Oxygen-17 NMR of Inorganic Materials

Recent directions in the solid-state NMR study of synthetic and natural calcium phosphates

“…Oxygen-17, however, has more rarely been studied, despite the high level of information that 17 O NMR can provide. [20,[93][94][95]] Indeed, only a few investigations have looked into the 17 O NMR study of enriched model calciumphosphates and related bioglasses, [21,66,69,96,97] and only one analysis of a bone sample has been reported, though the sensitivity was quite low. [66] With the current development of novel 17 O-labeling schemes based on mechanochemistry [98,99] and of 17 O DNP, [100,101] it can be expected that a much larger number of analyses on this nucleus will be performed in the future for these materials, including to help better understand the role played by one of the key components of bone, namely water.…”

High-Resolution 17O NMR Spectroscopy of Structural Water

“…In addition, 17 O NMR spectra are broadened by the second-order quadrupolar interaction which is not averaged by MAS. 28 Despite these shortcomings, 17 O has been used extensively to study biological and inorganic systems, by utilizing isotopic enrichment, 29–33 and high magnetic field strengths (≥ 16.4 T). 34–39 Approaches improving the resolution of 17 O MAS NMR spectra by attenuating the second-order quadrupolar interaction, such as multiple quantum MAS (MQMAS) 40 and satellite transition MAS (STMAS), 41 have been shown to yield well-resolved isotropic quadrupolar spectra.…”

“…44–47 For example, the increased resolution that is present in the MQMAS experiment allowed studies of inorganic glasses and minerals that could not be achieved with traditional MAS experiments. 32–33, 48–58…”

“…In addition, 17 O NMR spectra are broadened by the second-order quadrupolar interaction which is not averaged by MAS . Despite these shortcomings, 17 O has been used extensively to study biological and inorganic systems, by utilizing isotopic enrichment − and high magnetic field strengths (≥16.4 T). − Approaches improving the resolution of 17 O MAS NMR spectra by attenuating the second-order quadrupolar interaction, such as multiple quantum MAS (MQMAS) and satellite transition MAS (STMAS), have been shown to yield well-resolved isotropic quadrupolar spectra. And, despite the poor efficiency (∼5%) of these techniques in the presence of large quadrupole coupling constants (>5 MHz), , they have been used to successfully study 17 O-enriched biological samples and produced promising results. − For example, the increased resolution that is present in the MQMAS experiment allowed studies of inorganic glasses and minerals that could not be achieved with traditional MAS experiments. ,,− …”

Visualization of the effect of additives on the nanostructures of individual bio-inspired calcite crystals

“…The origins of these different strain components within the Mg-calcite lattice were then investigated further using 17 O solid-state NMR spectroscopy57,58 to determine whether they were associated with different local chemical environments. Conventional Magic-Angle Spinning (MAS) NMR spectra57,59 were recorded for calcium carbonate samples that had been precipitated by combining solutions of 17 O-enriched carbonate and calcium/magnesium ions, at calcium/magnesium ratios of 10/2 and 10/4.…”