Unleashing the Potential of17O NMR Spectroscopy Using Mechanochemistry (original) (raw)

17 O NMR spectroscopy has been the subject of vivid interest in recent years, because there is increasing evidence that it can provide unique insight into the structure and reactivity of many molecules and materials. However, due to the very poor natural abundance of oxygen-17, 17 O-labelling is generally a prerequisite. This is a real obstacle for most research groups, because of the high cost and/or strong experimental constraints of the most frequently used 17 O-labelling schemes. Here, we demonstrate for the first time that mechanosynthesis offers unique opportunities for enriching in 17 O a variety of organic and inorganic precursors of synthetic interest. The protocols are fast, user-friendly, and low-cost, which makes them highly attractive for a broad research community, and their suitability for 17 O solid state NMR applications is demonstrated.

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I. 1 A Review of Oxygen-17 Solid State NMR of Organic Materials

∎ ABSTRACT 17O solid state NMR of organic materials is developing rapidly. This article provides a snapshot of the current state of development of this field. The NMR techniques and enrichment protocols that are driving this progress are outlined. The 17O parameters derived from solid state NMR experiments are summarized and the structural sensitivity of the approach to effects such as hydrogen bonding highlighted. The prospects and challenges for 17O solid state

A review of oxygen-17 solid-state NMR of organic materials—towards biological applications

2004

17O solid state NMR of organic materials is developing rapidly. This article provides a snapshot of the current state of development of this field. The NMR techniques and enrichment protocols that are driving this progress are outlined. The 17O parameters derived from solid-state NMR experiments are summarized and the structural sensitivity of the approach to effects such as hydrogen bonding highlighted. The prospects and challenges for 17O solid-state NMR of biomolecules are discussed.

Variable-Temperature 17 O NMR Studies Allow Quantitative Evaluation of Molecular Dynamics in Organic Solids

Journal of the American Chemical Society, 2012

We report a comprehensive variable-temperature solid-state 17 O NMR study of three 17 O-labeled crystalline sulfonic acids: 2-aminoethane-1-sulfonic acid (taurine, T), 3aminopropane-1-sulfonic acid (homotaurine, HT), and 4-aminobutane-1-sulfonic acid (ABSA). In the solid state, all three compounds exist as zwitterionic structures, NH 3 + −R−SO 3 − ,i n which the SO 3 − group is involved in various degrees of O•••H−N hydrogen bonding. High-quality 17 O NMR spectra have been obtained for all three compounds under both static and magic angle spinning (MAS) conditions at 21.1 T, allowing the complete set of 17 O NMR tensor parameters to be measured. Assignment of the observed 17 O NMR parameters to the correct oxygen sites in the crystal lattice was achieved with the aid of DFT calculations. By modeling the temperature dependence of 17 O NMR powder line shapes, we have not only confirmed that the SO 3 − groups in these compounds undergo a 3-fold rotational jump mechanism but also extracted the corresponding jump rates (10 2 −10 5 s −1) and the associated activation energies (E a) for this process (E a =4 8± 7, 42 ± 3, and 45 ± 1 kJ mol −1 for T, HT, and ABSA, respectively). This is the first time that SO 3 − rotational dynamics have been directly probed by solid-state 17 O NMR. Using the experimental activation energies for SO 3 − rotation, we were able to evaluate quantitatively the total hydrogen bond energy that each SO 3 − group is involved in within the crystal lattice. The activation energies also correlate with calculated rotational energy barriers. This work provides a clear illustration of the utility of solid-state 17 O NMR in quantifying dynamic processes occurring in organic solids. Similar studies applied to selectively 17 O-labeled biomolecules would appear to be very feasible.

17O NMR in simple oxides

Chemical Physics, 1990

The following binary metal oxides have yielded high-resolution "0 nuclear magnetic resonance (NMR) spectra, obtained by magic-angle spinning (MAS) without isotopic enrichment: a

The determination of 17O NMR parameters of hydroxyl oxygen: a combined deuteration and DOR approach

Magnetic resonance in chemistry : MRC, 2007

The direct detection of hydroxyl oxygen (O-H) by (17)O double-rotation (DOR) NMR is very challenging because of the strong O-H dipole interaction. It is shown that deuteration of the hydroxyl site overcomes this using glycine.HCl as an illustration. Two well-separated sets of narrow (linewidth approximately 80-100 Hz) resonances with their spinning-sidebands are observed for the carboxyl and hydroxyl oxygens in the DOR spectrum of [(17)O,(2)H]glycine.HCl. The chemical shift anisotropy of these sites is obtained from a simulation of the DOR spinning-sideband intensities. The chemical shift span (Omega) for the carboxyl oxygen is found to be much larger than that of the hydroxyl oxygen, with Omega values of 540 +/- 15 and 210 +/- 10 ppm, respectively.

Natural Abundance Oxygen-17 Solid-State NMR of Metal Organic Frameworks Enhanced by Dynamic Nuclear Polarization

2020

The 17O resonances of Zirconium-oxo clusters that can be found in porous Zr carboxylate metal-organic frameworks (MOFs) have been investigated by magic-angle spinning (MAS) NMR spectroscopy enhanced by dynamic nuclear polarization (DNP). High-resolution 17O spectra at 0.037 % natural abundance could be obtained in 48 hours, thanks to DNP enhancement of the 1H polarization by factors e(1H) = Swith/Swithout = 28, followed by 1H®17O cross-polarization, allowing a saving in experimental time by a factor of ca. 800. The distinct 17O sites from the oxo-clusters can be resolved at 18.8 T. Their assignment is supported by density functional theory (DFT) calculations of chemical shifts and quadrupolar parameters.

15N NMR Spectroscopy in Structural Analysis: An Update (2001-2005)

Current Organic …, 2007

Since our previous review article (Curr. Org. Chem. 2002, 6, 35), significant improvements and an array of 15 N NMR applications in structural analysis have been published. This report aims to update coverage of improvements in methodology and various types of applications published over the period 2001 -2005. Substantial progress in cryogenic probe technology and the commercial availability of cryoprobes have facilitated the measurement of 15 N NMR parameters.

High-field 17 O NMR studies of the SiOAl bond in solids

Chemical Physics Letters, 1998

Oxygen-17 multiple-quantum magic-angle spinning and double rotation nuclear magnetic resonance studies were performed in the field of 17.6 T. A correlation between the isotropic value of the chemical shift and the SiOAl bond angle in zeolites was found. The correlation may be used for the determination of bond angles in SiOAl sites without long-range order. It is shown that multiple-quantum and double rotation techniques are complementary tools for getting highly-resolved 17 O NMR spectra of solids. q

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