Determination of structure in heterogeneous solids using heteronuclear dipolar coupling solid-state NMR

Solid-state NMR was applied to investigate atomic-level structure in heterogeneous materials that have proven challenging to study by existing physical methods. The ability of solid-state NMR to provide accurate structural information in these materials was demonstrated, and solid-state NMR techniques were applied to study chemical structure in bone tissue and to investigate the interactions of organic guest molecules inside a zeolite framework.; It was proven that accurate distances could be reliably obtained using 2D Lee-Goldburg Cross-Polarization under Magic-Angle Spinning. Distance measurements were made on natural abundance solids for the first time using this technique. The ability to obtain 1H spectra with correct chemical shift values using 2D correlation experiments was demonstrated. The sensitivity of a Frequency-Switched Lee-Goldburg Heteronuclear Correlation experiment was improved by a factor of 2.4, facilitating the investigation of natural abundance materials.; Structural changes in apatite minerals upon carbonate substitution were explored. Hydroxide ion changed orientation within the hydroxide channel to hydrogen bond with surrounding phosphate and carbonate ions. Carbonate ion was located within the apatite lattice. Molecular modeling suggests that carbonate oxygens occupy the same O1-O3-O3' oxygen positions as phosphate in hydroxyapatite.; An ordered water layer was directly observed for the first time on bone mineral crystallite surfaces. This layer may mediate the interaction between bone mineral and collagen, an interaction responsible for the unique biomechanical properties of bone.; Three structural roles for water were discovered in synthetic carbonated apatite, deproteinated bone and unmodified bone mineral. Isolated water molecules occupy hydroxide ion vacancies in the calcium-lined hydroxide channel. Other crystal waters occupy non-channel vacancies. Bone mineral-organic matrix interactions were directly observed in bone tissue using a 1H-31 P chemical shift correlation experiment. Signals observed above 7 ppm were concluded to arise from mineral-H2O-collagen hydrogen-bonding interactions. Spectral differences between model apatites and unmodified bone mineral suggest significant structural differences.; A novel method for preparing polyaniline (PANI) nanowires was developed. Guest p-aminobenzoic acid (PABA) molecules were loaded onto porous zeolite hosts from solution. Upon drying, the PABA molecules reacted to form PANI. Oxidized PANI is a semiconductor, and the presence of isolated radicals was evident in NMR spectra.