| Characterization of inorganic materials has always been an important area of research since the structural knowledge of known materials can provide valuable information which can be used to improve the performance of these materials and aid in designing novel materials demanded by new technologies. In this thesis, the host-guest interactions in several zeolites and the local environments of metal centers in several layered metal phosphates were characterized by solid-state NMR spectroscopy in combination with theoretical calculations and simulations.;Specifically, in the first part of this thesis, the adsorptions of toluene in zeolites Na-Y, LiNa-Y, and LiK-L were investigated using 23Na and 7Li magic angle spinning (MAS), 2H wideline NMR, 23Na{1H} and 7Li{ 1H} rotational-echo double-resonance (REDOR), 1H → 7Li cross polarization (CP), and Monte Carlo simulations. We demonstrate that comprehensive information on the cation locations, adsorption sites and dynamics of the guest species, as well as the cation-sorbate interactions can be obtained using the above mentioned techniques.;In the second part of this thesis, the metal centers, usually unreceptive NMR nuclei, within several layered metal phosphates were studied using solid-state NMR. Employing an ultra-high magnetic field, i.e. 21.1 T, and signal enhancement pulse sequences such as the quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) sequence, the spectra of these NMR unreceptive nuclei were obtained. NMR interaction tensors were extracted via spectral simulations and related to the local structures around these metal centres. For representative layered titanium (TiPs) and magnesium phosphates (MgPs), the spectra were found to be dominated by quadrupolar interactions. The quadrupolar coupling constants (CQ) are shown to be sensitive not only to the distortion of the MO6 octahedron, but also to the long-range charge distribution around the metal centres. In particular, correlations between CQ and the structural parameters reflecting the distortion such as longitudinal strain alpha and its products with angular DI and shear strain psi (DI*alpha, and psi*alpha) were observed. These empirical relationships can be used to predict the local metal centre environments of TiPs and MgPs with unknown structures. Theoretical calculation results show that the EFG, and therefore the CQ, of the metal center is not only determined by the distortion of the MO 6 octahedron but also affected by the spatial arrangement of the atoms in the second and third coordination spheres and beyond. The studies were also extended to include several microporous zirconium silicates and Mg doped aluminophosphates with 3-D framework structures.;The intercalation behavior of alkylamines in layer vanadyl phosphates (VPs) and the dehydration behavior of niobium phosphates (NbPs) were also investigated. The powder XRD, solid-state 51V, and 31P NMR results show that the alkylamines form bimolecular layers with the C-C chains tilted for short chain amines (NC < 8). For long chain amines (NC > 8), the alkyl chains were found to be perpendicular to the layers; the transition between the two orientations occurs when NC = 8. The 51V NMR results also suggest that when intercalating long chain amines (NC > 8), only part of the water molecules bonded to the V centre are replaced. The XRD, TGA, 93Nb, and 31P solid state NMR results indicate that the dehydration of alpha-NbP occurs through the following sequence: tri- and dihydrate phases → monohydrate phase → monohydrate and anhydrous phases → the anhydrous phase.;Keywords. Zeolites, Host-guest interactions, Solid-state NMR, Layered metal phosphates, Unreceptive quadrupolar nuclei, High field NMR. |
