Solid-State NMR Spectroscopy of Unreceptive Nuclei in Inorganic and Organic Systems

Nuclei are termed unreceptive if they are not amenable to solid-state NMR (SSNMR) experimentation at standard magnetic field strengths due to (i) low natural abundances or dilution; (ii) low gyromagnetic ratios; (iii) inefficient longitudinal relaxation; (iv) large quadrupole moments; or (v) combinations of these factors. This thesis focuses on applying a variety of SSNMR methods to study unreceptive nuclei in a variety of systems. The first portion of this thesis focuses upon ultra-wideline (UW) SSNMR of three main group nuclei: 209Bi, 137Ba and 115In. 209Bi and 137Ba SSNMR were applied to a series of systems with important structural motifs, while 115In SSNMR was applied to systems with In in the +1 oxidation state. Extremely broad SSNMR spectra were acquired at field strengths of 9.4 and 21.1 T. In all cases, the electric field gradient (EFG) and the chemical shift (CS) tensor parameters obtained from these spectra are used to probe the metal coordination environments. These data are complemented by first principles calculations of the NMR tensors using molecular orbital (MO) and plane wave density functional theory (DFT) methods. The second portion of this thesis examines applications of SSNMR of unreceptive nuclei to some practical problems. First, 109Ag and 15N SSNMR experiments were performed to study silver supramolecular frameworks, and structural changes which occur upon their reactions with primary amines. 1H-109Ag cross polarization/magic-angle spinning (CP/MAS) NMR spectra were used to differentiate Ag sites, and 1H-15N CP/MAS NMR spectra provided measurements of 1J(109Ag, 15N) coupling constants, which are used to probe bonding Ag-N bonding. First principles calculations of silver and nitrogen CS tensors and 1J(109Ag, 15N) constants aided in formulating the structural models for the new materials. Second, 35Cl SSNMR spectra, single-crystal and powder X-ray diffraction data, and ab initio calculations were utilized to study HCl pharmaceuticals and some of their polymorphs. The sensitivity of the 35Cl EFG tensor parameters to subtle changes in the chlorine environments is reflected in the powder patterns, which can be used for structural interpretation, identifying and distinguishing polymorphs, and rapidly providing a spectral fingerprint of each pure pharmaceutical and its polymorphs

Hydrogen Storage in Metal Fragments grafted Silicas and Chromium Hydrazide Gels

Hexagonally-packed mesoporous silicas (HMS) grafted with low-valent titanium, vanadium, and chromium organometallic fragments possessing oxidation states between (II) and (IV) were synthesized, tested for their hydrogen storage capacities, and characterized by XRD, nitrogen adsorption, XPS, and EA. The effects of the variation in the surface area, pore size, transition metal type, and metal oxidation state, the organometallic loading levels, as well as the ligand environment on the H2 adsorption capacity and the binding enthalpies of these systems were investigated. This study demonstrated that titanium is more effective at hydrogen binding than vanadium and chromium. HMS silica grafted with benzyl titanium (III) fragments can accommodate up to 4.85 H2 per Ti center. This compares to 2.74 H2 per vanadium center as for the HMS grafted with tris(mesityl) vanadium, and to 1.82 and 2.20 H2 per chromium as for the HMS treated with the tris[bis(trimethylsilyl)methyl] chromium and bis[(trimethylsilyl)methyl]chromium respectively. The hydrogenation of the metal centers had a pronounced effect on the adsorption capacity of the Cr-grafted HMS. This capacity increased from 1.82 to 3.20 H2 per chromium in the case of HMS treated with tris[bis(trimethylsilyl)methyl] chromium, and from 2.20 H2 to 3.50 H2 per chromium in the case of HMS treated with tris[(trimethylsilyl)methyl] chromium. The investigated systems in the first part were used as modules in the design of novel chromium hydrazide gels that use low valent chromium centers as H2 binding sites. These materials were synthesized at various Cr to hydrazine molar ratios and have room temperature excess hydrogen storage of up to 1.01 wt%, and binding enthalpy of up to viii 22.9 kJ/mol. However, the hydrogenation of these materials induced an amplification of the performance and binding enthalpies. The excess room temperature hydrogen storage of the hydrogenated samples goes up to 1.65 wt%, with the room absolute volumetric density goes up to 29.92 Kg/m3, and with binding enthalpy goes up to 51.59 kJ/mol. These materials would use pressure instead of temperature as a toggle and can thus be used in compressed gas tanks, to increase the amount of hydrogen stored, and therefore the driving range of any vehicle

The Induced Oxidative DNA Damage and Presenillin-1 Mutations by the Pharmacologically Used NaCl Saline Solutions Increase the Incidence of Alzheimer Disease in Mice

The addition of sodium chloride (NaCl) to food by the manufacturer or consumer and its medical use particularly as a drug dilution solvent result in elevated concentrations of sodium and chloride ions in human blood and tissues, including the brain. However, all previous studies were concerned on its induced renal toxicity and no attention on its neurotoxicity, thus the current study investigated the saline induced genotoxicity, mutagenicity and oxidative stress in mice brain tissue. Mice were administered 0.9, 3, or 5% saline solution by intraperitoneal injection (10 mL/kg body weight) every two days for a total of 6 injections and euthanized 24 h after the last injection. Multiple injections of NaCl saline solutions induced DNA damage in neurons and elicited a high incidence of presenillin-1 mutations and ?-amyloid accumulation in a dose-dependent manner. These outcomes could be attributed to the observed elevations in serum cholesterol levels and increased generation of reactive oxygen species, indicated by the elevated malondialdehyde and nitric oxide levels and reduced glutathione levels and catalase activity in NaCl-treated groups. We conclude that multiple injections of NaCl solution, even at the concentration of normal saline (0.9%), caused cholesterol accumulation and oxidative DNA damage that resulting in mutations in presenillin-1 and also increased ?-amyloid accumulation in the brain therapy increasing the incidence of Alzheimer disease in a dose-dependent manner in mice. Therefore, its recommended to reduce the uses of saline in drug dilutions

Application of Solid-State 209Bi NMR to the Structural Characterization of Bismuth-Containing Materials

Herein, we report the first detailed study of 209Bi solid-state NMR (SSNMR) spectroscopy of extremely broad central transition powder patterns. 209Bi ultrawideline SSNMR spectra of several bismuth-containing materials (bismuth oxyhalides, bismuth nitrate pentahydrate, nonaaquabismuth triflate, and bismuth acetate) were acquired at field strengths of 9.4 and 21.1 T using frequency-stepped techniques. The 209Bi SSNMR experiments at 9.4 T yield powder patterns with breadths ranging from 0.9 to 14.6 MHz, from which quadrupolar coupling constants, CQ(209Bi), between 78 and 256 MHz, were extracted via analytical simulations. The breadths of the quadrupolar-dominated spectra and overall experimental times are greatly reduced for experiments conducted at 21.1 T, which yield high signal-to-noise spectra in which the smaller effects of bismuth chemical shift anisotropy can be clearly observed. The 209Bi electric field gradient (EFG) and chemical shift (CS) tensor parameters extracted from these spectra are correlated to the molecular structures at the bismuth sites, via first principles calculations of 209Bi EFG and CS tensors performed using CASTEP for periodic solids and Gaussian 03 for molecular clusters. The rapidity with which 209Bi SSNMR spectra can be acquired at ultrahigh fields, the sensitivity of the 209Bi NMR parameters to the bismuth environment, and the predictive power of theoretically calculated NMR interaction tensors suggest that 209Bi SSNMR may be useful for the characterization of a variety of Bi-containing materials and compounds.Peer reviewed: YesNRC publication: Ye