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Solid State Nuclear Magnetic Resonance

Lena Marie Funke, Henrik Bradtmüller, Hellmut Eckert
The case of rotational echo double resonance (REDOR) experiments on the observe nuclei (11)B and (31)P interacting with multiple I=1 quadrupolar nuclei is analyzed in detail by SIMPSON simulations and experimental studies. The simulations define the region within the parameter space spanned by nutation frequency, quadrupolar coupling constant and spinning frequency where the parabolic analysis of the initial REDOR curve in terms of dipolar second moments has validity. The predictions are tested by experimental studies on the crystalline model compounds lithium diborate and lithium pyrophosphate, which are subsequently extended to measure dipolar second moments M2((11)B{(6)Li}) and M2((31)P{(6)Li}) in three borophosphate glasses...
February 20, 2017: Solid State Nuclear Magnetic Resonance
Habeeba K Miah, Rosalie Cresswell, Dinu Iuga, Jeremy J Titman
A (1)H anisotropic-isotropic chemical shift correlation experiment which employs symmetry-based recoupling sequences to reintroduce the chemical shift anisotropy in ν1 and ultrafast MAS to resolve (1)H sites in ν2 is described. This experiment is used to measure (1)H shift parameters for L-ascorbic acid, a compound with a relatively complex hydrogen-bonding network in the solid. The (1)H CSAs of hydrogen-bonded sites with resolved isotropic shifts can be extracted directly from the recoupled lineshapes. In combination with DFT calculations, hydrogen positions in crystal structures obtained from X-ray and neutron diffraction are refined by comparison with simulations of the full two-dimensional NMR spectrum...
February 13, 2017: Solid State Nuclear Magnetic Resonance
G Tricot, B Doumert, B Revel, M Bria, J Trebosc, H Vezin
Solid state NMR is applied in this contribution on the xAl2O3-(50-x/2)Na2O-(50-x/2)P2O5 composition line (with 0<x<5mol%) in order to investigate the distribution of Al(3+) ions in Al2O3-doped sodium phosphate glasses. The structure was analysed by (i) (27)Al 1D-, 3Q-, DQ- MAS-NMR analysis and (ii) 1D (31)P, (27)Al((31)P) 2D D-HMQC MAS-NMR and 2D (31)P R-INADEQUATE technique. The (27)Al NMR results confirm the presence of six-coordinated aluminate as major aluminate species and indicate that Al(3+) ions are fully dissociated in the glass network...
February 9, 2017: Solid State Nuclear Magnetic Resonance
Günter Hempel
A method is described for the elimination of artefacts that arise in time-domain signals because of the presence of digital and analogous filters. Such artefacts are mostly located at the beginning of the free-induction decay (FID). The procedure introduced here is particularly important if at least one signal component decays rather quickly, i.e. if there is only a small number of data containing this component (as for solid-state (1)H or (2)H FIDs). The method is able to restore the original signal by deconvolution of the spectrometer output from the transfer function of the spectrometer console...
February 3, 2017: Solid State Nuclear Magnetic Resonance
Ming Shen, Qun Chen, Bingwen Hu
(14)N MAS overtone spectroscopy is mainly limited by narrow excitation bandwidths owing to the use of very long pulses to get stronger signals. We previously reported the use of modified 90° composite pulses for broadband excitation in (1)H-{NOTDQ14}D-HMQC experiments at ultra-fast MAS. In this work, we modified the 180° composite pulses, which are originally designed for spin 1/2 nuclei, for both indirect detection in (1)H-{NOTDQ14}D-HMQC experiment and direct detection in one-pulse experiment, and found that the modified 180° composite pulses are useful for broadband excitation...
February 3, 2017: Solid State Nuclear Magnetic Resonance
Yue Zhang, Bryan E G Lucier, Victor V Terskikh, Renlong Zheng, Yining Huang
Ga-MIL-53 is a metal-organic framework (MOF) that exhibits a "breathing effect," in which the pore size and overall MOF topology can be influenced by temperature, pressure, and host-guest interactions. The phase control afforded by this flexible framework renders Ga-MIL-53 a promising material for guest storage and sensing applications. In this work, the structure and behavior of four Ga-MIL-53 phases (as, ht, enp and lt), along with CO2 adsorbed within Ga-MIL-53 at various loading levels, has been investigated using (69/71)Ga solid-state NMR (SSNMR) experiments at 21...
January 31, 2017: Solid State Nuclear Magnetic Resonance
Anna Naumova, Carsten Tschierske, Kay Saalwächter
In recent years, the analysis of proton double-quantum NMR build-up curves has become an important tool to quantify anisotropic mobility in different kinds of soft materials such as polymer networks or liquid crystals. In the former case, such data provides a measure of orientation-dependent residual (time-averaged) dipolar couplings arising from anisotropic segmental motions, informing about the length and the state of local stretching of the network chains. Previous studies of macroscopically ordered, i.e...
January 26, 2017: Solid State Nuclear Magnetic Resonance
Piotr Paluch, Natalia Potrzebowska, Agnieszka M Ruppert, Marek J Potrzebowski
In this work for the first time we show the power of solid state NMR spectroscopy in structural analysis of alumina and catalysts supported on the alumina surface employing very fast (60kHz) magic angle spinning (MAS) technique. In the methodological part we demonstrate that under such MAS condition, cross-polarization (CP) from proton to aluminum is an efficient process when a very weak (27)Al RF field is applied. The mechanism of CP transfer and the Hartmann-Hahn (H-H) matching conditions were tested for (27)Al RF fields equal to 3...
January 26, 2017: Solid State Nuclear Magnetic Resonance
Shaohui Xin, Qiang Wang, Jun Xu, Ningdong Feng, Wenzheng Li, Feng Deng
We demonstrated that the heteronuclear correlation experiments between two quadrupolar nuclei, (23)Na and (27)Al, with close Larmor frequencies can be achieved via D-HMQC and D-RINEPT approaches by using a diplexer connected to a conventional probe in magic-angle-spinning solid-state NMR. Low-power heteronuclear dipolar recoupling schemes can be applied on (23)Na or (27)Al to establish polarization transfers between the central transitions of (23)Na and (27)Al for a model compound, NaAlO2. Further, we showed a practical implementation of the two dimensional (23)Na-(27)Al dipolar-based heteronuclear correlation experiment on a heterogeneous catalyst, Na2CO3/γ-Al2O3...
January 21, 2017: Solid State Nuclear Magnetic Resonance
Henri Colaux, Daniel M Dawson, Sharon E Ashbrook
Although a popular choice for obtaining high-resolution solid-state NMR spectra of quadrupolar nuclei, the inherently low sensitivity of the multiple-quantum magic-angle spinning (MQMAS) experiment has limited its application for nuclei with low receptivity or when the available sample volume is limited. A number of methods have been introduced in the literature to attempt to address this problem. Recently, we have introduced an alternative, automated approach, based on numerical simulations, for generating amplitude-modulated pulses (termed FAM-N pulses) to enhance the efficiency of the triple- to single-quantum conversion step within MQMAS...
January 18, 2017: Solid State Nuclear Magnetic Resonance
Nghia Tuan Duong, Yusuke Nishiyama
Recent study has demonstrated the application of the proton-detected heteronuclear multi-quantum coherence (HMQC) at ultrafast Magic Angle Spinning (MAS) to probe quadrupolar nuclei including (14)N and (35)Cl. In addition, for half-integer quadrupolar nucleus like (35)Cl, the quadrupolar product can be calculated based on the shift difference between the center band of satellite transition (ST) and the central transition (CT) peaks. The applicability of this technique is further investigated on spin I=5/2, namely (27)Al nucleus, and kaolin is chosen as the testing sample...
January 4, 2017: Solid State Nuclear Magnetic Resonance
Christophe Odin
The aim of this work is to generalize the Ernst-Anderson model developed to account of the steady-state regime of isolated spins I=1/2 subject to a train of strictly identical pulse sequences separated by free evolution periods of same duration. We generalize this model to the general case of spins I≥1 and general pulse sequence within the framework of the Liouville space. In particular, it is proved that under reasonable assumptions, a well defined steady-state regime is reached which is independent of the initial conditions...
December 29, 2016: Solid State Nuclear Magnetic Resonance
Charlotte Martineau-Corcos, Jiri Dědeček, Francis Taulelle
In this paper, we review and illustrate applications, reported in the literature or used in our group, of (27)Al-(27)Al double-quantum single-quantum (DQ-SQ) MAS NMR experiments for the structural characterization of Al-containing microporous solids, namely zeolites, aluminophosphates and metal-organic frameworks. Information regarding the periodic frameworks or the localization of the various aluminum species in the materials are obtained from the analysis of the two-dimensional NMR spectra, which allows getting local structural details sometimes inaccessible from other characterization technique...
December 28, 2016: Solid State Nuclear Magnetic Resonance
Xianqi Kong, Yizhe Dai, Gang Wu
We report synthesis and solid-state (17)O NMR characterization of four site-specifically (17)O-labeled 2-acylbenzoic acids (2-RC(O)C6H4COOH) where R=H and CH3): 2-[3-(17)O]formylbenzoic acid, 2-[1,2-(17)O2]formylbenzoic acid, 2-[3-(17)O]acetylbenzoic acid, and 2-[1,2,3-(17)O3]acetylbenzoic acid. In the solid state, both 2-formyl- and 2-acetyl-benzoic acids exist as the cyclic phthalide form each containing a five-membered lactone ring and a cyclic hemiacetal/hemiketal group. Static and magic-angle-spinning (17)O NMR spectra were recorded at 14...
December 27, 2016: Solid State Nuclear Magnetic Resonance
T Jessat, M Adjei-Acheamfour, M Storek, R Böhmer
In solids the detection of ionic motion covering the time range of milliseconds and longer is often accomplished using stimulated-echo spectroscopy. For spectral line widths much below or much above 1MHz nonselective or fully selective radio-frequency pulse excitation, respectively, is typically applied in such experiments. To enable the study of samples with quadrupolarly broadened satellite spectra featuring intermediate widths (in the lower MHz range) the present work exploits microcoils. Using such coils, stimulated-echo spectroscopy can be performed under conditions of nonselective excitation for instance with (23)Na as a nuclear probe...
December 24, 2016: Solid State Nuclear Magnetic Resonance
M Bashi, H A Rahnamaye Aliabad, A A Mowlavi, Iftikhar Ahmad
We have calculated Nuclear Magnetic Resonance (NMR) spectroscopy for (127)I (quadrupolar nuclei I=5/2) in binary metal iodides XI (X=Li, Na, K, Rb and Cs) by using PBE- GGA, YS- PBE0 and mBJ exchange correlation potentials. The results show that the nature of bonds between Iodine and metal atoms are ionic. The main contribution in NMR spectroscopy is related to the induced current inside the atomic sphere and the remainder of the unit cell volume contributes only a few ppm. Obtained NMR shifts are compared with the NMR shielding data and the NMR shielding for metal-p band varies across the series about 221ppm...
December 23, 2016: Solid State Nuclear Magnetic Resonance
Stanislav L Veinberg, Austin W Lindquist, Michael J Jaroszewicz, Robert W Schurko
Several considerations for the acquisition, processing, and analysis of high quality ultra-wideline (UW) (14)N solid-state NMR (SSNMR) powder patterns under static conditions are discussed. It is shown that the (14)N quadrupolar parameters may be determined accurately using the frequencies of only two discontinuities in (14)N NMR powder patterns that are dominated by the first-order quadrupolar interaction, thereby eliminating the need for the acquisition of the entire pattern and concomitantly reducing experimental time...
December 21, 2016: Solid State Nuclear Magnetic Resonance
Baudouin Dillmann, Luc Dubois, Erick Paleczny, Julien Trébosc, Jean-Paul Amoureux, Frédérique Pourpoint, Olivier Lafon
The development of probes for Nuclear Magnetic Resonance (NMR) spectroscopy of metabolites, biomolecules or materials requires the accurate determination of the radio-frequency (RF) magnetic field strength, B1, at the position of the sample since this RF-field strength is related to the signal sensitivity and the excitation bandwidth. The Ball Shift (BS) technique is a commonly employed test bench method to measure the B1 value. Nevertheless, the influence of the RF electric field, E1, on BS is often overlooked...
December 18, 2016: Solid State Nuclear Magnetic Resonance
Sarra Aissani, Laouès Guendouz, Pierre-Louis Marande, Daniel Canet
Until now, NQR imaging has been considered mainly in the case of Chlorine-35. This is a spin 3/2 resonating at relatively high frequency (around 30MHz) thus affording a favorable sensitivity. Conversely, Nitrogen-14 (spin 1) NQR is much less sensitive because its resonances frequencies are below 6MHz. In contrast to already existing methodologies for object localization by (14)N NQR, we present here a new, more straightforward, approach and the principles of space dependent (14)N Quadrupole Resonance are laid down...
December 16, 2016: Solid State Nuclear Magnetic Resonance
Ivan Hung, Gang Wu, Zhehong Gan
NMR spectroscopy is a powerful tool for probing molecular dynamics. For the classic case of two-site exchange, NMR spectra go through the transition from exchange broadening through coalescence and then motional narrowing as the exchange rate increases passing through the difference between the resonance frequencies of the two sites. For central-transition spectra of half-integer quadrupolar nuclei in solids, line shape change due to molecular dynamics occurs in two stages. The first stage occurs when the exchange rate is comparable to the second-order quadrupolar interaction...
December 10, 2016: Solid State Nuclear Magnetic Resonance
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