Prediction of NMR J-coupling in solids with the planewave pseudopotential approach

Yates, Jonathan R.

doi:10.1002/mrc.2646

Cited by 26 publications

(16 citation statements)

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“…These variations in 2 JP;P constitute a potentially rich new source of information for the characterization of variations in bond angle and bond length. The observed spectral features, especially the distributions of parameters, can be compared with first principle calculations of J-couplings [66]. In crystalline systems, the narrower resonances under MAS and the longer lifetimes of the resonances (T 2 ) mean that the two-dimensional sequences are generally more straightforward.…”

Section: Magic Angle Spinning Nuclear Magnetic Resonancementioning

confidence: 99%

Titanium-containing bioactive phosphate glasses

Kiani

Lakhkar

Salih

et al. 2012

Phil. Trans. R. Soc. A.

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The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.

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Section: Magic Angle Spinning Nuclear Magnetic Resonancementioning

confidence: 99%

Titanium-containing bioactive phosphate glasses

Kiani

Lakhkar

Salih

et al. 2012

Phil. Trans. R. Soc. A.

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“…After 15 min, the crucible was removed and weight-loss measurements were performed to check that the expected reaction had occurred. The crucible was returned to the furnace at the higher 100 temperature of 1100°C to decrease the viscosity of the melt before pouring. After 5 min, the melt was poured onto a roomtemperature steel plate and allowed to crystallise.…”

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confidence: 99%

Towards homonuclear J solid-state NMR correlation experiments for half-integer quadrupolar nuclei: experimental and simulated 11B MAS spin-echo dephasing and calculated 2JBB coupling constants for lithium diborate

Barrow

Yates

Feller

et al. 2011

Phys. Chem. Chem. Phys.

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is observed: the B3 (larger C Q ) site dephases more slowly than the B4 site at all investigated MAS frequencies (5 to 20 kHz) at 14.1 T. Increasing the MAS frequency leads to markedly slower dephasing for the B3 site, while there is a much less evident effect for the B4 site. Considering samples at 5, 25, 80 (natural abundance) and 100 % 11 B isotopic 15 abundance, dephasing becomes faster for both sites as the 11 B isotopic abundance increases. The experimental behaviour is rationalised using density matrix simulations for two and three dipolarcoupled 11 B nuclei. The experimentally observed slower dephasing for the larger C Q (B3) site is reproduced in all simulations and is explained by the reintroduction of the dipolar coupling by the so-called "spontaneous quadrupolar-driven recoupling mechanism" having a different dependence 20 on the MAS frequency for different quadrupolar frequencies. Specifically, isolated spin-pair simulations show that the spontaneous quadrupolar-driven recoupling mechanism is most efficient when the quadrupolar frequency is equal to twice the MAS frequency. While for isolated spin-pair simulations, increasing the MAS frequency leads to faster dephasing, agreement with experiment is observed for three-spin simulations which additionally include the homogeneous nature of the 25 homonuclear dipolar coupling network. First-principles calculations, using the GIPAW approach, of the 2 J 11B-11B couplings in lithium diborate, metaborate and triborate are presented: a clear trend is revealed whereby the 2 J 11B-11B couplings increase with increasing B-O-B bond angle and B-B distance. However, the calculated 2 J 11B-11B couplings are small (0.95, 1.20 and 2.65 Hz in lithium diborate), thus explaining why no zero crossing due to J modulation is observed experimentally, 30 even for the sample at 25 % 11 B where significant spin-echo intensity remains out to durations of 200 ms.

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“…107,108 The GIPAW plane wave pseudopotential method can also be used to predict EFG, and, more recently, calculations of J-coupling parameters have also become possible using this approach. 109 The anisotropy and orientation of the J-tensors and their relationship to the crystal structure can be investigated using this approach.…”

Section: Methodsmentioning

confidence: 99%

Chapter 2. Solid‐State NMR in Drug Discovery and Development

Vogt¹

2013

New Developments in NMR

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Prediction of NMR J-coupling in solids with the planewave pseudopotential approach

Cited by 26 publications

References 40 publications

Titanium-containing bioactive phosphate glasses

Titanium-containing bioactive phosphate glasses

Towards homonuclear J solid-state NMR correlation experiments for half-integer quadrupolar nuclei: experimental and simulated 11B MAS spin-echo dephasing and calculated 2JBB coupling constants for lithium diborate

Chapter 2. Solid‐State NMR in Drug Discovery and Development

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