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Solid State Nuclear Magnetic Resonance

Dennis Lam, Jianqin Zhuang, Leah S Cohen, Boris Arshava, Fred R Naider, Ming Tang
The effects of various lipid bound paramagnetic metal ions on liposomes prepared in the presence of trehalose and chelator lipids are evaluated to observe site-specific signal changes on liposome samples with optimal resolution in solid-state NMR spectroscopy. We found that Mn2+ , Gd3+ and Dy3+ have different influences on the lipid 13 C sites depending on their penetration depths into the bilayer, which can be extracted as distance information. The trehalose-liposome mixture is efficiently packed into solid-state NMR rotors and provides optimal resolution at reasonable instrument temperatures (10-50 °C)...
July 27, 2018: Solid State Nuclear Magnetic Resonance
Hiroki Nagashima, Aany Sofia Lilly Thankamony, Julien Trébosc, Lionel Montagne, Gwendal Kerven, Jean-Paul Amoureux, Olivier Lafon
We introduce a novel heteronuclear dipolar recoupling based on the R21 -1 symmetry, which uses the tanh/tan (tt) shaped pulse as a basic inversion element and is denoted R21 -1 (tt). Using first-order average Hamiltonian theory, we show that this sequence is non-γ-encoded and that it reintroduces the |m| = 1 spatial component of the Chemical Shift Anisotropy (CSA) of the irradiated isotope and its heteronuclear dipolar interactions. Using numerical simulations and one-dimensional (1D) 27 Al-{31 P} through-space D-HMQC (Dipolar Heteronuclear Multiple-Quantum Correlation) experiments on VPI-5, we compare the performances of this recoupling to those of other non-γ-encoded |m| = 1 heteronuclear recoupling schemes: REDOR (Rotational-Echo DOuble Resonance), SFAM (Simultaneous Frequency and Amplitude Modulation) and R42 -1 (tt)...
July 20, 2018: Solid State Nuclear Magnetic Resonance
E E Ylinen, M Punkkinen, A Birczyński, Z T Lalowicz
We studied deuteron NMR spectra and spin-lattice relaxation of deuterated acetone-d6 , adsorbed into zeolites NaX (1.3) and NaY(2.4) at 100% coverage of sodium cations. At temperatures roughly below 160 K the deuterons are localized and their NMR characteristics are determined by CD3 rotation and rotational oscillations of acetone molecules. In NaX the CD3 rotation and rotational oscillations about the twofold axis of acetone dominate the spectra below 100 K, while above it oscillations also about other axes become important...
September 2018: Solid State Nuclear Magnetic Resonance
Lixin Liang, Guangjin Hou, Xinhe Bao
Proton chemical shift anisotropy (CSA) is significantly important as it provides the information of the dynamics and local environmental structure of the proton. The measurement of proton CSA keeps drawing the attention of NMR researchers, and great efforts have been expended. In the early years, measuring proton CSA in solid-state NMR, especially with the strong 1 H-1 H dipolar network, was hampered by ineffective decoupling or selectively recoupling techniques, and the applications were only limited to those with sparse proton sites or single crystals...
September 2018: Solid State Nuclear Magnetic Resonance
Alyxandra N Thiessen, Wesley Verbeek, Kelsey Gritter, Kristopher J Ooms
Double and zero quantum filtered (ZQF/DQF) 2 H NMR spectroscopy was used to study D2 O in five different Nafion membranes, N117, N115, NR212, XL, and HP, in order to assess the effectiveness of the technique for monitoring differences in thickness, membrane reinforcement, and the addition of chemical stabilizers. Experiments were also carried out at 20 and 80 °C to understand if the ZQF/DQF technique could detect changes in the water environments and exchange dynamics as a function of temperature. For two of the membranes, significant decreases in the 1/T2 relaxation rates were observed at 80 °C...
September 2018: Solid State Nuclear Magnetic Resonance
M Makrinich, E Nimerovsky, A Goldbourt
Dipolar recoupling under magic-angle spinning allows to measure accurate inter-nuclear distances provided that the two interacting spins can be efficiently and uniformly excited. Alexander (Lex) Vega has shown that adiabatic transfers of populations in quadrupolar spins during the application of constant-wave (cw) radio-frequency pulses lead to efficient and quantifiable dipolar recoupling curves. Accurate distance determination within and beyond the adiabatic regime using cw pulses is limited by the size of the quadrupolar coupling constant...
August 2018: Solid State Nuclear Magnetic Resonance
Christopher A Klug, Joel B Miller
The automated detection of broad NMR spectra via the controlled stepwise motion of the NMR probe along the field axis of the superconducting solenoid is demonstrated for the detection of 19 F NMR of paramagnetic UF4 and 195 Pt NMR of supported metal catalysts. The sensitivity advantages of performing these measurements at 2.3 T are discussed with reference to applying this methodology to room temperature in situ electrochemical 195 Pt NMR.
August 2018: Solid State Nuclear Magnetic Resonance
Clare P Grey, Tatyana Polenova, Shimon Vega
No abstract text is available yet for this article.
August 2018: Solid State Nuclear Magnetic Resonance
Sabu Varghese, Peter J Halling, Daniel Häussinger, Stephen Wimperis
Nuclear magnetic resonance (NMR) is a powerful tool for investigating atomic-scale structure in heterogeneous or composite materials where long-range order is absent. In this work solid-state 1 H and 1 H-detected NMR experiments were performed with fast magic angle spinning (νR  = 75 kHz) and at high magnetic fields (B0  = 20 T) and used to gain structural insight into a heterogeneous biocatalyst consisting of an enzyme, human carbonic anhydrase II (hCA II), covalently immobilized on epoxy-functionalized silica...
August 2018: Solid State Nuclear Magnetic Resonance
Sivakumar Paramasivam, Angela M Gronenborn, Tatyana Polenova
Chemical shift tensors (CSTs) are an exquisite probe of local geometric and electronic structure. 15 N CST are very sensitive to hydrogen bonding, yet they have been reported for very few proteins to date. Here we present experimental results and statistical analysis of backbone amide 15 N CSTs for 100 residues of four proteins, two E. coli thioredoxin reassemblies (1-73-(U-13 C,15 N)/74-108-(U-15 N) and 1-73-(U-15 N)/74-108-(U-13 C,15 N)), dynein light chain 8 LC8, and CAP-Gly domain of the mammalian dynactin...
August 2018: Solid State Nuclear Magnetic Resonance
Takahiro Iijima, Tadashi Shimizu
The relaxation-assisted separation method was applied to overlapping 2 H nuclear magnetic resonance (NMR) spectra of diamagnetic and paramagnetic solids to separate them based on the different relaxation behaviors caused by molecular motion. Carr-Purcell-Meiboom-Gill sequences for 2 H NMR were adopted to build two-dimensional data sets from one-dimensional NMR experiments. For diamagnetic α-glycine, the 2 H NMR spectrum collected at 198 K was separated into two components from static -CD2 - and dynamic -ND3 ...
July 2018: Solid State Nuclear Magnetic Resonance
Rupal Gupta, John Stringer, Jochem Struppe, Dieter Rehder, Tatyana Polenova
Electronic and structural properties of short-lived metal-peroxido complexes, which are key intermediates in many enzymatic reactions, are not fully understood. While detected in various enzymes, their catalytic properties remain elusive because of their transient nature, making them difficult to study spectroscopically. We integrated 17 O solid-state NMR and density functional theory (DFT) to directly detect and characterize the peroxido ligand in a bioinorganic V(V) complex mimicking intermediates non-heme vanadium haloperoxidases...
July 2018: Solid State Nuclear Magnetic Resonance
Gregory Lusk, Terry Gullion
Some MAS NMR experiments are sensitive to fluctuations or drifts in rf field strengths. We examine the simple 1 H-13 C CPMAS experiment and show that the 13 C signal intensities vary over time due to drifts in rf field strengths. The causes of the drifts in rf field strengths are studied. Stabilization of the rf field strengths are obtained by using an rf field-strength controller. The controller is a stand-alone unit, which can be easily incorporated in any spectrometer system. Details of the controller, including circuit design, are provided...
July 2018: Solid State Nuclear Magnetic Resonance
Kaustubh R Mote, Perunthiruthy K Madhu
We show here an effective way of implementing simultaneously homonuclear and heteronuclear dipolar decoupling in magic-angle spinning (MAS) solid-state NMR. Whilst the homonuclear spin decoupling is applied on the 1 H channel, heteronuclear spin decoupling is applied on the 13 C channel. The 1 H spins are observed in a windowed fashion in this case. The resultant 1 H spectrum has higher resolution due to the attenuation of broadening arising from both homonuclear 1 H-1 H and heteronuclear 1 H-13 C interactions, with the latter normally leading to additional line broadening in 13 C labelled samples...
April 2018: Solid State Nuclear Magnetic Resonance
A M Panich, N A Sergeev, M Paczwa, M Olszewski
No abstract text is available yet for this article.
April 2018: Solid State Nuclear Magnetic Resonance
Shenhui Li, Jing Li, Jing Tang, Feng Deng
Solid-state NMR was utilized to explore the host-guest interaction between adsorbate and adsorbent at atomic level to understand the separation mechanism of styrene (St) and ethylbenzene (EB) in MIL-53(Al). 13 C-27 Al double-resonance NMR experiments revealed that the host-guest interaction between St and MIL-53 was much stronger than that of EB adsorption. In addition, 13 C DIPSHIFT experiments suggested that the adsorbed St was less mobile than EB confined inside the MIL-53 pore. Furthermore, the host-guest interaction model between St, EB and MIL-53 was established on the basis of the spatial proximities information extracted from 2D 1 H-1 H homo-nuclear correlation NMR experiments...
April 2018: Solid State Nuclear Magnetic Resonance
Jaclyn Catalano, Anna Murphy, Yao Yao, Nicholas Zumbulyadis, Silvia A Centeno, Cecil Dybowski
Many oil paintings, dating from the 15th century to the present, are affected by the formation of heavy-metal carboxylates (soaps) that alter the structural integrity and appearance of the works. Through transport phenomena not yet understood, free fatty acids formed from oils used as binders migrate through the paint film and react with heavy-metal ions that are constituents of pigments and/or driers, forming metal carboxylates. The local molecular dynamics of fatty acids and metal carboxylates are factors influencing material transport in these systems...
February 2018: Solid State Nuclear Magnetic Resonance
Otto E O Zeman, Constantin Hoch, Rupert Hochleitner, Thomas Bräuniger
Orientation-dependent NMR spectra of a single crystal of the mineral vanadinite, Pb5 (VO4 )3 Cl, were acquired using only one rotation axis with a general orientation in the hexagonal crystal lattice (space group P63 /m). The chemical shift (CS) tensors for the207 Pb on Wyckoff positions 6h and 4f, and both CS and quadrupole coupling tensor Q for51 V at the positions 6h were determined by including the NMR response of symmetry-related atoms in the unit cell (and in case of207 Pb at 4f, also the isotropic shift from MAS NMR spectra)...
February 2018: Solid State Nuclear Magnetic Resonance
Kong Ooi Tan, Vipin Agarwal, Nils-Alexander Lakomek, Susanne Penzel, Beat H Meier, Matthias Ernst
Through-bond J-coupling based experiments in solid-state NMR spectroscopy are challenging because the J couplings are typically much smaller than the dipolar couplings. This often leads to a lower transfer efficiency compared to dipolar-coupling based sequences. One of the reasons for the low transfer efficiency are the second-order cross terms involving the strong heteronuclear dipolar couplings leading to fast magnetization decay. Here, we show that by employing a symmetry-based C9 sequence, which was carefully selected to suppress second-order terms, efficient polarization transfers of up to 80% can be achieved without decoupling on fully protonated two-spin model systems at a MAS frequency of 55...
February 2018: Solid State Nuclear Magnetic Resonance
Eva Meirovitch, Zhichun Liang, Jack H Freed
We report on a new approach to the analysis of dynamic NMR lineshapes from polycrystalline (i.e., macroscopically disordered) samples in the presence of Magic Angle Spinning (MAS). This is an application of the Stochastic Liouville Equation developed by Freed and co-workers for treating restricted (i.e., microscopically ordered) motions. The2 H nucleus in an internally-mobile C-CD3 moiety serves as a prototype probe. The acronym is2 H/MOMD/MAS, where MOMD stands for "microscopic-order-macroscopic-disorder...
February 2018: Solid State Nuclear Magnetic Resonance
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