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In this work, multinuclear solid-state nuclear magnetic resonance (NMR) spectroscopy is used to investigate a range of inorganic materials, often in combination with DFT (density functional theory) studies. Solid-state NMR is particularly suited to the study of aluminophosphates (AlPOs), as the basic components of their frameworks have NMR active isotopes (²⁷Al, ³¹P, ¹⁷O), as do many of the atoms that comprise the structure directing agent (¹³C, ¹H, ¹⁵N), and the charge-balancing anions (OH⁻, F⁻). A study of the AlPO STA-15 (St Andrews microporous solid-15) provides an introduction to using solid-state NMR spectroscopy to investigate AlPOs. More in-depth studies of AlPO STA-2 (St Andrews microporous solid-2) and MgAPO STA-2 (magnesium-substituted AlPO) examine charge-balancing mechanisms in AlPO-based materials. A range of scandium carboxylate metal-organic frameworks (MOFs), with rigid and flexible frameworks, have been characterised by multinuclear solid-state NMR spectroscopy (⁴⁵Sc, ¹³C and ¹H). The materials studied contain a variety of metal units and organic linkers. ¹³C and ¹H magic-angle spinning (MAS) NMR were used to study the organic linker molecules and ⁴⁵Sc MAS NMR was used to study the scandium environment in the MOFs Sc₂BDC₃ (BDC = 1,4-benzenedicarboxylate), MIL-53(Sc), MIL-88(Sc), MIL-100(Sc) and Sc-ABTC (ABTC = 3,3`,5,5`-azobenzenetetracarboxylate). Functionalised derivatives of Sc₂BDC₃ and MIL-53(Sc) were also studied. The ⁴⁵Sc MAS NMR spectra are found to be strongly dependant on the Sc³⁺ coordination environment. ²⁷Al and ²⁵Mg MAS NMR have been used to study Ti-bearing hibonite samples (of general formula Ca(Al, Ti, Mg)₁₂O₁₉), and results compared to a recent complementary neutron powder diffraction study, in order to investigate the substitution sites for Ti³⁺/⁴⁺ and Mg²⁺. A DFT investigation was also carried out on the aluminium end member, CaAl₁₂O₁₉, due to debate in the literature on the ²⁷Al NMR parameters for the trigonal-bipyramidal site. The substitution of Mg onto the tetrahedral site (M3) and Ti primarily onto one of the octahedral sites (M4) is supported.

The halogen bond has recently risen in prominence as a non-covalent interaction for use in supramolecular chemistry, allowing for the rational design of materials, pharmaceuticals, and functional molecules. The occurrence of the σ-hole opposite to the C-X covalent bond (X = F, Cl, Br, I) renders the halogen bond a highly directional and tuneable interaction, offering desirable features to crystal engineers. The halogen bond can be divided into its two components: the halogen bond donor bearing the halogen atom, and the electron-rich halogen bond acceptor. In this thesis, we investigate the nature of the halogen bond, its role in supramolecular assembly and impact on the local dynamics, along with developing synthetic methods to prepare this class of materials. We begin by fully characterizing the halogen bond donor by using 35Cl ultra-wideline solid-state nuclear magnetic resonance (NMR) spectroscopy on a series of single-component chloronitriles exhibiting the C-Cl···N halogen bond. We then perform the first modern nuclear quadrupole resonance (NQR) investigations of the halogen bond, observing the 79/81Br and 127I nuclei in a series of cocrystals exhibiting the C-Br···N and C-I···N halogen bond, respectively. Computational results attribute the observed increases in the quadrupolar coupling constants (CQ) to a reduction in the carbon-halogen σ-bonding contribution to V33 and an increase in the lone-pair and core orbital contributions, providing the first model of the electronic changes occurring on the halogen bond donor upon the formation of the halogen bond. Attention is then turned on characterizing the halogen bond acceptor and its surrounding environment, beginning by investigating a solid-state NMR approach relying on the 19F nucleus to characterize perfluorinated cocrystals. This strategy has reduced analysis times from hours to minutes while providing higher sensitivity and resolution, with the resulting chemical shifts permitting the unambiguous identification of the halogen bond and allowing for the refinement of X-ray crystal structures. The halogen bond acceptor is then investigated in a series of isomorphous dimers exhibiting both the halogen bond and hydrogen bond in the C≡C-I···X-···H-N+ motif, revealing the halogen bond’s relative contribution to the electric field gradient increasing in the order of Cl- > Br- > I-, contrasting the contributions of the hydrogen bond. We then explore the impact of the halogen bond on the surrounding environment, using the rotating methyl groups of 2,3,5,6-tetramethylpyrazine as a model. Upon the introduction of a halogen bond, we observe a reduction in the rotational energy barrier of 56% on average, overshadowing the 36% reduction observed in the hydrogen bonded cocrystals. This is the first instance of the halogen bond directly catalyzing the local dynamics, coining the term “dynamics catalyst”. These results provide an effective strategy of enhancing the dynamics in molecular systems, such as molecular machines, supramolecular catalyst, as well as correcting the faulty dynamics encountered in diseased proteins. The role of halogen bonding in crystal engineering is then explored, reporting the first supramolecular triangle, a series of discrete charged dimers, and supramolecular architectures built from 1,3,5-tri(iodoethynyl)-2,4,6-trifluorobenzene, with the potential of creating fully organic porous structures for gas absorption. Mechanochemistry is then investigated as a synthetic method, allowing for the preparation of cocrystals featuring 3-iodoethynylbenzoic acid as the donor, with the resulting structures exhibiting concurrent halogen and hydrogen bonding. Mechanochemical ball milling is shown to reduce preparation times of powdered cocrystals from days to a single hour, while using a fraction of the organic solvent. Lastly, we pioneer cosublimation as a solvent-free synthetic technique for rapidly preparing halogen bonded cocrystals, yielding quality single crystals within a few hours, and a microcrystalline product within 15 minutes. Among its advantages, cosublimation offers a significant acceleration of discovery, while eliminating the environmental footprint associated with conventional synthetic methods.

Multicomponent polymer systems comprised of two or more chemically different polymer moieties provide an effective way to attain the desired properties from a limited palette of commodity polymers. Variations in macromolecular topologies often result in unique and unusual properties leading to novel applications. This dissertation addresses the effect of topology on properties of two multicomponent polymers systems: blends and polyrotaxanes. Blends of cyclic and linear polymers were compared to their topological counterparts, polyrotaxanes, in which cyclic components are threaded onto the linear polymer chains. The first part of the dissertation focuses on the synthesis and purification of cyclic polymers derived from linear (polyoxyethylene) (POE). Cyclic POEs of different cycle sizes were synthesized and then purified from their linear byproducts by inclusion complexation with alpha-cyclodextrin. Polystyrene was threaded through the resulting cycles by in situ free radical polymerization of styrene monomer in the presence of an excess of POE cycles. A bulky free radical initiator was utilized to endcap the polystyrene molecule at the two ends to prevent dethreading of cyclic moieties. In the second part of the dissertation, phase behavior, morphology and dynamics of cyclic POE and polystyrene blends were compared to linear POE and polystyrene blends. Advanced solid-state NMR techniques and differential scanning calorimetry were employed for this purpose. Cyclic POE was found to be much more miscible with polystyrene when compared to linear POE, resulting in nanometer-sized domains and significantly reduced mobilities of the cyclic POE components in the blends. The unusual behavior of cyclic POE in the blends was attributed to topological as well as end-group effects with the topological effects being predominant. Polyrotaxanes composed of polystyrene and cyclic POE components exhibited cyclic POE domain sizes similar to that of physical blends. Cyclic POE dynamics in polyrotaxanes were considerably hindered, however, due to the threaded architecture. Surface segregation studies of cyclic POE/polystyrene blends and polyrotaxanes did not show segregation of POE to the surface because of the improved miscibility and the topological constraints present in these systems.

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Massey and Hemmerich proposed that the different reactivities displayed by different flavoenzymes could be achieved as a result of dominance of different flavin ring resonance structures in different binding sites. Thus, the FMN cofactor would engage in different reactions when it had different electronic structures. To test this proposal and understand how different protein sites could produce different flavin electronic structures, we are developing solid-state NMR as a means of characterizing the electronic state of the flavin ring, via the 15N chemical shift tensors of the ring N atoms. These provide information on the frontier orbitals. We propose that the 15N chemical shift tensors of flavins engaged in different hydrogen bonds will differ from one another. Tetraphenylacetyl riboflavin (TPARF) is soluble in benzene to over 250 mM, so, this flavin alone and in complexes with binding partners provides a system for studying the effects of formation of specific hydrogen bonds. For N5, the redoxactive N atom, one of the chemical shift principle values (CSPVs) changed 10 ppm upon formation of a hydrogen bonded complex, and the results could be replicated computationally. Thus our DFT-derived frontier orbitals are validated by spectroscopy and can be used to understand reactivity. Indeed, our calculations indicate that the electron density in the diazabutadiene system diminishes upon H-bond complex formation, consistent with the observed 100 mV increase in reduction midpoint potential. Thus, the current studies of TPARF and its complexes provide a useful baseline for further SSNMR studies aimed at understanding flavin reactivity in enzymes.

This thesis focuses on the determination and the modeling, by the PAW/GIPAW (Gauge Including Projector Augmented Waves) method, of NMR parameters in inorganic fluorides. In the first part, a correlation between experimental 19F isotropic chemical shift (diso) and calculated 19F isotropic shieldings (siso) of binary fluorides with obvious assignments is established that allows to predict 19F NMR spectra with a good accuracy. The quadrupolar parameters of these fluorides are also determined and calculated. In the second part, a complete and unambiguous assignment of the 19F NMR lines of NbF5 and TaF5 is obtained, ensured by the linearity between experimental 19F diso values and calculated 19F siso values. On the other hand, for the studied MF4 (b-ZrF4, HfF4, CeF4, ThF4) compounds, characterized by smaller 19F diso ranges, except for ThF4, the poor correlations between experimental 19F diso and calculated 19F siso values prevent us to propose an assignment of the 19F NMR lines. In the last part, NaAsF6 and KPF6, exhibiting large 19F-X 1J-coupling and phase transitions at temperatures close to room temperature (RT) are investigated by DTA or DSC and variable temperature X-ray powder diffraction and multinuclear solid-state NMR. The structures of a- and b-NaAsF6 are determined. KPF6 adopts a disordered high symmetry structure at RT. Unfortunately, attempts to determine the atomic positions of the two first low temperature phases remain unsuccessful. This work highlights the potentialities and some limitations of this method as well as the care that must be taken when dealing with optimized structures.

The focus of this work is to synthesize and immobilize novel rigid tetraphosphine linkers via the formation of phosphonium groups and by direct adsorption of tetraphosphine salts on oxide surfaces. These methods offer the possibility to study the mechanism of the phosphonium formation in more detail by utilizing solid-state NMR spectroscopy. It has also been a point of interest to study the linkers and catalysts under realistic conditions, in the presence of solvents. Therefore, HRMAS (high-resolution magic angle spinning) NMR spectra of several phosphonium salts, adsorbed on SiO2, have been studied. This technique allows one to probe the leaching and mobility of the linkers on the surface. The mobilities of the linkers and the catalysts are crucial factors for the performance and design of the immobilized catalysts. Finally, since the exact mode of binding to the surface is unknown and is being discussed in the literature, for example, as hydrogen bonding between the F atoms in BF4- and surface silanol protons, the influence of the counteranion on the binding of phosphonium salts on silica surfaces is of utmost interest. For surface mobility studies a monolayer of phosphonium salts on the silica surface, both without solvent and in the presence of solvent, has been studied via 31P and 2H CP/MAS and HRMAS. Our findings show that the integrity of the tetraphosphine scaffold linkers is based upon how it is immobilized. The best system is formed when the phosphine is immobilized on the SiO2 support by adding Cl(CH2)3Si(OEt)3 to the reaction mixture. In this way, phosphonium salts are obtained, which are bound to the surface irreversibly by electrostatic interactions, as proven by solid-state NMR. In addition, leaching and mobility studies prove that the solvents play a crucial role, and the more polar solvents, such as DMSO, lead to the most extensive leaching due to the solvents' strong adsorption on the SiO2 surface. Leaching studies also show that the counteranion has an influence on the binding of the phosphoniumn salts on the SiO2 surface. The leaching proceeds in the following manner: BF4- > I- > Br- > Cl-. This is an indication that there is an additional interaction between the anion and, most probably, the surface silanol protons.

Bone turnover has important impacts on bone health. The process modifies weak primary woven bone into the strong lamellar bone, repairs damage in bone, and maintains appropriate calcium homeostasis. The process relies heavily on controlled osteoclastic resorption by dissolution of mineral in the area undergoing remodelling. Bone degenerative diseases occur when the balance between bone resorption and deposition of new bone in the turnover process is altered. Bone is a nanocomposite material composed of a mineral phase (calcium phosphate) deposited within an organic matrix. In spite of the intensive research on the subject, the precise molecular structure of the bone mineral is still an open question. The incorporation of citrate within the mineral structure introduced by Davies et al has provide a more comprehensive structural model that could explain many observations in terms of the mineral structure. Based on this new structural model, a hypothesis has been proposed: that other metabolites similar to citrate can be incorporated into the mineral structure, and differences in metabolite incorporation cause fundamental differences in the physical properties of bone mineral. Thus understanding the effect of metabolite incorporation on the physical properties of bone mineral will lead to insight into the molecular mechanisms of bone degenerative diseases and provide a link between bone quality and bone cell function that is currently missing. Chapter 1 provides overview of the bone composite and formation, and changes in its properties during ageing. The development of the mineral structural model is described and the shortcoming of existing models are assessed. Chapter 2 introduces the theoretical foundations of solid-state NMR spectroscopy, which is the primary analytical method employed in this study, followed by specific experimental techniques that have been used in this work. Chapter 3 described the characterisation of seven different OCP-metabolite composites that have been synthesized in this work, and proposes possible structural model for these composites based on an NMR crystallography approach to determine a structural model for one of the synthetic OCP-metabolite compounds, OCP-SUC. In Chapter 4, the dissolution rate of OCP-metabolites is measured in acidic solution to mimic the resorption process by osteoclasts and assess the possible effects of different incorporated metabolites on the solubility of bone mineral. Finally, Chapter 5 summarises the conclusions from the work and suggests the next steps that arise from this work to uncover the complete molecular structure of bone mineral and its variability in disease.

This paper presents the results of a continuing investigation of several functionalized SPION MR contrast agents and the solid state NMR studies of plasma polymerized Allyl Alcohol thin films. Several species of functionalized SPIONs were tested; the most successful SPIONs were the melamine dendron, polyimidazole, and conjugated nucleic acid SPIONs. The study of the MR responses of the melamine dendron SPIONs determined that these SPIONs undergo reversible clustering and that their pH sensitive MR responses are due to increased clustering at pH> 4. The MR responses of the polyimidazole functionalized SPIONs (both the dopamine and carboxylate linked) indicate a pH sensitive MR response well within the physiological regime (inflection point pH ~6) as well as excellent baseline relaxivities. However, perhaps due to the low polyimidazole loading onto the SPION core, these agents were very sensitive to ionic environment. CPMAS studies of pulsed plasma polymerized allyl alcohol thin films indicated that the hydrophobic films had a more ordered structure than the hydrophilic films; however, all poly-allyl alcohol thin films had a highly amorphous structure. The use of synthetic mica as a substrate for CPMAS studies of polymer thin films is also discussed.