The interaction of transition metal carbonyl clusters with unsaturated cyclic and polycyclic ligand systems continues to stimulate ongoing research and this thesis is concerned mainly with the reactions of triosmium carbonyl clusters with such compounds. Chapter one contains a brief summary of triosmium dodecacarbonyl chemistry, incorporating both synthesis and reactivity. The arene chemistry of mononuclear complexes and cluster compounds is also discussed. Over the last decade there has been serious debate on the validity of the cluster-surface analogy; the boundary conditions are addressed herein. Chapter two details alternative synthetic routes to the compound M<SUB>3</SUB>(CO)<SUB>9</SUB>(μ-η<SUP>2.</SUP>.η<SUP>2.</SUP>.η<SUP>.2</SUP>-C<SUB>6</SUB>H<SUB>6</SUB>) [M = Ru, Os]. A series of substituted 1,3-cyclohexadiene ligands have also been prepared and reacted with the cluster Os<SUB>3</SUB>(CO)<SUB>10</SUB>(MeCN)<SUB>2</SUB>. The successful synthesis of the <I>bis</I>-benzene cluster Os<SUB>3</SUB>(CO)<SUB>6</SUB>(μ<SUB>3</SUB><SUP>-</SUP>η<SUP>2.</SUP>.η<SUP>2.</SUP>.η<SUP>2.</SUP>-C<SUB>6</SUB>H<SUB>6</SUB>)(η<SUP>6</SUP>-C<SUB>6</SUB>H<SUB>6</SUB>) is reported in chapter three. The systematic stepwise reaction of Os<SUB>3</SUB>(CO)<SUB>9</SUB>(μ<SUB>3</SUB>-η<SUP>2.</SUP>.η<SUP>2.</SUP>.η<SUP>2</SUP>-C<SUB>6</SUB>H<SUB>6</SUB>) with trimethylamine-N-oxide and 1,3-cyclohexadiene leads to the formation of a range of benzene-diene clusters, all of which have been fully characterised. Their isomeric and fluxional behaviour has also been studied. The reactions of acenaphthylene, C<SUB>12</SUB>H<SUB>8</SUB>, a stable tricyclic system with 12 π-electrons available for bonding, are reported for Ru<SUB>3</SUB>(CO)<SUB>12</SUB> and Os<SUB>3</SUB>(CO)<SUB>12</SUB> in chapter four. The resulting compounds demonstrate the range of bonding modes adopted by this flexible ligand.

This thesis describes work aimed at identifying new treatments for aluminium(oxide) surfaces which are based on complex formation at the interface by relatively simple organic ligands. Such an approach offers a more benign alternative to the surface roughening or passivation by strongly acidic and/or oxidising treatments which are currently used commercially. A specific objective of interest to the organisation sponsoring the work (Alcan) was the development of new dispersants for aluminium trihydroxide (ATH) which is used as a flame retardant in organic polymers. On the basis of reports of earlier work undertaken in Zeneca Specialities polyphenolic ligands were selected as candidates for the ligating headgroups. The synthesis of a series of esters of gallic acid (3, 4, 5-trihydroxybenzoic acid) with varying lengths of alkyl group tails is reported in Chapter 2 together with an investigation of their strength of binding to high surface area ATH (superfine grade) by monitoring the uptake by uv-spectrometry from 95% methanol/water. Analysis of results based on <i>Langmuir adsorption isotherm</i> behaviour confirms the suitability of pyrogallol-based ligands for ATH since all of the ligands exhibit very strong binding. The tail group contributes in no part to the binding efficiencies. Furthermore, no insight into binding modes can be inferred from isotherm results and no differentiation can be made between the binding strengths of closely related ligands. In an attempt to understand the modes of attachment, integrated use of experimental adsorption isotherm results and <i>molecular modelling </i>techniques have been used in Chapter 3. Additional classes of ligands involving dihydroxybenzene and 3-methyl-4,5-dihydroxybenzene headgroups were synthesised and tested. The approach involves simulating the chemisorption of a monolayer of the organic ligand onto the aluminium metal oxide surface. The results suggest that the stabilites and structures of the interfacial complexes depend not only on metal-ligand coordinate bonds, but also on secondary bonding interactions. Trihydroxybenzene headgroups bind more strongly than dihydroxy which bind much more strongly than monohydroxy headgroups.

Cisplatin, <I>cis</I>-[Pt(NH<SUB>3</SUB>)<SUB>2</SUB>Cl<SUB>2</SUB>], has been a successful and most widely used anticancer drug since its first discovery 30 years ago. Up to now the mechanism of action of this drug is still not well understood. In this thesis, pH dependent platinum-sulfur interactions, the solution structure of cisplatin DNA GpG intrastrand adduct and the chemistry of a new anticancer active drug have been investigated. Using [<SUP>1</SUP>H, <SUP>15</SUP>N] 2D NMR spectroscopy and HPLC, together with <SUP>15</SUP>N-labelled amine ligands highly pH dependent interconversion between S- and N-bound methionine adducts of {Pt(dien)}<SUP>2+</SUP> (dien = diethylenetriamine) <I>via</I> dien ring-opened intermediates has been observed. This isolated ring-opened intermediate exists as four diastereomers and was surprisingly long-lived. This study suggests a possible role for thioether-sulfur in the transfer and activation of platinum drugs. The solution structure of a DNA 14mer duplex containing a cisplatin 1,2-GpG intrastrand crosslink has been determined by combined NMR and estimated molecular dynamics. Plantation at GpG site causes significant bending and unwinding of the DNA duplex. Sequence dependent structural characteristics are discussed. The 2-picoline (2-methylpyridine) complex, <I>cis</I>[PtCl<SUB>2</SUB>(NH<SUB>3</SUB>)(2-Pic)] (1), is a recently reported anticancer active complex with high activity against cisplatin resistant cell-lines and has now entered clinical trials. The crystal structure of 1 shows steric hindrance induced by the 2-CH<SUB>3</SUB> group towards an axial approach to Pt. <SUP>15</SUP>N labelling of 1 and 2D [<SUP>1</SUP>H, <SUP>15</SUP>N] NMR spectroscopy allowed both the hydrolysis rates and pKa values of the complex to be determined. The steric effect of 2-picoline ligand reduces the reactivity of the complex during substitution reactions and the position <I>cis</I> to 2-picoline is more affected. Reactions between 1 and guanosine 5'-monophosphate (5'-GMP) were followed by 2D NMR and kinetic rates were calculated. The reactivity of 1 with thiol ligand of glutathione (GSH) was greatly reduced compared with its 3-picoline analogue which is less sterically hindered. Both mono- and bis-GMP adducts were observed in the competitive reactions of 1 with GSH and GMP. Slow rotation about the Pt-N picoline bond and fast rotation about Pt-N7 GMP bonds on the NMR time scale were observed for the bis(GMP) adducts. These features of 1 may play an important role in its altered spectrum of biological activity compared to cisplatin. Complex 1 forms four stereoisomers in the reactions with d(GpG) and a 14mer DNA single strand due to the different orientations of 2-picoline (either towards 5'-G or 3'-G) and slow rotation of Pt-N(2-Pic) bond. These contrast with reactions of 1 with a 14mer DNA duplex, in which only one major stereoisomer is observed. 2D NMR experiments and molecular modelling suggest that favourable steric interactions, H-bonding and van der Waals contact provide the structural basis for this unusually high stereoselectivity. These results give new insights into the effect of ligand design on the nature of platinated DNA lesions.

Introduction and Literature Review: Different families of oxide ion conductors and their applications are discussed. Experimental and Characterisation Methods: The synthetic methods and characterisation techniques used throughout this thesis are described. Synthesis, Structure and Transport Properties of Bi2Zr2-xTixO7 Phases: The characterisation of Bi2Zr2-xTixO7 compounds is reported for the first time. An increase in conductivity of 3 orders of magnitude is found for the Zr- rich end member. Bi2Ti2O7, which adopts centrosymmetric space group Fd-3m has been found to be SHG active. Structure Solution of beta-Bi2Sn2O7 and Properties of Bi2Sn2O7 Based Materials: Analysis of synchrotron powder X-ray and powder neutron diffraction data has shown for the first time that beta-Bi2Sn2O7 is not cubic and has a monoclinic structure, most likely in space group Pc. The effect of doping in both Bi2Sn2O7 and Bi2ScNbO7 on their respective conductivities has been explored. Synthesis and Characterisation of Nd2Zr2O7: A range of average and local structural techniques have been used to demonstrate that Nd2Zr2O7 prepared by wet-chemistry routes adopts the fluorite-type structure, as opposed to the pyrochlore structure adopted by samples synthesised by solid state methods. Synthesis, Characterisation, Simulations and Properties of Bi6WO12 and Related Oxide Ion Conductors: We report for the first time details of DFT molecular dynamics simulations to probe the oxide ion conduction pathways in the oxide ion conductor Bi6WO12. Appropriate doping has led to enhancements in oxide ion conductivity. Simulations, Characterisation and Properties of New Bismuth Vanadate Oxide Ion Conductors: DFT molecular dynamics simulations carried out on Bi19V2O33.5 have revealed the O2- migration pathways in this material with exceptional ionic conductivity. The synthesis and characterisation of new doped bismuth vanadates with formula Bi19-xMxV2O33.5-x/2 (M = Ca2+ or Sr2+), also excellent oxide ion conductors, is reported. Overall Conclusions and Suggestions for Future Work: This briefly reviews the conclusions and makes suggestions for further work.

Chapter 1 gives a brief review of oxychalcogenide materials and their properties, particularly those with structures similar to systems discussed in the later chapters. Particular attention is paid to the structural and magnetic properties of La2O2Fe2OSe2-type materials, work on which is presented in chapters 3–5. These oxychalcogenides, along with ZrCuSiAs-related materials, are of interest due to their potentially interesting magnetic and conducting properties. In particular they are close relatives of the LaOFeAs superconductors. Chapter 2 describes the synthetic and analytical techniques used in this project. The theory behind the powder diffraction techniques used throughout is described, and information on specific methodology used in the data collections and analysis of this work is given. SQUID magnetometry is also discussed. Chapter 3 discusses the variable temperature structural and magnetic properties of La2O2Mn2OSe2 and Pr2O2Mn2OSe2, as well as those of the newly prepared material Ce2O2Mn2OSe2. These materials are observed to undergo a phase transition on cooling revealed by a change in the thermal expansion of the c cell parameter, and show evidence for the static disorder of oxide ions from the [Mn2O]2+ plane below this temperature. Pr2O2Mn2OSe2 is also shown to undergo a further transition on cooling below 36 K to an orthorhombic unit cell. Neutron diffraction data have also shown that the Mn2+ moments in these materials order with an AFM1 structure on cooling below ~180 K. Chapter 4 describes the study of both La2O2Fe2OS2 and La2O2Fe2OSe2 by variable temperature neutron powder diffraction. These materials have been demonstrated to order with an AFM3 structure on cooling below ~100 K, which is coincident with a subtle structural change observed in the thermal expansion of the a cell parameter. The unexpected adoption of the AFM3 magnetic structure is discussed in relation to structurally similar iron-based superconductors. Chapter 5 presents the synthesis of several new La2O2Fe2OSe2-type materials, and the magnetic structure of La2O2Co2OSe2. The stability range over which these materials form is discussed with respect to the size of the metal ions present. A comparison of the structural properties of all the A2O2M2OSe2 materials is given and the various magnetic structures they adopt discussed. Chapter 6 reports the synthesis of a new family of transition metal oxychalcogenides (β La2O2MnSe2). Their structure has been solved from laboratory X ray diffraction data, using a combination of charge-flipping and direct methods, and confirmed by neutron diffraction. Variable temperature structural properties are discussed and show these materials undergo a phase transition on cooling associated with ordering of transition metal ions. SQUID magnetometry and neutron powder diffraction have both demonstrated these materials order antiferromagnetically at low temperatures. Chapter 7 describes the synthesis of two new ZrCuSiAs-related transition metal containing oxychalcogenides: Ce2O2FeSe2 and La2O2ZnSe2. The structure solution of Ce2O2FeSe2 by charge-flipping is reported, alongside the determination of the magnetic structure from neutron powder diffraction data collected at 12 K. The variable temperature structural properties of La2O2ZnSe2 are also reported.

One commercial application of emissive lanthanide complexes is in fluoroimmunoassays, which combine FRET with time-resolved detection of emission to glean information on biological interactions. Herein the development of highly emissive europium complexes to act as FRET donors in this process is described. Each complex reported in this thesis incorporates a coordinating ligand, which chelates to the metal ion centre, and a sensitising group, capable of populating the europium excited state. To maximise the molar extinction coefficient and emission quantum yield of the complexes, variation of the ligand and sensitising group, was addressed. An initial study into the use of 3-azaxanthone as a sensitising group was undertaken. A constitutional isomer of this chromophore is known to sensitise europium emission. The new system was developed to allow inclusion of four sensitising groups per complex, with a view to maximising the overall molar extinction coefficient. The resulting systems showed little improvement upon previously reported complexes and a new chromophore was devised, which possesses a much higher molar extinction coefficient and is able to sensitise europium emission efficiently. A series of complexes was synthesised in which the chelating ligand was varied to investigate the effect upon the photophysical properties. The complex with the properties best suited to the FRET application combines phenylphosphinate donating groups with a high degree of symmetry about the metal ion centre. The ability of this complex to withstand quenching of emission by a number of competitive anions and cations was explored and it was found that the complex possesses high kinetic stability. By bringing together the favourable photophysical properties imparted by the phenylphosphinate ligand and the high molar extinction coefficient of the new sensitising group, a final europium complex was synthesised with an extraordinarily high brightness, defined as the product of the emission quantum yield and molar extinction coefficient. This final complex met the specification for a FRET donor set out at the beginning of the project.

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No description available.

Chapter 1 begins with a brief introduction to the structural characteristics of cyclopentadienyl complexes and carbametallaboranes derived from [7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>]<SUP>2-</SUP>. This is followed by a discussion of the chemistry of monoanionic <i>nido</i>-icosahedral carbaboranes, paying particular attention to compounds containing the ligand [9-SMe<SUB>2</SUB>-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>]<SUP>-</SUP>. The chapter ends with a survey of compounds involving the sterically demanding species [7,8-Ph<SUB>2</SUB>-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>9</SUB>]<SUP>2-</SUP>. Chapter 2 describes the synthesis and spectroscopic and structural characterisation of three [ML<SUB>2</SUB>] derivatives of [9-SMe<SUB>2</SUB>-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>]<SUP>-</SUP>. The crystallographically observed cornformations of the [ML<SUB>2</SUB>] fragments with respect to the carbaborane ligand in 3,3-(CO)<SUB>2</SUB>-4-SMe<SUB>2</SUB>-4-SMe<SUB>2</SUB>-3,1,2-<i>closo</i>-RhC<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>, 1, and 3-(η2,η2-C<SUB>8</SUB>H<SUB>12</SUB>)-4-SMe<SUB>2</SUB>-3,1,2-<i>closo</i>-3,1,2-RhC<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>, 2, differ significantly from those adopted by (ML<SUB>2</SUB>) complexes of the unsubstituted ligand [7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>]<SUP>2-</SUP>. This has been traced to differences in the π frontier molecular orbitals of the carbaborane fragments, the observed orientations being consistent with the results of extended Hükel molecular orbital (EHMO) calculations. The conformation adopted in [3-(η2,η2-C_8H_12)-4-SMe_2-3,1,2-<i>closo</i>-PdC_2B_9H_10]BF_4, 4.BF_4, is strongly influenced by electrostatic interactions both within and between ion pairs within the crystal. 4^+ is a rare example of a cationic heteroborane, analogous to compound 2 except in the notional replacement of Rh^+ by Pd^2+ . Comparative EHMO calculations show that the additional charge in 4^+ is delocalised over the entire icosahedral framework and is not localised either at the metal vertex or at the pendant, cage-bound sulphur atom. Chapter 3 presents a series of palladium allyl derivatives of [9-SMe_2-7,8-<i>nido</i>-C_2B_9H_10]^- of the general formula 3-(C_3H_4R)-4-SMe_2-3,1,2-<i>closo</i>PdC_2B_9H_10, all of which have been characterised by ^1H and ^11B n.m.r. spectroscopy. and three of which have been structurally characterised.

The work described in this thesis is concerned with the synthesis of aluminophosphate and silica molecular sieves, in particular, the search for novel large pore materials. Reactions were studied systematically under a range of conditions and, to assist in this, a new type of reaction vessel was designed and fabricated. In the aluminophosphate system, a novel synthetic method using a water soluble aluminium phosphate hydrochloride ethanolate precursor is described. This provides a new synthesis route to the ultra-wide pore aluminophosphate molecular sieve VPI-5, without the use of quaternary ammonium compounds or amines. Aluminophosphates H2, H3 and H4 can also be synthesised using this method, and the relationship between AlPO<SUB>4</SUB>-H1 and VPI-5 is discussed. Further work on the aluminophosphate system has resulted in the synthesis of two new piperazine aluminophosphate materials, EA-5 and EA-6. EA-6 has been analysed by single crystal diffraction and found to possess a layered structure. Studies were also carried out on related heterocyclic organic compounds in an aluminophosphate synthesis gel. This resulted in the crystallisation of known materials, and a further phase not yet identified. In the silica system, the use of dual templates has been investigated using trioxane in combination with a variety of other organic compounds. In these experiments, the structure directing power of trioxane in the presence of Na<SUP></SUP>+ is clearly demonstrated. A single crystal study of trioxane silica sodalite has also been carried out and the synthesis of a sodium-free synthesis of silica sodalite is described for the first time.