scholarly journals Characterization of Phosphorus Species in Human Dentin by Solid-State NMR

Molecules ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 196 ◽  
Author(s):  
Yi-Ling Tsai ◽  
Meng-Wei Kao ◽  
Shing-Jong Huang ◽  
Yuan-Ling Lee ◽  
Chun-Pin Lin ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Molecular Structures ◽  
Spatial Proximity ◽  
Growth Stages ◽  
Apatite Structure ◽  
Phosphorus Species ◽  
Structural Water ◽  
Disordered Phase ◽  
Human Dentin

The rat has been considered as an appropriate animal model for the study of the mineralization process in humans. In this work, we found that the phosphorus species in human dentin characterized by solid-state NMR spectroscopy consist mainly of orthophosphate and hydrogen phosphate. Some orthophosphates are found in a disordered phase, where the phosphate ions are hydrogen-bonded to structural water, some present a stoichiometric apatite structure, and some a hydroxyl-depleted apatite structure. The results of this study are largely the same as those previously obtained for rat dentin. However, the relative amounts of the various phosphorus species in human and rat dentin are dramatically different. In particular, stoichiometric apatite is more abundant in human dentin than in rat dentin, whereas the converse is true for disordered-phase orthophosphates. Furthermore, spatial proximity among all phosphorus species in human dentin is identical within experimental error, in contrast to what observed for rat dentin. Although it is not clear how these spectroscopic data could relate to the hierarchical structure or the mechanical properties of teeth, our data reveal that the molecular structures of human and rat dentin at different growth stages are not exactly the same.

scholarly journals Self-assembly of arene ruthenium acylpyrazolone fragments to tetranuclear metallacycles. Molecular structures and solid-state 15N CPMAS NMR correlations

2016 ◽  
Vol 45 (9) ◽  
pp. 3974-3982 ◽  
Author(s):  
Riccardo Pettinari ◽  
Fabio Marchetti ◽  
Claudio Pettinari ◽  
Francesca Condello ◽  
Brian W. Skelton ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Self Assembly ◽  
Solid State Nmr ◽  
Molecular Structures ◽  
Sandwich Complexes ◽  
Solid State Nmr Spectroscopy ◽  
Half Sandwich

Mono- and tetranuclear Ru(ii) half-sandwich complexes containing acylpyrazolone ligands. 13C and 15N solid state NMR spectroscopy.

Tetra(alkynyl)silanes, a 3,6-Disila-triyne, a 3,6,9-Trisila-tetrayne, a 1,3,4,6-Tetrasiladiyne, and Bis(trimethylstannyl)ethyne. Molecular Structures and Solid-state NMR Studies

2010 ◽  
Vol 65 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Ezzat Khan ◽  
Amin Badshah ◽  
Elias Molla ◽  
Peter Thoma ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Mas Nmr ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Solution State ◽  
Nmr Data

The molecular structures of three alkynylsilanes, tetrakis(ethynyl-p-tolyl)silane, 3,3,6,6,-tetramethyl- 3,6-disila-triyne, 3,3,6,6,9,9,-hexamethyl-3,6,9-trisila-tetrayne, and of bis(trimethylstannyl)- ethyne have been determined by X-ray diffraction. The same alkynylsilanes, and in addition 1,2- bis(trimethylsilylethynyl)-1,1,2,2-tetramethyldisliane, were studied by solid-state 13C and 29Si MAS NMR spectroscopy. The results of these measurements were compared with crystallographic evidence and also with relevant solution-state NMR data.

Intactness and spatial proximity of acid–base groups in bifunctional SBA-15 as revealed by solid-state NMR

2010 ◽  
Vol 491 (1-3) ◽  
pp. 72-74 ◽  
Author(s):  
Wanling Shen ◽  
Wujun Xu ◽  
Qiang Gao ◽  
Jun Xu ◽  
Hailu Zhang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Spatial Proximity ◽  
Acid Base

scholarly journals t1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Amrit Venkatesh ◽  
Xuechen Luan ◽  
Frédéric Perras ◽  
Ivan Hung ◽  
Wenyu Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quantum Coherence ◽  
Pulse Sequence ◽  
Signal Amplitude ◽  
Spatial Proximity ◽  
Multiple Quantum ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Frequency Fluctuations ◽  
Multiple Quantum Coherence

<p>Heteronuclear correlation (HETCOR) spectroscopy is one of the key tools in the arsenal of the solid-state NMR spectroscopist to probe spatial proximity between two different nuclei and enhance spectral resolution. Dipolar heteronuclear multiple-quantum coherence (D-HMQC) is a powerful technique that can be potentially utilized to obtain <sup>1</sup>H detected 2D HETCOR solid-state NMR spectra of any NMR active nucleus. A long-standing problem in <sup>1</sup>H detected D-HMQC solid-state NMR experiments is the presence of <i>t</i><sub>1</sub>-noise which reduces sensitivity and impedes spectral interpretation. In this contribution, we describe novel pulse sequences, termed <i>t</i><sub>1</sub>-noise eliminated (TONE) D-HMQC, that suppress <i>t</i><sub>1</sub>-noise and can provide higher sensitivity and resolution than conventional D-HMQC. Monte-Carlo and numerical simulations confirm that <i>t</i><sub>1</sub>-noise in conventional D-HMQC primarily occurs because random MAS frequency fluctuations cause variations in the NMR signal amplitude from scan to scan, leading to imperfect cancellation of uncorrelated signals by phase cycling. The TONE D-HMQC sequence uses <sup>1</sup>H p-pulses to refocus the evolution of <sup>1</sup>H CSA across each recoupling block, improving the stability of the pulse sequence to random MAS frequency fluctuations. The <sup>1</sup>H refocusing pulses also restore the orthogonality of in-phase and anti-phase magnetization for all crystallite orientations, enabling the use of 90° flip-back or LG spin-lock trim pulses to reduce the intensity of uncorrelated signals. We demonstrate the application of these methods to acquire detected 2D <sup>1</sup>H-<sup>35</sup>Cl and <sup>1</sup>H-<sup>13</sup>C HETCOR spectra of histidine•HCl•H<sub>2</sub>O with reduced <i>t</i><sub>1</sub>-noise. To show generality, we also apply these methods to obtain 2D <sup>1</sup>H-<sup>17</sup>O spectra of 20%-<sup>17</sup>O fmoc-alanine and for the first time at natural abundance, 2D <sup>1</sup>H-<sup>25</sup>Mg HETCOR spectra of magnesium hydroxide. The TONE D-HMQC sequences are also used to probe <sup>1</sup>H-<sup>25</sup>Mg and <sup>1</sup>H-<sup>27</sup>Al proximities in Mg-Al layered double hydroxides and confirm the even mixing of Mg and Al in these materials.</p>

scholarly journals t1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Amrit Venkatesh ◽  
Xuechen Luan ◽  
Frédéric Perras ◽  
Ivan Hung ◽  
Wenyu Huang ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quantum Coherence ◽  
Pulse Sequence ◽  
Signal Amplitude ◽  
Spatial Proximity ◽  
Multiple Quantum ◽  
Heteronuclear Multiple Quantum Coherence ◽  
Frequency Fluctuations ◽  
Multiple Quantum Coherence

<p>Heteronuclear correlation (HETCOR) spectroscopy is one of the key tools in the arsenal of the solid-state NMR spectroscopist to probe spatial proximity between two different nuclei and enhance spectral resolution. Dipolar heteronuclear multiple-quantum coherence (D-HMQC) is a powerful technique that can be potentially utilized to obtain <sup>1</sup>H detected 2D HETCOR solid-state NMR spectra of any NMR active nucleus. A long-standing problem in <sup>1</sup>H detected D-HMQC solid-state NMR experiments is the presence of <i>t</i><sub>1</sub>-noise which reduces sensitivity and impedes spectral interpretation. In this contribution, we describe novel pulse sequences, termed <i>t</i><sub>1</sub>-noise eliminated (TONE) D-HMQC, that suppress <i>t</i><sub>1</sub>-noise and can provide higher sensitivity and resolution than conventional D-HMQC. Monte-Carlo and numerical simulations confirm that <i>t</i><sub>1</sub>-noise in conventional D-HMQC primarily occurs because random MAS frequency fluctuations cause variations in the NMR signal amplitude from scan to scan, leading to imperfect cancellation of uncorrelated signals by phase cycling. The TONE D-HMQC sequence uses <sup>1</sup>H p-pulses to refocus the evolution of <sup>1</sup>H CSA across each recoupling block, improving the stability of the pulse sequence to random MAS frequency fluctuations. The <sup>1</sup>H refocusing pulses also restore the orthogonality of in-phase and anti-phase magnetization for all crystallite orientations, enabling the use of 90° flip-back or LG spin-lock trim pulses to reduce the intensity of uncorrelated signals. We demonstrate the application of these methods to acquire detected 2D <sup>1</sup>H-<sup>35</sup>Cl and <sup>1</sup>H-<sup>13</sup>C HETCOR spectra of histidine•HCl•H<sub>2</sub>O with reduced <i>t</i><sub>1</sub>-noise. To show generality, we also apply these methods to obtain 2D <sup>1</sup>H-<sup>17</sup>O spectra of 20%-<sup>17</sup>O fmoc-alanine and for the first time at natural abundance, 2D <sup>1</sup>H-<sup>25</sup>Mg HETCOR spectra of magnesium hydroxide. The TONE D-HMQC sequences are also used to probe <sup>1</sup>H-<sup>25</sup>Mg and <sup>1</sup>H-<sup>27</sup>Al proximities in Mg-Al layered double hydroxides and confirm the even mixing of Mg and Al in these materials.</p>

Solid-State NMR Study on Phosphorus Species in Phosphorus-modified ZSM-5 Zeolite

2018 ◽  
Vol 39 (10) ◽  
pp. 1144-1148 ◽  
Author(s):  
Na Young Kang ◽  
Yong Ki Park ◽  
Chul Kim
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Phosphorus Species ◽  
Nmr Study

Solid-State NMR Investigation Of Mixed-Alkali Distribution In Phosphate Glasses

2000 ◽  
Vol 658 ◽  
Author(s):  
S. Prabakar ◽  
K.T. Mueller
Keyword(s):  
Solid State ◽  
Phosphate Glass ◽  
Solid State Nmr ◽  
Short Range ◽  
Double Resonance ◽  
Phosphate Glasses ◽  
Spatial Proximity ◽  
Alkali Cations ◽  
Mixed Alkali ◽  
O 31

ABSTRACTThe correlation between 31P and 23Na (or 133Cs) nuclei in a mixed-alkali phosphate glass has been investigated by TRAnsfer of Populations by DOuble Resonance (TRAPDOR) NMR spectroscopy. The variation in spatial proximity between 31P nuclei in phosphate tetrahedra and sodium (or cesium) modifier ions has been demonstrated in a phosphate glass with molar composition 25 Cs2O: 31 Na2O: 44P2O5. Interactions between 31P and 23Na (or 133Cs) nuclei are shown to exist even at low dephasing times indicating the short-range nature of these couplings. The ratios of resonance intensities from Q1 and Q2 phosphate units show different trends depending on whether couplings to 23Na or 133Cs are investigated, demonstrating the differing structural roles of the modifier alkali cations within the glass.

Solid-State NMR Structural Determination of Components in an Ion Channel Switch Biosensor

2003 ◽  
Vol 56 (3) ◽  
pp. 163 ◽  
Author(s):  
Aphrodite Anastasiadis ◽  
Frances Separovic
Keyword(s):  
Solid State ◽  
Ion Channels ◽  
Ion Channel ◽  
Lipid Membranes ◽  
Solid State Nmr ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Nmr Studies ◽  
Solution State ◽  
C Terminus

High-resolution structural analysis of membrane proteins is difficult to achieve with the commonly used methods of structural biology, X-ray diffraction, and solution-state NMR spectroscopy. By combining solid-state NMR studies of membrane peptides in powder and oriented samples, with solution-state studies in detergent micelles, three dimensional molecular structures can be obtained. We have used solid-state NMR methods to study the antibiotic, gramicidin A (gA), a peptide that forms ion channels in bilayer lipid membranes (BLMs). Receptor groups have been linked to gA channels embedded in a BLM tethered to a gold electrode in an 'ion channel switch' biosensor. The receptor is attached to gA via a protein (either streptavidin or avidin) bonded to a biotin (B) moiety, with B in turn being covalently linked to the C-terminus of gA by one or more aminocaproyl (X) groups. Using NMR, we determined that the structures of these biotinylated gA analogues are very similar to native gA, and that biotinylated gA analogues with longer linkers (more X groups) are more accessible for binding to streptavidin/avidin and hence function better as ligand-gated ion channels.

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