Tesi: "Alkaline Earth Metal hydrides"

1

Santoru, Antonio [Verfasser]. "Insights into the structure and reaction mechanism of alkali and alkaline-earth metal amide-metal hydride composite systems for hydrogen storage / Antonio Santoru". Hamburg : Helmut-Schmidt-Universität, Bibliothek, 2018. http://d-nb.info/1162510706/34.

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2

Verbraeken, Maarten Christiaan. "Doped alkaline earth (nitride) hydrides". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/714.

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3

Treuil-Dussouet, Félix. "Photoconductivity in rare earth metal-oxy-hydrides". Thesis, Uppsala universitet, Materialteori, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-416695.

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In this project the evolution of resistivity under light exposition in materials like rare earth metal-oxy-hydrides is studied. These materials observe a decrease of the resistance when exposed under the light of a 19,5 W power lamp, and slowly tend to return to their initial resistance. After having developed a resistance measurement setup, the photoconductivity of different samples (Gd, YHO) was measured in function of the oxygen concentration and in different conditions such as the face of illumination.

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4

Pianalto, Frederick Scott 1961. "Laser spectroscopy of strontium-sulfide and alkaline earth monoborohydrides". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276739.

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Three gas phase alkaline earth molecules were analyzed using dye laser spectroscopy. The A¹Σ⁺ - X¹Σ⁺ transition of gas phase SrS was studied with high resolution techniques. The 0-0, 0-1, 1-1, 2-1, 3-0, 3-2, 4-1, 5-1, and 5-2 bands were rotationally analyzed and spectroscopic constants were determined. The A¹Σ⁺ state was extensively perturbed. Ground state (X¹Σ⁺) constants derived from the analysis of the nine vibrational levels include: ωₑ = 388.2643 cm⁻¹, Bₑ = 0.1208034(33) cm⁻¹, and rₑ = 2.439687(14) Å. Excited state (A¹Σ⁺) constants determined include: Tₑ = 13932.7068(10) cm⁻¹, ωₑ = 339.1454(20) cm⁻¹, Bₑ = 0.1139895(38) cm⁻¹, and rₑ = 2.511601(17) Å. The spectra of calcium and strontium borohydrides were observed using low resolution laser spectroscopy. The spectra were assigned to the Ã²A₁ - Ẋ²A₁ and Ḃ²E - Ẋ²A₁ transitions of CaBH₄ and SrBH₄. The vibrational frequencies of the metal-ligand stretch determined for CaBH₄ were 457 cm⁻¹ (Ẋ²A₁), 473 cm⁻¹ (Ā²A₁), and 465 cm⁻¹ (Ḃ²E). The corresponding SrBH4 frequencies were 399 cm⁻¹, 420 cm⁻¹, and 421 cm⁻¹.

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5

Blake, Matthew Paul. "Alkaline earth- and rare earth-transition metal complexes". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d14f9c15-ec66-4317-82df-04d6ba1d4899.

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This Thesis describes the synthesis and characterisation of new alkaline earth- and rare earth-transition metal complexes. Experimental and computational studies were performed to investigate the structure and bonding in these complexes. Their reactivity was also studied. Chapter 1 introduces metal-metal bonded complexes and current alkaline earth- and rare earth-transition metal bonded complexes. Chapter 2 describes experimental and computational studies of new alkaline earth- and lanthanide-Fe complexes possessing the [CpFe(CO)2]- anion. Chapter 3 presents experimental studies of the reduction of Fe3(CO)12 with Ca. Chapter 4 describes experimental and computational studies of new alkaline earth- and lanthanide-Co complexes containing the [Co(CO)3(PR3)]- anion. Chapter 5 presents full experimental procedures and characterising data for the new complexes reported. Appendix describes the attempted synthesis of [Ca{CpRu(CO)2}2(THF)x]y and study by DFT of [CaRp2(THF)3]2 CD Appendix contains .cif files for all new crystallographically characterised complexes described.

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6

Huadsai, Wimonsiri. "Activation du dioxyde de carbone par des composés de Lewis hautement acidés". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES053.

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Cette recherche visait à étudier les applications potentielles des complexes d'hydrure de Mg et de Ca soutenus par des ligands ß-diketiminate et amidinate pour la réduction des molécules de CO2. Les capacités catalytiques de ces complexes ont été explorées dans le contexte de l'hydroboration et de l'hydrosilylation du CO2. Dans la première partie de l'étude, nous avons examiné la réactivité des hydrures ß-diketiminato de Mg et de Ca avec le CO2. Il a été observé que le complexe d'hydrure de Mg incorporait rapidement le CO2, conduisant à la formation de divers intermédiaires avec différentes nucléarités. Cela implique l'insertion de la liaison Mg—H dans le CO2, ce qui entraîne la génération de groupements formate. Sous l'effet de la chaleur, des complexes de formiate hexamériques ont été formés par un mécanisme de "retournement de ligand", libérant les entraves stériques autour des centres métalliques. Pour les réactions à l'hydrure de Ca et au CO2, l'analyse RMN in situ a été principalement réalisée. En outre, un nouveau complexe amidinate dihydride de Mg a été synthétisé avec succès et a réagi avec du CO2 pour donner un produit unique de complexe formate Mg dimérique, contrairement à l'échafaudage ß-diketiminate, où plusieurs espèces de formate ont été détectées. La deuxième partie de la recherche s'est concentrée sur l'hydroboration catalytique du CO2 à l'aide de complexes d'hydrures alcalino-terreux. En particulier, le système à base de Ca a démontré une grande efficacité dans la production de la réduction à quatre électrons du CO2 ou du produit BBA. Il s'agit du premier exemple d'utilisation de composés hydrides de Mg et de Ca pour catalyser l'hydroboration du CO2, produisant sélectivement le produit BBA. Le BBA généré in situ a ensuite été utilisé comme réactif de transfert de méthylène dans des réactions de condensation avec des thiols, ce qui a entraîné la formation de nouveaux composés hémithioacétals stables [RS—CH2—OBR2] dans des conditions douces et neutres. L'activation des composés hémithioacétals a été réalisée dans des conditions acides, conduisant à la formation de dithioacétals et d'hémithioaminals. La condensation du deuxième fragment OBR2 avec des amines secondaires, qui agissent comme des nucléophiles plus puissants, a abouti à la génération de sulfures d'aryle et de méthyle [RS—CH2—NR2]. Dans la dernière section, nous avons étudié l'hydrosilylation en tandem du CO2 en utilisant divers hydrosilanes en combinaison avec des complexes d'hydrures à base de [Ae] et l'acide de Lewis B(C6F5)3 comme catalyseurs. Cette recherche a élargi les études précédentes sur l'hydrosilylation du CO2 médiée par le Mg et a introduit le premier exemple d'hydrosilylation du CO2 catalysée par le Ca avec des hydrosilanes. L'efficacité de la réduction du CO2 en CH4 ou en bis(silyl)acétal [H2C(Ph3SiO)2] ou en BSA dépend de la nature des silanes et des encombrements stériques autour de la liaison Si—H du substrat. Le choix du catalyseur [Ae] a également influencé de manière significative la vitesse globale de la réaction. En outre, les analyses d'Eyring et d'Arrhenius ont permis de mieux comprendre les paramètres d'activation de la réduction du CO2 par certains catalyseurs, révélant que cette réaction est principalement régie par une contribution entropique. En résumé, cette recherche a démontré la réactivité des complexes d'hydrure de Mg et de Ca pour la réduction du CO2 et a exploré leurs applications dans les réactions d'hydroboration et d'hydrosilylation. Les recherches futures pourraient explorer les possibilités mécanistiques, les différences cinétiques et la réactivité des complexes d'hydrures métalliques du groupe 2 avec le monoxyde de carbone pour l'homologation du CO
This research aimed to investigate the potential applications of Mg and Ca hydride complexes supported by ß-diketiminate and amidinate ligands for the reduction of CO2 molecules. The catalytic abilities of these complexes were explored in the context of hydroboration and hydrosilylation of CO2. In the first part of the study, we examined the reactivity of ß-diketiminato Mg and Ca hydrides with CO2. It was observed that the Mg hydride complex rapidly incorporated CO2, leading to the formation of various intermediates with different nuclearities. This involved the insertion of Mg—H bond into CO2, resulting in the generation of formate moieties. Under heat, hexameric formate complexes were formed through a "ligand flip" mechanism, releasing steric hindrances around the metal centers. For Ca hydride and CO2 reactions, in situ NMR analysis was mainly conducted. Additionally, a novel Mg amidinate dihydride complex was successfully synthesized and reacted with CO2 to yield a unique single product of dimeric formate Mg complex, in contrast to the ß-diketiminate scaffold, where several formate species were detected. The second part of the research focused on the catalytic hydroboration of CO2 using alkaline-earth hydride complexes. In particular, the Ca-based system demonstrated high efficiency in the production of the four-electron reduction of CO2 or BBA product. This was the first example of using Mg and Ca hydride compounds to catalyze the hydroboration of CO2, selectively producing the BBA product. The in situ generated BBA was further used as a methylene transfer reagent in condensation reactions with thiols, resulting in the formation of novel stable hemithioacetal [RS—CH2—OBR2] compounds under mild and neutral conditions. Activation of the hemithioacetal compounds was achieved under acidic conditions, leading to the formation of dithioacetals and hemithioaminals. The condensation of the second OBR2 fragment with secondary amines, which act as stronger nucleophiles, resulted in the generation of aryl methyl sulfides [RS—CH2—NR2]. In the final section, we investigated the tandem hydrosilylation of CO2 using various hydrosilanes in combination with [Ae]-based hydride complexes and Lewis acid B(C6F5)3 as catalysts. This research expanded on previous studies of Mg-mediated hydrosilylation of CO2 and introduced the first example of Ca-catalyzed CO2 hydrosilylation with hydrosilanes. The effectiveness of reducing CO2 to CH4 or bis(silyl)acetal [H2C(Ph3SiO)2] or BSA depended on the nature of the silanes and the steric hindrances around the substrate Si—H bond. The choice of [Ae] catalyst also significantly influenced the overall reaction rate. Furthermore, Eyring and Arrhenius analyses provided insight into the activation parameters for reducing CO2 by certain catalysts, revealing that this reaction is primarily governed by an entropic contribution. In summary, this research has demonstrated the reactivity of Mg and Ca hydride complexes for CO2 reduction and explored their applications in hydroboration and hydrosilylation reactions. Future investigations may explore mechanistic possibilities, kinetic differences, and the reactivity of group 2 metal hydride complexes with carbon monoxide for CO homologation

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7

Rees, David Alan. "Synthesis of alkaline earth transition metal sulfides". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311775.

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8

Liang, Tao. "Chiral Phosphoric Acids and Alkaline Earth Metal Phosphates Chemistry". Thesis, University of South Florida, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3632228.

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Asymmetric synthesis and catalysis is one of the leading research areas in chemistry society, for its versatility and efficiency in obtaining chiral molecules that found the vast majority in natural active compounds and synthetic drugs. Developing asymmetric catalytic methodology is at the frontier in both industrial and academic research laboratories. Enantioselective organocatalysis has emerged as a powerful synthetic tool that is complementary to metal-catalyzed transformations. The development of chiral phosphoric acid and metal phosphate as catalysts has been a breakthrough in recent years. Chiral phosphoric acids have been shown to be powerful catalysts in many organic transformations. Moreover, chiral metal phosphates, which formed by simply replacing the proton in phosphoric acid with metals, have introduced new catalytic activations and broaden the scope of phosphoric acids. This thesis details new highly enantioselective chiral phosphoric acid-catalyzed Pinacol rearrangement and robust alkaline phosphates catalytic system, which utilizes novel carbonyl activation.

The Pinacol rearrangement has long been known to be difficult to control in terms of regioselectivity and stereoselectivity. The initial studies found that indolyl-diol compounds can be treated with chiral phosphoric acids to afford the Pinacol rearrangement with high regio- and enantioselectivity. Over 16 chiral phosphoric acids were screened, and it was found an H8-BINOL-phosphoric acid variant with 1-naphthyl groups at 3 and 3' position was the excellent catalyst. This asymmetric transformation is tolerant toward variety of substituents both on the indole ring and migrating groups.

During the study, it was found that different ways to generate the catalyst had critical effect on this catalytic transformation. Only those phosphoric acids washed with HCl after column chromatography afforded the rearrangement products with high enantioselectivity. And those without treating with HCl were found contaminated by alkaline metals. These "contamination" catalysts were also found active with carbonyl activations.

A highly enantioselective catalytic hetero-Diels-Alder reaction of alpha-keto esters has been developed with chiral alkaline metal phosphates. A calcium 1-naphthyl-BINOL phosphate was found to be the optimum catalyst. A large range of alpha-keto esters as well as isatins can be applied in this alkaline phosphates catalytic system with high efficiency and selectivity. The structure of the catalyst is detailed for the first time by X-ray crystal structure analysis. A proposed Transition state model is provided based on the catalyst crystal structure and Raman spectroscopy analysis.

This methodology was further developed with an asymmetric Mukaiyama-Michael addition of beta,gamma-unsaturated alpha-keto ester. The best catalyst was found to be a magnesium chiral phosphate. And the transformation was found capable of tolerating a wide variety of beta,gamma-unsaturated alpha-keto esters.

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9

Hamdy, Louise. "Developing new hydrogen bonded alkaline earth metal-organic complexes". Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675739.

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This investigation addresses the understudied area of the research and development of hydrogen bonded metal-organic complexes featuring the alkaline earth metals magnesium and calcium. This work presents the crystal structures and thermal behaviour of a series of metal-organic and organic crystalline complexes synthesised from metal salts and pyridine carboxylic, dicarboxylic acid and chloranilic acid ligands, characterised primarily by X-ray diffraction. Chapter 1 introduces crystal engineering, intermolecular interactions, and functional crystalline materials, followed by a literature review addressing metal-organic frameworks (MOFs), hydrogen bonded metal-organic complexes, magnesium MOFs and alkaline earth metal complexes synthesised from pyridine carboxylic, dicarboxylic and tricarboxylic acid and chloranilic acid. Chapter 2 outlines the theory of the techniques used to analyse the synthesised materials, focusing on single crystal X-ray diffraction, followed by Chapter 3 which documents the sample preparation and the experimental details. Chapter 4 describes the crystal structures of fourteen coordination complexes synthesised from magnesium and calcium salts and the three isomers of pyridine carboxylic acid. This work was carried out in order to identify structural trends such as the most common coordination geometries of the metal centres, the ways in which the ligands coordinate and any recurring hydrogen bonding motifs. Chapter 5 discusses attempts to synthesise an alkaline earth metal analogue of a metal-containing ‘metalloligand’ of the formula M(C7H4NO4)2(H2O)2, in which the metal (M) is N,O-chelated by pyridine-2-carboxylate-4-carboxylic acid, and the subsequent combination of these materials with the diamines o-tolidine and m-xylylenediamine. This chapter also reports the structure of a magnesium coordination complex resulting from a hydrothermal reaction, and the subsequent transformation of this complex to a new crystal structure which contains the doubly deprotonated magnesium analogue of the originally targeted ‘metalloligand’. Chapter 6 describes the crystal structures of three complexes synthesised from pyridine carboxylic acids and chloranilic acid, and the complex resulting from the combination of one of these organic ‘supramolecular ligands’ with a copper salt. Finally, two new calcium-chloranilate coordination polymers are reported, one of which has an interesting anionic 3D structure.

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10

Gillett-Kunnath, Miriam M. "Heavy alkaline earth metal amides: Synthetic and structural investigations". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.

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11

Hitzbleck, Julia Ruhlandt-Senge Karin. "Syntheses and structural survey of novel alkaline earth and rare earth metal complexes". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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12

Vargas, Gregory Wilda Ruhlandt-Senge Karin. "Nitrogen-based alkaline earth metal compounds syntheses, structures and applications /". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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13

Reid, Stephanie. "Heavier alkaline earth metal catalysis and application to organic synthesis". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/61488.

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This thesis describes the application of complexes of heavier alkaline earth metals to the intramolecular hydroalkoxylation/cyclisation of alkynyl and allenyl alcohols and in addition, to the hydroamination of polyunsaturated arenes. Cyclisation of alkynyl alcohols was achieved using [Ae{N(SiMe3)2}2] (Ae = Ca, Sr, Ba) in the formation of five- and six-membered enol ethers. The cyclisations produced mixtures of the possible endo- and exocyclic enol ether products, rationalised as a consequence of alkyne/allene isomerisation. Although a ‘catalyst of choice’ could not be deduced, [Ba{N(SiMe3)2}2] proved highly effective in these cyclisations. Extension of the hydroalkoxylation towards tandem C−O/C−C formation was attempted with dialkynyl alcohols but in all cases led to monocyclisation of the substrates. Catalytic tandem C−N bond-forming reactions have been successfully applied to the double hydroamination of polyunsaturated arenes using heteroleptic complexes of the type [LAe{N(SiMe3)2}(THF)n] (Ae = Ca, Sr, Ba). Chemo- and regioselective hydroamination reactions are coupled in sequence to construct tetrahydroisoquinoline frameworks. The amine scope of these reactions was determined and results have shown that these regioselective transformations occur under significant stereoelectronic control.

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14

Bradwell, David (David Johnathon). "Liquid metal batteries : ambipolar electrolysis and alkaline earth electroalloying cells". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62741.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 198-206).
Three novel forms of liquid metal batteries were conceived, studied, and operated, and their suitability for grid-scale energy storage applications was evaluated. A ZnlITe ambipolar electrolysis cell comprising ZnTe dissolved in molten ZnCl 2 at 500 0C was first investigated by two- and three-electrode electrochemical analysis techniques. The electrochemical behavior of the melt, thermodynamic properties, and kinetic properties were evaluated. A single cell battery was constructed, demonstrating for the first time the simultaneous extraction of two different liquid metals onto electrodes of opposite polarity. Although a low open circuit voltage and high material costs make this approach unsuitable for the intended application, it was found that this electrochemical phenomenon could be utilized in a new recycling process for bimetallic semiconductors. A second type of liquid metal battery was investigated that utilized the potential difference generated by metal alloys of different compositions. MgjlSb cells of this nature were operated at 700 °C, demonstrating that liquid Sb can serve as a positive electrode. Ca,MgIIBi cells also of this nature were studied and a Ca,Mg liquid alloy was successfully used as the negative electrode, permitting the use of Ca as the electroactive species. Thermodynamic and battery performance results suggest that Ca,MgIISb cells have the potential to achieve a sufficient cell voltage, utilize earth abundant materials, and meet the demanding cost and cycle-life requirements for use in grid-scale energy storage applications.
by David J. Bradwell.
Ph.D.

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15

Kumar, R. "Synthesis and molecular catalysis with organo- alkaline earth metal complexes". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2022. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/6167.

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16

Bezougli, Izoldi P. "Insertion reactions of Group 2 metal alkoxides". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484172.

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17

Robinson, Alex Lockwood. "Sonoluminescence for the quantitative analysis of alkali and alkaline earth chlorides /". Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8687.

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18

Sánchez, José Adán Reyes. "Synthesis and reactivity of alkaline earth and aluminium gallyl complexes". Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:5bf3dc4e-9cd6-4080-8f5f-9097e84ba12b.

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This Thesis describes the synthesis and characterisation of new alkaline earth metal and aluminium gallyl complexes. Experimental studies were performed to investigate their structure. The reactivity of these species was also studied. Chapter 1 introduces metal-metal bonded complexes containing alkaline earth metals and aluminium and the use of gallium(I) analogues of N-heterocyclic carbenes in the synthesis of heterobimetallic complexes of gallium. Chapter 2 describes the synthesis and reactivity of alkaline earth gallyl complexes supported by beta-diketiminate ligands. Chapter 3 presents the synthesis and reactivity of alkaline earth gallyl complexes supported by the carbazolide ligand CzOx. Chapter 4 describes synthesis of aluminium-gallium bonded complexes supported by amidinate and b-diketiminate ligands and the attempted study of their reactivity. Chapter 5 presents full experimental procedures and characterising data for the new complexes reported.

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19

Jones, Sally Anne. "Alkali and alkaline earth metal fluoride mediated aromoatic halogen exchange reactions". Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367085.

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20

Nimmagadda, Sri Krishna. "Asymmetric Transformations Catalyzed By Chiral BINOL Alkaline Earth Metal Phosphate Complexes". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6554.

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Small molecule hydrogen bond donors have emerged as versatile catalysts in asymmetric synthesis. Within this class, chiral BINOL phosphoric acid is regarded as one of the pioneer catalysts used in several asymmetric transformations. The ability of the catalyst to activate the substrates could be controlled in two different ways. (1) Dual activation/bifunctional activation of substrate by hydrogen bond interactions or ion pairing with phosphoric acid or (2) By forming chiral BINOL phosphate metal complex that could significantly alter the interactions in chiral space. In particular, chiral alkaline earth metal phosphate complexes have unique advantages as catalysts owing to the ubiquitous availability of alkaline earth metals, strong Brønsted basicity of their counterions, mild but significant Lewis acidity of the metal and their ability to coordinate at multiple reactive sites due to large ionic radius. Chapter 1 summarizes the recent development of alkaline earth metal complexes in asymmetric catalysis. My thesis dissertation is focused on the application of chiral alkaline earth metal phosphate complexes in novel asymmetric reactions. In Chapter 2, we disclosed an efficient asymmetric one-pot synthesis of chiral 1,3-oxazolidines and chiral 1,3-oxazinanes. Chiral oxazolidines and oxazinanes are widely used as auxiliaries in asymmetric transition metal catalysis and also key structural motifs in natural products with biological activities. We developed a new synthetic method for chiral 1,3-oxazolidines which follows the enantioselective addition of alcohols to imines catalyzed by chiral 3,3’-(triisopropylphenyl)-derived BINOL magnesium phosphate to form hemiaminal intermediate, which then undergoes mild base mediated intramolecular nucleophilic substitution to afford highly enantioselective 1,3-oxazolidines and 1,3-oxazinanes in good yields. In Chapter 3, we developed the first catalytic enantioselective desymmetrization process for the synthesis of novel axially chiral cyclohexylidene oxime ethers. Even though these molecules were found to be optically active in 1910, methods to synthesize these molecules are scarce. We have developed an efficient desymmetrization process of 4-phenyl cyclohexanones with phenoxyamines catalyzed by chiral BINOL strontium phosphate complex to afford highly enantioselective products. We then extended this methodology to the dynamic kinetic resolution of 2-substituted cyclohexanones to form chiral 2-substituted cyclohexyl oximes in good enantioselectivities, as demonstrated in Chapter 4. We further demonstrated the utility of these compounds by converting them to chiral 2-aryl cyclohexylamines which are important synthetic intermediates.

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21

Ekvall, Katrin. "Time resolved laser spectroscopy : non-linear polarisation studies in condensed phase and lifetime studies of alkaline earth hydrides /". Stockholm, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3063.

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22

Witherow, Rebecca A. "Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-Basin Lakes". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250628213.

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23

Hill, Matthew Roland Chemistry Faculty of Science UNSW. "The single source chemical vapour deposition of alkaline earth metal oxide thin films". Awarded by:University of New South Wales. School of Chemistry, 2006. http://handle.unsw.edu.au/1959.4/32903.

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Metal oxide thin films are dynamic materials that have revolutionised the nature of semiconductor and electronic thin film devices. Recently, progress has stagnated in some aspects due to the increasingly complex deposition apparatus required, and the dearth of suitable precursor complexes of certain ???difficult??? metals. This thesis seeks to address both of these issues. The application of a precursor complex, Mg6(O2CNEt2)12 to the SSCVD of MgO thin films delivered the highest quality films ever reported with this technique. The resultant films were found to be of purely (111) orientation. Due to the nature of the precursor, the chemical reactions occurring at the surface during SSCVD growth result in a high growth rate, low flux environment and films of (111) orientation have been achieved without the amorphous underlayer. This finding has important implications for buffer layers in perovskite thin film devices. The unprecedented precursor chemistry has been used as a basis for the extremely high quality material produced, along with the unusual, yet beneficial structural morphology it possesses. A new range of barium complexes with single encapsulating ligands have been prepared for use in chemical vapour deposition (CVD) of BaTiO3 thin films. A novel pathway to an unprecedented class of barium carbamates is reported, and also new dianionic bis ??-ketoesterates and their barium, strontium, and calcium analogues were synthesised. High resolution mass spectrometry showed the barium bis ??-ketoesterate derivatives to be monomeric, and preliminary testing indicated some volatility in these species. Insights were gained into the likely successful pathways to building a volatile heterobimetallic precursor complex containing an alkaline earth metal. The knowledge of intimate mixing in heterobimetallic precursor complexes was extended by some novel chemistry to develop the first mixed Zn/Mg carbamato cluster complexes. These complexes were found to be excellent SSCVD precursors for ZnxMg1-xO thin films. Thin films were deposited with these precursors and exhibited a single preferred orientation, with a constant amount of magnesium throughout the bulk of the films. Investigation of the light emission properties of the films revealed significant improvements in the structural order commensurate with the incorporation of magnesium, and the formation of the ZnxMg1-xO alloy.

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24

Demydov, Dmytro V. "Nanosized alkaline earth metal titanates : effects of size on photocatalytic and dielectric properties". Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/177.

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25

Davidson, Matthew Gwilym. "Alkali and alkaline earth metal complexes of multifunctional amines : syntheses, structures and uses". Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272659.

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26

Frankland, Andrew D. "Studies on organic compounds of the group II metals Ca, Sr and Ba". Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336274.

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27

Sobaczynski, Adam [Verfasser], e Rhett [Akademischer Betreuer] Kempe. "Alkane Elimination Reactions between Transition Metal Hydrides and Rare-Earth Alkyls / Adam Sobaczynski. Betreuer: Rhett Kempe". Bayreuth : Universität Bayreuth, 2014. http://d-nb.info/1060010151/34.

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28

Yadav, S. "Preparation of well-defined alkaline earth metal complexes and their applications in molecular catalysis". Thesis(Ph.D.), CSIR National Chemical Laboratory, Pune, 2019. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4572.

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29

Tulyapitak, Tulyapong. "CURE AND MECHANICAL PROPERTIES OF CARBOXYLATED NITRILE RUBBER (XNBR) VULCANIZED BY ALKALINE EARTH METAL COMPOUNDS". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1158067153.

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30

Fleming, Kathleen. "The Gas-Phase Ligand Exchange of Select Alkaline Earth and Transition Metal ß-diketonate Complexes". Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1465062889.

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31

Zuniga, Maria Felisa A. "Progress in molecular heterobimetallic alkaline earth metal chemistry New synthetic strategies, structural features and properties /". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.

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32

Chen, Chun-che. "Correlation between electrical and magnetic properties in alkali and alkaline earth metal doped lanthanum manganites /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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33

Xiao, Xingxing [Verfasser], Anke [Akademischer Betreuer] Weidenkaff e Rainer [Akademischer Betreuer] Niewa. "Thermoelectric Properties of Alkaline Earth Metal Substituted Europium Titanates / Xingxing Xiao ; Anke Weidenkaff, Rainer Niewa". Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/1225865751/34.

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34

Diteepeng, Nichabhat. "Alkaline earth hydroborate complexes for the ring-opening polymerisation of cyclic esters". Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:d5b45f1c-b8a9-41da-a967-7f569b69aa35.

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Abstract (sommario):

This Thesis describes the activity and mechanism of alkaline earth organohydroborate, tetrahydroborate and alkoxide catalysts for the ring-opening polymerisation (ROP) of cyclic esters including rac-, L-, D- and meso-lactide (LA), and rac-β-butyrolactone (rac-BBL). Chapter One introduces cyclic esters and general mechanisms for their ROP to give polyesters. Living and immortal ROP, an overview of stereocontrolled ROP, and determination of polylactide (PLA) stereosequences are given. Various techniques for polymer characterisations are also described. Chapter Two describes the activity and mechanism of heavy alkaline earth organohydroborate complexes for the ROP of LA. The synthesis and characterisation of alkaline earth alkoxide complexes serving as model species are also described, together with their activities for the ROP of LA. Chapter Three describes the activity and mechanism of a cyclic organohydroborate calcium complex for the ROP of LA. The role of borinic esters as chain transfer agents in the ROP of rac-LA is also discussed. Chapter Four describes the activity and mechanism of heavy alkaline earth tetrahydroborate complexes for the ROP of LA. The immortal ROP of rac-LA using heavy alkaline earth alkoxide complexes and borate esters as chain transfer agents is discussed. Chapter Five describes the activity and mechanism of alkaline earth organohydroborate, tetrahydroborate and alkoxide complexes for the ROP of rac-BBL. Chapter Six presents experimental procedures and characterising data for new complexes reported.

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35

Sturgeon, Matthew Robert. "Cyanide Bridged Multimetallics Derived From Extended Arrays of Alkaline Earth, Rare Earth, and Transition Metals: A Study From Complexes To Catalysts". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250009077.

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36

O'Brien, Anna Yosick. "Advances in the design of heavy alkaline earth metal complexes as precursors for chemical vapor deposition". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.

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37

Vilayannur, Sitaraman. "Fundamental mechanisms of oxidation of alkaline earth bearing metal precursors : Y-Ba-Cu-Ag-Pd and Ag?Ba /". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488193272067643.

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38

Potratz, Christopher M. "The Synthesis, Structure and Characterization of Extended Cobalt Ruthenium Carbonyl Compounds". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275413923.

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39

Teng, Weijie Ruhlandt-Senge Karin. "From polymerization initiators to precursors for solid-state materials syntheses and structures of a series of molecular alkali and alkaline earth metal derivatives /". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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40

Siggelkow, Lisa [Verfasser], Thomas F. [Akademischer Betreuer] Fässler e Wolfgang [Akademischer Betreuer] Domcke. "Synthesis, Characterization and Computational Studies of Binary and Ternary Intermetallic Compounds in the Systems Alkaline Earth Metal, Transition Metal, Tetrel Element / Lisa Siggelkow. Gutachter: Wolfgang Domcke. Betreuer: Thomas F. Fässler". München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1029350175/34.

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41

Ballmann, Gerd [Verfasser], Sjoerd [Akademischer Betreuer] Harder, Romano [Gutachter] Dorta e Norbert [Gutachter] Jux. "Encapsulating Dipyrromethene Ligands for the Stabilization of Low-Coordinate Alkaline Earth and Zinc Metal Complexes / Gerd Ballmann ; Gutachter: Romano Dorta, Norbert Jux ; Betreuer: Sjoerd Harder". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1202608477/34.

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42

Marchuk, Alexey [Verfasser], e Wolfgang [Akademischer Betreuer] Schnick. "Mineralizer-assisted high-pressure high-temperature synthesis and characterization of novel phosphorus nitride imides and luminescent alkaline earth metal (oxo)nitridophosphates / Alexey Marchuk. Betreuer: Wolfgang Schnick". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1098130766/34.

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43

Margadonna, Sarena. "Fulleride salts : from polymers to superconductors". Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323048.

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44

Gagné, Olivier C. "Bond lengths and bond valences of ions bonded to oxygen: their variability in inorganic crystals". Acta Crystallographica B, 2015. http://hdl.handle.net/1993/31697.

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Abstract (sommario):

A large amount of information concerning interatomic distances in the solid state is available, but little has been done in recent times to comprehensively filter, summarize and analyze this information. Here, I examine the distribution of bond lengths for 135 ions bonded to oxygen, using 180,331 bond lengths extracted from 9367 refined crystal structures collected from the Inorganic Crystal Structure Database (ICSD). The data are used to evaluate the parameterization of the bond-length—bond-valence relation of the bond-valence model. Published bond-valence parameters for 135 cations bonded to oxygen, and the various methods used in their derivation, are evaluated. New equations to model the relation are tested and the common form of the equation is found to be satisfactory. A new method (the Generalized Reduced Gradient Method, GRG method) is used to derive new bond-valence parameters for 135 cations bonded to oxygen, leading to significant improvements in fit for many of the ions. The improved parameterization is used to gain crystal-chemical insight into the milarite structure. A literature review of 350+ published compositions is done to review the end-members of the milarite group and to identify compositions that should have been described as distinct minerals species. The a priori bond-valences are calculated for minerals of this structure, and are used to examine the controls of bond topology on site occupancy, notably by localizing the major source of strain of the structure (the B site). Examination of the compositions of all known milarite-group minerals shows that compositions with a fully occupied B site are less common than those with a vacant B site, in accord with the idea that the B site is a local region of high strain in the structure. The bond-length distributions for the ions of the alkali and alkaline-earth metal families are examined. Variations in mean bond-lengths are only partly explained by the distortion theorem of the bond-valence model. I have found that bond length also correlates with the amount of vibrational displacement of the constituent ions. The validity of some uncommon coordination numbers, e.g., [3]-coordinated Li+, [3]-coordinated Be2+, is confirmed.
October 2016

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45

Köhne, Ingo. "Novel Bulky Bis(benzoxazol-2-yl)methane Ligands in s-Block Metal Coordination". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E3E8-1.

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46

Barbosa, Helliomar Pereira. "Síntese e estudo da luminescência de matrizes de tungstatos dopadas com íons terras raras". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-22102013-110137/.

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Abstract (sommario):

Materiais luminescentes contendo íons terras raras (TR3+) dopados nas matrizes de tungstatos [WO4]2- têm se mostrado excelentes candidatos como fósforos. Portanto, neste trabalho os materiais MWO4:TR3+ (M: Ca2+, Sr2+, Ba2+ e TR3+: Eu, Tb) foram preparados pelo método da coprecipitação com concentração de dopantes 0,1, 1,0, 5,0 e 10 % em mol. Este método comparado aos convencionais (cerâmico, combustão etc.), apresenta vantagens por ser um método simples de operação e rápido, baixo custo, preparado a temperatura ambiente, o processo de obtenção ambientalmente é correto e também produzem-se nanopartículas. Na caracterização destes fósforos foram utilizadas as técnicas: espectroscopia de absorção no infravermelho (IV), análise termogravimétrica (TG), difração de raios X - método do pó (DRX), microscopia eletrônica de varredura (MEV) e energia dispersiva de raios X (EDS). Os picos de difração de raios X foram indexados na estrutura tetragonal scheelita. Os fósforos dopados com Eu3+ e Tb3+ apresentaram cristalitos com dimensões nanométricas. Os estados de oxidação dos íons terras raras foram investigados com a espectroscopia de absorção de raios X com radiação Síncrotron (XANES), onde indicaram a presença apenas do estado trivalente para o európio nos materiais \"como preparados\" e calcinados. No entanto, foram detectados os estados trivalente e tetravalente do térbio dopado nas matrizes CaWO4 e BaWO4, calcinados à 500 ºC. As propriedades fotoluminescentes dos compostos foram investigadas com base nas transições intraconfiguracionais 4f6 (Eu3+) e 4f8 (Tb3+). Os espectros de excitação apresentaram bandas largas na região do UV, atribuídas às bandas de transferência de carga LMCT O→W e O→Eu3+. Os espectros de excitação dos fósforos MWO4:Tb3+ apresentaram as bandas de absorção largas atribuídas transferência de carga LMCT O2-(2p)→W6+(5d) sobrepostas às transições 4f8→4f75d e também picos finos oriundos das transições 4f8 do íon Tb3+. Ademais, os seus espectros de emissão exibiram bandas finas características das transições das 5D4→7FJ do íon térbio trivalente. Os valores altos do parâmetro de intensidade experimental (Ω2 ~18 x 10-20 cm2) indicam que o sítio de simetria ocupado pelo íon Eu3+ dopado nas matrizes de tungstatos não apresentam caráter centrossimétrico, uma vez que os altos valores de Ω2 são mais influenciados pelas pequenas mudanças angulares da geometria local do íon terra rara. Os valores de eficiência quântica de emissão η do nível 5D0 dos fósforos MWO4:Eu3+ estão em torno de 30 %, sugerindo que não há variação significativa quando se altera os íons metálicos alcalinos terrosos. As coordenadas CIE (Commission Internationale l\'Eclairage) sugerem emissões multicolores dos sistemas MWO4:Eu3+ X mol-% que podem ser ajustáveis, em função das intensidades de emissão das bandas largas LMCT e dos picos finos das transições 5D0→7F0-4 e da concentração de dopagem (X mol-%) do íon Eu3+. Estes materiais luminescentes exibem cores de emissão vermelha, verde assim como cores intermediárias.
Luminescent materials containing rare earth ions (RE3 +) doped in [WO4]2- tungstate matrices have demonstrated excellent candidates as phosphors. Therefore, in this work the materials MWO4:TR3+ (M: Ca2+, Sr2+, Ba2+ e TR3+: Eu, Tb) were prepared by the coprecipitation method with doping concentration 0.1, 1.0, 5.0 and 10% mol. This method compared to conventional ones (ceramic, combustion, etc.), has advantages because it is a simple operation and fast, low cost, prepared at room temperature, the process of obtaining is environmentally correct and also make up the nanoparticles. The characterization techniques of these phosphors were investigated by infrared absorption spectroscopy (IR), thermogravimetric analysis (TG), X-ray diffraction patterns - powder method (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDS). The tungstate matrices doped with Eu3+ and Tb3+ showed crystallite sizes with nanometer dimensions. The rare earth oxidation states were investigated using absorption spectroscopy X-ray synchrotron radiation (XANES), which indicated the presence of only trivalent europium state materials \"as prepared\" and calcined. However, it was observed the trivalent and tetravalent state of terbium doped in CaWO4 and BaWO4 matrices, calcined at 500 º C. The photoluminescent properties of the compounds were investigated based on 4f6 (Eu3+) and 4f8 (Tb3+) intraconfigurational transitions. The excitation spectra showed broad bands in the UV region, assigned to the bands of charge transfer LMCT O→W e O→Eu3+. The excitation spectra of MWO4Tb3+ phosphors showed the broad absorption bands attributed charge transfer LMCT O2-(2p)→W6+(5d) overlapping with 4f8→4f75d transitions and narrow peaks arising from 4f8 transitions of Tb3+ ion. Moreover, their emission spectra exhibited narrow characteristic bands assigned to the 5D4→7FJ transitions of trivalent terbium ion. The high values of experimental intensity parameters (Ω2 ~ 18 x 10-20 cm2) indicate that the site symmetry occupied by the Eu3+ ion doped in the tungstates matrix not present centrosymmetric character, since high values of Ω2 are more affected by small angular changes of the local geometry around of rare earth ion. The values of emission quantum efficiencies (η) of the 5D0 level MWO4:Eu3+ phosphors were at around 30%, suggesting that there is no significant variation when changing the alkaline earth metal ions. The CIE coordinates (Commission Internationale l\'Eclairage) data suggest multicolored emissions for the MWO4:Eu3+ X mol-% systems can be tuneable, which depending on the emission intensities of the LMCT broad bands and 5D0→7F0-4 narrow peaks and concentration doping (X mol-%) of the Eu3+ ion. These materials exhibit luminescent emissions with red, green and intermediate colors.

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47

Ganesan, Parameshwari. "Investigation of Luminescent Properties in Rare-Earth free Metallophosphonate Hybrid Materials : structural Insights in photophysical studies". Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMC266.

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Durant ce travail de thèse, les propriétés structurelles et photoniques des metallophosphonates luminescents hybrides ont été étudiées en abordant le rôle de leur structure dans les propriétés luminescentes. Les métallophosphonates possèdent différentes coordinations chimiques montrant leurs capacités à former plusieurs centres métalliques ainsi qu’une forte liaison chimique de type P-O-M. L’objective de ce travail est l’étude des matériaux hybrides organiques-inorganiques luminescents dont le composant organique offre une plateforme solide facilement amovible avec divers groupes fonctionnels. Cette étude s’articule sur différents metallophosphonates hybrides synthétisés par voie hydrothermale à l’aide de ligands organiques tels que le fluorène, le thianthrène et l’acide phosphonique avec des éléments alcalino-terreux (Mg, Ca, Sr, Ba) et des métaux de transitions (Mn, Co, Cu, Zn). Ces derniers ont été obtenus en manipulant la nature de la molécule, le nombre de groupes fonctionnels et les propriétés cationiques au sein de la structure. Grace à leurs caractéristiques liés à leurs différents arrangements structurels, les matériaux synthétisés montrent diverses propriétés, notamment la rigidité et la stabilité thermique. De plus, ces matériaux montrent des propriétés de luminescences intéressantes tel que la fluorescence, phosphorescence à température ambiante (PTA), les déplacements bathochrome et hypsochrome, l’émission de type excimère ainsi que l’apparition de nouvelles bandes de luminescence rouge et verte pour certains cations spécifiques. Enfin, la variation des propriétés de composés hybrides en fonction de la structure est discutée, en tenant compte le phénomène d’émission induite par Agrégation (AIE) et d’émission améliorée par agrégation (AEE)
This thesis work systematically investigates the structural and photophysical properties of rare-earth-free metallophosphonate hybrid luminescent materials, emphasizing the role of structure in luminescent properties. Metallophosphonates demonstrate exceptional versatility with their coordination chemistry, highlighted by their ability to interact with multiple metal centers and form robust P-O-M metal bonds. We aim to study crystalline organic-inorganic hybrid luminescent materials in which the organic part provides a rigid platform which is easily modifiable with various functional groups. we present various metallophosphonate hybrids synthesized through the hydrothermal route using functionalized organic ligands such as Fluorene, Thianthrene, and Tetraphenylethylene (TPE) phosphonic acid with different alkaline-earth elements (Mg, Ca, Sr, Ba) and transition elements (Mn, Co, Cu, Zn). Different metallophosphonate materials are obtained by manipulating the nature of molecules, the number of functional groups, and the characteristics of cations in the structure. Due to that, the synthesized metallophosphonate hybrid materials exhibit diverse structural properties, including rigidity, thermal stability, and different arrangements like face-to-face or edge-to-face and herringbone stacking patterns. Furthermore, these materials display intriguing luminescent properties, such as Fluorescence, Room Temperature Phosphorescence (RTP), Bathochromic and Hypsochromic shift (red and blue shift), Excimer emission, and other novel green and red luminescence bands, particularly in the presence of specific cations. Lastly, we discuss and explore the interconnection between structural and physical properties including the phenomena of Aggregation Induced Emission (AIE) and Aggregation Enhanced Emission (AEE) for hybrid compounds

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48

Seyyidoglu, Semih. "High Temperature Chemistry Of Some Borophosphates, Phase Relations And Structural Studies". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1045863/index.pdf.

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The solid state, hydrothermal and flux methods were used for the investigation of alkaline earth and transition metal borophosphate compounds. The products and the phase relations were investigated by XRD, IR, DTA, and EDX methods. The solid state reactions of several boron compounds with different phosphating agents have been studied in the temperature range of 400-1200 oC. Hydrothermal and flux techniques were performed at 150 oC and 1200 oC, respectively. On the other hand, an attempt has been made to prepare a novel borophosphate compound MIIMIV[BPO7] (where MIV= Zr4+, Si4+, and MII= Sr2+, Ca2+) by solid state reactions and to investigate intermediate and final products. (NH4)2HPO4 and NH4H2PO4 were used as a phosphating agent. For the synthesis of these new compounds, the following reaction was predicted using the stoichiometric amount of the reactants: 2MIVO2 + 2MIICO3 + B2O3 + 2(NH4)2HPO4 &
#8594
2MIIO.MIVO2.B2O3.P2O5 + 4NH3 + 3H2O + 2CO2 (According to IUPAC formulation for the compounds composed of oxides) In the case of MIV=Zr4+ and MII=Sr2+, the formation of ZrSr[BPO7] was observed together with ZrO2 and SrBPO5. The formation of a new phase was proved by indexing the XRD pattern of the product after separating ZrO2 and SrBPO5 lines. Its crystal system was found to be orthorhombic and the unit cell parameters are a=11.85Å
, b=12.99 Å
, c=17.32 Å
. IR analysis shows that there is [BPO7]6- bands in the spectrum. At higher temperatures, Sr7Zr(PO4)6 was obtained. In the case of MIV=Si4+, SrBPO5 was the main product together with unreacted SiO2. At 1100 oC, Si4+ entered SrBPO5 structure and the product was indexed in orthorhombic system with a=8.9243 Å
, b=13.1548 Å
, and c=5.4036 Å
. Several other M:B:P ratios were tried for solid state systems. For compositions with different cations (such as Al3+, Ca2+, Na+), reactions generally pass through metal phosphates and BPO4. The X-ray diffraction powder pattern and infrared spectrum of several intermediate products obtained at different temperatures were presented and the several phase relations were investigated. The DTA and EDX analyses of some products were also reported.

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49

Castillo, Rodrigo. "Synthesis of silicon- and germanium-rich phases at high-pressure conditions". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-207708.

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The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge. Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow. By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6.

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50

Malki, Mustapha. "Proprietes structurales, magnetiques et electroniques d'oxydes ternaires de terres-rares". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13143.

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Etude des composes limlno::(4), ou m = eu, sr; ln = eu, gd, dy, er, y. Mesures de susceptibilite et d'aimantation, mesures des interactions hyperfines au site des terres rares par effet moessbauer. Temperature de mise en ordre magnetique; structure cristallographique; moment magnetique; parametres de champ cristallin d'ordre 2 au site des lanthanides

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Tesi sul tema "Alkaline Earth Metal hydrides"

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