

    A novel high-κ organometallic lanthanide complex, Eu(tta){sub 3}L (tta=2-thenoyltrifluoroacetonate, L = 4,5-pinene bipyridine), is used as gate insulating material to fabricate low-voltage pentacene field-effect transistors (FETs). The optimized gate insulator exhibits the excellent properties such as low leakage current density, low surface roughness, and high dielectric constant. When operated under a low voltage of −5 V, the pentacene FET devices show the attractive electrical performance, e.g. carrier mobility (μ{sub FET}) of 0.17 cm{sup 2} V{sup −1} s{sup −1}, threshold voltage (V{sub th}) of −0.9 V, on/off current ratio of 5 × 10{sup 3}, and subthreshold slope (SS) of 1.0 V dec{sup −1}, which is much better than that of devices obtained on conventional 300 nm SiO{sub 2} substrate (0.13 cm{sup 2} V{sup −1} s{sup −1}, −7.3 V and 3.1 V dec{sup −1} for μ{sub FET}, V{sub th} and SS value when operated at −30 V). These results indicate that this kind of high-κ organometallic lanthanide complex becomes a promising candidate as gate insulator for low-voltage organic FETs.

  6. Trivalent lanthanide lacunary phosphomolybdate complexes: a structural and spectroscopic study across the series [Ln(PMo11O39)2]11-.

    PubMed

    Copping, Roy; Gaunt, Andrew J; May, Iain; Sarsfield, Mark J; Collison, David; Helliwell, Madeleine; Denniss, Iain S; Apperley, David C

    2005-04-01

    We report the syntheses and crystal structures of (NH4)11[Ln(III)(PMo11O39)2.xH2O (where Ln = every trivalent lanthanide cation except promethium) in which two lacunary [PMo11O39]7- anions sandwich an 8-coordinate Ln(III) cation to yield the complex anion, [LnIII(PMo11O39)2]11-. The 14 salts crystallise in two different space groups, C2/c or P1, but the LnIII containing anions are isostructural across the whole series, a very rare example of such a complete study. Solid state and solution 31P NMR, Raman and IR spectroscopies have been used to prove the stability of [Ln(PMo11O39)2]11- in aqueous solution. As expected, the LnIII cation contracts across the series and the Ln-O bond distances decrease uniformly. Interestingly, the splitting in the nu(P-O) mode within the [PMo11O39]7- unit increases uniformly across the series, which we attribute to the stronger interaction with the smaller, higher charge density LnIII cation as the series is traversed. For the 31P NMR measurements a direct comparison of Lanthanide Induced (paramagnetic) Shift could be made with the analogous [P(W11O39)2]11- complexes. PMID:15782262

  7. 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.

  8. Dynamics of the layer-by-layer assembly of a poly(acrylic acid)-lanthanide complex colloid and poly(diallyldimethyl ammonium).

    PubMed

    Xu, Jiali; Wang, Zhiliang; Wen, Lingang; Zhou, Xianju; Xu, Jian; Yang, Shuguang

    2016-01-21

    Poly(acrylic acid) (PAA) and lanthanide (Ln) ions, such as Ce(3+), Eu(3+), and Tb(3+), were prepared as dispersed complex colloidal particles through three different protocols with rigorous control of the pH value and mixing ratio. The negatively charged PAA-Ln complex particles were layer-by-layer (LbL) assembled with positively charged poly(diallyldimethyl ammonium) (PDDA) to prepare a thin film. The film thickness growth is much quicker than PDDA/PAA film. Due to the incorporation of Ln(3+) ions, the film exhibits fluorescence. During LbL assembly, PDDA-PAA association based on electrostatic force and PAA-Ce association based on coordination are in competition, which leads to the LbL assembly of PDDA and PAA-Ln complex colloidal particles being a complicated dynamic process. PMID:26549538

  9. New Family of Lanthanide-Based Complexes with Different Scorpionate-Type Ligands: A Rare Case Where Dysprosium and Ytterbium Analogues Display Single-Ion-Magnet Behavior.

    PubMed

    Lannes, Anthony; Luneau, Dominique

    2015-07-20

    A new family of lanthanide complexes [Ln(Tpz)2Bpz]·xCH2Cl2 (Ln = Gd, Tb, Dy, Ho, x = 0.5; Ln = Yb, x = 1; Tpz = hydrotris(pyrazolyl)borate; Bpz = dihydrobis(pyrazolyl)borate) has been synthesized. Those complexes have been characterized by single-crystal X-ray diffraction, and the magnetic properties have been investigated. Both dysprosium and ytterbium analogues display single-ion-magnet behavior, despite the difference in their spatial distribution of 4f electronic charges. Theoretical calculations with crystal field parameters have been carried out to gain better insight of the relaxation pathways that may be involved in those two complexes. PMID:26132295

  10. Effect of Lanthanide Metal Complexation on the Properties and Electronic Structure of Single-Walled Carbon Nanotube Films.

    PubMed

    Moser, Matthew L; Pekker, Aron; Tian, Xiaojuan; Bekyarova, Elena; Itkis, Mikhail E; Haddon, Robert C

    2015-12-30

    We spectroscopically analyze the effect of e-beam deposition of lanthanide metals on the electronic structure and conductivities of films of semiconducting (SC) single-walled carbon nanotubes (SWNTs) in high vacuum. We employ near-infrared and Raman spectroscopy to interpret the changes in the electronic structure of SWNTs on exposure to small amounts of the lanthanides (Ln = Sm, Eu, Gd, Dy, Ho, Yb), based on the behavior of the reference metals (M = Li, Cr) which are taken to exemplify ionic and covalent bonding, respectively. The analysis shows that while the lanthanides are more electropositive than the transition metals, in most cases they exhibit similar conductivity behavior which we interpret in terms of the formation of covalent bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = La, Nd, Gd, Dy, Ho]. However, only M = Eu, Sm, Yb show the continually increasing conductivity characteristic of Li, and this supports our contention that these metals provide the first examples of mixed covalent-ionic bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = Sm, Eu, Yb]. PMID:25902843

  11. Ligand Field Affected Single-Molecule Magnet Behavior of Lanthanide(III) Dinuclear Complexes with an 8-Hydroxyquinoline Schiff Base Derivative as Bridging Ligand.

    PubMed

    Wang, Wen-Min; Zhang, Hong-Xia; Wang, Shi-Yu; Shen, Hai-Yun; Gao, Hong-Ling; Cui, Jian-Zhong; Zhao, Bin

    2015-11-16

    New dinuclear lanthanide(III) complexes based on an 8-hydroxyquinoline Schiff base derivative and β-diketonate ligands, [Ln2(hfac)4(L)2] (Ln(III) = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)), [Ln2(tfac)4(L)2] (Ln(III) = Gd (6), Tb (7), Dy (8), Ho (9)), and [Dy(bfac)4(L)2·C7H16] (10) (L = 2-[[(4-fluorophenyl)imino] methyl]-8-hydroxyquinoline, hfac = hexafluoroacetylacetonate, tfac = trifluoroacetylacetonate, and bfac = benzoyltrifluoroacetone), have been synthesized. The single-crystal X-ray diffraction data show that complexes 1-10 are phenoxo-O-bridged dinuclear complexes; each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate β-diketonate coligands and two μ2-O bridging 8-hydroxyquinoline Schiff base derivative ligands. The magnetic study reveals that 1 and 6 display cryogenic magnetic refrigeration properties, whereas complexes 3, 8, and 10 show different SMM behaviors with energy barriers of 6.77 K for 3, 19.83 K for 8, and 25.65 K for 10. Meanwhile, slow magnetic relaxation was observed in 7, while no out-of-phase alternating-current signals were found for 2. The different dynamic magnetic behaviors of two Tb2 complexes and the three Dy2 complexes mainly derive from the tiny crystal structure changes around the Ln(III) ions. It is also proved that the β-diketonate coligands can play an important role in modulating magnetic dynamics of the lanthanide 8-hydroxyquinoline Schiff base derivative system. PMID:26516660

  12. 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.

  13. 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

  14. 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. PMID:24258617

  15. Potential lanthanide ion selective reagents. 3. Metal complex formation with 1,7-diaza-4,10-13-trioxacyclopentadecane-N,N'-diacetic acid

    SciTech Connect

    Chang, C.A.; Ochaya, V.O.

    1986-01-29

    Stability constants for the ligand 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N'-diacetic acid (dapda or K21DA) with the lanthanides and several other metal ions have been determined at 25 /sup 0/C in aqueous 0.1 M (CH/sub 3/)/sub 4/NCl medium by a potentiometric method. The results obtained are compared to those obtained for a similar ligand of large cavity size, 1,20-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid (dacda or K22DA), which has been previously studied and reported. The stability of dapda is found to reach a peak at Eu(III) with the lanthanide series and is rationalized in terms of the matching of the ligand properties with metal ion characteristics. The transition-metal ions Ni(II), Cu(II), and Zn(II) all form stronger dapda (as compared to dacda) complexes due to a better match of the ligand cavity size and metal ion radius. 18 references, 3 figures, 1 table.

  16. Completing the series of +2 ions for the lanthanide elements: synthesis of molecular complexes of Pr2+, Gd2+, Tb2+, and Lu2+.

    PubMed

    MacDonald, Matthew R; Bates, Jefferson E; Ziller, Joseph W; Furche, Filipp; Evans, William J

    2013-07-01

    The first examples of crystallographically characterizable complexes of Tb(2+), Pr(2+), Gd(2+), and Lu(2+) have been isolated, which demonstrate that Ln(2+) ions are accessible in soluble molecules for all of the lanthanides except radioactive promethium. The first molecular Tb(2+) complexes have been obtained from the reaction of Cp'3Ln (Cp' = C5H4SiMe3, Ln = rare earth) with potassium in the presence of 18-crown-6 in Et2O at -35 °C under argon: [(18-crown-6)K][Cp'3Tb], {[(18-crown-6)K][Cp'3Tb]}n, and {[K(18-crown-6)]2(μ-Cp')}{Cp'3Tb}. The first complex is analogous to previously isolated Y(2+), Ho(2+), and Er(2+) complexes, the second complex shows an isomeric structural form of these Ln(2+) complexes, and the third complex shows that [(18-crown-6)K](1+) alone is not the only cation that will stabilize these reactive Ln(2+) species, a result that led to further exploration of cation variants. With 2.2.2-cryptand in place of 18-crown-6 in the Cp'3Ln/K reaction, a more stable complex of Tb(2+) was produced as well as more stable Y(2+), Ho(2+), and Er(2+) analogs: [K(2.2.2-cryptand)][Cp'3Ln]. Exploration of this 2.2.2-cryptand-based reaction with the remaining lanthanides for which Ln(2+) had not been observed in molecular species provided crystalline Pr(2+), Gd(2+), and Lu(2+) complexes. These Ln(2+) complexes, [K(2.2.2-cryptand)][Cp'3Ln] (Ln = Y, Pr, Gd, Tb, Ho, Er, Lu), all have similar UV-vis spectra and exhibit Ln-C(Cp') bond distances that are ~0.03 Å longer than those in the Ln(3+) precursors, Cp'3Ln. These data, as well as density functional theory calculations and EPR spectra, suggest that a 4f(n)5d(1) description of the electron configuration in these Ln(2+) ions is more appropriate than 4f(n+1). PMID:23697603

  17. Highly Efficient Visible-to-NIR Luminescence of Lanthanide(III) Complexes with Zwitterionic Ligands Bearing Charge-Transfer Character: Beyond Triplet Sensitization.

    PubMed

    Pan, Mei; Du, Bin-Bin; Zhu, Yi-Xuan; Yue, Mei-Qin; Wei, Zhang-Wen; Su, Cheng-Yong

    2016-02-01

    Two zwitterionic-type ligands featuring π-π* and intraligand charge-transfer (ILCT) excited states, namely 1,1'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)dipyridinium-4-olate (TMPBPO) and 1-dodecylpyridin-4(1 H)-one (DOPO), have been prepared and applied to the assembly of lanthanide coordination complexes in an effort to understand the ligand-direction effect on the structure of the Ln complexes and the ligand sensitization effect on the luminescence of the Ln complexes. Due to the wide-band triplet states plus additional ILCT excitation states extending into lower energy levels, broadly and strongly sensitized photoluminescence of f→f transitions from various Ln(3+) ions were observed to cover the visible to near-infrared (NIR) regions. Among which, the Pr, Sm, Dy, and Tm complexes simultaneously display both strong visible and NIR emissions. Based on the isostructural feature of the Ln complexes, color tuning and single-component white light was achieved by preparation of solid solutions of the ternary systems Gd-Eu-Tb (for TMPBPO) and La-Eu-Tb and La-Dy-Sm (for DOPO). Moreover, the visible and NIR luminescence lifetimes of the Ln complexes with the TMPBPO ligand were investigated from 77 to 298 K, revealing a strong temperature dependence of the Tm(3+) ((3) H4 ) and Yb(3+) ((2) F5/2 ) decay dynamics, which has not been explored before for their coordination complexes. PMID:26784018

  18. 4 f-4 f hypersensitivity in the absorption spectra and NMR studies on paramagnetic lanthanide chloride complexes with 1,10-phenanthroline in non-aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hussain, H. A.; Iftikhar, K.

    2003-03-01

    The optical absorption and NMR studies of trivalent lanthanide chloride complexes with 1,10-phenanthroline (phen) are presented and discussed. The 1H NMR spectra of the complexes of La, Pr, Nd, Eu and Yb have been studied in methanol- d4. The resonances of phen in the NMR spectra of the paramagnetic complexes have been shifted to lower as well as higher fields, which is a manifestation of dipolar interaction. The H (2) protons of the heterocyclic amine display broad resonances. The degree of broadening in Pr, Nd, and Yb complexes follows the order Prcomplexes have been investigated in methanol, pyridine, DMSO and DMF, which reveal that the hypersensitive transitions exhibit larger variation in oscillator strength values and band shapes. The change in the coordination geometry of the complexes and relative basicity of ligand are found responsible for oscillator strength and band shape variation. The interelectronic repulsion and covalency parameters show covalent nature of bonding between the metal and the ligand.

  19. 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.

  20. 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

  1. Isoprene-styrene chain shuttling copolymerization mediated by a lanthanide half-sandwich complex and a lanthanidocene: straightforward access to a new type of thermoplastic elastomers.

    PubMed

    Valente, Andreia; Stoclet, Gregory; Bonnet, Fanny; Mortreux, André; Visseaux, Marc; Zinck, Philippe

    2014-04-25

    A lanthanide half-sandwich complex and a ansa lanthanidocene have been assessed for isoprene-styrene chain shuttling copolymerization with n-butylethylmagnesium (BEM). In the presence of 1 equiv BEM, a fully amorphous multiblock microstructure of soft and hard segments is achieved. The microstructure consists of poly(isoprene-co-styrene) blocks, with hard blocks rich in styrene and soft blocks rich in isoprene. The composition of the blocks and the resulting glass transition temperatures (Tg ) can be easily modified by changing the feed and/or the relative amount of the catalysts, highlighting a new class of thermoplastic elastomers (TPEs) with tunable transition temperatures. The materials self-organize into nanostructures in the solid state. PMID:24668565

  2. The effect of ring size variation on the structure and stability of lanthanide(III) complexes with crown ethers containing picolinate pendants.

    PubMed

    Roca-Sabio, Adrián; Mato-Iglesias, Marta; Esteban-Gómez, David; de Blas, Andrés; Rodríguez-Blas, Teresa; Platas-Iglesias, Carlos

    2011-01-14

    The coordination properties of the macrocyclic receptor N,N'-bis[(6-carboxy-2-pyridyl)methylene]-1,10-diaza-15-crown-5 (H(2)bp15c5) towards the lanthanide ions are reported. Thermodynamic stability constants were determined by pH-potentiometric titration at 25 °C in 0.1 M KCl. A smooth decrease in complex stability is observed upon decreasing the ionic radius of the Ln(III) ion from La [log K(LaL) = 12.52(2)] to Lu [log K(LuL) = 10.03(6)]. Luminescence lifetime measurements recorded on solutions of the Eu(III) and Tb(III) complexes confirm the absence of inner-sphere water molecules in these complexes. (1)H and (13)C NMR spectra of the complexes formed with the diamagnetic La(III) metal ion were obtained in D(2)O solution and assigned with the aid of HSQC and HMBC 2D heteronuclear experiments, as well as standard 2D homonuclear COSY and NOESY spectra. The (1)H NMR spectra of the paramagnetic Ce(III), Eu(III) and Yb(III) complex suggest nonadentate binding of the ligand to the metal ion. The syn conformation of the ligand in [Ln(bp15c5)](+) complexes implies the occurrence of two helicities, one associated with the layout of the picolinate pendant arms (absolute configuration Δ or Λ), and the other to the five five-membered chelate rings formed by the binding of the crown moiety (absolute configuration δ or λ). A detailed conformational analysis performed with the aid of DFT calculations (B3LYP model) indicates that the complexes adopt a Λ(λδ)(δδλ) [or Δ(δλ)(λλδ)] conformation in aqueous solution. Our calculations show that the interaction between the Ln(III) ion and several donor atoms of the crown moiety is weakened as the ionic radius of the metal ion decreases, in line with the decrease of complex stability observed on proceeding to the right across the lanthanide series. PMID:21116555

  3. The effect on the lanthanide luminescence of structurally simple Eu(III) cyclen complexes upon deprotonation of metal bound water molecules and amide based pendant arms.

    PubMed

    Plush, Sally E; Clear, Naomi A; Leonard, Joseph P; Fanning, Ann-Marie; Gunnlaugsson, Thorfinnur

    2010-04-21

    A series of substituted 1,4,7,10-tetraazacylcododecane ligands 1-4, possessing sensitizing nitrobenzene or naphthalene antennae, as one of the amide pendant arms, and their complexes with europium(III) were synthesised. The protonation constants and the metal ion stability constants of two of these ligands were determined by potentiometric titration. The pK(a) of the water molecules coordinated to the complexed metal ion were determined by both luminescent and potentiometric measurements. The luminescence pH dependence of a further three Eu(III) complexes, 5-7, which lack any antennae, were also studied with the aim of gaining a better understanding of the role of the metal bound water molecules in the luminescence properties of such complexes upon direct excitation of the lanthanide ion. The results from these luminescent measurements demonstrate that the Eu(III) emission was significantly modulated as a function of pH for all the complexes, which we assigned to changes occurring in the coordination environment of the ion within the cyclen system, caused by deprotonation of metal bound water molecules and/or deprotonation of pendent amide arms. PMID:20354617

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Synthesis and characterization of heterodinuclear Ln(3+)-Fe3+ and Ln(3+)-Co3+ complexes, bridged by cyanide ligand (Ln3+ = lanthanide ions). Nature of the magnetic interaction in the Ln(3+)-Fe3+ complexes.

    PubMed

    Figuerola, Albert; Diaz, Carmen; Ribas, Joan; Tangoulis, Vassilis; Granell, Jaume; Lloret, Francesc; Mahía, José; Maestro, Miguel

    2003-01-27

    The reaction of Ln(NO3)3.aq with K3[Fe(CN)6] or K3[Co(CN)6] in N,N'-dimethylformamide (DMF) led to 25 heterodinuclear [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O and [Ln(DMF)4(H2O)3(mu-CN)Co(CN)5].nH2O complexes (with Ln = all the lanthanide(III) ions, except promethium and lutetium). Five complexes (Pr(3+)-Fe3+), (Tm(3+)-Fe3+), (Ce(3+)-Co3+), (Sm(3+)-Co3+), and (Yb(3+)-Co3+) have been structurally characterized; they crystallize in the equivalent monoclinic space groups P21/c or P21/n. Structural studies of these two families show that they are isomorphous. This relationship in conjunction with the diamagnetism of the Co3+ allows an approximation to the nature of coupling between the iron(III) and the lanthanide(III) ions in the [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O complexes. The Ln(3+)-Fe3+ interaction is antiferromagnetic for Ln = Ce, Nd, Gd, and Dy and ferromagnetic for Ln = Tb, Ho, and Tm. For Ln = Pr, Eu, Er, Sm, and Yb, there is no sign of any significant interaction. The isotropic nature of Gd3+ helps to evaluate the value of the exchange interaction. PMID:12693250

  10. Open-shell lanthanide(II+) or -(III+) complexes bearing σ-silyl and silylene ligands: synthesis, structure, and bonding analysis.

    PubMed

    Zitz, Rainer; Arp, Henning; Hlina, Johann; Walewska, Małgorzata; Marschner, Christoph; Szilvási, Tibor; Blom, Burgert; Baumgartner, Judith

    2015-04-01

    Complexes featuring lanthanide (Ln)-Si bonds represent a highly neglected research area. Herein, we report a series of open-shell Ln(II+) and Ln(III+) complexes bearing σ-bonded silyl and base-stabilized N-heterocyclic silylene (NHSi) ligands. The reactions of the Ln(III+) 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 Sm(II+) 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

  11. 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

  12. Configuration-averaged 4f orbitals in ab initio calculations of low-lying crystal field levels in lanthanide(iii) complexes.

    PubMed

    Van den Heuvel, Willem; Calvello, Simone; Soncini, Alessandro

    2016-06-21

    A successful and commonly used ab initio method for the calculation of crystal field levels and magnetic anisotropy of lanthanide complexes consists of spin-adapted state-averaged CASSCF calculations followed by state interaction with spin-orbit coupling (SI-SO). Based on two observations valid for Ln(iii) complexes, namely: (i) CASSCF 4f orbitals are expected to change very little when optimized for different states belonging to the 4f electronic configuration, (ii) due to strong spin-orbit coupling the total spin is not a good quantum number, we show here via a straightforward analysis and direct calculation that the CASSCF/SI-SO method can be simplified to a single configuration-averaged HF calculation and one complete active space CI diagonalization, including spin-orbit coupling, on determinant basis. Besides its conceptual simplicity, this approach has the advantage that all spin states of the 4f(n) configuration are automatically included in the SO coupling, thereby overcoming one of the computational limitations of the existing CASSCF/SI-SO approach. As an example, we consider three isostructural complexes [Ln(acac)3(H2O)2], Ln = Dy(3+), Ho(3+), Er(3+), and find that the proposed simplified method yields crystal field levels and magnetic g-tensors that are in very good agreement with those obtained with CASSCF/SI-SO. PMID:27231024

  13. Lanthanides: Applications in Cancer Diagnosis and Therapy.

    PubMed

    Teo, Ruijie D; Termini, John; Gray, Harry B

    2016-07-14

    Lanthanide complexes are of increasing importance in cancer diagnosis and therapy, owing to the versatile chemical and magnetic properties of the lanthanide-ion 4f electronic configuration. Following the first implementation of gadolinium(III)-based contrast agents in magnetic resonance imaging in the 1980s, lanthanide-based small molecules and nanomaterials have been investigated as cytotoxic agents and inhibitors, in photodynamic therapy, radiation therapy, drug/gene delivery, biosensing, and bioimaging. As the potential utility of lanthanides in these areas continues to increase, this timely review of current applications will be useful to medicinal chemists and other investigators interested in the latest developments and trends in this emerging field. PMID:26862866

  14. 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.

  15. Yttrium and lanthanide complexes of β-dialdehydes: synthesis, characterization, luminescence and electrochemistry of coordination compounds with the conjugate base of bromomalonaldehyde.

    PubMed

    Bortoluzzi, Marco; Battistel, Dario; Roppa, Stefania; Daniele, Salvatore; Perosa, Alvise; Enrichi, Francesco

    2014-06-28

    Novel yttrium, europium and terbium coordination compounds having formulae [AsPh4][Ln(BrMA)4] (6LN), Ln(BrMA)3(bipyO2) (7Ln), Ln(NMA)3(phen) (8Ln) and Ln(NMA)3(terpy) (9Ln) (Ln = Y, Eu, Tb; BrMA = conjugate base of bromomalonaldehyde; bipyO2 = 2,2'-bipyridine-N,N'-dioxide; phen = 1,10-phenantroline; terpy = 2,2':6',2''-terpyridine) were synthesized and characterized by using spectroscopic and electrochemical techniques. Uncharged europium and, to a lesser extent, terbium complexes showed appreciable luminescence in the solid state upon excitation with UV light. Polymeric materials and ionic liquids containing BrMA and lanthanides were prepared and photoluminescence measurements were carried out. From an electrochemical point of view, europium(III) BrMA-complexes showed a quasi-reversible one-electron reduction process. The one electron transfer reaction Eu(III) to Eu(II) allowed the photoluminescence tuning of 8Eu deposited on the surface of a glassy carbon electrode. PMID:24819039

  16. A BTP1 prophage gene present in invasive non-typhoidal Salmonella determines composition and length of the O-antigen of the lipopolysaccharide.

    PubMed

    Kintz, Erica; Davies, Mark R; Hammarlöf, Disa L; Canals, Rocío; Hinton, Jay C D; van der Woude, Marjan W

    2015-04-01

    Salmonella Typhimurium isolate D23580 represents a recently identified ST313 lineage of invasive non-typhoidal Salmonellae (iNTS). One of the differences between this lineage and other non-iNTS S. Typhimurium isolates is the presence of prophage BTP1. This prophage encodes a gtrC gene, implicated in O-antigen modification. GtrC(BTP) (1) is essential for maintaining O-antigen length in isolate D23580, since a gtr(BTP) (1) mutant yields a short O-antigen. This phenotype can be complemented by gtrC(BTP) (1) or very closely related gtrC genes. The short O-antigen of the gtr(BTP) (1) mutant was also compensated by deletion of the BTP1 phage tailspike gene in the D23580 chromosome. This tailspike protein has a putative endorhamnosidase domain and thus may mediate O-antigen cleavage. Expression of the gtrC(BTP) (1) gene is, in contrast to expression of many other gtr operons, not subject to phase variation and transcriptional analysis suggests that gtrC is produced under a variety of conditions. Additionally, GtrC(BTP) (1) expression is necessary and sufficient to provide protection against BTP1 phage infection of an otherwise susceptible strain. These data are consistent with a model in which GtrC(BTP) (1) mediates modification of the BTP1 phage O-antigen receptor in lysogenic D23580, and thereby prevents superinfection by itself and other phage that uses the same O-antigen co-receptor. PMID:25586744

  17. 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

    2010-09-01

    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. PMID:20704320

  18. 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

  19. 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. PMID:22522543

  20. Structure-based description of a step-by-step synthesis of homo- and heterodinuclear (4f, 4f ') lanthanide complexes.

    PubMed

    Costes, Jean-Pierre; Dahan, Françoise; Nicodème, Franck

    2003-10-01

    The stepwise course of the synthesis of homo- (4f, 4f) and heterodilanthanide (4f, 4f ') complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, the tripodal ligand H(3)L is reacted with Ln(NO(3))(3) x 5H(2)O to give a complex (H(3)L)Ln(NO(3))(3) in which the ligand does exist in a zwitterionic form. This unexpected feature has been definitely supported by a structural determination performed on a closely related complex (HL')(3)Ln(NO(3))(3) (1). These species are fairly stable and may be isolated. In basic medium, (H(3)L)Ln(NO(3))(3) is deprotonated to yield a neutral LLn complex crystallized as LLnNaClO(4) (2), the lanthanide ion being linked to the inner N(4)O(3) coordination site of the ligand. Finally, addition of Ln'(NO(3))(3) x 5H(2)O (Ln' being similar or different from Ln) to the LLn complex yields the desired homo- or heterodinuclear LLnLn'(NO(3))(3) complex 3, where the Ln' ion is coordinated to the outer O(3)O(3) coordination site of the tripodal ligand. Complex 1 (Ln = La) crystallizes in the triclinic space group P1 (No. 2): a = 11.1883(7) A, b = 11.8993(9) A, c = 16.4197(10) A, alpha = 81.900 (6) degrees, beta = 79.406(5) degrees, gamma = 79.470(6) degrees, V = 2099.5(2) A(3), Z = 2. Complex 2 (Ln = Eu) crystallizes in the monoclinic space group P2(1)/n (No. 14): a = 13.6333(13) A, b = 15.3799(12) A, c = 17.1473(13) A, beta = 111.283(10) degrees, V = 3350.2(5) A(3), Z = 4. Complex 3 (Ln = Ln' = Dy) crystallizes in the trigonal space group R3 (No. 148) with a = b = 23.847(3) A, c = 42.982(2) A, V = 21168(4) A(3), Z = 18. Complex 3 possesses a Dy(O(phenoxo))(3)Dy core, and a nitrato anion has been replaced by a eta(2)-chelated o-vanillin anion. We did not succeed in obtaining crystals of any of the heterodinuclear LLnLn'(NO(3))(3) entities, but their existence was unambiguously confirmed by positive fast atom bombardment mass spectrometry experiments. PMID

  1. Synthesis and Characterization of Electroresponsive Materials with Applications In: Part I. Second Harmonic Generation. Part II. Organic-Lanthanide Ion Complexes for Electroluminescence and Optical Amplifiers.

    NASA Astrophysics Data System (ADS)

    Claude, Charles

    1995-01-01

    Materials for optical waveguides were developed from two different approaches, inorganic-organic composites and soft gel polymers. Inorganic-organic composites were developed from alkoxysilane and organically modified silanes based on nonlinear optical chromophores. Organically modified silanes based on N-((3^' -trialkoxysilyl)propyl)-4-nitroaniline were synthesized and sol-gelled with trimethoxysilane. After a densification process at 190^circC with a corona discharge, the second harmonic of the film was measured with a Nd:YAG laser with a fundamental wavelength of 1064nm, d_{33} = 13pm/V. The decay of the second harmonic was expressed by a stretched bi-exponential equation. The decay time (tau _2) was equal to 3374 hours, and was comparable to nonlinear optical systems based on epoxy/Disperse Orange 1. The processing temperature of the organically modified silane was limited to 200^circC due to the decomposition of the organic chromophore. Soft gel polymers were synthesized and characterized for the development of optical waveguides with dc-electrical field assisted phase-matching. Polymers based on 4-nitroaniline terminated poly(ethylene oxide-co-propylene oxide) were shown to exhibit second harmonic generation that were optically phase-matched in an electrical field. The optical signals were stable and reproducible. Siloxane polymers modified with 1-mercapto-4-nitrobenzene and 1-mercapto-4-methylsulfonylstilbene nonlinear optical chromophores were synthesized. The physical and the linear and nonlinear optical properties of the polymers were characterized. Waveguides were developed from the polymers which were optically phase -matched and had an efficiency of 8.1%. The siloxane polymers exhibited optical phase-matching in an applied electrical field and can be used with a semiconductor laser. Organic lanthanide ion complexes for electroluminescence and optical amplifiers were synthesized and characterized. The complexes were characterized for their thermal and

  2. 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

    2010-01-01

    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. PMID:19957317

  3. 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.

  4. 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…

  5. Phosphoramides bearing isoxazole derivative: spectroscopic and structural characterization, study of hydrogen-bonding interactions and two lanthanide complexes (LnIII = Ce and Eu).

    PubMed

    Gholivand, Khodayar; Molaei, Foroogh; Hosseini, Mahdieh

    2015-04-01

    In this study, the synthesis and spectroscopic characterization of new phosphoramides based on 3-amino-5-methylisoxazole with the formula R2P(O)[NH-C4H4NO], R = C6H5O (1), C6H5 (2), RP(O)[NH-C4H4NO]2, R = C6H5O (3), CH3-C6H4O (4), C6H5NH (5), (C6H5)ClP(O)[NH-C4H4NO] (6) and two lanthanide complexes [Ln(2)2(NO3)3(EtOH)]·EtOH, Ln(III) = Ce (7) and Eu (8), have been reported. The structural study of (3) shows the presence of two conformers (crystallographically independent molecules) in the crystalline lattice, caused by different orientations of the phenyl and isoxazole rings. For (3), the intermolecular interactions have been studied by Hirshfeld surface analysis and fingerprint plots. Furthermore, the electronic and energy aspects of hydrogen bonds between molecules of (3) have been explored by density functional theory (DFT) calculations. X-ray crystallography of complexes (7) and (8) reveals that two phosphoramide ligands take part in coordination to the metal, one as monodentate from O(phosphoryl), and the other one as chelate through O(phosphoryl) and N(ring). The complexes are also composed of two conformers in the solid-state structure. Quantum theory of atoms in molecules (QTAIM) analysis discloses the electrostatic nature of the Ln-ligand interaction. PMID:25827370

  6. 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.

  7. 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.

  8. 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.

  9. 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. PMID:24497945

  10. 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