Dissertations / Theses on the topic 'Lanthanide'
To see the other types of publications on this topic, follow the link: Lanthanide.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Lanthanide.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Dickins, Rachel Sarah. "Chiral lanthanide complexes." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4706/.
Full textAbstract:
The use of chiral lanthanide complexes as probes to investigate interactions with other chiral molecules and macromolecules is of particular interest. A key step in the development of such systems is the preparation of a single, rigid enantiomer of the complex which is conformationally rigid on the NMR timescale or the lifetime of the metal-based emission. Chiral europium and terbium complexes are of particular concern as they may function as emissive probes and are amenable to analysis by circular dichroism and circularly polarised lummescence. Charge neutral and cationic complexes of N-substituted 1,4,7,10- tetraazacyclododecane, functionahsed with three phosphmate and one amide pendent arms, or two, three and four pendent amide arms containing a remote chiral centre, have been prepared. The chirality of the remote stereocentre determmes the helicity of the arrangement of the pendent arms and the conformation of the 12-membered macrocycle.The chiral europium and terbium complexes of the tetraamide complexes exist as single, rigid enantiomers, exhibiting a well-defined metal-based circularly polarised emission. Circular dichroism studies reveal that exciton coupling occurs between adjacent pairs of 1-naphthyl chromophores of tetraamides, whereas the constitutional 2- naphthyl isomers exhibit excimer formation. The behaviour of the di-, tri-, and tetraamide complexes in the presence of added anions has been investigated. The measurement of the luminescent lifetime of the excited state and the circularly polarised emission exhibited by the enantiopure complexes in aqueous solution affords a novel way of signalling the presence of selected oxy-anions.
2
Smith, David Geoffrey. "Intracellular responsive lanthanide probes." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/3591/.
Full textAbstract:
The use of lanthanide complexes for the detection of biologically relevant species such as anions, pH and metal ions has grown significantly over the past decade. Such probes offer significant advantages over conventional probes; sharp narrow emission lines encode detailed spectral information and allow ratiometric analysis, and their luminescence is long-lived allowing selective spectral acquisition. Many lanthanide-based probes operate in aqueous media, but few have been applied to intracellular measurements. The introductory chapter considers the design of lanthanide based probes for cellular applications. The fundamentals of lanthanide emission are discussed, and how the ligand structure needs to be carefully constructed to maximise emission efficiency. Reported bicarbonate- and pH-responsive probes, both lanthanide based and non-lanthanide based, are reviewed, leading to a set of proposed novel probe structures. The synthesis of these probes with further reasoning behind their design is described in chapter two. The chapter concludes with an overview of the complexes in terms of their emission spectral form, hydration number, HPLC and mass spectrometry properties. Chapter three presents work on bicarbonate-responsive probes. Through a series of spectral titrations, affinity constants for a range of anions were assessed. A high selectivity for bicarbonate was observed over other oxy-anions, and in the presence of protein. The complexes exhibited a mitochondrial localisation profile, and the europium luminescence intensity was modulated reversibly in response to pCO2. The terbium analogues showed negligible change under such conditions, and thus a europium to terbium emission intensity ratio could be used to calibrate pCO2. This principle was also applied to the analysis of bicarbonate levels in simulated biological fluid, and in a serum sample. Several pH-responsive complexes are described in chapter four. Key aspects of pH-probe design were highlighted in early examples, leading to the final set of probes based on reversible sulphonamide ligation. Spectral titrations were performed to assess pKa values, and the use of europium to terbium emission intensity ratios was again found to offer a convenient method for assessing pH. Unprecedented changes in CPL were found in response to pH in these systems, and gem values could be used to report upon pH. The complexes were observed to exhibit a lysosomal distribution. Finally, chapter five contains experimental procedures for each compound synthesised, as well as general experimental procedures. Both sets of complexes described in this thesis show great promise for use as well-defined intracellular probes of bicarbonate or pH.
3
Cunningham, Sharron Anne. "Soluble lanthanide thiolate complexes." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367207.
Full text
4
Timmins, Phillipa L. "Dinuclear luminescent lanthanide complexes." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274520.
Full text
5
Lilley, Johnathon Robert. "Lanthanide nanoparticles in immunodiagnostics." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8157/.
Full textAbstract:
This thesis shows the surface functionalisation of gold nanoparticles with surface active, luminescent Eu complexes and free light chain antibodies, to produce free light chain antibody functionalised gold nanoparticles which show characteristic, Eu luminescence. We show how these particles can be used in the development of a novel FRET based assay whereby the Eu luminescence is quenched on addition of free light chain specific antibody, labelled with a suitable organic FRET acceptor for Eu luminescence as measured by lifetime measurements. We show how these particles can be used to develop a competitive immunoassay to measure the concentration of free light chain antibodies. We also report the preparation of a novel functionalised dibenzoylmethane molecule with a thiol surface active group as to functionalise gold nanoparticles which can bind and sensitize Eu ions.
6
Xu, Xiaohan. "Acidity of Lanthanide Clusters." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619532111562154.
Full text
7
Smith, Steven P. "Lanthanide-containing Nanostructured Materials." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145459.
Full textAbstract:
The research described in this Dissertation is concerned generally with the exploration of the potential use of lanthanide elements in nanostructured materials for the purpose of modification of the magnetic and optical properties. This is explored through a focus on the development of lanthanide-containing iron oxide nanosystems. Our objectives of producing lanthanide containing nanostructured materials with potentially useful optical and magnetic applications has been achieved through the development of lanthanide-doped Fe3O4 and -Fe2O3 nanoparticles, as well as a unique core-shell magnetic-upconverting nanoparticle system.Necessary background information on nanomaterials, rationale for the study of lanthanide-containing iron oxide nanosystems and context for discussion of the results obtained in each project is provided in the Introduction Chapter. The syntheses of Fe3O4 nanoparticles doped with Eu(III) and Sm(III) are discussed, along with structural characterization and magnetic property investigation of products In Chapter 2. The following Chapter expands the study of lanthanide doping to -Fe2O3, a closely related yet distinct magnetic nanoparticle system. A completely different synthesis is attempted, and comparisons between the two systems are made.The development of novel synthetic methodologies used to create such products has yielded high-quality lanthanide-containing materials and are evidenced by TEM images displaying nearly monodisperse particles in each of our efforts. The modifications to the magnetic properties resulting from lanthanide doping include theobservation of ferromagnetism in the Fe3O4 system and increased magnetic saturation of -Fe2O3 nanoparticles, and are characterized by VSM and the visual observation of magnetic alignment of products. Our efforts towards developing a novel methodology capable of producing high quality Fe3O4 nanoparticles, and subsequent characterization of products, were published in the Journal of the American Chemical Society.Optically active, magnetic, core-shell nanoparticles are investigated in Chapter 4 for the potential uses in diagnosis and treatment of cancer. This multifunctional system uses Fe3O4 as a magnetic core, shelled by upconverting lanthanide-containing nanomaterials, and is rendered biocompatible through encapsulation of the core-shell structure by a silica shell. Added functionality is achieved through amine functionalization of the silica surface, with the goal of coupling the inorganic nanoparticle with drug targeting groups. TEM results indicate successful formation of the core-shell nanoparticles, and expected magnetic and optical properties are shown by visual observation and luminescence spectroscopy, respectively.
8
Bruce, James I. "Supramolecular photochemistry of lanthanide complexes." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308689.
Full text
9
Clarkson, Ian Michael. "Energy transfer in lanthanide complexes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4498/.
Full textAbstract:
This thesis details investigations into the photophysical properties of lanthanide ions in a number of different systems. The preparation and characterisation of lanthanide containing surfactant salts of the type Ln(A0T)(_3) (Ln = Tb, Nd, Eu, AOT = bis-(2-ethylhexyl) sulfosuccinate) is described. Small angle neutron scattering experiments have been used to determine the size and shape of reverse micelles formed by these surfactants in water/cyclohexane microemulsions. The luminescence lifetimes of the lanthanide ions have been used to investigate the solvation environment within reverse micelle systems as a function of water content. The use of lanthanide complexes based on 1,4,7,10-tetraazacyclododecane bearing phenanthridine antenna in luminescence microscopy has been explored. Samples such as silica particles, onion skin cells and guinea pig heart cells have been imaged. Time- resolved measurements have allowed time gating of the sample from a fluorescent background and lifetime maps of the images have been obtained. The preparation and characterisation of deuteriated complexes of dota (1,4,7,10- tetraazacyclododecane-1,4,7,10-tetraacetic acid) with lanthanide ions is described. Selective deuteriation of both the ring and arm sites allow the relative quenching effects of C-H/D oscillators to be determined for various lanthanides in a series of structurally well defined complexes. Finally, investigations into the distance dependence of the energy transfer between aromatic chromophores and lanthanide ions have been undertaken. The synthesis of a model system linking a phenanthridine donor to a europium complex by poly(valine) spacer units is described. Preliminary photophysical results show that the quantum yield of emission by europium decreases as the distance between the donor acceptor pair is increased.
10
Song, Se Ahn. "Electron microscopy of lanthanide diphthalocyanines." Thesis, University of Essex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328597.
Full text
11
Neil, Emily Rose. "Highly luminescent lanthanide chirality probes." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11390/.
Full textAbstract:
The chirality of biological systems can be probed using highly emissive lanthanide complexes with the aid of circularly polarised luminescence and emission spectroscopy. Such chirality probes can be synthesised through the incorporation of a remote chiral centre within the ligand framework, which can preferentially stabilise a particular stereoisomer giving an enantiopure complex of well-defined helicity. Alternatively, lanthanide chirality probes can be derived from achiral or dynamically racemic ligands, where the selective induction of a CPL signal can be monitored as a function of the nature and concentration of a selected chiral analyte. A series of chiral lanthanide complexes has been synthesised. Each complex is based on an amide substituted 1,4,7-triazacyclononane system derived from either R-(+) or S-(-)-α-methylbenzyl amine. The stereochemistry of the amide moiety controls the helicity of the complex, and one major diastereoisomer is formed for each lanthanide metal. The absolute stereochemistry of the major diastereoisomer was determined by X-ray crystallography (S-Δ-λλλ and R-Λ-δδδ). Inclusion of an aryl-alkynyl chromophore generated complexes that exhibited large extinction coefficients (up to 55,000 M-1 cm-1) and high quantum yields (up to 37%) in water. A second set of bright Eu (III) complexes has been prepared based on an achiral heptadentate ligand system, which vary in the nature of the pyridyl donor (phosphinate, carboxylate and amide). The binding of a number of chiral acids including lactate, mandelate and cyclohexylhydroxyacetate was monitored by a change in the emission spectrum and the induction of strong CPL. Empirical analysis of the ΔJ = 4 region of each of the Eu (III) complexes allows an assignment of the complex-anion adducts as R-Δ and S-Λ. Furthermore, variations in the sign and magnitude of CPL allow the enantiomeric purity of samples with unknown enantiomeric composition to be assessed. Finally, several dynamically racemic lanthanide chirality probes have been synthesised and characterised. Induced CPL has been assessed, which arises as a result of the change in complex constitution upon binding to important chiral biomolecules such as, sialic acid, O-phosphono-amino acids and peptides and oleoyl-L-lysophosphatidic acid (LPA). This work presents the first example of induced CPL in the detection of cancer biomarkers, sialic acid and LPA, and demonstrates the utility of this class of dynamically racemic Eu (III) complexes as chirality probes.
12
Iwu, Kingsley Odinaka. "Nanoencapsulation of luminescent lanthanide complexes." Master's thesis, Universidade de Aveiro, 2006. http://hdl.handle.net/10773/2260.
Full textAbstract:
Mestrado em Ciência dos MateriaisNanopartículas de sílica e titânia foram usadas para encapsulamento de complexos lantanídeos (Ln) de 3-hidroxipicolinato e picolinato, sintetizados por hidrólise de alcóxidos por meio de micelas invertidas – microemulsão de óleo em água, estabilizada com um agente surfactante, em que a fase aquosa existe na forma de domínios nanométricos. A alteração da dimensão destes domínios aquosos ou nano-reactores, conseguida variando a quantidade de água e mantendo constante a concentração de surfactante, determina aproximadamente o tamanho das partículas formadas no seu interior. As características ópticas dos nano-compósitos tal como preparados, foi investigada e comparada com as de complexos lantanídeos puros, tendo em vista o seu potencial e futura aplicação como bio-marcadores. A microscopia electrónica de transmissão foi extensamente usada no estudo da morfologia dos nano-compósitos. Os resultados mostram que as propriedades luminescentes dos complexos de picolinato nos nano-compósitos foram severamente afectados pelo processo sintético, enquanto que os de complexos de 3-hidroxipicolinato nas matrizes, foram substancialmente distintos das suas propriedades originais. Estas propriedades ópticas foram correlacionadas com a estratégia sintética empregada e foram discutidas as suas implicações nas bio-aplicações em vista. ABSTRACT: Silica and titania nanoparticles encapsulating lanthanide (Ln) complexes of 3- hydroxypicolinate and picolinate were synthesized by the hydrolysis of alkoxides in a reverse micelle medium-water in oil microemulsion stabilized by a surface active agent (surfactant) in which the water phase exists as nanosized domains. The size of the water droplets or nano-reactors, which was varied by using distinct amount of water while maintaining constant the surfactant concentration, approximately determined the size of the nanoparticles formed therein. The optical features of the as prepared nanocomposites were investigated and compared to those of the pure Ln complexes, having in mind their potential and future application as bio-labels. Transmission electron microscopy was chiefly employed to study the morphology of the nanocomposites. The results showed that the luminescence properties of the picolinate complexes in the nanocomposites were severely affected by the synthetic process while those of the 3-hydroxypicolinate complexes in the matrixes were markedly different from their original features. These optical properties were correlated to the synthetic strategy employed and the implication for the envisaged bioapplications discussed.
13
Isler, Jeremy Payton. "Interactions of Lanthanides and Liquid Alkali Metals for "Liquid-Like" Lanthanide Transport in U-Zr Fuel." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492607350430645.
Full text
14
Dai, Lixiong. "Structural modifications to optimise lanthanide luminescence." HKBU Institutional Repository, 2017. http://repository.hkbu.edu.hk/etd_oa/403.
Full textAbstract:
Luminescent lanthanide coordination complexes have attracted significant attention due to their unique optical properties. The poor absorption of a lanthanide ion can be resolved by so-called antenna effect and improve the intensity of its luminescence. Three bidentate chromophores: phosphate-pyridine chromophore, 1,2-Hydroxy pyridone (1,2-HOPO) and 2-thenoyltrifluoroacetone (TTA), functioned as both chelator and sensitizer, their energy levels are well matched with the excited state energy levels of the Eu(III) and Sm(III).. To get highly luminescent and stable lanthanide complex, we designed and synthesized various Eu(III) complexes with different backbones to compare different parameters that will affect the sensitizing efficiency of the chromophores, such as rigidity, geometry and coordination saturation.. In chapter two we combined the phosphate-pyridine chromophore with the well-studied cyclen-based chelator to fulfil the requirement of high stability and brightness. We designed a nine-coordinate europium(III) complex as platform, through coupling reactions to realise fast screen of the chromophores energy transfer efficiency.. Chapter three focuses on the structure modifications based on the chromophore of 1,2-HOPO, different chelators and backbones were compared, a europium complex EuL4 with the highest quantum yield with this chromophore was obtained and it could goes into cells and localized on lysosome very fast. Two-phonon in vitro imaging was done which showed its high potential bioapplications.. Chapter four focuses on the structure modification based on the chromophore of TTA. Different backbone directly determined the europium complexes saturation number and sensitization efficiency, therefore, their quantum yields.
15
Sudhakaran, Pillai S. "Luminescent materials based on Lanthanide ions." Thesis, Kingston University, 2010. http://eprints.kingston.ac.uk/20413/.
Full textAbstract:
The inclusion of lanthanide (III) (Ln[sup]3+) ions into polymers by “covalent” bonding has applications. Heteroleptic hydrotris(pyrazolyl)borate crotonate and cinnamate complexes were synthesised for reasons that, firstly, knowledge of the polymerisable double bond was helpful in establishing the conditions of any copolymerisation reaction; secondly, the chosen ligands are very good at receiving energy in the UV region; and thirdly, lanthanide complexes might undergo changes in properties, on moving between adjacent lanthanide ions, allowing potentially convenient isolations of pure materials at the monomer production stage, or even at the polymerisation stage. For both complexes, two classes of target complex were identified: the mononuclear (Er-Lu) and dinuclear (La-Ho). Mononuclear forms were identified by MS, [sup]1H NMR and elemental analysis and dinuclear forms were characterised by X-ray crystallography. For heteroleptic hydrotris(pyrazolyl)borate crotonate and cinnamate complexes, the ligands act as antennae for receiving and then transferring energy to metal ions and these complexes were studied in several homogeneous and heterogeneous copolymers as well as in rigid PMMA or polystyrene matrices. Luminescence decay of these complexes depends on the distance between the metal and C-H oscillators so the cinnamate complexes showed better luminescence life-times compared to crotonate complexes. The copolymer system helped to reduce the concentration quenching compared to corresponding metal complex / polymer blend systems. The thermal stabilities of the complex monomers were increased by incorporating them into polymer chains. Europium crotonate and cinnamate complexes in the poly(p-phenylenevinylene) (PPV) precursor blends showed the characteristic emission of europium, and the emission from PPV was quenched by increasing the europium content in the PPV precursor blends.
16
Liu, Sung Ying. "Steric effects in Lanthanide pyrazolylborate chemistry." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.561271.
Full text
17
Dent, Phillip Damian. "Asymmetric ligands for lanthanide(II) reagents." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4583/.
Full textAbstract:
Although the use of Ln(^2+) species as one electron reducing agents has recently become popular, relatively few processes have focused on the control of stereochemistry by the incorporation of chiral auxiliaries at the metal centre. This thesis discusses work aimed at the synthesis of chiral bis(pentaalkylcyclopentadienyl) and polyaza/oxo ligands for Ln(II) ions, and their subsequent application in asymmetric organic synthesis. Synthesis of enantiomerically pure bis(pentaalkylcyclopentadienyl) ligands was attempted via a novel double Nazarov cyclisation of 5,6-di-(methyl)-decane-3,8-dione. A competing intermolecular aldol reaction reduced the efficiency of this route, although subsequent work suggests that the alternative ketone, (3,4-RR/SS)-bis(2'- oxobutyl)tetrahydrofuran, could inhibit aldol formation. In addition, a route for bis(tetramethylcyclopentadienyl) ligands was developed via oxidative coupling of 4-(S)-isopropyl-3-propionyl-oxazolidin-2-one.A range of tetradentate polyaza/oxo ligands have been prepared and their application in enantioselective carbon-carbon bond formation, in particular the Barbier reaction between 2-octanone and bromobutane, investigated. Using N,N'-bis(3'- propionamide)cyclohexane-l,2-diamine, asymmetric induction and a marked acceleration in reaction rate was observed. This represents the first enantioselective Sm(II)-mediated Barbier reaction. The use of aryl ketones affords pinacols with low enantioselectivity.
18
Creaser, Dale Abel. "Aspects of composite lanthanide oxide chemistry." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334547.
Full text
19
Amoli, Hossein Salar. "Chromatographic investigation of some lanthanide complexes." Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258243.
Full text
20
Bissett, James S. "Lanthanide Lewis acid catalysed allylation reactions." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367709.
Full text
21
Jayasundera, Anil. "Solvothermal chemistry of luminescent lanthanide fluorides." Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/2125.
Full textAbstract:
Exploration of novel lanthanide fluoride framework materials in inorganic-organic hybrid systems under solvothermal conditions towards development of new luminescent materials is discussed. X-ray single crystal and powder diffraction methods have been used as crystallographic characterisation techniques. Determination and study of luminescence properties for selected hybrid materials has also been carried out. The first organically templated luminescent lanthanide fluoride framework, [C₂N₂H₁₀]₀.₅ [Ln₂F₇] (Ln= Nd, Tb, Dy, Ho, Er, Yb and Lu), has been synthesised and characterised. This structure type consists of a three-dimensional yttrium fluoride framework incorporating two similar, but crystallographically distinct, yttrium sites. Photoluminescence studies of [C₂N₂H₁₀]₀.₅ [Y₂F₇]: Ln³⁺ (Ln³⁺ = Gd³⁺, Eu³⁺ and Tb³⁺) have been explored and characteristic luminescence emissions are reported. An inorganic-organic hybrid indium fluoride and its scandium fluoride analogue, [C₄H₁₄N₂][MF₅](M=In and Sc) is reported. The structure consists of infinite trans vertex sharing (InF₅)[subscript(∞)] chains, which are linked via H-bonded organic moieties. The scandium and fluorine local environments of [C₄H₁₄N₂][ScF₅] are characterised by ¹⁹F, and ⁴⁵Sc solid-state MAS NMR spectroscopies. A single scandium site has been confirmed by ⁴⁵Sc MAS NMR. ¹⁹F MAS NMR clearly differentiates between bridging and terminal fluorine. The photoluminescence properties of these complexes, [C₄H₁₄N₂][In[subscript(1-x)] Ln[subscript(x)]F₅] (Ln=Tb and/or Eu), have been explored. The optimum composition for Eu³⁺ doped samples occurs at x = 0.05 Eu³⁺ and the “asymmetry ratio” of R = I₅₉₀/I₆₁₅ ( ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁) gives a clear picture of the sensitivity for crystal field of the compound. For x = 0.08 Tb³⁺, a strong down-conversion fluorescence corresponding to ⁵D₄ → ⁷F₅ (green at 543.5 nm) occurs. In addition, a Tb³⁺/Eu³⁺ co-doped sample exhibits a combination of green (Tb³⁺) and orange (Eu³⁺) luminescence, with Tb³⁺ enhancing the emission of Eu³⁺ in this host. Exploration of novel indium, aluminium, and zirconium fluoride crystal structures with potential luminescent properties has also been undertaken. A chiolite-like phase K₅In₃F₁₄ (space group P4/mnc) has been synthesised. No phase transition occurs over the temperature range 113K< T< 293 K, as has been seen in other chiolite-like structures. An organically templated indium fluoride, [NH₄]₃[C₆H₂₁N₄]₂[In₄F₂₁] has been prepared; this features the trimeric unit [In₃F₁₅]³⁻ which appears to be the first of its type in a metal fluoride. A new hybrid fluoride, Sr[N₂C₂H₁₀]₂[Al₂F₁₂].H₂O has been synthesised. Because the ionic radius of Eu²⁺ is similar to that of Sr ²⁺ this may be a potential host for blue luminescent Eu²⁺. The new material KZrF₅.H₂O shows pentagonal-bipyramidal geometry of Zr⁴⁺ with a polar space group, Pb2₁m, which may potentially have ferroelectric properties.
22
Poole, Robert. "Luminescent lanthanide complexes for cellular applications." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/1343/.
Full textAbstract:
The tetraazatriphenylene chromophore, dpqC, efficiently sensitises europium(III) and terbiiim(lll) emission. It has been incorporated into a series of ligands, based on the :yclen macrocycle, which saturate the coordination sphere of the metal ion and lead to complexes that exhibit high luminescent quantum yields in aerated aqueous media of the order of 15 - 50 %, with long emission hfetimes of the order of milliseconds.The complexes have been shown to be taken up by a number of eukaryotic cell lines and are amenable to time resolved fluorescence microscopy. By relating the structure of the complexes to their uptake and locahsation profiles, it should be possible to design complexes for specific intracellular applications, for example, as probes or components in biological assays.
23
Bushby, Lisa Marie. "Photochemistry and photophysics of lanthanide complexes." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/4208/.
Full textAbstract:
Luminescent lanthanide complexes have proven to be a productive area of research due in essence to their unique emission properties enabling their use in a variety of applications. A major drawback to using lanthanides is their low extinction coefficients, so that the antenna effect is often used to overcome this problem. In this way, the antenna chromophore absorbs incoming radiation and transfers the energy to the ion, leading to indirect excitation of the lanthanide. Understanding this mechanism of energy transfer is of fundamental importance both for the theory of the photophysical processes, and for the development of more efficient materials. In this thesis, many of the areas of both the population and the deactivation of the lanthanide excited states are discussed. The time resolved data of the Tm(^3+) ion in a variety of solvents and chelate systems have been measured, and the effects of deuteration on the decay kinetics investigated. The mechanism of energy transfer is followed by detailed kinetic measurements of a complex with a benzophenone containing chromophore. The calculation of the pure radiative lifetime allowed the efficiency of each of the steps involved in the sensitisation process to be determined for the first time. Changing the coordination environment around the ion, even slightly, by the addition of a single CH(_2) group into the arm of the ligand affects the oscillator strength of the hypersensitive transitions in both the Eu(^3+) and Tb(^3+) complexes, and influences the efficiency of energy transfer. Intramolecular sensitisation of Eu(^3+) ions by acetophenone containing ligands was investigated in a series with increasing electron donating ability of the chromophore. It was found that the efficiency of energy transfer increases with the polarity of the antenna, but that in the case of a dimethylamino substituted ligand, the solvent also has a profound effect on the intensity of Eu(^3+) emission. Energy transfer to bound Eu(^3+) and Tb(^3+) ions in aqueous micellar systems is demonstrated, with the process dependent on the hydrophobic properties of the chromophore and the properties of the surfactant. Photoinduced electron transfer reactions are found to occur in ethoxybenzyl substituted complexes with the emission from the chromophore and from the lanthanide ion dependent upon the lanthanide reduction potential and the AG value of both the forward and backward electron transfer reactions.
24
Jones, Claire Frances. "Lanthanide complexes of bulky hybrid ligands." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/4009.
Full textAbstract:
The synthetic and redox chemistry of lanthanide organometallic complexes has considerably expanded since the discovery of Kagan’s reagent in 1977 and divalent ionic complexes are now known for the entire lanthanide series. The synthesis, solid-state structures and reductive chemistry of trivalent and divalent lanthanide complexes with cyclopentadienyl-type ligands is reviewed with a focus on the impact of the ligand on the reducing power of the metal centre. Trimethylsilyl and more recently, phosphine-borane stabilised carbanions have facilitated the isolation of trivalent and divalent lanthanide complexes of alkyl ligands with Ln—C σ-bonds. The synthesis, structures and known reactivity of these compounds is discussed. In order to probe the impact of alkyl carbanion and cyclopentadienyl coordination on lanthanide complex stability, structure and redox reactivity we have designed a novel set of hybrid ligands that combine these two functional groups into a single dianionic ligand. These ligands are potentially very versatile as the sterics and electronics of both groups in the ligand can be modified. The ligands are viable to support sterically congested trivalent complexes for sterically induced reduction as well as metal based reduction and they are good ligands for heteroleptic complexes because they chelate the metal avoiding ligand redistribution equilibria. The synthesis and characterisation of a range of trimethylsilyl-, phosphine-borane- and phosphine-stabilised alkyl bromo- and chlorosilane precursors is described: (Me3Si)2CHSiMe2Br [4], (Me3Si){PMe2(BH3)}CHSiMe2Cl [9], (Me3Si){PnPr2(BH3)}CHSiMe2Cl [13], {PMe2(BH3)}2CHSiMe2Cl [23], {PMe2(BH3)}{PPh2(BH3)}CHSiMe2Cl [27], {PPh2(BH3)}2CHSiMe2Cl [31] and (nPr2P)2CHSiMe2Cl [32]. iv The results of a computational study using NBO methods to investigate the relative stabilising effect of each of these silyl, phosphine-borane and phosphine carbanion stabilising groups on a model system akin to the alkyl part of the hybrid ligand are described. Reaction of (Me3Si)2CHSiMe2Br with Li/Na/K Cp/Cp’/Cp4Me followed by aqueous work-up gave the hybrid proligands {(CpH)Me2Si}(Me3Si)2CH [5], {(Cp’H)Me2Si}(Me3Si)2CH [6] and {Cp4MeH)Me2Si}(Me3Si)2CH [7] as mixtures of regioisomers [Cp4Me = 1,2,3,4-Tetramethyl-cyclopentadiene]. Reaction of LiCp4Me/KCp4Me with (Me3Si){PMe2(BH3)}CHSiMe2Cl and (Me3Si){PnPr2(BH3)}CHSiMe2Cl gave the hybrid proligands (CpH4MeMe2Si)(Me3Si)CH{PMe2(BH3)} [10] and (CpH4MeMe2Si)(Me3Si)- CH{PnPr2(BH3)} [14]. The compounds {Cp4MeH)Me2Si}(Me3Si)2CH, (CpH4MeMe2Si)- (Me3Si)CH{PMe2(BH3)} and (CpH4MeMe2Si)(Me3Si)CH{PnPr2(BH3)} crystallise as solvent-free monomers with very similar molecular conformations. The hybrid pro-ligands exhibit variable moisture sensitivity. Reaction of (Me3Si){PMe2(BH3)}CHSiMe2Cl with NaCp followed by aqueous work-up and column chromatography of the oily residue obtained gave the siloxane [(Me3Si){PMe2(BH3)}HCMe2Si]2O [19] and dicyclopentadiene. Reaction of (nPr2P)2CHSiMe2Cl with NaCp followed by aqueous work-up using deoxygenated water gave (nPr2P)2CH2 in quantitative yield. The same reaction avoiding the aqueous work-up gave (CpHMe2Si)CH(PnPr2)2 [33]. Hybrid ligands were prepared by metalation of {Cp4MeH)Me2Si}(Me3Si)2CH, {(Cp’H)Me2Si}(Me3Si)2CH and {(CpH)Me2Si}(Me3Si)2CH with MeK to give the hemisolvated dipotassium salts [(CpMe2Si)(Me3Si)2C]K2(Et2O)0.5 [50], [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O)0.5 [51] and [(Cp’Me2Si)(Me3Si)2C]K2(C6H6)0.5 [52], which decomposed slowly in THF and toluene. [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O) [51.Et2O] was crystallised as an alternative solvate from diethyl ether and the v extended structure consists of chelated [(hybrid ligand)K(Et2O)]- anionic units linked nose to tail by unsolvated K cations in a non-linear (zig-zag) polymer chain. [(Cp’Me2Si)(Me3Si)2C]K2(C6H6)·C6H6 [52.C6H6] also crystallised as a monosolvate from benzene, but with addition uncoordinated solvent present in the structure. There are two distinct types of polymer chain in the structure of [(Cp’Me2Si)(Me3Si)2C]K2(C6H6)·C6H6, one is similar to the chain in [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O) and in the other half the potassium cations in this chain are coordinated by only a cyclopentadienyl ring and a benzene ring. The remainder of the K cations are sandwiched between a carbanion and cyclopentadienyl ring of different hybrid ligands, as in [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O). These chains are cross-linked by a short contact between K and the –SiMe3 substituent of the Cp’ ring. Due to their more acidic alkyl protons metalation of (CpH4MeMe2Si)(Me3Si)CH{PMe2(BH3)}, (CpH4MeMe2Si)(Me3Si)CH{PnPr2(BH3)} and (CpHMe2Si)CH(PnPr2)2 could be achieved with BnK in THF. (CpH4MeMe2Si)(Me3Si)CH{PMe2(BH3)} is isoelectronic and isosteric with {Cp4MeH)Me2Si}(Me3Si)2CH. [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]K2(THF) [53.THF] crystallises as a solvate from benzene/THF with a 3D polymeric network structure through multiple agostic-type B—H····K contacts. Of the two symmetry inequivalent K cations in the structure the alkyl carbanion interacts directly only with the unsolvated cations and the solvated cations are coordinated through the borane-hydrogens. Metathesis reactions of [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O)0.5 and [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]K2(THF)0.5 with LaI3(THF) and SmI3(THF) in THF gave [(Cp4MeMe2Si)(Me3Si)2C]LaI(THF)2 [56] and [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]-SmI(THF)2 [57] after extraction into diethyl ether and crystallisation from toluene/THF and diethyl ether respectively. The vi hybrid ligand bound successfully to the lanthanide metal cations. [(Cp4MeMe2Si)(Me3Si)2C]LaI(THF)2 is a monomer in the solid-state, chelated by the hybrid ligand forming pseudo-four-membered ring and two coordinating molecules of THF in addition to the iodine anion. A zwitterion structure is adopted by [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]SmI(THF)3 with no contact between the Sm(III) cation and the alkyl carbanion centre. The hybrid ligands have a much larger cone angle and are far more sterically bulky when chelating the lanthanide metal, as in [(Cp4MeMe2Si)(Me3Si)2C]LaI(THF)2. The metathesis reaction of [(Cp4MeMe2Si)(Me3Si)2C]K2(Et2O)0.5 with CaI2 gave [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]Ca(THF)2 [58] after extraction and crystallisation from diethyl ether. In this structure the phosphine-borane stabilised carbanion group of the hybrid ligand coordinates the Ca cation through the carbanion centre. Synthesis of the Yb(II) analogue, [(Cp4MeMe2Si)(Me3Si){PMe2(BH3)}C]Yb(THF)x gave an almost identical NMR spectrum, but could not be crystallised.
25
Dyer, Hellen Elizabeth. "New lanthanide complexes as polymerisation catalysts." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.560913.
Full textAbstract:
This Thesis describes the synthesis and characterisation of a series ofbisphenolate supported samarium borohydride, amide and zwitterionic rare earth complexes and their ability to effect the ring opening polymerisation (ROP) of cyclic esters and methylmethacrylate (MMA). Chapter 1 introduces ROP from both an industrial and an academic perspective and describes in detail the research in this area, with emphasis on rare earth initiators. The lanthanide elements and the bisphenolate ligand are also introduced. Chapter 2 describes the synthesis and characterisation ofbisphenolate supported samarium borohydride and silylamide complexes. Chapter 3 describes the ability of a selection of samarium borohydride and amide complexes to effect the ROP of the cyclic esters s-caprolactone (f-CL) and rac- lactide (rac-LA). Emphasis is placed on the effect that the nature of the bisphenolate pendant arm and the initiating moiety has on the polymerisation process. Chapter 4 describes the synthesis and characterisation of rare earth zwitterionic complexes and the ability ofa range of these complexes to effect the ROP of s-Cl. and rac-lactide. Mechanistic aspects ofthe ROP process will be discussed, as will the ability of these complexes to yield amide functionalised poly(rac-LA). Chapter 5 describes the ability ofbisphenolate samarium borohydride complexes to initiate the polymerisation of MMA. The experimental work conducted as part of this study is further supported computationally by calculations at the DFT level, both aspects will be described. Aspects concerning the synthesis and characterisation of the related borohydride derivative [Sm(N2siMe3NNPY)(BH4)2Li]oo will also be emphasised. Chapter 6 contains full experimental and characterising data for all 0 f the new compounds reported in this Thesis. Appendices A- T contain tables of selected crystallographic data for all new crystallographically characterised complexes described in this Thesis (partially on CD).
26
Saines, Paul James. "Structural Studies of Lanthanide Double Perovskites." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3939.
Full textAbstract:
This project focuses on the examination of the structures of lanthanide containing double perovskites of the type Ba2LnB'O6-d (Ln = lanthanide or Y3+ and B' = Nb5+, Ta5+, Sb5+ and/or Sn4+) using synchrotron X-ray and neutron powder diffraction. The first part of this project examined the relative stability of R3 rhombohedral and I4/m tetragonal structures as the intermediate phase adopted by the series Ba2LnB'O6 (Ln = lanthanide (III) or Y3+ and B' = Nb5+, Ta5+ or Sb5+). It was found that I4/m tetragonal symmetry was favoured when B' was a transition metal with a small number of d electrons, such as Nb5+ or Ta5+. This is due to the presence of p-bonding in these compounds. In the Ba2LnNbO6 and Ba2LnTaO6 series R3 rhombohedral symmetry was, however, favoured over I4/m tetragonal symmetry when Ln = La3+ or Pr3+ due to the larger ionic radius of these cations. The incompatibility of the d0 and d10 B'-site cations in this family of compounds was indicated by significant regions of phase segregation in the two series Ba2Eu1-xPrxNb1-xSbxO6 and Ba2NdNb1-xSbxO6. In the second part of this project the compounds in the series Ba2LnSnxB'1-xO6-d (Ln = Pr, Nd or Tb and B' = Nb5+ or Sb5+) were examined to understand the relative stability of oxygen vacancies in these materials compared to the oxidation of the lanthanide cations and to determine if any oxygen vacancy ordering occurred. It was found, using a combination of structural characterisation, X ray Absorption Near Edge Structure and Ultra-Violet, Visible and Near Infrared spectroscopies, that with Ln = Pr or Tb increased Sn4+ doping results in a change in the oxidation state of the Ln3+ cations to Ln4+. This leads to those series containing little or no oxygen vacancies. A loss of B site cation ordering was found to accompany this oxidation state change and phase segregation was found to occur in the Ba2PrSnxSb1-xO6-d series most likely due to the Pr3+ and Pr4+ cations segregating into different phases. The Nd3+ cations in the series Ba2NdSnxSb1-xO6-d, however, can not oxidise to the tetravalent state so the number of oxygen vacancies rises with increasing x. It was found that oxygen vacancies concentrate onto the axial site of the compounds with x = 0.6 and 0.8 at ambient temperature. In Ba2Sn0.6Sb0.4O5.7 the oxygen vacancies were found to change to concentrating on the equatorial site at higher temperatures and it is suggested that this oxygen vacancy ordering plays a role in the adoption of I2/m monoclinic symmetry.
27
Saines, Paul James. "Structural Studies of Lanthanide Double Perovskites." Faculty of Science. School of Chemistry, 2008. http://hdl.handle.net/2123/3939.
Full textAbstract:
Doctor of Philosophy(PhD)This project focuses on the examination of the structures of lanthanide containing double perovskites of the type Ba2LnB'O6-d (Ln = lanthanide or Y3+ and B' = Nb5+, Ta5+, Sb5+ and/or Sn4+) using synchrotron X-ray and neutron powder diffraction. The first part of this project examined the relative stability of R3 rhombohedral and I4/m tetragonal structures as the intermediate phase adopted by the series Ba2LnB'O6 (Ln = lanthanide (III) or Y3+ and B' = Nb5+, Ta5+ or Sb5+). It was found that I4/m tetragonal symmetry was favoured when B' was a transition metal with a small number of d electrons, such as Nb5+ or Ta5+. This is due to the presence of p-bonding in these compounds. In the Ba2LnNbO6 and Ba2LnTaO6 series R3 rhombohedral symmetry was, however, favoured over I4/m tetragonal symmetry when Ln = La3+ or Pr3+ due to the larger ionic radius of these cations. The incompatibility of the d0 and d10 B'-site cations in this family of compounds was indicated by significant regions of phase segregation in the two series Ba2Eu1-xPrxNb1-xSbxO6 and Ba2NdNb1-xSbxO6. In the second part of this project the compounds in the series Ba2LnSnxB'1-xO6-d (Ln = Pr, Nd or Tb and B' = Nb5+ or Sb5+) were examined to understand the relative stability of oxygen vacancies in these materials compared to the oxidation of the lanthanide cations and to determine if any oxygen vacancy ordering occurred. It was found, using a combination of structural characterisation, X ray Absorption Near Edge Structure and Ultra-Violet, Visible and Near Infrared spectroscopies, that with Ln = Pr or Tb increased Sn4+ doping results in a change in the oxidation state of the Ln3+ cations to Ln4+. This leads to those series containing little or no oxygen vacancies. A loss of B site cation ordering was found to accompany this oxidation state change and phase segregation was found to occur in the Ba2PrSnxSb1-xO6-d series most likely due to the Pr3+ and Pr4+ cations segregating into different phases. The Nd3+ cations in the series Ba2NdSnxSb1-xO6-d, however, can not oxidise to the tetravalent state so the number of oxygen vacancies rises with increasing x. It was found that oxygen vacancies concentrate onto the axial site of the compounds with x = 0.6 and 0.8 at ambient temperature. In Ba2Sn0.6Sb0.4O5.7 the oxygen vacancies were found to change to concentrating on the equatorial site at higher temperatures and it is suggested that this oxygen vacancy ordering plays a role in the adoption of I2/m monoclinic symmetry.
28
Accorsi, Gianluca <1973>. "Trivalent lanthanide ions: luminescence and applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/472/1/Accorsi_Gianluca_Tesi_di_Dottorato_XIX_Ciclo.pdf.
Full text
29
Accorsi, Gianluca <1973>. "Trivalent lanthanide ions: luminescence and applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/472/.
Full text
30
Knoche, Krysti Lynn. "Density gradient films, lanthanide electrochemistry, and magnetic field effects on hydrogen evolution, oxygen reduction, and lanthanide electrochemistry." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/3124.
Full textAbstract:
Electroanalytical techniques are used to investigate mass transport through density gradient films; lanthanide triflate reduction and oxidation in a Nafion/acetonitrile matrix; and magnetic field effects on hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and lanthanide electrochemistry.
Graded density films are more dense at the electrode surface and become less dense out into solution due to a brush polymer structure. Fick's second law expands to account for a diffusion coefficient that varies with distance x normal to the electrode surface. Confocal microscopy, cyclic voltammetry, and computer simulations are used to investigate density graded Ficoll® films. Mass transport approaches steady state (scan rate independence) at slow scan rates where the diffusion length samples the entire film. The use of Ficoll to template an ion exchange polymer is explored by casting Nafion® Ficoll composites.
Lanthanide electrochemistry is enabled in acetonitrile at a Nafion modified platinum electrode in the presence of triflate ligands. Formal potentials are shifted into the voltage window of acetonitrile accessible due to triflate complexation. The Nafion further solubilizes the compounds. The mechanism (ECEC) is studied with cyclic voltammetry and x-ray photoelectron spectroscopy.
Magnetic field effects on electrochemical systems have been of interest to researchers for the past 65 years. Mass transport effects, such as magnetohydrodynamics and magnetic field gradient effects have been reported, but the Leddy group focuses on electron transfer effects. Electrode surfaces are modified with composite films of magnetic microparticles suspended in ion exchange polymer Nafion. Effects are verified to be electron transfer related and due to the magnetization of chemically inert microparticles. The magnets catalyze the rates of important electron transfer reactions such as hydrogen evolution and oxygen reduction.
Magnetic field effects on HER at various noncatalytic metal electrodes are explored with linear scan voltammetry. There is a correlation between the magnetic susceptibility of the electrode metals and the HER exchange currents (reaction rates). Exchange currents are 103× larger for a paramagnetic metal electrode than a diamagnetic one with the same work function. The overpotential at diamagnetic electrodes is decreased by modification with a Nafion + magnetic microparticle composite film. A decrease in overpotential of ∼70 % for all electrodes except platinum is observed. The overpotential decrease correlates with the magnetic susceptibility of the particles.
Magnets can enhance differences between lanthanide cyclic voltammograms by shifting current densities at a given potential and enhancing current based on the number of 4f electrons and magnetic moment of each lanthanide ion.
Magnetic field effects on ORR in acetonitrile are investigated with cyclic voltammetry. In aprotic solvents, ORR proceeds by a one electron transfer reaction to paramagnetic O2.–. Enhanced reversibility and electron transfer kinetics are observed as well as a decrease in overpotential of ∼100 mV. Magnetic field effects on ORR in a lanthanide triflate solution are also examined. Electron transfer kinetics and reversibility are further enhanced in the presence of lanthanide triflate.
31
Gainer, Christian Forrest. "Synthesis, Characterization, and Biomedical Application of Upconverting Lanthanoid Nanoparticles." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293467.
Full textAbstract:
Cancer currently represents one of the greatest burdens on human health in the world, claiming in excess of 7 million lives a year worldwide. Advances in both our understanding of the disease as well as our ability to diagnose it before it has had a chance to metastasize will lead to a reduction in its burden on society. To these ends, optical imaging techniques are particularly attractive. The ability to resolve cellular details noninvasively is paramount to improved cancer detection and to research on diseased tissue and cells. Lanthanoid nanoparticles, a group of photoluminescent contrast agents developed within the last two to three decades, have numerous unique optical properties that enable their use in improved and novel optical techniques. They possess large Stokes and anti-Stokes shifts, sharp electronic transitions, long luminescence lifetimes, and exceptional photostability. For these reasons, they are a good choice for biomedical applications that benefit from low background fluorescence or long illumination times. The major goal of the research presented in this dissertation was to synthesize functional lanthanoid nanoparticles for optical imaging modalities, and to explore their potential uses in a variety of biomedical applications. To this end, the research can be broken up into three specific aims. The first aim was to successfully and reproducibly synthesize downconverting and upconverting lanthanoid nanoparticles, and to functionalize these nanoparticles for use in optical techniques that would aid in the research and diagnosis of cancer. The second aim was to conduct a thorough investigation of the optical properties of these nanoparticles, and the third aim was to explore the utility of these nanoparticles in a variety of biomedical applications. First, both downconverting and upconverting lanthanoid nanoparticles were synthesized using several different methods, resulting in nanoparticles of varying size and surface functionality. Novel methods were employed to improve the utility of these nanoparticles for specific applications, including the incorporation of a mixed surface ligand population in downconverting lanthanoid nanoparticles and the use of a biomimetic surface coating to render upconverting nanoparticles water dispersible. These coated particles were further functionalized by the addition of folic acid and an antibody for epidermal growth factor receptor, both of which bind to cell surface receptors overexpressed in a number of cancers. Second, the spectral properties of lanthanoid nanoparticles were explored in detail, with special attention paid to many of the unique optical properties of upconverting lanthanoid nanoparticles. This included the discovery of one such unique property, the excitation frequency dependent emission of NaYF₄ nanocrystals codoped with Yb³⁺ and Er³⁺. Third, lanthanoid nanoparticles were used as contrast agents in a number of biomedical applications, including the development of a homogenous assay based on diffusion enhanced luminescence resonance energy transfer, a wide-field luminescence lifetime microscope, and a super resolution microscope based on the aforementioned excitation frequency dependent emission of NaYF₄:Yb³⁺,Er³⁺ nanoparticles. Specific binding of functionalized upconverting lanthanoid nanoparticles was investigated with laser scanning multiphoton microscopy, and an image processing technique was developed to overcome the challenge of working with long lived luminescent contrast agents using this imaging modality.
32
Barrera, Bello Elixir William. "Lanthanide-based dielectric nanoparticles for upconversion luminescence." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/108960.
Full textAbstract:
En esta tesis se ha estudia la luminiscencia y la emisión anti-stokes visible por excitación infrarroja a 980 nm, en iones lantánidos embebidos en nanoestructuras de Lu2O3 y KLu(WO4)2, en los cuales los iones lantánidos muestran interesantes propiedades ópticas. Se han producido tres tipos de nanoestructuras con alta cristalinidad a través del método Pechini modificado y síntesis hidrotermal. Se han descrito los mecanismos de fotoluminiscencia, catodoluminiscencia y eficiencia cuántica, en base a las especies adsorbidas en la superficie y la potencia de excitación.
Se han sintetizado nanobarras y partículas núcleo-capa que puede ser utilizadas como bloques de construcción de estructuras más complejas en aplicaciones fotónicas. Se ha logrado la generación de luz blanca en nanocristales de (Tm,Ho,Yb)KLu(WO4)2. Estas nanopartículas pueden formar parte de estructuras más complejas en dispositivos emisores de luz o como indicadores para visualización biológica de células.Nowadays especially attention has been given to materials capable of generating visible light by conversion of near infrared photons (upconversion) for save-energy technologies and reduction of photo-degradation caused by UV high energy photons. Nanoparticles using optically active Ln3+ have shown great potential for use as upconverting luminescent materials in bio-analysis applications, counterfeit fighting and back-lighting. However materials with nanometer dimensions may affect the luminescence dynamics of the Ln3+ ion modifying the emission lifetime, quantum yield, and concentration quenching. This thesis discusses the synthesis and upconversion emission of lanthanide doped nanostructures with Lu2O3 and KLu(WO4)2 as host because they posses high chemical stability; they offer favorable incorporation of Ln3+ ions and high absorption and emission cross sections. Er3+, Ho3+ and Tm3+ are used as emitting ions and Yb3+ as sensitizer. Luminescence dynamics of these ions into these nanostructures and the possibility of white light emission in KLuW nanocrystals are discussed.
33
Farkas, Ildiko. "Coordination Chemistry of Actinide and Lanthanide Ions." Doctoral thesis, KTH, Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3236.
Full text
34
Farkas, Ildikó. "Coordination chemistry of actinide and lanthanide ions /." Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3236.
Full text
35
Jin, Geng Bang. "Synthesis and characterization of new Lanthanide chalcogenides." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Dissertations/JIN_GENGBANG_37.pdf.
Full text
36
McCaw, Charles Stuart. "Electronic structure of lanthanide ions in crystals." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298628.
Full text
37
De-Luca, Elena. "Fluorinated responsive lanthanide complexes for magnetic resonance." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/538/.
Full textAbstract:
A series of novel fluorinated lanthanide complexes has been synthesised for use as responsive probes for 19F MRS and MRI. The careful positioning of the CF3 group within 6.5 Å from the metal ion caused the fluorine longitudinal and transversal relaxation rates to be strongly enhanced. This allows faster MR signal acquisition, reducing the sample concentration and acquisition time required to obtain the desired signal intensity. The lanthanide ion also enhanced the chemical shift sensitivity of the fluorine nucleus to changes in the chemical environment. These characteristics have been exploited to develop responsive probes. A series of pH reporters containing an aromatic mono-amide arm has been prepared and their pH sensitivity assessed. Deprotonation of the amide proton caused a large variation of the 19F chemical shift. The pKa of the probe was modulated by varying the substituents on the aromatic group and an optimal value of 7.1 was obtained with an ortho cyano substituent. The introduction of phosphinate pendant arms allowed narrower linewidths and faster longitudinal relaxation rates to be achieved. The spectroscopic properties and the conformational isomerism of the same series of complexes have been analysed. In particular, their 19F NMR chemical shift, relaxation properties and 1H relaxivity characteristics were studied. A series of complexes bearing different ester functional groups was prepared and their ability as reporters for enzymatic activity assessed. PLE and -chymotripsin recognised the substrate and catalysed its transformation. Modification of the probe structure was revealed by variation of the relative signal intensity of the substrate and product fluorine resonances in the 19F NMR spectrum. Glycol chitosan conjugates with paramagnetic fluorinated complexes were prepared and their NMR properties assessed. In vivo MRI studies in animal models were undertaken and a selective uptake of the contrast agent in the tumour was observed with the Gd analogue.
38
Kielar, Filip. "Development of lanthanide probes for cellular imaging." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2193/.
Full textAbstract:
Luminescent complexes of europium and terbium, incorporating new sensitizing chromophore moieties containing carboxylic acid functional groups, have been synthesised. It has been shown that the new tetraazatriphenylene chromophore leads to highly emissive complexes. A thiaxanthone chromophore, despite sensitizing lanthanide emission, results in complexes with lower quantum yields and is only practically useful for europium. Modification of the azaxanthone chromophore by formation of its N-oxide was investigated as a possibility of extending its longest wavelength absorption maximum beyond 340 nm. Phosphinate pendant arms were introduced into complexes containing the azaxanthone chromophore and resulted in highly emissive complexes Complexes of the new chromophores were investigated, together with numerous further examples, in terms of their susceptibility to quenching by electron rich species (iodide, ascorbate, urate). These experiments enhanced the mechanistic understanding of this process. Complexes using an azaxanthone chromophore with a carboxylic function and phenyl amide arms were used in coupling reactions. The coupling reactions involved isolation of the NHS ester of the complex. Cellular uptake and cytotoxicity experiments were carried out with several of these conjugate complexes. The possibility to observe these complexes using two photon excitation fluorescence microscopy was demonstrated.
39
Murray, Ben. "Anion binding studies with responsive lanthanide complexes." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2237/.
Full textAbstract:
The binding of a range of biologically prevalent anions to several novel lanthanide(III) complexes has been studied by emission spectroscopy, (^1)H-NMR and mass spectrometry. In each case, the resultant solution adduct and the mode of anion binding was characterised through analysis of spectral response. Following the first chapter, in which relevant background work and literature reports are discussed, the novel lanthanide(III) complexes described herein are separated into three chapters. Chapter 2 describes a range of complexes bearing a pendant azaxanthone or aza-thioxanthone derived chromophore. Binding of anions was examined largely through sensitised emission, additionally the cellular localisation and toxicity profiles of each complex was studied. Of particular interest was the discovery of a family of complexes that localised within the mitochondria of the cell lines examined, and exhibited pC0(_2) dependent luminescence, notwithstanding protein quenching. Chapter 3 describes the synthesis and evaluation of two stereoisomeric dimeric complexes, in which the conformation of each was controlled by the differing relative stereochemistry of their linking unit. A range of luminescence and NMR studies was performed to establish the relative affinities of these complexes for selected anionic species, and to compare their binding properties to that of the related monomeric complex. Chapter 4 describes the immobilization of two related complexes onto various solid-phase supports. The ability of the immobilized complexes to selectively bind to, retain then release phospho-anions on addition of a competitive aqueous anionic buffer is examined. The utility and advantages of using such materials as tools for the enrichment of phospho-peptides is discussed in relation to previously published procedures and materials.
40
楊友源 and Yau-yuen Yeung. "Alternative parametrization schemes in lanthanide crystal fieldtheory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31231044.
Full text
41
Blaudeck, Robert Peter. "Catalysis and photonics with chiral lanthanide complexes." Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478960.
Full text
42
Gathergood, Nicholas Keith Peter. "Chiral cyclopentadienyl lanthanide and transition metal complexes." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284648.
Full text
43
GUERRERO, REYNALDO GREGORINO REYES. "ORGANIC ELECTROLUMINESCENT DEVICES BASED ON LANTHANIDE COMPLEXES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4641@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOREDE DE NANOTECNOLOGIA MOLECULAR E DE INTERFACES
Este trabalho consiste no estudo de dispositivos eletroluminescentes orgânicos (OLEDs) onde as camadas emissoras de luz são oriundas dos complexos lantanídeos. A estrutura dos OLEDs fabricados é constituida a partir de uma heterojunção de três materiais orgânicos, onde o 1-(3- metilfenil)-1,2,3,4 tetrahidroquinolina-6-carboxialdeido- 1,1 -difenilhidrazona (MTCD) é utilizado como camada transportadora de buracos, o tris(8-hidroxiquinolinolato) de alumínio (III) (Alq3) como camada transportadora de elétrons e como camadas emissoras de luz são utilizados os complexos lantanídeos tipo [TR(TTA)3(TPPO)2], onde TR3+ são o Sm, Eu ou Gd. Foi estudado, também, a possibilidade de utilizar os complexos [Eu(btfa)3bipy] e [Tb(DPM)3] como materiais emissores. As camadas orgânicas foram depositadas termicamente uma após a outra sobre substratos de vidro recobertos por um filme de oxido de estanho e índio (ITO) e no final é depositado um filme de alumínio. A emissão luminosa destes OLEDs contém as transições eletrônicas dos íons de Sm3+ e Eu3+, enquanto que no caso do dispositivo fabricado com o complexo de gadolínio a emissão detectada é devida à eletrofosforescência molecular do ligante TTA. Usando uma mistura dos complexos de Sm e Eu indicada por [SmxEuy(TTA)3(TPPO)2], observamos que é possível controlar a cor da luz emitida através da variação da tensão aplicada ao dispositivo. Na caraterização elétrica encontramos que a curva j-V pode ser descrita pela relação j infinito Vm+1, que corresponde ao modelo de condução elétrica limitada por cargas aprisionadas. Para calcular o gap óptico dos materiais orgânicos foram realizadas medidas de absorção óptica enquanto que utilizando a espectroscopia de fluorescência, foi possível estudar o efeito da irradiação ultravioleta na degradação dos materiais orgânicos utilizados. Com o intuito de melhorar a injeção dos elétrons nos OLEDs, filmes de carbono amorfo (a-C:N e a- SiC:N) foram depositados por pulverização catódica assistida por radiofrequência (rf-sputtering) sobre as camadas orgânicas. A presença do filme de a-C:N incrementa efetivamente a densidade de corrente. Utilizando o modelo de bandas rígidas, é possível demonstrar que isto se deve a uma redução na altura da barreira para a injeção dos elétrons. Como resultado adicional mostramos que os filmes de carbono amorfo apresentam também o fenômeno da eletroluminescência, a temperatura ambiente e para baixos valores da tensão, que os tornam atraentes candidatos para novos dispositivos optoeletrônicos.
In this work, electroluminescent organic devices (OLEDs), where the emitting layers are lanthanide complexes, have been studied. The OLEDs structure was an heterojunction with three organic materials, where the 1-(3-methylphenil)- 1,2,3,4 tetrahydroquinoline-6-carboxyaldehyde-1,1- diphenylhydrazone (MTCD) is used as the hole transporting layer, the tris 8-hydroxyquinoline aluminum (Alq3) as the electron transporting layer, while the lanthanide complexes [TR(TTA)3(TPPO)2], where TR3+ are Sm, Eu or Gd, were used as the emitting layers. Also, the [Eu(btfa)3bipy] and [Tb(DPM)3] complexes was analyzed for a possible emitting layer employment. The organic layers were successively deposited onto glass substrate coated with indium tin oxide film (ITO) with an Al electrode cap layer. Spectral analysis shown that the emitted light correspond to electronic transitions arising from the of Sm3+ and Eu3+ ions, while for the gadolinium complex it is found that the emission corresponds to the molecular electrophosphorescence of the TTA ligand. Using a [SmxEuy (TTA)3(TPPO)2] blend complex, it was shown that is possible to obtain a voltage-controlled emission color OLED. For the majority of the fabricated devices the electrical characterization shown that the j-V curve can be described by the j infinit Vm+1 relation, that correspond to a trapped- charge-limited (TCL) conduction model. Optical absorption measurement were performed in order to calculate the optical band gap and through the fluorescence spectroscopy the effect of ultraviolet irradiation in the degradation of the organic materials have been also studied. Finally, in order to increase the electron injection in the fabricated devices, amorphous carbon films (a-C:N and a-SiC:N), were deposited by sputtering onto organic layer, just before the Al electrode. It was found that the presence of the a-C:N layer increases the current density. This fact can be explained by using the rigid band model that shows a barrier height reduction for the electron injection when the a-C:N layer is introduced between the Alq3 and the Al. Furthermore, it was also shown that these particular amorphous carbon films present themselves the electroluminescence phenomena at room temperature and with low voltages, which opens new possibilities for their applications in novel optoelectronic devices.
44
Shuvaev, Sergey Viktorovich. "Responsive luminescent lanthanide probes for biological applications." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12429/.
Full textAbstract:
Lanthanide-based complexes play a significant role in biological applications, spanning MRI contrast agents to molecular luminescent tags. Regardless of their application, these complexes should conform to general requirements, such as high stability against decomplexation at physiologically relevant conditions and sufficient solubility in water. Other more specific requirements may also apply, demanding a customised design of the ligand for a specific application. Emissive bio-responsive lanthanide complexes comprise a large and dynamically developing area, which possesses several intrinsic advantages over non-lanthanide analogues. Large Stokes’ shifts, long-lived excited states, ratiometric bands in the emission spectrum, strong cirularly-polarised signals are but a few to be named. These beneficial properties can be employed for efficient measurement of pH or determination of bioactive molecules both in vitro and in cellulo. For instance, europium complexes bearing sulphonamide arms showed reversible pH-response, producing noticeable changes in both the total emission and CPL spectra (Chapter 2). Other europium complexes possessing polarity-sensitive emission intensity were successfully used for detection of human serum albumin and α1-AGP – two the most abundant serum proteins – by following both total emission and CPL spectra, and these results are discussed in Chapter 3. Selective detection of biologically relevant anions needs specific probe design requirements. Even subtle changes in the structure of the ligand may lead to considerable changes in selectivity and affinity towards selected species. Such a correlation between structure and binding properties was exemplified in a series of europium complexes for the detection of nucleotides and zinc and led to the creation of probes spanning 5 orders of affinity constants. Furthermore, a nucleotide-specific induced CPL signal allowed monitoring the ratio between ADP and ATP – a parameter that characterises metabolic rates in mitochondria. These observations are thoroughly analysed in Chapter 4.
45
Jones, Marcus. "The ligand-field analysis of lanthanide complexes." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621393.
Full text
46
Funk, Alexander Max. "Dissecting the theories of lanthanide magnetic resonance." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10905/.
Full textAbstract:
The NMR relaxation and chemical shift behaviour of isostructural series of macrocyclic lanthanide(III) complexes has been investigated. The 1H, 31P and 19F longitudinal relaxation rates of multiple series of lanthanide(III) complexes (Tb, Dy, Ho, Er, Tm, Yb) have been measured in solution at five magnetic field strengths in the range 4.7 to 16.5 Tesla. The electronic relaxation time, T1e, is a function of both the lanthanide(III) ion and the local ligand field. Analysis of the field-dependent nuclear relaxation rates, based on Solomon-Bloembergen Morgan theory, describing the paramagnetic enhancement of the nuclear relaxation rates, has allowed reliable estimates of the electronic relaxation times, T1e. It has been shown that in systems of high symmetry, the electronic relaxation times are directly proportional to the ligand field and that in some cases changing the ligand field can have a greater effect on the nuclear relaxation rates than lanthanide selection. The chemical shift data for the series of lanthanide(III) complexes were analysed. The pseudocontact shift of lanthanide(III) complexes is described by Bleaney’s theory of magnetic anisotropy. Most of the assumptions in this theory were shown to be questionable. In particular for systems in low symmetry significant deivations between the experimental chemical shifts and those predicted by theory were found. The low symmetry systems exhibit crystal field splittings of the same order of magnitude as the spin-orbit coupling. The possibility of a mixing of the electronic energy levels of the lanthanide(III) ion has to be considered. The effect of the coordination environment on the magnetic susceptibility was investigated using a variety of methods. Significant deviation (10 – 20%) from the theoretical values was observed in systems of low symmetry. These investigations show that paramagnetic relaxation enhancements and magnetic susceptibility are dependent on the ligand field. Applying this knowledge allows the design of more efficient paramagnetic probes, as needed in PARASHIFT magnetic resonance.
47
Congreve, Aileen. "Responsive lanthanide complexes for metal ion sensing." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/3668/.
Full textAbstract:
The speciation and distribution of zinc (II) within cells is not well established and the range of zinc (II) probes available are of limited use. The quest was to develop responsive lanthanide complexes to bind selectively and respond (by change in hydration state) to biologically relevant concentrations of zinc at physiological pH for possible application in MRI and luminescence. A pyridyl sulfonamide ligand with an a-CH(_2)NHSO(_2)CF(_3) substituent was found to have the desired properties for strong zinc (II) coordination. The presence of a methyl group at 6', inhibited the formation of related square planar copper (II) complexes. Pyridyl amide appended europium and gadolinium (III) complexes, based on cyclen were developed with C(_2) and (C_3) spacers separating the macrocyclic ring and the amide. The mono-aqua C(_2) complex exhibited fast water exchange, due to the steric hindrance of the seven-membered chelate between the amide carbonyl and the lanthanide centre. The increase in steric hindrance caused by the eight-ring chelate in the C(_3) analogue rendered it q = 0. A trifluoromethanesulfonamide moiety at the 6' position of the pyridine group resulted in a mono-aqua complex for the C(_2) and C(_3) appended systems. This system showed no change in hydration state on addition of Zn(^2+). The addition of a-N- carboxyalkyl groups to give a GdaD03A system resulted in the formation of q = 2 complexes which showed no zinc (II) responsive properties. However, the C(_2)- linked species exhibited a high binding affinity to HSA which resulted m a dramatic increase in the relaxivity. Eu and Gd complexes of an octadentate N(_5)O(_3) pyridyl sulfonamide containing ligand were developed as pH and pZn responsive probes. The pyridyl nitrogen bound irreversibly to the lanthanide centre, resisting protonation even in the presence of zinc and copper ions, for which the pyridyl sulfonamide group has an establiblished high affinity.
48
Affholter, Kathleen. "Synthesis and crystal chemistry of lanthanide allanites." Diss., Virginia Tech, 1987. http://hdl.handle.net/10919/37332.
Full textAbstract:
Metamictization and complex chemistry are major obstacles to the crystal chemical characterization of natural allanites. To overcome these problems, allanites, Ca(REE)Fe²+Al₂Si₃O₁₂(OH), where REE = La, La-Ce, Ce, Nd, Sm, Eu, Gd, Er, Dy, Yb and Y have been synthesized hydrothermally from unbuffered and buffered oxide mixes at 500 to 650°C, 5.5 kbar (550 MPa), and 700 to 725°C, 4 kbar (400 MPa). Although allanite is readily synthesized, high yields are obtained only for allanite-(LREE) compositions, and end"member composition is obtained only for allanite-(La). Er and Yb ions are too small to substitute at the A(2) site in allanite, but a small amount can substitute at the VI~coordinated M(3) site. Fe²+ in the M(3) site favors LREE substitution, which supports the contention that allanite is Ce'selective.Ph. D.
49
Li, King Fai. "Photoluminescent mechanism of trivalent lanthanide organic complexes." HKBU Institutional Repository, 2002. https://repository.hkbu.edu.hk/etd_ra/364.
Full text
50
Engilberge, Sylvain. "Nouveaux développements en biologie structurale basés sur des complexes de lanthanide." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY094/document.
Full textAbstract:
Depuis les premières structures de protéines déterminées dans les années 1950, la cristallographie aux rayons X s’est imposée comme une méthode de choix pour l’obtention de données structurales à l’échelle atomique. Malgré les progrès technologiques qui ont révolutionné cette méthode (sources synchrotron, détecteurs pixel, programmes informatiques performants), l’obtention d’une carte de densité électronique permettant de modéliser la structure d’une macromolécule demeure toujours limitée par deux goulots d’étranglement qui sont, l’obtention de cristaux de la macromolécule d’intérêt et la résolution du problème des phases inhérent à l’enregistrement des données de diffraction.Cette thèse présente un nouveau complexe de lanthanide appelé « crystallophore » (Tb-Xo4). Cette molécule a été développé en collaboration avec Olivier Maury et François Riobé du laboratoire de chimie Matériaux Fonctionnels et Photonique (ENS –Lyon). La conception de ce nouveau complexe est basée sur quinze années de développement dans le domaine de la biologie structurale. Cette thèse présente les effets uniques induits par de Tb-Xo4 sur la cristallisation et sur la détermination des structures de macromolécules biologiques. L’ajout de Tb-Xo4 au cours de la cristallisation permet d’induire un nombre important de conditions de cristallisation exploitables dont certaines sont propres à la présence du crystallophore. L’analyse des structures atomiques de différentes protéines co-cristallisées en présence de Tb-Xo4 a permis à la fois de mettre en avant le pouvoir phasant élevé de Tb-Xo4 mais également de décrire finement l’interaction supramoléculaire du complexe avec la surface des macromolécules. Ce travail a conduit à la mise en place de protocoles de cristallisation et de phasage des macromolécules biologique assistés par Tb-Xo4. Sur la base de la compréhension du mode d’interaction de ce nouveau composé, cette thèse aboutit à la proposition d’un modèle expliquant les propriétés uniques de ce nouveau complexe de lanthanideSince the first protein structure determined in the 1950s, X-ray crystallography emerged as a method of choice to obtain structural data at atomic resolution. Despite technological advances such as new synchrotron sources, hybrid pixel detectors, and high-performance softwares, obtaining an electron density map of a biological macromolecule is always limited by two major bottlenecks namely, producing high quality single crystals and solving the phase problem.This thesis presents a new lanthanide complex called “Crystallophore” (Tb-Xo4). This compound has been developed in collaboration with Olivier Maury and François Riobé of the Laboratoire de chimie Matériaux Fonctionnels et Photonique (ENS –Lyon). The design of this new complex is based on fifteen years of development in the field of structural biology. This thesis highlights the effects of Tb-Xo4 on the crystallisation and the structure determination of biological macromolecules. Indeed, the addition of Tb-Xo4 to a protein solution induces a large number of new and unique crystallization conditions. The analysis of the structures of several proteins co-crystallized with Tb-Xo4 allowed both, to highlight the high phasing power of Tb-Xo4 but also to describe finely the supramolecular interaction of the complex with the macromolecules. This work led to protocols dedicated to crystallization and phasing assisted with Tb-Xo4. Finally, this thesis leads to a model explaining the unique properties of this new lanthanide complex