Development and Application of Chlorine Solid-State Nuclear Magnetic Resonance and Quantum Chemical Calculations to the Study of Organic and Inorganic Systems

• Main Author: Chapman, Rebecca
• Other Authors: Bryce, David L.
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2012
• Subjects: Solid State NMR; Chlorine; Magnetic Resonance; Electric Field Gradient; Chemical Shift; Quantum Chemical Calculations; Amino Acids; Polymorphism; Ion Receptors; GIPAW-DFT; Group 13 Chlorides; Catalysts
• Online Access: http://hdl.handle.net/10393/20555; http://dx.doi.org/10.20381/ruor-5167

Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra. Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR. Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined. An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values. Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.