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1
Rageb, Shakir Mahmud. "Ionic transport in lithium salts and composites". Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278268.
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Zhao, Shujing. "Core-Shell Nanofiber Assemblies Containing Ionic Salts". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366808400.
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Lui, Matthew Yuk Yu. "Special solvation behaviour of salts in ionic liquid". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9250.
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In a previous study1 from the Welton Group, the reactivity resulting from mixing two different and reactive salts together was observed to be highly dependent on the type of solvent, with molecular and ionic liquids exhibiting fundamentally different reaction pathways. Ionic liquids were shown to be extremely dissociating solvents and the salts behaved as discrete reactive species. Conversely, in molecular solvents neutral ion pairs or clusters were formed. In this thesis, further evidence of the charge screening behaviour of ionic liquids will be presented. The investigation was carried out by using Kosower's charge-transfer complex, 1-ethyl-4-(methoxycarbonyl)pyridinium iodide,2 which is only spectroscopically active when its ions are in direct contact, hence allowing charge transfer to occur. The behaviour of this salt is therefore a good indicator of the number of pyridinium iodide contact ion pairs in solution and can be used as a probe for the amount of ion-pairing in both ionic and molecular liquids. In the second part of the investigation, the SN2 reaction of two reactive salts (1-butyl-1-methylpyrrolidinium bromide and dimethyl-4-nitrophenylsulfonium bis(trifluoromethanesulfonyl)imide) in ionic liquid/molecular liquid mixtures was studied. The aim was to examine whether complete charge screening behaviour could be achieved in ionic liquid/molecular liquid mixtures of different compositions. This research also provided some insights of general behaviour of salts in ionic liquid/molecular solvent mixtures.
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Tomaszowska, Alina Agnieszka. "Synthesis and characterisation of ionic liquids and related salts". Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527915.
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Banik, Ishani. "Physico-Chemical studies on interaction of biologically active solutes and ionic salts in some industrially important solvent media". Thesis, University of North Bengal, 2014. http://ir.nbu.ac.in/handle/123456789/1491.
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Byrne, Peter Joseph. "Structural studies of ionic liquids and ionothermally-prepared materials". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/780.
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Bansiwal, Mukesh. "Investigation of drug ionic liquid salts for topical delivery systems". Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/17161.
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Pharmaceutical companies and FDA (Federal Drug Administration) rules rely heavily on crystalline active pharmaceutical ingredients delivered as tablets and powders in the form of neutral compounds, salts and solvates of neutral compounds and salts. About half of all drugs sold in the market are in the form of salts which are held together by ionic bonds along with some other forces. Recently, Ionic liquids (ILs) an interesting class of chemical compounds have offered potential opportunity for exploration as novel drug ionic liquid salts, particularly in the field of transdermal/topical drug delivery. Due to the multifunctional nature of these salts they could allow generation of new pathway to manipulate the transport and deposition behaviour of the drug molecule. It is this modular approach of IL that forms the basis of the research presented here, in which pharmaceutically acceptable compounds are combined with selected drugs with known problems.
IL salts were generated by combining at least one drug molecule with FDA approved compounds and were assessed for physicochemical properties, skin deposition and permeation studies. Skin deposition data suggested that these systems exhibit high skin retention, which was found to correlate with the molecular weight. On the other hand, permeation data displayed an inverse relationship between flux values and molecular weight of the permeant. Similar work was extended with ILs with mixed anions containing two drugs. The benzalkonium-sulfacetamide ILs were investigated for synergism and the biological studies data display no synergistic effect. It was also illustrated that in-situ IL based ibuprofen hydrogels systems could be manipulated via IL approach for topical application. These findings suggest the potential applicability of IL based formulations for topical delivery of drugs.
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Kuah, Yongcheun. "Ionic liquids and salts for contaminant removal in the petroleum industry". Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602354.
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This thesis, separated into Parts A and B, is a combination of work on two projects with overlapping themes. Both projects aimed to design an ionic liquid, or a salt system, to remove deleterious contaminants in the petroleum industry in a green and sustainable manner. In Part A, systematic studies have been conducted to design various salt systems that extract mercury via oxidative complexation, from natural gas and liquid hydrocarbon streams. These compounds were characterised using a wide range of analytical techniques. In the mercury extraction from the gas phase, a remarkable discovery of a custom-designed ionic liquid has led to the successful development of a commercial mercury scrubber (containing 15 tonnes of catalyst) at a PETRONAS Gas Processing Plant in Malaysia. In addition, cheaper binary inorganic systems have also been investigated. These were initially prepared as benchmarks to the ionic liquid systems, but have proved to be effective in their own right. This has (led to the development of a second generation of mercury scrubber, currently. under pilot scale evaluation. For mercury extraction from liquid hydrocarbons, again, two of the systems examined, namely the ionic liquids and binary inorganic salt systems, showed significant activity, and these systems are also currently under pilot scale evaluation. [n Part B, the aim was to develop a novel approach to remove C02 from natural gas streams using ionic liquids. Various ionic liquids were synthesised and characterised using various analytical techniques. Remarkably, these novel systems were found to absorb up to 1.5 mol CO2 per mol of ionic liquid, exceeding the best literature value of equimolar capacity, making them very attractive for further pilot scale testing.
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Dean, Pamela Mary. "Structural analysis of low melting organic salts an approach to ionic liquid design". Monash University. Faculty of Science. School of Chemistry, 2009. http://arrow.monash.edu.au/hdl/1959.1/75056.
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Ionic liquid forming compounds often display low melting points (a lack of crystallisation at ambient temperature and pressure) due to decreased lattice energies in the crystalline state. The degree of anion-cation contact with respect to the type, strength and number of interactions is a major factor determining the lattice energies, melting point and general behaviour of ionic liquid forming salts. Intermolecular interactions between the anion and cation and the conformational states of each component of the salt are of interest since distinctive properties ascribed to ionic liquids are determined to a significant extent by these interactions. The direct insight into the spatial relationship between cation and anion provided by the analysis of crystal structures provides a basis from which features of the ionic liquid can be generally understood, since the short range order and interactions of related, non-crystalline compounds may be similar to those of the crystalline form. However, it is difficult to predict whether a particular ionic pair will produce a liquid at room temperature, due to numerous possible combinations of cations and anions and the subtleties of their interactions. Crystal engineering is the ability to assemble molecular or ionic components into the desired crystalline architecture by engineering a target network of supramolecular interactions known as synthons. In this investigation the problem of ionic liquid design is addressed using the concepts of crystal engineering in an inverse sense, the so-called anti crystal-engineering approach. A topical area in which the anti crystal-engineering concept may be of some value is that of Ionic Liquid Phases of Pharmaceutically Active Ions (Active Ionic Liquids). Thus, by using the knowledge gained of the intermolecular interactions, packing and ionic conformation which occur within ‘traditional’ ionic liquids, combined with the knowledge of which functional group combinations yield supramolecular synthons resulting in crystalline subjects, and the subsequent prevention thereof (anti crystal-engineering), appropriate ions shall be selected which may result in ionic liquid formation. The intermolecular interactions of a series of: • crystallised bis(trifluoromethanesulfonyl)amide (NTf2) and bis(methanesulfonyl)amide (NMes2) ionic liquids, • low melting N-alkyl-2-methyl-3-benzylimidazolium iodide salts with a range of alkyl chain lengths, from n=1 to 6 and including both n-butyl and s-butyl chains, • 1-methyl-1-propylpyrrolidinium chloride and, • a number of low melting salts containing trihalide and monohalide ions, in combination with typical IL organic cations namely, 1-ethyl-3-methylimidazolium, 1-ethyl-1-methylpyrrolidinium and 1-propyl-1-methylpyrrolidinium, were qualitatively investigated and/or compared using a combination of crystallographic, Hirshfeld surface and thermal analysis techniques. The NMes2 salts are known to exhibit higher glass transitions and higher viscosities than those of the NTf2 salts. The origins of these differences were analysed in terms of the importance of factors such as the C-H•••O hydrogen bond, fluorination, presence of an aromatic moiety and length of alkyl chain, using the Hirshfeld surfaces and their associated fingerprint plots. Additionally, the existence of C-F•••π and C-H•••π interactions were elucidated and the significance of anion-anion interactions was recognised. Thermal analysis of the N-alkyl-2-methyl-3-benzylimidazolium iodide salts revealed that the methyl- and (s-)butyl substituted salts have a significantly higher melting point than the rest of the series. Analysis of these crystal structures allowed examination of the influence of the substitutions on the different cation-anion and cation-cation interactions and thus the physical properties of the salts. Thermal analysis of the monohalide and trihalide salts revealed that the tribromide salts are lower melting than their monohalide analogues. Analysis of these crystal structures revealed the influence of the anions and the crystal packing on the physical properties of the salts. A series of crystalline and liquid salts were prepared from cations and anions drawn from Active Pharmaceutical Ingredients (APIs) and Generally Recognized As Safe (GRAS) materials. The solid-state structures of the crystalline salts were used as a basis for the anti-crystal engineering approach in the preparation of several “Active Ionic Liquids” (AILs). However, a side product also resulted during the synthetic route namely, methyl 9H-xanthene-9-carboxylate, a side product resulting from the API, propantheline. The results and methodology of the anti-crystal engineering procedure and the subsequent successful preparation and characterization of pharmaceutical ionic compounds are reported herein.
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Tasseven, Cetin. "Contributions to the theory of a class of ionic liquids". Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338101.
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MacMillan, Malcolm Gordon. "Thermodynamic and electrochemical studies in molten chloroaluminate systems of relevance to advanced secondary battery applications". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295234.
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Chinnam, Parameswara Rao. "MULTI-IONIC LITHIUM SALTS FOR USE IN SOLID POLYMER ELECTROLYTES FOR LITHIUM BATTERIES". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/311780.
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ChemistryPh.D.
Commercial lithium ion batteries use liquid electrolytes because of their high ionic conductivity (>10-3 S/cm) over a broad range of temperatures, high dielectric constant, and good electrochemical stability with the electrodes (mainly the cathode cathode). The disadvantages of their use in lithium ion batteries are that they react violently with lithium metal, have special packing needs, and have low lithium ion transference numbers (tLi+ = 0.2-0.3). These limitations prevent them from being used in high energy and power applications such as in hybrid electric vehicles (HEVs), plug in electric vehicles (EVs) and energy storage on the grid. Solid polymer electrolytes (SPEs) will be good choice for replacing liquid electrolytes in lithium/lithium ion batteries because of their increased safety and ease of processability. However, SPEs suffer from RT low ionic conductivity and transference numbers. There have been many approaches to increase the ionic conductivity in solid polymer electrolytes. These have focused on decreasing the crystallinity in the most studied polymer electrolyte, polyethylene oxide (PEO), on finding methods to promote directed ion transport, and on the development of single ion conductors, where the anions are immobile and only the Li+ ions migrate (i.e. tLi+ = 1). But these attempts have not yet achieved the goal of replacing liquid electrolytes with solid polymer electrolytes in lithium ion batteries. In order to increase ionic conductivity and lithium ion transference numbers in solid polymer electrolytes, I have focused on the development of multi-ionic lithium salts. These salts have very large anions, and thus are expected to have low tanion- and high tLi+ transference numbers. In order to make the anions dissociative, structures similar to those formed for mono-ionic salts, e.g. LiBF4 and lithium imides have been synthesized. Some of the multi-ionic salts have Janus-like structures and therefore can self-assemble in polar media. Further, it is possible that these salts may not form non-conductive ion pairs and less conductive ion triplets. First, we have prepared nanocomposite electrolytes from mixtures of two polyoctahedral silsesquioxanes (POSS) nanomaterials, each with a SiO1.5 core and eight side groups. POSS-PEG8 has eight polyethylene glycol side chains that have low glass transition (Tg) and melt (Tm) temperatures and POSS-phenyl7(BF3Li)3 is a Janus-like POSS with hydrophobic phenyl groups and -Si-O-BF3Li ionic groups clustered on one side of the SiO1.5 cube. The electron-withdrawing POSS cage and BF3 groups enable easy dissociation of the Li+. In the presence of polar POSS-PEG8, the hydrophobic phenyl rings of POSS-phenyl7(BF3Li)3 aggregate and crystallize, forming a biphasic morphology, in which the phenyl rings form the structural phase and the POSS-PEG8 forms the conductive phase. The -Si-O-BF3- Li+ groups of POSS-phenyl7(BF3Li)3 are oriented towards the polar POSS-PEG8 phase and dissociate so that the Li+ cations are solvated by the POSS-PEG8. The nonvolatile nanocomposite electrolytes are viscous liquids that do not flow under their own weight. POSS-PEG8/POSS-phenyl7(BF3Li)3 at O/Li = 16/1 has a conductivity, σ = 2.5 x 10-4 S/cm at 30°C, 17 x greater than POSS-PEG8/LiBF4, and a low activation energy (Ea ~ 3-4 kJ/mol); σ = 1.6 x 10-3 S/cm at 90°C and 1.5 x 10-5 S/cm at 10°C. The lithium ion transference number was tLi+ = 0.50 ± 0.01, due to reduced mobility of the large, bulky anion and the system exhibited low interfacial resistance that stabilized after 3 days (both at 80°C). Secondly, solid polymer electrolytes have been prepared from the same salt, POSS-phenyl7(BF3Li)3 and polyethylene oxide (PEO). These exhibit high ambient temperature conductivity, 4 x 10-4 S/cm, and transference number, tLi+ = 0.6. A two-phase morphology is proposed in which the hydrophobic phenyl groups cluster and crystallize, and the three -BF3- form an anionic pocket, with the Li+ ions solvated by the PEO phase. The high ionic conductivity results from interfacial migration of Li+ ions loosely bonded to three -BF3- anions and the ether oxygens of PEO. Physical crosslinks formed between PEO/Li+ chains and the POSS clusters account for the solid structure of the amorphous PEO matrix. The solid polymer electrolyte has an electrochemical stability window of 4.6 V and excellent interfacial stability with lithium metal. In order to further enhance the ionic conductivity of solid polymer electrolytes, we have made two improvements. First, we have used so called half cube structures, T4-POSS, that contain 4 phenyl groups on one side of a Si-O- ring, and 4 ionic groups on the other side, and so are true Janus structures. They contain a 4/4 ratio of phenyl/ionic groups, unlike the previous structures that contain 7 phenyl groups/3 ionic groups. At the same O/Li ratio, the ionic conductivity of [PhOSi(OLi)]4 with POSS-PEG8 is higher than POSS-phenyl7Li3 because of more Li+ dissociation in the former case. Second, we have increased the dissociation of the lithium salts by replacing the Si-O-BF3Li groups with Si-(C3H4NLiSO2CF3)4. Both T4-POSS-(C3H4NLiSO2CF3)4 and POSS-(C3H4NLiSO2CF3)8 have been synthesized and characterized, with some preliminary conductivity data obtained.
Temple University--Theses
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Beauchamp, Andrew Michael. "The Synthesis of Room-Temperature Ionic Liquids and Their Metathesis Reactions with Dilithium Phthalocyanine". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1334348776.
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Wasse, Jonathan Carl. "The progresson from ionic to covalent bonding in disordered systems as studied by using neutron diffraction". Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267774.
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Bwambok, David. "The facile synthesis of 2-substituted imidazolium room temperature ionic liquids and investigation of their solvent properties". Diss., Online access via UMI:, 2005.
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Wilhelm, René. "Development of new organic salts as versatile materials for catalysis, ionic liquids and carbon nanomaterials". Clausthal-Zellerfeld [Univ.-Bibliothek], 2009. http://d-nb.info/998632694/34.
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Wang, Shanshan. "Development of solid polymer electrolytes of polyurethane and polyether-modified polysiloxane blends with lithium salts". Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1196139638.
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Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2007."December, 2007." Title from electronic dissertation title page (viewed 01/30/2008) Advisor, Kyonsuku Min; Committee members, Mark Soucek, Kevin A. Cavicchi, Gary R. Hamed, Michael H. Cheung; Department Chair, Sadhan C. Jana; Dean of the College, Stephen Z. D. Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Ong, Tien Teng. "Crystal Engineering of Molecular and Ionic Cocrystals". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3270.
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Solubility enhancement of poorly-soluble active pharmaceutical ingredients (APIs) remains a scientific challenge and poses a practical issue in the pharmaceutical industry. The emergence of pharmaceutical cocrystals has contributed another dimension to the diversity of crystal forms available at the disposal of the pharmaceutical scientist. That pharmaceutical cocrystals are amenable to the design principles of crystal engineering means that the number of crystal forms offered by pharmaceutical cocrystals is potentially greater than the combined numbers of polymorphs, salts, solvates and hydrates for an API. The current spotlight and early-onset dissolution profile ("spring-and-parachute" effect) exhibited by certain pharmaceutical cocrystals draw attention to an immediate question: How big is the impact of cocrystals on aqueous solubility? The scientific literature and in-house data on pharmaceutical cocrystals that are thermodynamically stable in water are reviewed and analyzed for trends in aqueous solubility and melting point between the cocrystal and the cocrystal formers. There is poor correlation between the aqueous solubility of cocrystal and cocrystal former with respect to the API. The log of the aqueous solubility ratio between cocrystal and API has a poor correlation with the melting point difference between cocrystal and API. Structure-property relationships between the cocrystal and the cocrystal formers remain elusive and the actual experiments are still necessary to investigate the desired physicochemical properties.
Crystal form (cocrystals, polymorphs, salts, hydrates and solvates) diversity is and will continue to be a contentious issue for the pharmaceutical industry. That the crystal form of an API dramatically impacts its aqueous solubility (a fixed thermodynamic property) is illustrated by the histamine H2-receptor antagonist ranitidine hydrochloride and HIV protease inhibitor ritonavir. For more than a century, the dissolution rate of a solid has been shown to be directly dependent on its solubility, cçterîs paribus. A century later, it remains impossible to predict the properties of a solid, given its molecular structure. If delivery or absorption of an API are limited by its aqueous solubility, aqueous solubility then becomes a critical parameter linking bioavailability and pharmacokinetics of an API. Since the majority of APIs are Biopharmaceutical Classification System (BCS) Class II (low solubility and high permeability) compounds, crystal form screening, optimization and selection have thus received more efforts, attention and investment. Given that the dissolution rate, aqueous solubility and crystal form of an API are intricately linked, it remains a scientific challenge to understand the nature of crystal packing forces and their impact upon physicochemical properties of different crystal forms. Indeed, the selection of an optimal crystal form of an API is an indispensable part of the drug development program. The impact of cocrystals on crystal form diversity is addressed with molecular and ionic targets in ellagic acid and lithium salts. A supramolecular heterosynthon approach was adopted for crystal form screening. Crystal form screening of ellagic acid yields molecular cocrystals, cocrystal solvates/hydrates and solvates. Crystal form screening of lithium salts (chloride, bromide and nitrate salts) afforded ionic cocrystals and cocrystal hydrates.
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Lang, Christopher M. "Development of quaternary ammonium based electrolytes for rechargeable batteries and fuel cells". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-10262006-140639/.
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Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2007.Kohl, Paul, Committee Chair ; Bottomley, Lawrence, Committee Member ; Eckert, Charles, Committee Member ; Fuller, Tom, Committee Member ; Teja, Amyn, Committee Member.
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Fechler, Nina. "Salts as highly diverse porogens : functional ionic liquid-derived carbons and carbon-based composites for energy-related applications". Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6477/.
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The present thesis is to be brought into line with the current need for alternative and sustainable approaches toward energy management and materials design. In this context, carbon in particular has become the material of choice in many fields such as energy conversion and storage.
Herein, three main topics are covered:
1)An alternative synthesis strategy toward highly porous functional carbons with tunable porosity using ordinary salts as porogen (denoted as “salt templating”)
2)The one-pot synthesis of porous metal nitride containing functional carbon composites
3)The combination of both approaches, enabling the generation of highly porous composites with finely tunable properties
All approaches have in common that they are based on the utilization of ionic liquids, salts which are liquid below 100 °C, as precursors.
Just recently, ionic liquids were shown to be versatile precursors for the generation of heteroatom-doped carbons since the liquid state and a negligible vapor pressure are highly advantageous properties. However, in most cases the products do not possess any porosity which is essential for many applications. In the first part, “salt templating”, the utilization of salts as diverse and sustainable porogens, is introduced. Exemplarily shown for ionic liquid derived nitrogen- and nitrogen-boron-co-doped carbons, the control of the porosity and morphology on the nanometer scale by salt templating is presented. The studies within this thesis were conducted with the ionic liquids 1-Butyl-3-methyl-pyridinium dicyanamide (Bmp-dca), 1-Ethyl-3-methyl-imidazolium dicyanamide (Emim-dca) and 1 Ethyl 3-methyl-imidazolium tetracyanoborate (Emim-tcb). The materials are generated through thermal treatment of precursor mixtures containing one of the ionic liquids and a porogen salt. By simple removal of the non-carbonizable template salt with water, functional graphitic carbons with pore sizes ranging from micro- to mesoporous and surface areas up to 2000 m2g-1 are obtained. The carbon morphologies, which presumably originate from different onsets of demixing, mainly depend on the nature of the porogen salt whereas the nature of the ionic liquid plays a minor role. Thus, a structural effect of the porogen salt rather than activation can be assumed. This offers an alternative to conventional activation and templating methods, enabling to avoid multiple-step and energy-consuming synthesis pathways as well as employment of hazardous chemicals for the template removal.
The composition of the carbons can be altered via the heat-treatment procedure, thus at lower synthesis temperatures rather polymeric carbonaceous materials with a high degree of functional groups and high surface areas are accessible. First results suggest the suitability of the materials for CO2 utilization.
In order to further illustrate the potential of ionic liquids as carbon precursors and to expand the class of carbons which can be obtained, the ionic liquid 1-Ethyl-3-methyl-imidazolium thiocyanate (Emim-scn) is introduced for the generation of nitrogen-sulfur-co-doped carbons in combination with the already studied ionic liquids Bmp-dca and Emim-dca. Here, the salt templating approach should also be applicable eventually further illustrating the potential of salt templating, too.
In the second part, a one-pot and template-free synthesis approach toward inherently porous metal nitride nanoparticle containing nitrogen-doped carbon composites is presented. Since ionic liquids also offer outstanding solubility properties, the materials can be generated through the carbonization of homogeneous solutions of an ionic liquid acting as nitrogen as well as carbon source and the respective metal precursor. The metal content and surface area are easily tunable via the initial metal precursor amount. Furthermore, it is also possible to synthesize composites with ternary nitride nanoparticles whose composition is adjustable by the metal ratio in the precursor solution.
Finally, both approaches are combined into salt templating of the one-pot composites. This opens the way to the one-step synthesis of composites with tunable composition, particle size as well as precisely controllable porosity and morphology. Thereby, common synthesis strategies where the product composition is often negatively affected by the template removal procedure can be avoided. The composites are further shown to be suitable as electrodes for supercapacitors. Here, different properties such as porosity, metal content and particle size are investigated and discussed with respect to their influence on the energy storage performance.
Because a variety of ionic liquids, metal precursors and salts can be combined and a simple closed-loop process including salt recycling is imaginable, the approaches present a promising platform toward sustainable materials design.Die vorliegende Arbeit basiert auf der Notwendigkeit für eine alternative und nachhaltige Energiewirtschaft sowie alternativer Herstellungsmethoden der damit verbundenen Materialien. Hierbei kommt besonders Kohlenstoffen und kohlenstoffbasierten Systemen eine hohe Bedeutung zu. Im Rahmen der Dissertation wurden drei Ansätze verfolgt, die zu der Entwicklung alternativer Strategien zur Herstellung poröser Heteroatom-enthaltender Kohlenstoffe und deren Komposite beitragen. Die Materialien wurden des Weiteren für die CO2 Nutzung sowie Energiespeicherung in Form von Superkondensatoren getestet. Allen Materialien ist gemeinsam, dass sie ausgehend von ionischen Flüssigkeiten, Salze mit einem Schmelzpunkt unterhalb von 100 °C, als Kohlenstoffvorstufe durch Hochtemperaturverfahren hergestellt wurden. Im ersten Teil wird ein alternatives und nachhaltiges Verfahren zur Herstellung hochporöser Stickstoff und Stickstoff-Bor-haltiger Kohlenstoffe vorgestellt. Bei dieser als „Salztemplatierung“ bezeichneten Methode werden herkömmliche Salze als Porogen verwendet. Damit sind sehr hohe Oberflächen erreichbar, die neben der Porengröße und dem Porenvolumen durch die Variation der Salzspezies und Salzmenge einstellbar sind. Dies bietet gegenüber herkömmlichen Templatierungsverfahren den Vorteil, dass das Salz nach erfolgter Karbonisierung der ionischen Flüssigkeit in Anwesenheit der nicht karbonisierbaren Salzspezies einfach mit Wasser auswaschbar ist. Hierbei ist ein Recyclingprozess denkbar. Bei hohen Synthesetemperaturen werden graphitische, bei niedrigen hochfunktionalisierte, polymerartige Produkte erhalten. Letztere erwiesen sich als vielversprechende Materialien für die CO2 Nutzung. Unter Verwendung einer bisher nicht eingesetzten ionische Flüssigkeit konnte weiterhin die Einführung von Schwefel als Heteroatom ermöglicht werden. Im zweiten Teil wird eine Templat-freie Einschrittsynthese von porösen Kompositen aus Metallnitrid Nanopartikeln und Stickstoff-dotiertem Kohlenstoff vorgestellt. Die Materialien werden ausgehend von einer Lösung aus einer ionischen Flüssigkeit und einem Metallvorläufer hergestellt, wobei die ionische Flüssigkeit sowohl als Kohlenstoffvorläufer als auch als Stickstoffquelle für die Metallnitride dient. Der Metallgehalt, das Metallverhältnis in ternären Nitriden und die Oberfläche sind über den Anteil des Metallvorläufers einstellbar. Schließlich werden beide Ansätze zur Salztemplatierung von den Kompositen kombiniert. Dadurch wird die Einschrittsynthese von Kompositen mit einstellbarer Oberfläche, Zusammensetzung, Partikelgröße und Morphologie ermöglicht. Diese Materialien wurden schließlich als Elektroden für Superkondensatoren getestet und der Einfluss verschiedener Parameter auf die Leistungsfähigkeit untersucht. Aufgrund verschiedener Kombinationsmöglichkeiten von ionischen Flüssigkeiten, Metallvorläufern und Salzen, stellen die hier präsentierten Ansätze eine vielversprechende Plattform für die nachhaltige Materialsynthese dar.
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Wilhelm, René [Verfasser]. "Development of new organic salts as versatile materials for catalysis, ionic liquids and carbon nanomaterials / vorgelegt von René Wilhelm". Clausthal-Zellerfeld : [Univ.-Bibliothek], 2009. http://d-nb.info/998632694/34.
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Zhang, Mengxue. "INFLUENCE OF SODIUM SALTS ON THE SWELLING AND RHEOLOGY OF HYDROPHOBICALLY CROSSLINKED, NON-IONIC HYDROGELS DETERMINED BY QCM-D". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555682656086202.
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Ahmed, Ejaz, Joachim Breternitz, Matthias Friedrich Groh y Michael Ruck. "Ionic liquids as crystallisation media for inorganic materials". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138932.
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Ionic liquids (ILs) have made a great impact on materials science and are being explored for potential applications in several disciplines. In this article, we briefly highlight the current state-of-the-art techniques employing ILs as new crystallisation media, working as neutral solvent, template or charge compensating species. The use of an IL as environmental friendly solvent offers many advantages over traditional crystallisation methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room temperature ILs have been found to be excellent solvent systems for the crystallisation of a wide range of substances and morphologies ranging from nanoscopic crystals to micro- and even to macroscopic crystals. Moreover, high temperature routes, such as crystallisation from melts or gas phase deposition, have been replaced by convenient room or low temperature syntheses, employing ILs as reaction mediaDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Ahmed, Ejaz, Joachim Breternitz, Matthias Friedrich Groh y Michael Ruck. "Ionic liquids as crystallisation media for inorganic materials". Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27794.
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Ionic liquids (ILs) have made a great impact on materials science and are being explored for potential applications in several disciplines. In this article, we briefly highlight the current state-of-the-art techniques employing ILs as new crystallisation media, working as neutral solvent, template or charge compensating species. The use of an IL as environmental friendly solvent offers many advantages over traditional crystallisation methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room temperature ILs have been found to be excellent solvent systems for the crystallisation of a wide range of substances and morphologies ranging from nanoscopic crystals to micro- and even to macroscopic crystals. Moreover, high temperature routes, such as crystallisation from melts or gas phase deposition, have been replaced by convenient room or low temperature syntheses, employing ILs as reaction media.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Bejan, Dana [Verfasser]. "The strong N–H acid bis[bis(pentafluoroethyl)phosphinyl]imide, H[(C2F5)2P(O)}2N] Salts and ionic liquids / Dana Bejan". Wuppertal : Universitätsbibliothek Wuppertal, 2011. http://d-nb.info/101829824X/34.
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Arkhipova, Maria [Verfasser]. "Hexaalkylguanidinium salts as ionic liquids - new applications in titanium and aluminium alcoholates assisted synthesis and as electrolytes for electrodeposition of metals / Maria Arkhipova". Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2016. http://d-nb.info/1093557486/34.
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Ma, Kefeng. "Correlations between structure and phase-properties of phosphonium salts ionic liquid crystals and media for stereoselective brominations and solutue structural studies by NMR spectroscopy". Connect to Electronic Thesis (CONTENTdm), 2009. http://worldcat.org/oclc/458544853/viewonline.
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Fechler, Nina [Verfasser] y Markus [Akademischer Betreuer] Antonietti. "Salts as highly diverse porogens : functional ionic liquid-derived carbons and carbon-based composites for energy-related applications [[Elektronische Ressource]] / Nina Fechler. Betreuer: Markus Antonietti". Potsdam : Universitätsbibliothek der Universität Potsdam, 2013. http://d-nb.info/1033036706/34.
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Pastre, Júlio Cezar 1979. "Reações de Heck de acrilatos substituidos com sais de arenodiazonio em solventes organicos e liquidos ionicos. Aplicação na sintese da paroxetina, da nocaina, da indatralina e da sertralina". [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249878.
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Orientador: Carlos Roque Duarte CorreiaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-14T14:22:36Z (GMT). No. of bitstreams: 1 Pastre_JulioCezar_D.pdf: 10159507 bytes, checksum: 4f4f32c2c414df354e1d53179d9ebe18 (MD5) Previous issue date: 2009
Resumo: Neste trabalho, efetuou-se um estudo da reação de Heck de acrilatos substituídos com sais de arenodiazônio. Um protocolo estereosseletivo para a preparação de acrilatos b,b-diarilssubstituidos foi desenvolvido, baseando-se na arilação Heck do cinamato de metila com sais de arenodiazônio, catalisada por Pd(OAc)2, em metanol. A diastereosseletivade da reação de Heck apresentou uma acentuada dependência com a natureza eletrônica do sal de arenodiazônio empregado. A metodologia ainda forneceu uma rota conveniente para 3-arilindanonas e 4-ariltetralonas, permitindo as sínteses formais totais da (±)-indatralina (4 etapas, 54 % de rendimento global) e da (±)-sertralina (7 etapas, 49 % de rendimento global). A extensão da metodologia para acrilatos mais substituídos (inclusive para acrilatos cíclicos) foi feita com sucesso para a maioria dos casos e os adutos de Heck foram obtidos em bons rendimentos e seletividades, independente do padrão de substituição do sal de arenodiazônio empregado. Esta metodologia foi aplicada à síntese total da (±)-paroxetina (8 etapas, 15 % de rendimento global) e da (±)-nocaína (6 etapas, 20 % de rendimento global). Verificou-se ainda que a reação de arilação de Heck empregando sais de arenodiazônio ocorre de maneira eficiente em meios reacionais alternativos, como PEG e líquidos iônicos. Uma série de líquidos iônicos quirais inéditos do tipo piridínio, imidazolínio e imidazólio foi preparada e testada, não revelando nenhuma incidência no curso estereoquímico da reação. Os resultados obtidos demonstram o enorme potencial sintético do emprego de sais de arenodiazônio em reações de Heck, constituindo uma metodologia bastante versatil em Síntese Orgânica.
Abstract: In this work, we present a study of the Heck reaction of substituted acrilates with arenediazonium salts. A stereoselective protocol for the preparation of b,b-disubstituted acrylates in good yields by means of a Heck-Matsuda reaction was accomplished. The method employs a base- and ligand-free Heck reaction of methyl cinnamate using arenediazonium salts as electrophiles. The Heck reaction displays a remarkable electronic dependence regarding the diastereoselectivity of the arylation process, which correlates with the electronic nature of the arenediazonium salts employed. The overall methodology provides a convenient route to 3-arylindanones and 4-aryltetralones allowing the concise formal total syntheses of the therapeutically important psychoactive compounds (±)-indatraline (4 steps, 54 % global yield) and (±)-sertraline (7 steps, 49 % global yield). The methodology was also successfully extended to more substituted acrylates and the Heck adducts were obtained in good to excellent yields, regardless of the substitution pattern of the arenediazonium salt employed. This methodology was applied to the total synthesis of (±)-paroxetine (8 steps, 15 % global yield) and (±)nocaine (6 steps, 20 % global yield). We also verified that the Heck reaction using arenediazonium salts occurs in an efficient way in alternative reaction media, like PEG and ionic liquids. A series of new chiral ionic liquids was prepared and evaluated in the Heck reaction. In spite the overall performance of the Heck reaction, in all the cases studied no asymmetric induction was detected. Our results demonstrate the enormous synthetic potential of the Heck reaction using arenediazonium salts, constituting a versatile methodology in Organic Synthesis.
Doutorado
Quimica Organica
Doutor em Ciências
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Mahdalová, Kateřina. "Vzájemné působení záporných elektrod a iontových kapalin". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318179.
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This work deals with electrolytes and ionic liquids for Li-ion batteries. Following interaction of electrolytes and ionic liquids to electrodes material. In the theoretical part attention is focused on the description of battery electrolytes and ionic liquids for lithium-ion batteries.
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Nackos, Aaron N. "Optimizing the Release and Methylation of Bacterial Endospore Dipicolinic Acid". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3193.pdf.
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Santos, Filipe Miguel de Almeida Marques dos. "Novos materiais com polioxotungstatos substituídos com metais d e f". Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13112.
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Doutoramento em QuímicaThe present work reports studies on the new compounds obtained by the combination of polyoxoanions derived from the Keggin and Lindquist structures with several cations. The studies were first focused on the monolacunary Keggin polyoxoanions [PW11O39M(H2O)]n- (M = FeIII, MnIII and n = 4; M = CoII and n = 5) and its combination with the organic cation 1-butyl-3-methylimidazolium (Bmim+). The association of Bmim+ cation with the polyoxoanion [PW11O39Fe(H2O)]4- allowed to isolate for the first time both the monomeric and the dimeric [PW11O39Fe)2O]10- anions, with the same cation and using simple bench techniques by pH manipulation. Studies regarding the stability of these inorganic species in solution indicated that both species are present in solution in equilibrium. However, the inability to up until now isolate the dimeric unit through simple bench methods, lead to the hypothesis that the cation had a role to play in the selective precipitation of either the monomer or the dimer. Repetition of the same procedures with the polyoxoanions [SiW11O39Fe(H2O)]5- and [PW11O39M(H2O)]n- (M = FeIII, MnIII and n = 4; M = Co and n = 5), afforded only the corresponding monomeric compounds, (Bmim)5[SiW11O39FeIII(H2O)]· 4H2O (3), (Bmim)5[PW11O39CoII(H2O)]· 0.5 H2O, (4) and (Bmim)5[PW11O39MnIII(H2O)]· 0.5 H2O (5). Moreover, the combination of Bmim+ and the polyoxotungstate [PW11O39Co(H2O)]5- afforded two different crystal structures, depending on the synthetic conditions. Thus, a ratio Bmim+:POM of 5:1 and the presence of K+ cations (due to addition of KOH) led to a formula Na2K(Bmim)2[PW11.2O39Co0.8(H2O)]·7H2O (4a), whilst a ratio Bmim:POM of 7:1 led to the formation of a crystal with the chemical formula Na2(Bmim)8[PW11O39Co(H2O)]2·3H2O (4b). Electrochemical studies were performed with carbon paste electrodes modified with BmimCl to investigate the influence of the Bmim+ cation in the performance of the electrodes. The voltametric measurements obtained from solutions containing the anions [PW11O39]7- and [SiW11O39]8- are presented. Results pointed to an improvement of the acquired voltametric signal with a slight addition of BmimCl (up to 2.5% w/w), specially in the studies regarding pH variation. Additional synthesis were carried out with both the cations Omim+ and THTP+.
No presente trabalho apresentam-se os estudos efetuados com polioxometalatos derivados das estruturas de Keggin e de Lindquist. Numa primeira parte, estudaram-se compostos obtidos por combinação de polioxoaniões de Keggin de fórmula [PW11O39M(H2O)]n- (M = FeIII, MnIII e n = 4; M = Co e n = 5) com o catião 1-butil-3-metilimidazólio (Bmim+). A combinação do catião Bmim+ com o polioxoanião [PW11O39Fe(H2O)]4- permitiu, pela primeira vez, isolar tanto o anião monomérico de Fe, como o anião dimérico [(PW11O39Fe)2O]10- através de simples manipulação do pH, com a obtenção da respetiva estrutura cristalina. Estudos de estabilidade em solução vieram mostrar que a formação do dímero estava dependente do pH da solução e sugeriram que tanto a forma dimérica como a monomérica existem em equilíbrio em solução. No entanto, a incapacidade de, até agora, se conseguir obter este dímero através de métodos de bancada levaram a supor que o contra-catião utilizado possa desempenhar um papel no isolamento seletivo do dímero ou do monómero, independentemente do pH a que a reação se dava. A repetição destas experiências com os aniões correspondentes [SiW11O39Fe(H2O)]5- e [PW11O39M(H2O)]n- (M = FeIII, MnIII e n = 4; M = Co e n = 5) levou sempre à obtenção dos compostos monoméricos correspondentes, (Bmim)5[SiW11O39FeIII(H2O)]· 4H2O (3), (Bmim)5[PW11O39CoII(H2O)]· 0.5 H2O, (4) e (Bmim)5[PW11O39MnIII(H2O)]· 0.5 H2O (5). A utilização do catião Bmim+ permitiu obter duas estruturas cristalinas contendo o polioxoanião de CoII, dependendo das condições de síntese, nomeadamente do rácio Bmim+:POM. Assim, a utilização de um rácio de 5:1 ou de 7:1 levaram à obtenção de cristais com as fórmulas Na2K(Bmim)2[PW11O39Co(H2O)]·7H2O (4a) e Na(Bmim)4[PW11O39Co(H2O)]·1.5H2O (4b). Efetuaram-se ainda estudos eletroquímicos com elétrodos de pasta de carbono modificados. Os estudos iniciais, feitos com elétrodos de pasta de carbono modificados com BmimCl, pretendiam averiguar a influência no elétrodo da presença de uma partícula condutora como o catião Bmim+. Para esse efeito, fizeram-se medições voltamétricas de soluções contendo os aniões [PW11O39]7- e [SiW11O39]8-. Os resultados obtidos, permitiram concluir que a presença de pequenas quantidades de BmimCl (até uma adição de 2.5% (p/p)) resultaram num elétrodo com um desempenho melhorado, principalmente nos estudos de variação de pH. Efetuou-se ainda a combinação destes aniões com os catiões 3-metil-1- octilimidazólio (Omim+) e ainda com o catião trihexil(tetradecil)fosfónio (THTP+). Em comum, todos estes catiões estão associados a líquidos iónicos, compostos inteiramente constituídos por iões e com pontos de fusão inferiores a 100 ºC. Os compostos obtidos por associação dos catiões Omim+ e THTP+ com o anião de FeIII, levaram única e exclusivamente à obtenção do sal monomérico do anião [(PW11O39Fe(H2O)]4-, independentemente das condições de síntese. Estes resultados, bem como os dados disponíveis na literatura, apontam para um papel do catião no isolamento do anião de Fe, tendo-se observado que catiões mais volumosos tendem a precipitar exclusivamente o sal monomérico de Fe. A combinação com os aniões de CoII e MnIII originou os compostos (Omim)4H[PW11O39CoII(H2O)·H2O (7) e (Omim)4[PW11O39MnIII(H2O)] (8) com caraterísticas idênticas às dos obtidos para as sínteses com Bmim+, mas uma melhor solubilidade em solventes mais apolares como o clorofórmio. Por último, a combinação dos polioxoaniões [PW11O39M(H2O)]n-, com M = FeIII e MnIII e n = 4; M = CoII e n = 5 com o catião THTP+ levou à obtenção de líquidos iónicos contendo estes mesmos polioxoaniões num rácio THTP:POM igual ao rácio molar. Apesar de já existirem na literatura relatos de líquidos iónicos contendo polioxometalatos, os resultados aqui expostos representam a primeira vez que polioxoaniões tetra e pentavalentes formam líquidos iónicos isentos de água, um dos principais contaminantes deste tipo de compostos. Num segundo momento, prepararam-se novos materiais por combinação de metais como o AlIII, CrIII e FeIII com os lantanopolioxometalatos [Ln(W5O18)2]9- (Ln = SmIII, EuIII), apresentando-se aqui os resultados obtidos. Estes lantanopolioxometalatos estão referenciados na literatura pelas suas propriedades luminescentes e a sua associação aos metais indicados pode abrir perspetivas interessantes na exploração destas propriedades. Os compostos obtidos, de fórmulas Na[Fe(H2O)5(OH)]4[Sm(W5O18)2]·11H2O (12) , [Al(H2O)6]3[Sm(W5O18)2]·16H2O (13), Na4[Cr(H2O)4(OH)2]5[Sm(W5O18)2]·13H2O (14), Na[Fe(H2O)5(OH)]4[Eu(W5O18)2]·6H2O (15), [Al(H2O)6]3[Eu(W5O18)2]·12H2O (16) e H3Na[Cr(H2O)4(OH)2]5[Eu(W5O18)2]·3H2O (17), mostram que os catiões de FeIII e CrIII adicionados sofreram reações de hidrólise aquando da adição à solução aquosa contendo os lantanopolioxotungstatos. Os estudos de luminescência efetuados indicam que a presença de metais como o FeIII e o CrIII afetam as propriedades de luminescência dos compostos preparados, devido á existência de bandas de transição d-d na zona de excitação dos centros de EuIII.
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Blank, Jan Hendrik. "Carbon monoxide hydrogenation using ruthenium catalysts". Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3470.
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Ehrhardt, Alexandre. "Cimento de ionômero de vidro modificado com sal imidazólico : biomaterial funcionalizado com propriedades antibiofilme fúngico". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/164358.
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Os cimentos de ionômero de vidro são biomateriais constituídos de polímeros ácidos, vidro básico (ionizável) e água, sendo usados amplamente no campo odontológico, como materiais restauradores ou ainda como cimentadores de bandas ortodônticas. Estes compostos podem ser suscetíveis a formação de biofilmes por espécies de Candida na sua superfície em função da rugosidade associada a colonização fúngica do meio bucal. Pesquisas na área de desenvolvimento de biomateriais funcionais tem buscado desenvolver compostos de alta eficácia e baixa toxicidade que sejam capazes de inibir a formação de biofilmes sobre superfícies biológicas. Considerando a busca por novos biomateriais, foi desenvolvido um estudo ex vivo com o objetivo de modificar a estrutura de um cimento de ionômero de vidro comercialmente disponível (Ketac® Cem Easymix 3M) através da inserção do sal imidazólico cloreto de 1-nhexadecil- 3-metilimidazol comparado ao cloreto de cetilpiridínio para compor um novo composto com atividade antibiofilme. O sal imidazólico e o cloreto de cetilpiridínio foram acrescentados diretamente ao pó do ionômero de vidro na proporção de 10 ppm p/p. A partir desta adição inicial, foi realizada a reação de polimerização do ionômero, obtendo corpos de prova (CP) medindo 5 mm Ø × 3 mm h, os quais foram divididos em 03 grupos: CP1, constituído do ionômero na formulação original (controle de crescimento de biofilme); CP2, constituído do ionômero acrescido com o cloreto de cetilpiridínio (referência) e CP3, constituído do ionômero acrescido do sal imidazólico. Foram testadas nove cepas de Candida não albicans resistentes ao antifúngicos usuais, sendo três cepas de C. glabrata (RL22, RL24 e RL25), três cepas de C. tropicalis (57A, 72A e 72P) e três cepas de C. parapsilosis (RL11, RL20 e RL32), todas depositadas no Laboratório de Micologia da UFRGS. Avaliou-se a resistência a deformação plástica pelo teste de microdureza; a atividade antibiofilme pela avaliação de inibição de crescimento na superfície dos CP por microscopia eletrônica de varredura e avaliação de hipoalerginicidade pelo teste da membrana cório-alantoide. O teste de microdureza não apresentou diferença significativa (p>0,05) entre os três grupos, com valor médio de 44.2 HV para o CP1, 43.5 HV para o CP2 e 43,1 HV para o CP3. A avaliação da superfície dos CP através da análise de microscopia eletrônica demonstrou haver inibição completa da formação do biofilme de todas as cepas testadas. O teste da membrana cório-alantoide indicou que o ionômero de vidro na sua composição original, bem como acrescido dos dois compostos testados, demonstrou ser hipoalergênico. Considerando os dados apresentados, podemos concluir que a adição do sal imidazólico na formulação do ionômero de vidro promoveu a ação antibiofilme contra cepas multirresistente sem perda nas características de microdureza e hipoalergenicidade.Glass ionomer cements are biomaterials composed of acid polymers, basic glass (ionizable) and water, being widely used in dentistry, as restorative materials or as orthodontic bands. These compounds may be susceptible to biofilm formation on their surface by Candida species because of the roughness associated with fungal colonization of the oral cavity. Research on antifungal drugs development has focused on the synthesis of new compounds, that present effective action and low toxicity that are able to inhibit the formation of biofilms on biological surfaces. Considering the demand for biomaterials with antibiofilm activity, an ex vivo study was developed with the objective of modifying the structure of a commercially available glass ionomer cement (Ketac® Cem Easymix 3M) by insertion of the imidazole salt 1-n-hexadecyl-3- methylimidazole chloride compared to the cetylpyridinium chloride to make a novel compound with antibiofilm activity. The imidazole salt and cetylpyridinium chloride were added directly to the glass ionomer powder at a ratio of 10 ppm w/w. From this initial addition, the ionomer polymerization reaction was performed, obtaining test specimens (TS) measuring 5 mm Ø × 3 mm h, divided into three groups; i) TS1, composed only of GIC (growth control reference); ii) TS2, glass ionomer and cetylpyridinium chloride added directly to the powder (drug reference); and iii) TS3, glass ionomer and imidazolium salt using the same procedure. Nine strains of nonalbicans Candida, resistant to usual antifungals, were used; three C. glabrata strains (RL22, RL24 and RL25), three C. tropicalis strains (57A, 72A and 72P) and three C. Parapsilosis strains (RL11, RL20 and RL32), all the strains are deposited in the Mycology Collection at UFRGS. The plastic deformation was evaluated by the microhardness test; the antibiofilm activity by the evaluation of inhibition of growth on the surface of the specimens by scanning electron microscopy and evaluation of hypoallerginicity by the test of the chorioallantoic membrane. The plastic deformation evaluation showed no significant difference among the three groups, with a mean value of 44.2 HV for TS1, 43.5 HV for TS2 and 43,1 HV for TS3. Evaluating the biofilm formation on TSs, all the isolates form biofilm on TS1 (reference). On the other hand, both TS2 and TS3 were able to inhibit surface biofilm growth. The allergenicity evaluation of the three TSs showed no evidence of tissue alteration, considering that the eggs’ chorioallantoic membrane remained intact. Considering the presented data, we can conclude that the addition of the imidazole salt in the glass ionomer formulation promoted the antibiofilm action against multiresistant strains without loss in the characteristics of microhardness and hypoallergenicity.
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Avila, Jocasta Neves Libório de. "Estrutura e ambiente local de dimetil sulfóxido (DMSO) em diferentes meios iônicos". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-07022019-110023/.
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Apesar de ser utilizado há muito tempo como solvente para espécies orgânicas e inorgânicas, bem como carreador de fármacos, muitos aspectos relativos à auto-associação intermolecular do dimetil sulfóxido (DMSO) e às suas interações com espécies iônicas são ainda motivos de controvérsia na literatura. No presente estudo, a estrutura e ambiente local de dimetil sulfóxido (DMSO) em diferentes meios iônicos foram estudados por meio de três abordagens diferentes. Na primeira abordagem, o efeito de não-coincidência Raman (NCR) observado na banda atribuída ao modo ν(S=O) do DMSO, ca. 1050 cm-1, foi investigado para o líquido puro e em soluções de tetracloreto de carbono (CCl4) e água. Além disso, foi investigado o efeito de espécies iônicas (Kl, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg(ClO4)2) na frequência ν(S=O), bem como no NCR das soluções. Os resultados de NCR juntamente com as técnicas de infravermelho, RMN e de medidas de propriedades físico-químicas mostraram que essas espécies iônicas não somente afetam a estrutura de associação do DMSO, como são capazes de interagir fortemente com o solvente. Na segunda abordagem, com a finalidade de modular as propriedades de um líquido iônico, fez-se a análise estrutural das misturas envolvendo DMSO e água como solventes e o líquido iônico EAN como soluto por meio das técnicas de espalhamento de raios-X e de nêutrons. Os resultados mostraram que a estrutura cátion-ânion do EAN é afetada pela presença de DMSO e, que em ambos os solventes são evidentes fortes ligações de hidrogênio entre o cátion EA+ e os oxigênios do solvente e do ânion nitrato. As moléculas de água não afetam drasticamente a estrutura do EAN, pois seu caráter doador/aceptor de LH e seu tamanho permite a formação de pontes entre cátion e o ânion, no entanto, EAN consegue distorcer a rede tridimensional de ligação de hidrogênio da água. Por outro lado, as moléculas de DMSO afastam os ânions da região polar do EA+ na competição pela formação de LH com o cátion e o EAN, por sua vez, provoca a ruptura das estruturas de associação do DMSO. Na terceira abordagem, misturas envolvendo três diferentes SEPs (uma classe de líquidos iônicos); Relina, MUCHCl e DMUCHCl; com DMSO foram investigadas por meio de suas propriedades físico-químicas e por espectroscopia Raman, tendo em vista modular as propriedades dos SEPs. Neste caso, os resultados não apontaram para interações fortes e específicas envolvendo as espécies iônicas e o DMSO, mas a um maior empacotamento do sistema, onde os desvios de suas propriedades físico-químicas com relação à idealidade são negativos e sua mobilidade iônica juntamente com a análise dos espectros vibracionais não evidenciaram interações específicas. No entanto, as viscosidades e densidades diminuíram nas misturas e a mobilidade iônica foi favorecida.Although it has long been used as a solvent for organic and inorganic species, as well as drug carriers, many aspects concerning the intermolecular self-association of dimethyl sulfoxide (DMSO) and their interactions with ionic species are still controversial in the literature. In the present study, the structure and local environment of dimethyl sulfoxide (DMSO) in different ionic media were studied using three different approaches. In the first approach, the Raman non-coincidence effect (NCE) observed in the band assigned to the DMSO ν(S = O) mode, ca. 1050 cm-1, was investigated for the pure liquid and in its solutions of carbon tetrachloride (CCl4) and water. In addition, the effect of ionic species (K1, KSCN, KBr, TBAN3, TBAOCN, LiClO4, Mg (ClO4)2) on the frequency ν(S = O) as well as the NCE of the solutions were investigated. The results of NCR together with the infrared, NMR and physico-chemical properties measurements showed that these ionic species not only affect the association structure of DMSO, but are also capable of interacting strongly with the solvent. In the second approach, with the purpose of modulating the properties of an ionic liquid, the structural analysis of the mixtures involving DMSO and water as solvents and the ionic liquid EAN as a solute were carried out by X-ray and neutron scattering techniques. The results showed that the cation-anion structure of the EAN is affected by the presence of DMSO and that in both solvents strong hydrogen bonds between the EA+ cation and the oxygen from solvent and from nitrate anion are evident. The water molecules do not affect the structure of the EAN drastically, because its LH donor/acceptor character and its size allows the formation of bridges between cation and anion, however, EAN can distort the hydrogen bonding three-dimensional network in water. On the other hand, the DMSO molecules repels the anions from the polar head of EA+ in the competition in forming LH with the cation, however EAN break down DMSO association structures. In the third approach, mixtures involving three different SEPs (a class of ionic liquids); Relina, MUCHCl and DMUCHCl; with DMSO were investigated by means of their physicochemical properties and by Raman spectroscopy, in order to modulate the properties of SEPs. In this case, the results did not point to strong and specific interactions involving the ionic species and DMSO, but to a greater packaging of the system, where the deviations of its physicochemical properties with respect to the ideality are negative and its ionic mobility together with the analysis of the vibrational spectra showed no specific interactions. However, the viscosities and densities decreased in the mixtures and the ionic mobility was favored.
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Brunel, Frédéric. "Synthèse, conception et élaboration de nouveaux systèmes dérivés de liquides ioniques antibactériens à base de phosphonium". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4087.
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Un récent rapport de l’OMS met en garde les autorités de santé sur l’émergence de résistances chez les bactéries et le développement de souches bactériennes multi-résistantes aux traitements antibiotiques actuels. La progression de ces phénomènes est dû à différents facteurs. L’environnement hospitalier concentre un usage important de traitements antibiotiques et représente ainsi un terreau favorable au développement de résistances chez les bactéries. Le staphylocoque doré, ainsi que sa souche résistante (SARM), s’avèrent problématiques et entraînent un grand nombre de maladies nosocomiales. Dans ce contexte, il est primordial de mettre au point de nouveaux agents antibactériens permettant de lutter contre ces bactéries. Les liquides ioniques (sels à point de fusion bas) démontrent d’importantes propriétés antibactériennes. Néanmoins les mécanismes de cet effet bactéricide n’ont pas encore été établis. Ainsi nous nous proposons, dans un premier temps, de synthétiser des liquides ioniques di-cationiques afin d’étudier les différents facteurs structuraux qui régissent leur activité antibactérienne. Dans un second temps, nous concevrons des liquides ioniques à base de phosphoniums fonctionnalisés avec une sonde fluorescente. En exploitant les propriétés spectroscopiques, nous tenterons d’observer leurs interactions avec les cellules bactériennes. Enfin, nous nous proposons d'utiliser les phosphoniums comme agents de fonctionnalisation de surface dans le but de mettre au point des surfaces aux qualités bactéricides intrinsèques. Pour ce faire nous utiliserons différentes méthodes comme la conception de monocouches auto-assemblées ou l’électropolymérisationA recent WHO report warns the health authorities about the emergence of new bacterial resistances and the development of multi-resistant strains against current antibiotics treatments. The growth of those resistances is due to several factors. The hospital environment concentrates a significant use of antibiotics and disinfectant representing a favorable ground for bacterial resistance development. Among them the Staphylococcus aureus and its methicillin resistant strain (MRSA) represent a crucial issue in care environments and is a major cause of hospital acquired infections. In this context, it is essential to develop new antibacterial agents to fight against these bacteria. Ionic liquid are low melting point salts, they show significant antibacterial properties. However, the fact that the mechanisms of action of their bactericidal effect have not been established yet constitutes a major obstacle to their development as bactericidal agents. Thus, we propose to synthetize ammonium- and phosphonium-based di-cationic ionic liquids in order to study the different structural factors that govern their antibacterial activity. Then we will develop phosphonium based ionic liquids functionalized with a fluorescent probe. By taking advantage of their spectroscopic properties we will try to observe their interactions with bacterial cells. Finally, we propose to use the phosphonium salts as surface functionalization agents in order to design surfaces with intrinsic antibacterial properties. To do so, we will use innovative methods such as conception of self-assembled monolayers or electropolymerization technics
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Moura, Leila. "Liquides ioniques pour la séparation des d'hydrocarbures gazeux". Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01064777.
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L'objectif de ces travaux était de synthétiser, caractériser et étudier le potentiel d'une sélection de liquides ioniques, pour la séparation de l'éthane et de l'éthène. L'influence dans l'absorption de l'éthène de la présence de trois cations métalliques, le lithium (I), le nickel (II) et le cuivre (II) dans un liquide ionique était également étudiée. Les liquides ioniques sélectionnés sont basés sur le cation imidazolium contenant des groupes fonctionnels au niveau de la chaine alkyle latérale. Les anions choisis sont le bis(trifluorométhylsulfonyl)imide, [NTf2], la dicyanamide, [DCA] et le méthylphosphite, [C1HPO3]. Sachant qu'un solvant de séparation idéale doit avoir une capacité d'absorption et une sélectivité de séparation élevées, une faible viscosité, une haute stabilité thermique et une cinétique d'absorption rapide pour le gaz sélectionné. Pour évaluer ces propriétés pour les milieux sélectionnés, plusieurs paramètres ont été déterminés la densité et la viscosité des liquides ioniques ainsi que l'absorption de chaque gaz dans les liquides ioniques. L'absorption de l'éthane et de l'éthène dans les liquides ioniques purs ainsi que dans les solutions de liquide ionique + sel métallique a été mesurée dans une gamme de températures comprises entre 303.15 K et 353.15 K et pour des pressions proches de l'atmosphérique. La sélectivité idéale des liquides ioniques pour l'absorption de l'éthane par rapport à l'éthène a ainsi pu être déterminée. La détermination de l'absorption en fonction de la température a permis d'accéder aux propriétés thermodynamiques de solvatation de ces gaz dans des liquides ioniques et à comprendre la manière dont les liquides ioniques interagissent avec ces solutés comment les liquides ioniques se structurent autour de ces molécules
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Tang, Chi Ming. "Structure and dynamics of doped ionic clusters : a computational study". HKBU Institutional Repository, 1991. https://repository.hkbu.edu.hk/etd_ra/5.
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Fouchet, Julien. "Couplage de type Ullmann : une méthodologie pour la synthèse de matériaux ioniques". Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE019/document.
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Les liquides ioniques à base d’imidazolium présentent une plateforme architecturale unique aisément fonctionnalisable permettant de préparer des matériaux ioniques avec des propriétés mésomorphes. Dans le but d’introduire des propriétés supplémentaires, nous avons élaboré des composés à coeur rigide étendu. La stratégie de synthèse adoptée passe par un couplage de type Ullmann. Nous avons développé une méthodologie nécessitant uniquement du Cuivre (II) supporté sur zéolithe (Na-Y) et du carbonate de potassium. Cette approche a pour avantage d’éviter l’utilisation de solvant, d’atmosphère inerte et de ligands. Ce couplage a été optimisé en utilisant la technique de synthèse en micro-ondes (réduction du temps de réaction, diminution des sous-produits formés). Après avoir étudié cette méthodologie, nous l’avons étendu à d’autres propriétés notamment à des matériaux (scintillateurs) présentant des propriétés de détection et de discrimination des rayonnements neutrons/gamma en introduisant des chromophores au sein de nos composés. Le couplage de type Ullmann utilisé a également permis d’élaborer des composés pouvant présenter des propriétés électroniques (conduction et électrochromisme)Ionic liquids based on imidazolium are an excellent platform that can be designed to promote liquid crystalline phases. In order to introduce additional properties, we synthesized compounds with a rigid expanded core. Herein, we reported an Ullmann-type coupling using only Cu(II)-NaY as catalyst and potassium carbonate as base. This synthetic approach avoids the use of solvents, inert atmosphere and ligands. We have optimized this coupling using the technique of microwave synthesis (reduction of reaction time and by-products formed). After studying this methodology, we have extended it to other behaviors. Thus we have synthesized ionic materials (scintillators) with properties of detection and discrimination of radiation neutrons/gamma by introducing chromophores in our compounds. This Ullmann-type coupling has allowed to prepare compounds that can have electronic properties (conduction and electrochromism)
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Tsiantis, Miltiades S. "Regulation of V-ATPase gene expression by ionic stress in higher plants". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337540.
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Chakraborty, Gulmi. "Studies on the Aggregation characteristics of selected surfactants and surface active ionic liquids". Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/handle/123456789/2620.
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Shibata, Manabu. "Accurate Determination of pH by Use of Ionic Liquid Salt Bridge". 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157605.
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Senanayake, Gamini. "Ionic activities in strong salt solutions and mixed solvents of hydrometallurgical importance". Thesis, Senanayake, Gamini (1986) Ionic activities in strong salt solutions and mixed solvents of hydrometallurgical importance. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/52730/.
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This thesis presents a comparative study and analysis of ionic activities in aqueous acid and salt solutions of high ionic strength, and in mixed aqueous-organic solutions as used or proposed for the hydrometallurgical processing of complex sulfides, precious metal residues, or by-products. The representative ions or solvents chosen for this study are as follows:
simple cations : H+,Na+,Ca2+,Mg2+ ,Ag+,Cu+,Cu2+,Pb2+,Zn2+,Ni2+
simple anions: CT, SO2-4, CIO-4
complex anions: AgCl-2, CuCl-2
solvents: acetonitrile, ethanol, dimethylsulfoxide
The various experimental and empirical methods of estimating ionic activities are discussed, focussing on the measurement of emf of appropriate cells as the most convenient and practical approach. Because this method requires an accurate calculation or measurement of liquid junction potentials (Ej) associated with a salt bridge and the test solution, the origin and basis of determining Ej is analysed for various salt bridges using high ionic strength and mixed solvent test solutions. The measured values of Ej are presented and recommended for different salts and solvent systems which allow emf values to be corrected and provide more accurate ionic activities.
The measured ionic activities are rationalised in terms of the various competing ion-water, ion-solvent, ion-ion and waters-olvent interactions. It is shown that in concentrated acid and salt solutions, the ionic activity coefficients are related to the activity of water in solution according to their ionic hydration numbers. Thus for simple non-associated electrolytes, like HCl or NiCl2, hydration numbers and hydration models were readily determined. For those metal ions which form chloro-, hydroxo- or sulfato-complexes, the changes in activity are related to the formation of complex ions. In these cases the species distribution and relevant Eh-pH or Eh-log Cl diagrams are discussed and presented.
Mixed solvent systems are shown to increase the activity of simple anions, but increase or decrease the activity of metal ions in perchlorate media according to the relative strength of the ion-water and ion-solvent interactions. However with mixed solvent systems containing chloride ions, the solvent also promotes complex ion formation, leading to even greater changes in activity of those metal ions with comparable ion-chloride and ion-solvent interactions.
Finally, a comparison is made between the changes in ionic activities and reduction potentials brought about by adding salts or solvents to aqueous solutions. It is shown that solvent effects are generally much greater than salt effects. The practical applications of using such systems for the recovery or separation of metals or metal salts from hydrometallurgical leach solutions and residues are briefly reviewed and further possible applications are discussed.
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Deshpande, S. S. "Rate enhancement of diels-alder reactions in salt solutions and Ionic liquids". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2006. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2504.
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Reichenbach, Judith. "Structure and dynamics in ionic liquids and concentrated salt solutions : an ultrafast spectroscopy study". Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8571/.
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A combination of spectroscopic methods and symmetry considerations were used throughout the presented studies to investigate the terahertz spectra showing liquid dynamics in varied systems. Optical Kerr effect spectroscopy revealed clusters of different sizes in aqueous sodium thiosulfate solutions with non-Newtonian behaviour. In conjunction with terahertz infrared spectroscopy, optical Kerr effect spectroscopy showed the charge-ordered nature of butylammonium ionic liquids, which manifested through phonon modes in the terahertz spectra. In eutectic lithium thiocyanate solutions, a combination of mid-infrared spectroscopy, optical Kerr effect spectroscopy and X-ray scattering showed a separation into nanoscale water-rich and salt-rich domains at low temperatures. In summary, the use of terahertz spectroscopy on selected model system provides information on the dynamics governing the behaviour of liquids and solutions.
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Chen, Jing. "SOLUTION AND SOLID STATE INTERACTIONS BETWEEN IONIC π-SYSTEMS". UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/289.
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Although attractive interactions between π systems (π-π interaction) have been known for many years, understanding of its origin is still incomplete. Quantitative measuring of π-stacking is challenging due to the weak nature of the π-π interaction. This dissertation aims at elucidating a quantitative conformational analysis by NMR ring current anisotropy of an organic compound capable of intramolecular π-stacking in solution and studying charge effects on the stacking of π-systems. This dissertation offers four contributions to the area. (1) A general approach to four-state, conformational analysis based on the magnetic anisotropy of molecules undergoing fast dynamic exchange is described. (2) Study unveiled the importance of charges in the conformation of a dication in the solution. (3) Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized and studied. (4) Study unveiled ionic π-systems preferred face-to-face stacking due to strong cation-π and anion-cation attractions.
A general protocol for the application of magnetic anisotropy to quantitative multi-state conformational analysis of molecules undergoing fast conformational exchange was suggested in the current study. The reliability of this method of conformational analysis was checked by the mass balance. VT-NMR was also conducted to study the enthalpic parameters. This technique can be further used to study canonical interactions such as ion pairing, hydrogen boning, and molecular recognition.
In the current study, dependence of the probe conformations on the dispersive interactions at the aromatic edges between solvent and probes was tested by conformational distributions of the fluorinated derivatives (2b and 2c) of the probe molecule (1a). Solution and solid studies of these molecules put the previous conclusion drawn by the Cammers group in question. Current studies show that the dispersive interaction at the aromatic edge could not be the predominant force on the conformational changes in the probe molecule 1a during the fluoroalkanol perturbation. This study indicated that charges might be important in the formation of the folding conformations in the solution and solid state of 1a, 2b, and 2c. A contribution of this thesis was to prepare and study a conformational model that lacked charges. The previous molecules were charged.
The solid-state structures of pyridinium-derived aromatic rings from the CSD (Cambridge Structural Database) were studied to investigate the π-π interaction between cationic π-systems in solid state. Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized to study the π-π interaction between two aromatic rings that carried opposite charges. This study showed that the interaction between ionic π-systems can be enhanced by cation-π and anion-cation attractions. The stackings of these π-systems introduce more overlap, closer packing and stronger atomic contact than that of the solid states of comparable neutral species. Cation-π and anion-cation attractions are synergistic in aromatic salts.
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Huang, Yan. "Micro- and Nanogel Formation through the Ionic Crosslinking of Polyelectrolytes". University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1417781855.
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Lee, Minjae. "Design, Synthesis and Self-Assembly of Polymeric Building Blocks and Novel Ionic Liquids, Ionic Liquid-Based Polymers and Their Properties". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77166.
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The convergence of supramolecular and polymer sciences has led to the construction of analogs of traditional covalently-constructed polymeric structures and architectures by supramolecular methods. Host-guest complexations of polymers are also possible through well-defined synthesis of polymeric building blocks, for novel supramolecular polymers.
Monotopic polymeric building blocks were synthesized by controlled radical polymerizations with a crown or paraquat initiator. The combinations of terminal and central functionalities of host and guest polymeric building blocks provided chain-extended and tri-armed homopolymers, and diblock and tri-armed copolymers.
A supramolecular graft copolymer was formed from a main-chain poly(ester crown ether) and a paraquat terminated polystyrene. This comb-like copolymer was characterized by a large viscosity increase. A four-armed polystyrene-b-poly(n-butyl methacrylate) was synthesized from a pseudorotaxane macroinitiator derived from a complex of a crown-centered polystyrene and a dufunctional paraquat compound. A single peak with higher molecular weight from size exclusion chromatography proved the copolymer formation.
Supramolecular interactions enhance the ionic conductivity of semi-crystalline ionic polymers; the ionic conductivity of a C₆-polyviologen and dibenzo-30-crown-10 mixture was 100 times higher than the polyviologen itself. However, ionic conductivities of amorphous polyviologens with polyethers were influenced only by glass transition temperature changes.
New imidazolium ionic liquid monomers and imidazolium based polymers were synthesized for potential applications in electroactive devices, such as actuators. Structure-property relationships for pendant imidazolium polyacrylates and main-chain imidazolium polyesters were investigated. Terminal ethyleneoxy moeties enhanced ionic conduction 2~3 times; however, the alkyl chain length effect was negligible. For the imidazoium polyesters, higher ion conductivities result from 1) mono-imidazolium over bis-imidazolium, and 2) bis(trifluoromethanesulfonyl)imide polymers over hexafluorophosphate analogs. A semi-crystalline hexafluorophosphate polyester with C₁₀-sebacate-C₁₀, displayed 400-fold higher ionic conductivity than the amorphous C₆-sebacate-C₆ analogue, suggesting the formation of a biphasic morphology in the former polyester.
New dicationic imidazolium salts have interesting features. 1,2-Bis[N-(N'-alkylimidazoilum)]ethane salts stack well in the solid state and possess multiple solid-solid phase transitions. They complex with dibenzo-24-crown-8 and a dibenzo-24-crown-8 based pyridyl cryptand with Ka = ~30 and 360 M¹, respectively. Some of these dicationic imidazolium salts have low entropies of fusion, typical of plastic crystals.
These newly discovered imidazolium homopolymers have ionic conductivities up to 10⁴ (S cm⁻¹); however, better properties are still required. Well-designed block copolymers should provide both good electrical and mechanical properties from bicontinuous morphologies, such ion channels.Ph. D.
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Madenci, Dilek. "Study of the aggregation behaviour of egg yolk lecithin/bile salt mixtures by increasing the ionic strength". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4918.
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This thesis describes a study of the aggregational behaviour of egg yolk lecithin (EYL), a natural lecithin, and bile salt mixtures especially with respect to an increase of the ionic strength of the solvent. Mixtures of two amphiphiles with very different spontaneous curvature as EYL lecithin and bile salt form mixed micelles and vesicles in aqueous solution. Their properties have been well-studied under physiological conditions, i.e. 150 mM electrolyte concentration and pH 7- 8, while other conditions are still hardly explored. Upon increasing ionic strength the formed structures and the transitional pathways (micelles, coexistence of micelles and vesicles, and vesicles) change the generated structures completely from those observed under physiological conditions. We quantitatively determined these structures formed in a broad range of electrolyte concentrations with various scattering techniques, x-ray, light and neutron scattering and calorimetry. With calorimetry, phase diagrams in the EYL and bile salt concentration phase plane were determined at various ionic strength ranging from physiological salt concentration to up to 1000 mM. Additionally a new electrochemical approach using functionalised electrodes, i.e. sensitive and selective to bile salt, and thus to control the bile salt concentration in solution (concentrations below the critical micellar concentration (cmc)) was attempted, since bile salt removal or injection drives the micelle-to-vesicle or the vesicle-to-micelle transition, respectively, of the mixed aggregational system of EYL/bile salt. Although this control was not achieved within the framework of this thesis, promising results show directions for future experiments.
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Chen, Xi. "Designing Acrylic Block Copolymers with Multiple Hydrogen Bonding or Multiple Ionic Bonding". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/84961.
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The dynamic characteristics of hydrogen and ionic bonding contributes to the reversible properties of acrylic polymers, opening new avenues for designing materials with mechanical strength and processability. These non-covalent interactions function as physical crosslinks, which provide enhanced structural and mechanical integrity to acrylic block copolymers. The strong hydrogen bonding or ionic interaction also directs self-assembly to hierarchical microstructures, which enables many applications including thermoplastic elastomers and energy storage devices. Inspired by complementary hydrogen bonding interactions between nucleobase pairs in DNA, a series of bioinspired nucleobase-acrylate monomers such as adenine acrylate (AdA), thymine acrylate (ThA), cytosine acrylate (CyA) were designed, whose synthesis were afforded by aza-Michael addition. Among those nucleobases, cytosine arises as a unique category. It is not only able to self-associate via weak hydrogen bonds, but also forms quadruple hydrogen-bond bearing units (ureido-cytosine) when functionalized with isocyanates. Reversible addition-fragmentation chain transfer polymerization (RAFT) yielded acrylic ABA triblock copolymers with CyA external hard blocks. A subsequent post-functionalization using hexyl-isocyanate generated the corresponding ureido-cytosine acrylate(UCyA)-containing triblock copolymers. The self-complementary quadruple hydrogen bonding in the UCyA polymers achieved a broader service
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temperature window, while the alkyl chain ends of UCyA units allowed tunability of the mechanical strength to apply as thermoplastic elastomers. In addition, quadruple hydrogen bonding induced stronger propensity of self-assembly and denser packing of the polymers, which contributed to a well-defined ordered morphology and enhanced resistance to moisture uptake. A facile 2-step synthesis provided doubly-charged styrenic DABCO salt monomer(VBDC18BrCl) containing an octadecyl tail. RAFT polymerization allowed the preparation of DABCO ABA block copolymers with defined molecular weights and low polydispersity. Thermal analysis revealed a melting transition of the VBDC18BrCl block copolymer resulting from the side-chain crystallization of the long alkyl tail. Systematic mechanical comparisons between DABCO salt-containing copolymers and the corresponding singly-charged polymer controls demonstrated superior mechanical properties attributable to a stronger ionic interaction between the doubly-charged groups. Morphological characterizations revealed a well-ordered lamellar microstructure and a unique three-phase morphology of the DABCO block copolymers, which involve a soft phase, a hard phase, and an ionic aggregates domain dispersed within the hard domain.Master of Science