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    From Gas Phase Observations to Solid State Reality: The Identification and Isolation of Trinuclear Salicylaldoximato Copper Complexes
    (MDPI (Basel, Switzerland), 2022-09-29) Roach BD; Forgan RS; Kamenetzky E; Parsons S; Plieger PG; White FJ; Woodhouse S; Tasker PA; Morazzoni F
    Conditions have been identified in which phenolic aldoximes and ketoximes of the types used in commercial solvent extraction processes can be doubly deprotonated and generate polynuclear Cu complexes with lower extractant:Cu molar ratios than those found in commercial operations. Electrospray mass spectrometry has provided an insight into the solution speciation in extraction experiments and has identified conditions to allow isolation and characterization of polynuclear Cu-complexes. Elevation of pH is effective in enhancing the formation of trinuclear complexes containing planar {Cu3-μ3-O}4+ or {Cu3-μ3-OH}5+ units. DFT calculations suggest that such trinuclear complexes are more stable than other polynuclear species. Solid structures of complexes formed by a salicylaldoxime with a piperidino substituent ortho to the phenolic OH group (L9H2) contain two trinuclear units in a supramolecular assembly, {[Cu3OH(L9H)3(ClO4)](ClO4)} 2, formed by H-bonding between the central {Cu3-μ3-OH}5+ units and oxygen atoms in the ligands of an adjacent complex. Whilst the lower ligand:Cu molar ratios provide more efficient Cu-loading in solvent extraction processes, the requirement to raise the pH of the aqueous phase to achieve this will make it impractical in most commercial operations because extraction will be accompanied by the precipitation (as oxyhydroxides) of Fe(III) which is present in significant quantities in feed solutions generated by acid leaching of most Cu ores.
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    Exploring methods of magnetic manipulation in defective dicubanes, dinuclear, and extended structures : a thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry, School of Natural Sciences, Massey University
    (Massey University, 2023) Woodhouse, Sidney
    Transition metal (3d) and lanthanide (4f) coordination clusters form a base for which many fields of research expand from. One field of interest, magnetic materials, has risen in popularity due to the discovery of single molecule magnets (SMMs), which are currently capable of operation up to 80 K. Although this field is highly researched, significant improvements are still required in order for SMMs to be stable enough for implementation into modern technological devices. One fundamental area of interest is the electron sharing pathway between metal ions, which is responsible for the magnetic properties of the molecules. Methods which optimise this to promote ferromagnetic exchange, an intrinsic property of SMMs, are an important focus. Polynuclear homometallic 3d and heterometallic 3d3d’ and 3d4f coordination clusters are reported, which explore different ways as to which the exchange pathway angles can be manipulated. Several complexes have undergone magnetic and computational analyses to explore how the different manipulations have affected the exchange pathways. A series of Niᴵᴵ₄ defective dicubanes composed of both ligand and anion based exchange pathways present a platform for manipulations based on the switching of key donor groups and solvate molecules found in the crystal lattice. The results revealed that the strongest manipulator was the introduction of lattice-bound solvent molecules, capable of hydrogen bonding to the metal ion donor groups. Moving from a combination of ligand and anion based exchange pathways to those that are solely ligand derived were explored by synthesising a series of homometallic and heterometallic 3d3d’ dinuclear complexes, and conducting a study which closely looked at how different metal ion combinations affected the magnetic properties. Transmetalation reactions were performed alongside a computational analysis to determine the stabilities of the 3d3d’ dinuclear complexes, with the most stable being that of the CuᴵᴵMnᴵᴵ complex. Unexpectedly, the Cuᴵᴵ₂ complex was found to have the largest ferromagnetic coupling, indicating the large coordination number for a Cuᴵᴵ ion to be the strongest magnetic manipulator. Expanding on the 3d3d’ dinuclear series was achieved by the introduction of 4f ions with the aim of producing a series of 3d4f dinuclear complexes, where the use of different metal ions, anions, and coordinated solvent molecules have been structurally analysed to determine the success of the manipulations. It was found that the complexes with smaller exchange angles had a common similarity, that being additional bridging groups between the metal ions. Finally, a series of clusters ranging from mononuclear to icosanuclear are reported, all of which were unexpected results. These complexes reveal unusual and uncommon properties, such as the coordination of an alkyloxime oxygen.
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    The synthesis and chemistry of Quinolino(7,8-h)quinoline derivatives : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatu, New Zealand
    (Massey University, 2021) Severinsen, Rebecca
    Proton sponges are a class of neutral organic superbases. Quinolino[7,8-h]quinoline (QQ) is one such molecule. Structurally it has two closely positioned nitrogen atoms which cause a destabilising lone electron overlap which manifests as a helical torsional twist that can be relieved by monoprotonation or complexation. These compounds are highly basic and are chelators that can accommodate a variety of ion sizes. Exploration of the structural properties of QQ provides an avenue for non-symmetric compound synthesis. Research interest arose in developing original synthetic pathways and exploring the chemistry of this QQ moiety, and its potential uses. This work primarily focussed on the development of methods towards new derivatives containing the QQ core structure, of which several were developed. Exploration of their properties as bases was begun in the context of both experimental measurements and theoretical calculations, allowing some to be classified as superbases. Computational analysis also gave insight into structural changes taking place during the protonation process. Potential uses of QQ derivatives as chelators for metals were examined. An X-ray crystal structure of a beryllium containing 4,9-dihydroxyquinolino[7,8-h]quinoline was achieved, the 7th reported ion to be chelated by a QQ compound.
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    Photophysical and catalytic properties of multicomponent metal-organic frameworks : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2021) Cornelio, Joel
    Multicomponent metal-organic frameworks (MC-MOFs) are crystalline, porous materials built from multiple geometrically distinct organic ligands. The ligands are located in specific lattice sites in the MOF. The properties of these materials can be tuned by incorporating ligands with functional groups for a desired application. This thesis deals with studying the applications of MC-MOFs named Massey University Frameworks (MUFs) for luminescence, energy transfer, photochromism, and catalysis. Firstly, we obtain white-light emission in MC-MOFs from the combination of blue and yellow luminescence of the ligands. The trends observed in the emission spectra originate from inter-ligand energy transfer interactions. These interactions have been explored further using a variety of crystallographic and spectroscopic techniques including time-resolved luminescence at the nanosecond and picosecond timescales. In another chapter, we have studied photochromism in some MC-MOFs which is caused by light-generated organic radicals. The differences between their radical and non-radical forms has been elucidated using X-ray crystallography. We also research the impact of pore environment on the outcome of an enantioselective intramolecular aldol reaction catalysed by MC-MOFs. Finally, a number of ideas are proposed as part of future work, that take advantage of the multicomponent nature of these materials.
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    Hetero-interpenetrated metal-organic frameworks : supramolecular interactions between ligands in metal-organic framework formation : a thesis presented in fulfilment of the requirements of the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2020) Perl, David
    Metal-organic frameworks are an exciting class of materials formed through the self-assembly of their metal ion and organic ligand components into ordered, nanoporous lattice structures whose pore spaces are open to solvent, gas, and other guest molecules. Their consequently high surface areas render them suitable for diverse applications including gas storage, separations, and catalysis. The ability to precisely engineer the chemistry of the pores in framework materials and thus tune their properties is one of their most attractive features. Interpenetration, a phenomenon where multiple lattices are woven through each other, is an important handle on tuning their properties, mediating between pore shapes and volumes, chemistries, and robustness. In this thesis new frameworks are presented where two chemically distinct lattices are interpenetrated, a longstanding target in the field. These frameworks therefore have two orthogonal handles on both pore shape and functionalisation and have been applied to asymmetric organocatalysis by embedding an achiral catalytic site within a chiral pore space. Additionally, some insight is gained into the underlying principles of the formation of complex types of interpenetration through the exploitation of several analogous novel ligands.
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    Catch ⁹₄Be if you can : exploiting second-sphere hydrogen bonding toward chelation of beryllium : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Nixon, David J.
    Beryllium is a crucial metal in the automotive, aviation, nuclear and consumer industries. The unique combination of high rigidity, low density, thermal stability and conductivity makes it highly useful in consumer products such as cell phones and computers. However, beryllium is considered to be the most toxic non-radioactive element, a class A carcinogen, and the cause oflife-threatening chronic beryllium disease. Even with its poor reputation, its use is continued in commercial, industrial, and governmental applications. In contrast, the efforts to understand beryllium's fundamental chemistry have been severely neglected. We are interested in developing a suite of chemical chelators which show strong and selective binding towards beryllium. These studies will lead to specific applications such as the detection of beryllium in the environment, protocols to remediate its contamination, and therapies for individuals exposed to its toxicity. This work will focus on both the computational studies of tetradentate ligands and their synthesis. These have been designed to bind strongly to beryllium.
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    Synthesis of multicomponent metal-organic frameworks and investigations of their physical properties : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Alkaş, Adil
    Multicomponent metal-organic frameworks (MOFs) are built up from multiple ligands that are geometrically distinct. These ligands occupy specific positions in the MOF lattice. Installing different functionalities at precise locations in the framework is an important step in making MOFs for specific applications. This can be achieved by designing functionalized ligands for multicomponent MOFs. This study was, firstly, focused on design and synthesis of new linkers. The study then covered preparation of a number of quaternary MOFs. Furthermore, the study was focused on the physical and chemical properties of these MOFs, such as their catalytic activity, gas adsorption and fluorescence behaviours.
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    Interior decoration of metal-organic frameworks through a thermolabile protecting group strategy : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2019) Jameson, Heather
    Metal-organic frameworks are porous nanomaterials of modular construction that have shown themselves amenable to different modes of functionalization. Thermolytic deprotection (thermolysis) of incorporated thermolabile protecting groups (TPGs) has been one of these methods applied to tune the chemistry of MOFs and their material properties, accessing otherwise unattainable MOF topologies with enhanced porosity and reactive functionalities of particular interest in gas storage and separation and catalytic applications. In this thesis the TPG post-synthetic modification (PSM) technique is expanded upon in two ways. Firstly, through investigation of mono-and dual-functionalization within a flexible pillar-layer MOF family: localization of the TPG, influence on framework topology and gas sorption characteristics. Secondly, in synthesis of a set of novel ketene-protecting TPG ligands: ligand characterization, and endeavours at MOF incorporation.
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    Synthesis and characterisation of pyrazine-based ligands for the analysis of metal-metal communication : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2018) Brown, Michael James
    Pyrazine is an attractive molecule that has been incorporated as a bridging ligand between two metal centres. These complexes have been shown to exhibit both magnetic and electrochemical exchange between the metal centres through the pyrazine unit. Addition of functionality onto the 2 and 5 position of pyrazine can reinforce the coordination of 3d octahedral metal ions to the pyrazine ring. The Schiff base condensation of A1 with various primary amine reactants produced three unique ligand systems. The confirmed synthesis of these ligands was verified with a variety of characterisation techniques. A single crystal structure was generated for one ligand system (L3), which revealed both imine – π stacking interactions, as well as alkane hydrogen – pyridine interactions. Several complexations were attempted with the three ligand systems synthesised. Manganese and cobalt complexes were successfully synthesised with L3, the single crystal structures generated showed cyclohelicate triangles, which were unique at the time. The electrochemical analysis of these complexes in MeCN showed similar redox processes as was seen in the electrochemical analysis of L3. Signs of possible metal-metal communication within the cyclohelicate triangles was also noticed, with oxidation (and reduction) processes present. Further analysis is necessary to verify these interpretations, including magnetic analysis. Complexations with identical metal salts and L2 could not be characterised by SCXRD Other techniques such as mass spectrometry and conductivity measurements indicated the likely formation of a polymorphic – potentially cyclohelical structure with this ligand. Complexations with L1 incorporated the inclusion of a larger collection of metal salts. Unfortunately, due to time constraints, only three complexes were suitably characterised. From the various characterisation methods used, it was deduced that all three complexes were likely simple M2L1 systems, where the coordination of the 6-coordinate 3d metal centres were accompanied by the coordination of either water, solvent, counterion or a combination of these.
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    Salicylaldoxime derivatives for new magnetic materials : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Woodhouse, Sidney
    Salicylaldoxime (H₂Sao) is an appealing unit for metal ion coordination, specifically that of transition metal (3d) ions. During this research, four ligands were synthesised, of which two were previously unknown (L2 and L3). These ligands differed by the secondary amine added to the simple H₂Sao molecule. These H₂Sao derived ligands were complexed with a variety of 3d ions, resulting in three distinct topologies: mononuclear, triangular, and defective dicubane. The nine new complexes (C1-C9) synthesised were all structurally characterised, with Mössbauer spectroscopy performed on the iron complexes, and magnetic characterisation performed on complexes C1-C6, C8-C9. Analysis of the synthesised complexes has led to new insights into magnetostructural correlations and new pathways to unique ligand designs.