Hydrated sodium-magnesium sulfate minerals are common in many continental evaporite settings around the world. The crystallization sequence of these minerals depends on such parameters as the composition of the parent brine, the temperature, the evaporation rate of the brine, and the differences in the atomic structure and water content of the minerals. The atomic structures of konyaite [Na2Mg(SO4)2·5H2O] and sodium-magnesium decahydrate [Na2Mg(SO4)2·10H2O], a newly described sulfate salt, have been determined from single-crystal X-ray diffraction experiments. The refined structures are discussed and compared to that of blödite [Na2Mg(SO4)2·4H2O]. The arrangement and importance of hydrogen bonds within all three structures are also discussed, and have been further investigated by infrared spectroscopy. Löweite [Na12Mg7(SO4)13·15H2O] was included in this experiment to provide a low-hydration end-member. Differences in water content and the importance of hydrogen bonds in the respective structures were clearly reflected in the generated infrared spectra. The growth conditions of the decahydrate, konyaite, blödite, löweite, and other phases of the Na2O-MgO-H2O system, as well as their stability relationships, were studied in a temperature-controlled crystal-growth experiment. Konyaite and the decahydrate phase were found as first precipitates over a range of temperatures and brine compositions where they are not considered to be the thermodynamically stable phase. The importance of evaporation rate in the formation of these, and other metastable phases, is discussed in relation to inland saline systems. Possible localities where the decahydrate could exist in nature are discussed, and challenges for future research are presented. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2010-09-16 09:02:33.843

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This study investigates the metallosupramolecular chemistry of functionalised 1,2-diazole ligands, by the preparation and characterisation of a range of first-row transition metal coordination polymers and discrete assemblies. To this end, twenty-six ligands containing 1,2-diazole functionality have been synthesised, twenty-one of which have not previously appeared in the coordination chemistry literature. Utilising these compounds, forty new coordination compounds have been prepared and characterised by single-crystal X-ray crystallography and other analytical techniques, and their solid-state structural features discussed in the search for reproducible new diazole-based synthons for the designed synthesis of new functional materials. Particular attention is paid to the contribution of the second nitrogen atom on the diazole ring, which participates in structure-directing hydrogen bonding interactions, or acts as a synthetic handle to easily append further functionality to the ligand system. The design of the ligands is separated into two primary categories, representing the different approaches adopted for the synthesis of the metallosupramolecular architectures. The combination of 1H-pyrazole and carboxylic acid functionality in mixed-ligand assemblies was investigated with the combination of bis-pyrazole and bis-carboxylic acid ligands, and with the preparation of ligands containing both functional groups. This approach was extended to the related heterocyclic species indazole, with all five possible isomers of indazole-carboxylic acid synthesised and used in coordination chemistry for the first time. The 1H-diazole-carboxylate synthon was employed in the synthesis of fourteen coordination polymers and three discrete assemblies. Heteroaryl substitution at the 1-position of pyrazole or indazole compounds was employed to generate chelating ligands containing pyridine or benzimidazole functionality, which were used to form nineteen discrete complexes, including dinuclear helicates and metallocycles, and five coordination polymers. The effect of flexibility and distance between coordination sites in bis-bidentate ligand systems was examined, in conjunction with studies into the effect of steric bulk and variation of the electronic nature of the coordinating groups. While this study is primarily concerned with the solid-state structural chemistry of 1,2-diazole coordination compounds, attention is paid where appropriate to solution-based measurements such as NMR and UV/Visible studies, and the pertinent behaviour of functional materials, such as thermogravimetric analysis for solvated species and gas uptake studies for stable void-containing materials.

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Phase formation studies in the quaternary section Ca_2-<I>y</I>Sr<I>_y</I>Fe_2-<I>x</I>B'<I>_x</I>O<I>_γ</I> : B' = Nb, Ta, 0 ≤ <I>y</I> ≤ 2.0 and 0 ≤ <I>x</I> ≤ 2.0 were carried out. Results are summarised below for B' = Nb; for B' = Ta they were broadly similar. Four solid solution phases were found: i) a cubic solid solution, with a variable compositional extent <I>x</I>, which increased with substitution of Ca by Sr, from 0.45 ≤ <I>x</I> ≤ 0.65 for <I>y</I> = 0, to 0 ≤ <I>x</I> ≤ 1.2 for <I>y</I> = 2.0. ii) A limited orthorhombic solid solution along the Ca₂Fe₂O₅-Ca₂B'₂O₇ join with 0.8 ≤ <I>x</I> ≤ 1.0. iii) A complete range of orthorhombic, brownmillerite solid solution for <I>x</I> = 0 and iv) an orthorhomic, perovskite-related solid solution, isostructural with Ca₂Nb₂O₇, for <I>x</I> = 2.0. A combination of differential thermal analysis, thermogravimetry, Mössbauer spectroscopy, high temperature powder X-ray diffraction, Rietveld refinement, a.c. impedance spectroscopy and magnetic susceptometry has been used to characterise these new phases. Solid solution (i) has variable oxygen content with an oxygen-deficient perovskite structure. As synthesised, for <I>x</I> = 0.6 it contains a mixture of Fe⁴⁺ and Fe³⁺ in the ratio 13/87. The oxygen content could be modified by heat treatment under various atmospheres over the range 5.5. ≤ <I>γ</I> ≤ 5.92 which corresponded to the ratios: 93/7 to Fe³⁺/Fe²⁺ and 42/58 of Fe⁴⁺/Fe³⁺. At higher oxygen contents, <I>γ</I> > 5.7, transformation to an orthorhombic structure was observed. The electrical resistivity was dominated by grain boundary effects. Conduction is electronic and is attributed to hopping between iron in mixed oxidation states. The resistivity increased dramatically on reduction and became <I>n</I>-type, presumably due to a small fraction of Fe²⁺ present.

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High Wire is a chamber ballet in five movements for multiple woodwind player (piccolo, Eb clarinet, alto saxophone, bass clarinet) and piano. It was inspired by Frederick H. Graham's Wait For The Muncie Boys: Indiana's Early Circuses, and was first performed, with choreography by Michele Kriner, at a concert of the Middletown Arts Project on January 26, 2003. The work is somewhat unusual in that it is both tonal and serial. It evokes popular musical styles of the turn of the twentieth century, with particular reference to circus music, and yet it is based on a twelve-tone series and generally adheres to strict serial techniques. The genesis of the work, the relationship of the music to the choreography, and the way in which two rather different musical sensibilities are reconciled are discussed in the written report that serves as an introduction to the score. A recording of the first performance is included in the side-pocket. / School of Music

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