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Lanthanide Ions (lanthanide + ion)
Selected AbstractsSpectroscopy of High-Energy States of Lanthanide IonsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Michael F. Reid Abstract We discuss recent progress and future prospects for the analysis of the 4fN,15d excited states of lanthanide ions in host materials. We demonstrate how ab initio calculations for Ce3+ in LiYF4 may be used to estimate crystal-field and spin-orbit parameters for the 4f1 and 5d1 configurations. We show how excited-state absorption may be used to probe the electronic and geometric structure of the 4fN,15d excited states in more detail and we illustrate the possibilities with calculations for Yb2+ ions in SrCl2. [source] Fluorinated ,-Diketones for the Extraction of Lanthanide Ions: Photophysical Properties and Hydration Numbers of Their EuIII ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006Anne-Sophie Chauvin Abstract Tris(,-diketonato)europium(III) with a series of variably fluorinated ligands derived from 3,5-heptanedione were synthesised with the aim of determining their hydration state under extraction conditions. The number of coordinated water molecules was determined by measuring the lifetime of the Eu(5D0) excited level in water and deuterated water. The hydration gain (,q = q , q0) after shaking chloroform solutions during 10 min with 0.1 M NaClO4 aqueous solutions depends on the fluorination extent of the diketonates: fluorination of one methyl group leads to a decrease in ,q of ca. 0.5 unit, while fluorination of one ethyl group results in a decrease of ca. 1.3 units. Highly fluorinated complexes (i.e with hexafluoroacetylacetonate and related ligands) display a hydration number close to one while poorly fluorinated compounds (or nonfluorinated ones, such as the acetylacetonate complex) have a hydration state close to two. Photophysical properties of the EuIII ,-diketonates are also described and the synthesis of the fluorinated ,-diketones is re-investigated and discussed in details. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Modulation of the Communication between Redox Centers in a Tris(ferrocene)-tren Ligand by Complexation of Lanthanide IonsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2003Marie Heitzmann The tripodal ligand L built on the tren platform and bearing three chemically equivalent ferrocene units was prepared and characterized. Electrochemical investigations indicate that electrostatic communication occurs between the three ferrocene groups in L, which leads to the observation of two distinct voltammetric waves. The electrochemical communication between the three ferrocene moieties is disrupted in 1:1 (L:M3+) type complexes formed between L and Y3+ or Eu3+ metal cations and their electrochemical response tends towards that of a single three-independent-electrons oxidation wave. Modulation of the electrochemical properties of L in the presence of lanthanide ions might be exploited with a view to their electrochemical sensing in organic and aqueous media. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis of 1,3-Bis(acetylacetonyloxy)- and 1,3-Bis(benzoylacetonyloxy)benzene and Their Complexation with Lanthanide Ions.CHEMINFORM, Issue 8 2006S. N. Podyachev Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF. [source] Solid-State and Solution Structure of Lanthanide(III) Complexes with a Flexible Py-N6 Macrocyclic LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2009Cristina Núñez Abstract Lanthanide complexes of a hexaaza macrocyclic ligand containing a pyridine head unit (L) were synthesized (Ln = La,Lu, except Pm). The solid-state structures of the corresponding La, Ce, Pr, Nd, and Lu complexes were determined by single-crystal X-ray crystallography, and they reveal the presence of three different mononuclear complexes with three different conformations of the macrocycle and coordination environments around the metal ions. In all complexes the lanthanide ion is coordinated in an endomacrocyclic manner to the six nitrogen donor atoms of the ligand. In the La, Ce, and Pr complexes the metal ions show a 12-coordinate mononuclear environment in which 3 nitrate anions coordinate in a bidentate fashion. However, in the Nd analogue the metal ion displays a 10-coordinated environment with the coordination of 2 bidentate nitrate groups, whereas Lu shows a 9-coordinate environment interacting with 2 nitrate ligands, one of them acting as bidentate and the second one coordinating in a monodentate fashion. The 1H and 13C NMR spectra of the complexes recorded in CD3CN suggest that the complexes adopt in solution a similar structure to that observed for the Nd complex in the solid state. The [Ln(L)(NO3)3] and [Ln(L)(NO3)2]+ complexes were characterized by density functional theory (DFT) calculations (B3LYP model). The structures obtained from these calculations for La, Ce, Pr, and Nd are in good agreement with the experimental solid-state structures. The relative stabilities of the [Ln(L)(NO3)2]+ complexes with respect to the [Ln(L)(NO3)3] ones (Ln = La, Nd, Gd, Ho, or Lu) were studied both in vacuo and in acetonitrile solution (PCM model) at the same computational level. Our calculations indicate that in solution the [Ln(L)(NO3)2]+ species is the most stable one along the whole lanthanide series, in agreement with the NMR spectroscopic data.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A PCP-Pincer RuII,Terpyridine Building Block as a Potential "Antenna Unit" for Intramolecular SensitizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Marcella Gagliardo Abstract The redox- and photoactive mononuclear complex [Ru(PCP)(tpy,DTTANa4)]Cl {PCP = [C6H3(CH2PPh2)2 -2,6],; tpy,DTTA4, = 4,-(2,2,:6,,2,-terpyridine)-diethylenetriamine- N,N,N,,N, -tetraacetate} possesses an externally directed, vacant N3O4 polyaminocarboxylate-type binding site that coordinates to lanthanide(III) ions to give the neutral heterodinuclear RuII,LnIII complexes [Ru(PCP)(tpy,DTTA)Ln(H2O)2] (Ln = Gd3+, Eu3+). The photophysical properties of solutions of the mononuclear complex [Ru(PCP)(tpy,DTTANa4)]Cl were investigated in MeOH/EtOH (1:4) and compared to those of the solutions of heterodinuclear complexes [Ru(PCP)(tpy,DTTA)Ln(H2O)2] (Ln = Gd3+, Eu3+). Rigid matrix excitation at 77 K of the ,,* level of the ruthenium chromophore in the [Ru(PCP)(tpy,DTTA)Eu(H2O)2] complex results in a weak europium(III) emission pointing to a transfer of energy from Ru,Eu as a result of the metal-to-ligand charge-transfer (MLCT) excited state of the ruthenium component to the luminescent lanthanide ion. The excited state lifetime of the europium complex is 0.2 ms in methanol solution. In deuterated solvents, the lifetime increases to 0.4 ms, which indicates that the process is solvent-dependent as a result of the strongly coordinated molecules of water that are responsible for the quenching in nondeuterated solvents.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Structure Comparison of Early and Late Lanthanide(III) Homodinuclear Macrocyclic Complexes with the Polyamine Polycarboxylic Ligand H8OHECEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2004Ulrike A. Böttger Abstract The solid-state structures of two new homodinuclear chelate complexes with the late lanthanide(III) ions Yb and Lu, [Na2(Yb2OHEC)].14.5H2O (1), and [Na2(Lu2OHEC)].14.5H2O (2) (H8OHEC = 1,4,7,10,14,17,20,23-octaazacyclohexacosane- 1,4,7,10,14,17,20,23-octaacetic acid), have been determined by X-ray crystal structure analysis. Each lanthanide(III) ion is coordinated by eight donor atoms of the ligand and the geometry of the coordination polyhedron approaches a bicapped trigonal prism. These structures are compared with those of the homodinuclear chelate complexes with the same ligand and the mid to early lanthanide(III) ions Gd, Eu, La and also Y. A distinctive structural change occurs across the lanthanide series. The centrosymmetric mid to early lanthanide(III) complexes are all ninefold-coordinated in a capped square antiprismatic arrangement with a water molecule coordinated in a prismatic position. This structure is maintained in aqueous solution, together with an asymmetric minor isomer. The late lanthanide(III) OHEC complexes not only lack the inner-sphere water, but the change of coordination sphere also results in a loss of symmetry of the whole complex molecule. The observed change of coordination mode and number of the lanthanide ion may offer a geometric model for the isomerization process in eight- and ninefold-coordinated complex species that are isomers in a possible coordination equilibrium observed by NMR in aqueous solution. This model may also explain the intramolecular rearrangements necessary during water exchange in the inner coordination sphere of the complex [(Gd2OHEC)(H2O)2]2, through a slow dissociative mechanism. Protonation constants of the H8OHEC ligand and complex formation constants of this ligand with GdIII, CaII, CuII and ZnII have been determined by solution thermodynamic studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Potential MRI Contrast Agents Based on Micellar Incorporation of Amphiphilic Bis(alkylamide) Derivatives of [(Gd,DTPA)(H2O)]2,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Kristof Kimpe Abstract DTPA-bisamide derivatives with alkyl chains containing 14, 16 and 18 carbon atoms were synthesized and complexes of various trivalent lanthanide ions (Ln = Gd, La, Pr, Eu) were formed. Variable temperature proton NMR spectroscopy of paramagnetic praseodymium(III) and europium(III) complexes revealed that long aliphatic substituents considerably increase the energy barrier for the intramolecular rearrangement around the lanthanide ion. The gadolinium(III) complexes were incorporated into mixed micelles, and photon correlation spectroscopy showed that the mean sizes of all the micelles were within the same range. The NMRD curves of all three DTPA-bisamide-gadolinium complexes incorporated in mixed micelles display higher relaxivity values than the commercially available Gd,DTPA contrast agent. The higher relaxivity obtained for the micellar DTPA-bisamide-gadolinium complexes with C14 and C16 chains relative to the micellar DTPA-bisamide-GdIII C18 chain complex could be attributable to the fact that the alkyl chain containing 18 carbon atoms is longer than the alkyl chain of the major component of the micelles, DPPC, in which it is inserted. This would allow increased mobility of the polar head and hence a lower relaxivity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Adducts of Schiff Bases with Tris(,-diketonato)lanthanide(III) Complexes: Structure and Liquid-Crystalline BehaviourEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Koen Binnemans Abstract Adducts of the Schiff base 2-hydroxy- N -octadecyloxy-4-tetradecyloxybenzaldimine with tris(,-dibenzoylmethanato)lanthanide(III) complexes are described. The stoichiometry of the complexes is [Ln(dbm)3Lx], where Ln is a trivalent lanthanide ion (all lanthanides except Ce and Pm), Hdbm is dibenzoylmethane and L is the Schiff base; x = 2 for Ln = La,Er and x = 1 for Ln = Tm,Lu. The Schiff-base ligands are in a zwitterionic form and coordinate through the phenolic oxygen only. The X-ray single-crystal structure of [La(dbm)3L,2] with L, = N -butyl-2-hydroxy-4-methoxybenzaldimine is described. The solution structure of lanthanum(III) complexes has been investigated by 1D and 2D 1H NMR techniques. Although the long-chain Schiff-base ligand and the tris(,-dibenzoylmethanato)lanthanide(III) complexes are non-mesomorphic, some of the adducts exhibit a monotropic smectic A phase. The mesomorphic behaviour depends on the lanthanide ion, in the sense that only a mesophase is observed for the series Ln = La,Eu, not for the heavier lanthanides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] X-ray birefringence and dichroism obtained from magnetic materialsJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2001S. W. Lovesey In the past decade, synchrotron radiation has triggered a surge in studies of the polarization dependence of X-ray beams passing through non-isotropic materials. A vast range of experimental results concerning polarization-dependent absorption (dichroism) and dispersion (birefringence, for example) are available from materials which are either magnetic or exhibit preferred directions due to the local atomic environment. This article aims to bring together the diversity of modern experiments in this field with established methods of optical calculus, in a way that highlights the simplicity of the underlying physics. A useful framework is formed when observable quantities, in the X-ray case, are related to atomic variables of the sample material. Atomic descriptions of absorption spectra with various levels of complexity are considered, and some well documented sum-rules are encountered. The framework is the most general allowed within the electric dipole approximation. By way of illustration, dichroic X-ray absorption by two materials with highly anisotropic properties and magnetic ions with different valence shells are considered; namely, a 3d -transition ion in ferrous niobate, and a lanthanide ion in dysprosium borocarbide. Both materials display interesting magnetic properties that are challenging to interpret at an atomic level of detail, and it is shown how absorption experiments can contribute to resolving some issues. [source] Encapsulating Eu3+ complex doped layers to improve Si-based solar cell efficiencyPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 8 2009Alessia Le Donne Abstract This paper reports the electrical characterization of commercially available crystalline silicon solar cells encapsulated with poly-vinylacetate doped with different Eu3+ organic complexes. The inclusion of these complexes in the encapsulating matrix allows down-shifting of the solar spectrum components below 420,nm toward the maximum quantum efficiency of the solar cells. This effect has been proven under Air Mass 1·5 conditions (simulating terrestrial applications) where an increase of the total power delivered by the encapsulated cells has been observed. Moreover, this enhancement has been obtained using very low percentage by weight of organolanthanide dopants, allowing a reduction in the Watt peak price. At higher concentrations a strong quenching of the energy transfer from the organic antenna to the lanthanide ion has been observed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Hydrogen-bonded three-dimensional network of a lanthanum(III) exocyclic complex with 5,10,15,20-tetra-4-pyridylporphyrinACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Sophia Lipstman In the complex diaquatetranitrato[5-(pyridinium-4-yl)-10,15,20-tri-4-pyridylporphyrin]lanthanum(III) 1,2-dichlorobenzene trisolvate, [La(NO3)4(C40H27N8)(H2O)2]·3C6H4Cl2, the lanthanum ion is coordinated to one of the peripheral pyridyl substituents of the porphyrin entity. Units of the complex are interlinked to one another in three dimensions by a network of O,H...N, O,H...O and N,H...O hydrogen bonds between the water ligands, nitrate ions, and pyridyl and pyridinium groups of adjacent species. This is the first structural report of an exocyclic complex of the tetrapyridylporphyrin ligand with any lanthanide ion and its self-assembly into a three-dimensional architecture sustained by hydrogen bonds. [source] Designing Simple Tridentate Ligands for Highly Luminescent Europium ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 41 2009Abstract A series of tridentate benzimidazole-substituted pyridine-2-carboxylic acids have been prepared with a halogen, methyl or alkoxy group in the 6-position of the benzimidazole ring, which additionally contains a solubilising N -alkyl chain. The ligands form neutral homoleptic nine-coordinate lanthanum, europium and terbium complexes as established from X-ray crystallographic analysis of eight structures. The coordination polyhedron around the lanthanide ion is close to a tricapped trigonal prism with ligands arranged in an up,up,down fashion. The coordinated ligands serve as light-harvesting chromophores in the complexes with absorption maxima in the range 321,341,nm (,=(4.9,6.0)×104,M,1,cm,1) and triplet-state energies between 21,300 and 18,800,cm,1; the largest redshifts occur for bromine and electron-donor alkoxy substituents. The ligands efficiently sensitise europium luminescence with overall quantum yields () and observed lifetimes (,obs) reaching 71,% and 3.00,ms, respectively, in the solid state and 52,% and 2.81,ms, respectively, in CH2Cl2 at room temperature. The radiative lifetimes of the Eu(5D0) level amount to ,rad=3.6,4.6,ms and the sensitisation efficiency ,sens=(,rad/,obs) is close to unity for most of the complexes in the solid state and equal to approximately 80,% in solution. The photophysical parameters of the complexes correlate with the triplet energy of the ligands, which in turn is determined by the nature of the benzimidazole substituent. Facile modification of the ligands makes them promising for the development of brightly emissive europium-containing materials. [source] Backbone-Only Protein Solution Structures with a Combination of Classical and Paramagnetism-Based Constraints: A Method that Can Be Scaled to Large MoleculesCHEMPHYSCHEM, Issue 6 2004Renato Barbieri Dr. Abstract Herein, it is shown that a medium-resolution solution structure of a protein can be obtained with the sole assignment of the protein backbone and backbone-related constraints if a derivative with a firmly bound paramagnetic metal is available. The proof-of-concept is provided on calbindin D9k, a calcium binding protein in which one of the two calcium ions can be selectively substituted by a paramagnetic lanthanide ion. The constraints used are HN (and H,) nuclear Overhauser effects (NOEs), hydrogen bonds, dihedral angle constraints from chemical shifts, and the following paramagnetism-based constraints: 1) pseudocontact shifts, acquired by substituting one (or more) lanthanide(s) in the C-terminal calcium binding site; 2) NHN residual dipolar couplings due to self-orientation induced by the paramagnetic lanthanide(s); 3) cross-correlations between the Curie and internuclear dipole,dipole interactions; and 4) paramagnetism-induced relaxation rate enhancements. An upper distance limit for internuclear distances between any two backbone atoms was also given according to the molecular weight of the protein. For this purpose, the paramagnetism-based constraints were collectively implemented in the program CYANA for solution structure determinations, similarly to what was previously done for the program DYANA. The method is intrinsically suitable for large molecular weight proteins. [source] Spectroscopy of High-Energy States of Lanthanide IonsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Michael F. Reid Abstract We discuss recent progress and future prospects for the analysis of the 4fN,15d excited states of lanthanide ions in host materials. We demonstrate how ab initio calculations for Ce3+ in LiYF4 may be used to estimate crystal-field and spin-orbit parameters for the 4f1 and 5d1 configurations. We show how excited-state absorption may be used to probe the electronic and geometric structure of the 4fN,15d excited states in more detail and we illustrate the possibilities with calculations for Yb2+ ions in SrCl2. [source] Heterometallic CoIII,LnIII (Ln = Gd, Tb, Dy) Complexes on a p -Sulfonatothiacalix[4]arene Platform Exhibiting Redox-Switchable Metal-to-Metal Energy TransferEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2008Viktoriya Skripacheva Abstract Nuclear magnetic relaxation along with pH metric data have been used to reveal pH-dependent heterometallic CoIII,LnIII (Ln = Gd, Tb, and Dy) complex formation on a p -sulfonatothiacalix[4]arene (TCAS) platform in aqueous solution. The previously obtained 1D and 2D 1H NMR spectroscopic and X-ray data prove the outer sphere binding of the CoIII block with the upper rim of TCAS, whereas the LnIII ion is coordinated with the phenolate groups of the lower rim of TCAS. The inclusive outer-sphere binding of CoIII tris(dipyridyl) and tris(ethylendiaminate) complexes with the upper rim of TCAS favors binding of the inner-sphere lanthanide ions through the lower rim of TCAS, whereas noninclusive binding of CoIII bis(histidinate) provides no effect on the binding of lanthanide ions. The emission properties of [Co(dipy)3]3+,LnIII (Ln = Gd, Tb, Dy) complexes indicate the quenching of 4f luminescence by the 3d block. This quenching can be switched off by electrochemical CoIII/CoII reduction with further switching on by reoxidation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Rare Earth Benzotriazolates: Coordination Polymers Incorporating Decomposition Products from Ammonia to 1,2-Diaminobenzene in,1[Ln(Btz)3(BtzH)] (Ln = Ce, Pr), ,1[Ln(Btz)3{Ph(NH2)2}] (Ln = Nd, Tb, Yb), and ,1[Ho2(Btz)6(BtzH)(NH3)],EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2006Klaus Müller-Buschbaum Abstract The solvent-free melt reactions of benzotriazole (BtzH, C6H4N2NH) with rare earth metals result in three different types of benzotriazolate coordination polymers. Early 4f metals yield ,1[Ln(Btz)3(BtzH)] [Ln = Ce (1), Pr (2)], from neodymium to ytterbium the type ,1[Ln(Btz)3{Ph(NH2)2}] is observed [Ln = Nd (3), Tb (4), Yb (5)], whereas the late 4f metal Ho gives ,1[Ho2(Btz)6(BtzH)(NH3)] (6). Depending on the reaction conditions and the respective rare earth element, ligand fragments originating from decomposition products are incorporated in the coordination polymers. Compounds 1,3 and 6 were obtained as single crystals and their crystal structures determined by single-crystal X-ray analysis, whilst 4 and 5 were obtained as powders. X-ray powder diffraction shows the isotypic character of polymers 3, 4, and 5. The benzotriazolates contain trivalent lanthanide ions with complete nitrogen coordination. Decomposition of the ligand accompanies the formation of the coordination polymers. X-ray analysis was combined with thermal analysis and mass spectrometry to investigate the influence of reaction temperatures on ligand decomposition. Ln-benzotriazolates exhibit aspects of materials science such as luminescence {5D4,7FJ, J = 4,6 for ,1[Tb(Btz)3{Ph(NH2)2}] (4)} without quenching by concentration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Modulation of the Communication between Redox Centers in a Tris(ferrocene)-tren Ligand by Complexation of Lanthanide IonsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2003Marie Heitzmann The tripodal ligand L built on the tren platform and bearing three chemically equivalent ferrocene units was prepared and characterized. Electrochemical investigations indicate that electrostatic communication occurs between the three ferrocene groups in L, which leads to the observation of two distinct voltammetric waves. The electrochemical communication between the three ferrocene moieties is disrupted in 1:1 (L:M3+) type complexes formed between L and Y3+ or Eu3+ metal cations and their electrochemical response tends towards that of a single three-independent-electrons oxidation wave. Modulation of the electrochemical properties of L in the presence of lanthanide ions might be exploited with a view to their electrochemical sensing in organic and aqueous media. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Potential MRI Contrast Agents Based on Micellar Incorporation of Amphiphilic Bis(alkylamide) Derivatives of [(Gd,DTPA)(H2O)]2,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Kristof Kimpe Abstract DTPA-bisamide derivatives with alkyl chains containing 14, 16 and 18 carbon atoms were synthesized and complexes of various trivalent lanthanide ions (Ln = Gd, La, Pr, Eu) were formed. Variable temperature proton NMR spectroscopy of paramagnetic praseodymium(III) and europium(III) complexes revealed that long aliphatic substituents considerably increase the energy barrier for the intramolecular rearrangement around the lanthanide ion. The gadolinium(III) complexes were incorporated into mixed micelles, and photon correlation spectroscopy showed that the mean sizes of all the micelles were within the same range. The NMRD curves of all three DTPA-bisamide-gadolinium complexes incorporated in mixed micelles display higher relaxivity values than the commercially available Gd,DTPA contrast agent. The higher relaxivity obtained for the micellar DTPA-bisamide-gadolinium complexes with C14 and C16 chains relative to the micellar DTPA-bisamide-GdIII C18 chain complex could be attributable to the fact that the alkyl chain containing 18 carbon atoms is longer than the alkyl chain of the major component of the micelles, DPPC, in which it is inserted. This would allow increased mobility of the polar head and hence a lower relaxivity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Plasmonic Enhancement or Energy Transfer?ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Its Potential for Light-Emitting Devices, Lanthanide-Doped Silicate Glasses, On the Luminescence of Gold-, Silver- Abstract With the technique of synchrotron X-ray activation, molecule-like, non-plasmonic gold and silver particles in soda-lime silicate glasses can be generated. The luminescence energy transfer between these species and lanthanide(III) ions is studied. As a result, a significant lanthanide luminescence enhancement by a factor of up to 250 under non-resonant UV excitation is observed. The absence of a distinct gold and silver plasmon resonance absorption, respectively, the missing nanoparticle signals in previous SAXS and TEM experiments, the unaltered luminescence lifetime of the lanthanide ions compared to the non-enhanced case, and an excitation maximum at 300,350,nm (equivalent to the absorption range of small noble metal particles) indicate unambiguously that the observed enhancement is due to a classical energy transfer between small noble metal particles and lanthanide ions, and not to a plasmonic field enhancement effect. It is proposed that very small, molecule-like noble metal particles (such as dimers, trimers, and tetramers) first absorb the excitation light, undergo a singlet-triplet intersystem crossing, and finally transfer the energy to an excited multiplet state of adjacent lanthanide(III) ions. X-ray lithographic microstructuring and excitation with a commercial UV LED show the potential of the activated glass samples as bright light-emitting devices with tunable emission colors. [source] Lanthanide-Containing Light-Emitting Organic,Inorganic Hybrids: A Bet on the FutureADVANCED MATERIALS, Issue 5 2009Luís D. Carlos Abstract Interest in lanthanide-containing organic,inorganic hybrids has grown considerably during the last decade, with the concomitant fabrication of materials with tunable attributes offering modulated properties. The potential of these materials relies on exploiting the synergy between the intrinsic characteristics of sol,gel derived hosts (highly controlled purity, versatile shaping and patterning, excellent optical quality, easy control of the refractive index, photosensitivity, encapsulation of large amounts of isolated emitting centers protected by the host) and the luminescence features of trivalent lanthanide ions (high luminescence quantum yield, narrow bandwidth, long-lived emission, large Stokes shifts, ligand-dependent luminescence sensitization). Promising applications may be envisaged, such as light-emitting devices, active waveguides in the visible and near-IR spectral regions, active coatings, and bio-medical actuators and sensors, opening up exciting directions in materials science and related technologies with significant implications in the integration, miniaturization, and multifunctionalization of devices. This review provides an overview of the latest advances in Ln3+ -containing siloxane-based hybrids, with emphasis on the different possible synthetic strategies, photoluminescence features, empirical determination [source] Study on macromolecular lanthanide complexes (V): Synthesis, characterization, and fluorescence properties of lanthanide complexes with the copolymers of styrene and acrylic acidJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009Xing Liang Abstract In this study, the luminescent macromolecular lanthanide complexes Ln-PSt/AA (Ln = Eu and Tb; St = styrene; AA = acrylic acid) have been synthesized, and an extensive characterization has been carried out by means of elemental analysis, FTIR, thermal analysis, and fluorescence determination. The results showed that the carboxylic groups on the chain of the polymers acted as bidentate ligands coordinated to lanthanide ions; and the coordination degree of COO,/Ln3+ in the macromolecular complexes was closely dependent on both the pH value of the solution and the molar ratio of St to AA in the polymeric ligands. Thermal analysis manifested that these Ln-PSt/AA (Ln = Eu and Tb) complexes had high thermal stability and solvent resistance, and these macromolecular complexes were highly crosslinked. The fluorescence determination indicated that Ln-PSt/AA complexes could emit characteristic fluorescence with comparatively high brightness and good monochromaticity, and the fluorescence intensity changed with increasing lanthanide ions content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Effects of M3+ Ions on the Conductivity of Glasses and Glass-Ceramics in the System Li2O,M2O3,GeO2,P2O5 (M = Al, Ga, Y, Dy, Gd, and La)JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2000Jie Fu Glasses with compositions Li1.2M0.2Ge1.8(PO4)3 (M = Al, Ga, Y, Gd, Dy, and La) were prepared and converted to glass-ceramics by heat treatment. The effects of the M3+ ions on the conductivity of the glasses and glass-ceramics were studied. The main phase present in the glass-ceramics was the conductive phase LiGe2(PO4)3. Al3+ and Ga3+ ions entered the LiGe2(PO4)3 structure by replacing Ge4+ ions, but lanthanide ions did not. The glass-ceramics exhibited much higher conductivity than the glasses. With increased ionic radius of the M3+ ions, the conductivity remained almost unchanged at ,3 × 10,12 S/cm for the glasses, but it decreased from 1.5 × 10,5 to 8 × 10,9 S/cm for the glass-ceramics at room temperature. The higher conductivity for Al3+ - and Ga3+ -containing glass-ceramics was suggested to result from the substitutions of Al3+ and Ga3+ ions for Ge4+ ions in the LiGe2(PO4)3 structure. [source] NMR-based analysis of structure of heteroleptic triple-decker (phthalocyaninato) (porphyrinato) lanthanides in solutionsMAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2010Kirill P. Birin Abstract A novel approach for the structural analysis of heteroleptic triple-decker (porphyrinato)(phthalocyaninato) lanthanides(III) in solutions is developed. The developed approach consists in molecular mechanics (MM+) optimization of the geometry of the complex taking into account the lanthanide-induced shift (LIS) datasets. LISs of the resonance peaks in 1H NMR spectra of a series of symmetric complexes [An4P]Ln[(15C5)4Pc]Ln[An4P], where An4P2, is 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinato-dianion, [(15C5)4Pc]2, is 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninato-dianion and Ln = La, Ce, Pr, Nd, Sm, Eu, are analyzed. Analysis of LISs showed two sets of protons in the molecule with opposite signs of shift. Two-nuclei analysis of LISs testifies isostructurality of the whole series of investigated complexes in solution despite contraction of the lanthanide ions. Model-free separation of contact and dipolar contributions of LISs was performed with one-nucleus technique and did not show changes in contact and dipolar terms within the investigated series. MM+ optimization of the molecular structure allowed the interpretation of features of LIS for each particular group of protons. Parameterization of MM + -optimized model of molecule with values of structure-dependent dipolar contributions of LIS allows the development of the precise structural model of the triple-decker complex in solution. This approach allows the determination of the geometry and structure of the sandwich macrocyclic tetrapyrrolic complexes together with conformational analysis of flexible peripheral substituents in solutions. The developed method can be applied with minor modifications for the determination of structural parameters of other types of lanthanides(III) complexes with tetrapyrrolic ligands and also supramolecular systems based on them. Copyright © 2010 John Wiley & Sons, Ltd. [source] Luminescent organo-polysiloxanes containing complexed lanthanide ionsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2009Lei Liu Abstract In this study, a type of polysiloxane with the ester as the functional side group was prepared via a hydrosilylation reaction. The functionalized polysiloxane was then allowed to complex with Tb3+ and Eu3+ ions. Fourier transform infrared, ultraviolet absorption spectra and 1H-NMR, 13C-NMR and 29Si-NMR spectra were used to confirm the modification. Differential scanning calorimetry and thermal gravity analysis were used to study the polysiloxane's thermal properties. The complexes' luminescence spectra were recorded, and narrow-width green and red emissions were achieved. Copyright © 2009 John Wiley & Sons, Ltd. [source] 3-Mercapto-2,6-Pyridinedicarboxylic Acid: A Small Lanthanide-Binding Tag for Protein Studies by NMR SpectroscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2010Bradley Man Abstract Paramagnetic effects from lanthanide ions present powerful tools for protein studies by nuclear magnetic resonance (NMR) spectroscopy provided that the lanthanide can be site-specifically and rigidly attached to the protein. A new, particularly small and rigid lanthanide-binding tag, 3-mercapto-2,6-pyridinedicarboxylic acid (3MDPA), was synthesized and attached to two different proteins via a disulfide bond. The complexes of the N-terminal domain of the E.,coli arginine repressor (ArgN) with seven different paramagnetic lanthanide ions and Co2+ were analyzed in detail by NMR spectroscopy. The magnetic susceptibility anisotropy (,,) tensors and metal position were determined from pseudocontact shifts. The 3MDPA tag generated very different ,, tensor orientations compared to the previously studied 4-mercaptomethyl-DPA tag, making it a highly complementary and useful tool for protein NMR studies. [source] Synthesis, Crystal Structures, and Properties of Oxovanadium(IV),Lanthanide(III) Heteronuclear ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2005Wei Shi Abstract A new series of oxovanadium(IV),lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)]3,21,H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5}, 8.5,H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5},8.5,H2O (3), {[Eu(H2O)7][(VO)2(TTHA)]1.5}, 10.5,H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H6TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2, unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2, ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2, ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2, ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV),lanthanide(III) coordination polymers and thus enlarge the realm of 3d,4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions. [source] Convenient Synthesis of Multifunctional EDTA-Based Chiral Metal Chelates Substituted with an S -MesylcysteineCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2005Andrei Leonov Dr. Abstract We describe the synthetic route to ethylenediaminetetraacetic acid (EDTA) derivatives that can be attached to surface-exposed thiol functional groups of cysteine residues in proteins, via a methylthiosulfonate moiety that is connected in a stereochemically unique way to the C-1 carbon atom of EDTA. Such compounds can be used to align proteins in solution without the need to add liquid crystalline media, and are, therefore, of great interest for the NMR spectroscopic analysis of biomolecules. The binding constant for the paramagnetic tag to lanthanide ions was determined by measuring luminescence. For the Tb+3,ligand complex, a Kb value of 6.5×1017,M,1 was obtained. This value is in excellent agreement with literature values for the related EDTA compound. In addition, it could be shown that there is no significant reduction in the luminescence intensity upon addition of a 104 excess of Ca2+ ions, indicating that this paramagnetic tag is compatible with buffers containing high concentrations of divalent alkaline earth ions. [source] Lanthanide (Eu3+, Tb3+) Centered Mesoporous Hybrids with 1,3-Diphenyl-1,3-Propanepione Covalently Linking SBA-15 (SBA-16) and Poly(methylacrylic acid)CHEMISTRY - AN ASIAN JOURNAL, Issue 7 2010Ya-Juan Li Dr. Abstract 1,3-Diphenyl-1,3-propanepione (DBM)-functionalized SBA-15 and SBA-16 mesoporous hybrid materials (DBM-SBA-15 and DBM-SBA-16) are synthesized by co-condensation of modified 1,3-diphenyl-1,3-propanepione (DBM-Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as-synthesized mesoporous hybrid material DBM-SBA-15 and DBM-SBA-16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM-SBA-15)3PMAA and Ln(DBM-SBA-16)3PMAA (Ln=Eu, Tb) are obtained by a sol-gel process. For comparison, binary lanthanide SBA-15 and SBA-16 mesoporous hybrid materials (denoted as Ln(DBM-SBA-15)3 and Ln(DBM-SBA-16)3) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA-15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA-16 mesoporous hybrids, indicating that SBA-15 is a better host material for the lanthanide complex than mesoporous silica SBA-16. [source] Sensitized Emission from Lanthanide-Doped Nanoparticles Embedded in a Semiconductor Sol,Gel Thin Film,CHEMPHYSCHEM, Issue 11 2007Sri Sivakumar Dr. Abstract In2O3 sol,gel thin films made with LaF3:Ln3+ (Ln=Er, Nd, and Eu) nanoparticles were prepared and showed sensitized emission of the lanthanide ions after In2O3 matrix excitation. The excitation spectra showed an In2O3 absorption band in addition to the excitation peaks of the lanthanide ions, clearly demonstrating that there is energy transfer from the In2O3 matrix to Ln3+ (Er3+, Nd3+, and Eu3+). Similarly, HfO2 and ZrO2 sol,gel thin films made with LaF3:Ln3+ nanoparticles also showed energy transfer from the semiconductor matrix to the lanthanide ions. [source] | |||||||||||||||||||||||||