51
|
Nagashima H, Lilly Thankamony AS, Trébosc J, Pourpoint F, Lafon O, Amoureux JP. γ-Independent through-space hetero-nuclear correlation between spin-1/2 and quadrupolar nuclei in solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 84:216-226. [PMID: 28666574 DOI: 10.1016/j.ssnmr.2017.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/08/2017] [Accepted: 06/10/2017] [Indexed: 06/07/2023]
Abstract
We introduce novel sequences using indirect detection to correlate quadrupolar nuclei and spin-1/2 isotopes, other than 1H and 19F. These sequences use γ-encoded symmetry-based RNnν schemes that reintroduce the space component |m| = 1 of the heteronuclear dipolar coupling. These schemes can be applied to the indirectly detected spin in Dipolar-mediated Heteronuclear Multiple-Quantum Correlation (D-HMQC) sequence or to the detected isotope in a novel sequence, named Dipolar-mediated Heteronuclear Universal-Quantum Correlation (D-HUQC). We show that the signal of these sequences using γ-encoded recoupling does not depend on the γ Euler angle relating the inter-nuclear vector between the coupled spins to the MAS rotor-fixed frame. Therefore, the transfer efficiency of these sequences is in principle higher than that of D-HMQC methods using non-γ-encoded recoupling. Furthermore, numerical simulations show that the heteronuclear correlation experiments employing γ-encoded recoupling are more robust to Chemical Shift Anisotropy (CSA) of the irradiated spin and MAS frequency fluctuations. These results are confirmed by 13C-{15N} heteronuclear correlation on glycine and 31P-27Al ones on VPI-5 and Na7(AlP2O7)4PO4. These experiments indicate that R1635 recoupling produces the highest signal-to-noise ratio in heteronuclear correlation 2D experiments when the detected spin-1/2 nuclei are subject to large CSA.
Collapse
|
52
|
Giovine R, Volkringer C, Ashbrook SE, Trébosc J, McKay D, Loiseau T, Amoureux J, Lafon O, Pourpoint F. Solid‐State NMR Spectroscopy Proves the Presence of Penta‐coordinated Sc Sites in MIL‐100(Sc). Chemistry 2017; 23:9525-9534. [DOI: 10.1002/chem.201700584] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Indexed: 11/06/2022]
|
53
|
Dillmann B, Dubois L, Paleczny E, Trébosc J, Amoureux JP, Pourpoint F, Lafon O. Local measure of the electromagnetic field in magnetic resonance coils: How do simulations help to disentangle the contributions of the electric and magnetic fields? SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 82-83:1-9. [PMID: 28027500 DOI: 10.1016/j.ssnmr.2016.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/29/2016] [Accepted: 12/04/2016] [Indexed: 06/06/2023]
Abstract
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. Herein, we derive, from Maxwell equations, an analytical expression of the BS, which shows the contribution of both the electric and magnetic energies to the BS value. This equation shows that the BS allows quantifying the B1 field strength only in regions where the electric energy is small with respect to the magnetic one. The numerical simulations of electromagnetic (EM) field and energy prove that this condition is fulfilled at 100.5MHz inside the electrically balanced coil of a double-resonance 1H/X 4mm Magic Angle Spinning (MAS) probe since for that circuit, the center of the coil is an antinode for the B1 standing wave and a node for the E1 one. We also show that the simulated BS values agree well with the experimental ones. Conversely, NMR experiments show that the contribution of the electric energy to BS becomes significant when the X channel of this probe is connected to a frequency splitter. In that case, the use of BS method to estimate the B1 value is compromised.
Collapse
|
54
|
Giovine R, Volkringer C, Trébosc J, Amoureux JP, Loiseau T, Lafon O, Pourpoint F. NMR crystallography to probe the breathing effect of the MIL-53(Al) metal–organic framework using solid-state NMR measurements of 13C–27Al distances. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2017; 73:176-183. [DOI: 10.1107/s2053229616017915] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 11/08/2016] [Indexed: 11/11/2022]
Abstract
The metal–organic framework MIL-53(Al) (aluminium terephthalate) exhibits a structural transition between two porous structures with large pore (lp) or narrow pore (np) configurations. This transition, called the breathing effect, is observed upon changes in temperature or external pressure, as well as with the adsorption of guest molecules, such as H2O, within the pores. We show here how these different pore openings can be detected by observing the dephasing of 13C magnetization under 13C–27Al dipolar couplings using Rotational-Echo Saturation-Pulse Double-Resonance (RESPDOR) solid-state NMR experiments with Simultaneous Frequency and Amplitude Modulation (SFAM) recoupling. These double-resonance NMR experiments between 13C and 27Al nuclei, which have close Larmor frequencies, are feasible thanks to the use of a frequency splitter. The experimental SFAM–RESPDOR signal fractions agree well with those simulated from the MIL-53(Al)-lp and -np crystal structures obtained from powder X-ray diffraction analysis. Hence, these 13C–27Al solid-state NMR experiments validate these structures and confirm their rigidity. A similar agreement is reported for the framework ligands in the as-synthesized (as) MIL-53(Al), in which the pores contain free ligands. Furthermore, in this case, 13C–{27Al} SFAM–RESPDOR experiments allow an estimation of the average distance between the free ligands and the 27Al nuclei of the framework.
Collapse
|
55
|
Wang Z, Jiang Y, Lafon O, Trébosc J, Duk Kim K, Stampfl C, Baiker A, Amoureux JP, Huang J. Brønsted acid sites based on penta-coordinated aluminum species. Nat Commun 2016; 7:13820. [PMID: 27976673 PMCID: PMC5172364 DOI: 10.1038/ncomms13820] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 11/03/2016] [Indexed: 01/24/2023] Open
Abstract
Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (AlIV) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (AlV) by 27Al-{1H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-AlIV and -AlV show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of 1H and 27Al sites demonstrates that BAS-AlV co-exists with BAS-AlIV rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.
Collapse
|
56
|
Qi G, Wang Q, Xu J, Trébosc J, Lafon O, Wang C, Amoureux JP, Deng F. Synergic Effect of Active Sites in Zinc-Modified ZSM-5 Zeolites as Revealed by High-Field Solid-State NMR Spectroscopy. Angew Chem Int Ed Engl 2016; 55:15826-15830. [DOI: 10.1002/anie.201608322] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/21/2016] [Indexed: 11/12/2022]
|
57
|
Qi G, Wang Q, Xu J, Trébosc J, Lafon O, Wang C, Amoureux JP, Deng F. Synergic Effect of Active Sites in Zinc-Modified ZSM-5 Zeolites as Revealed by High-Field Solid-State NMR Spectroscopy. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201608322] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
58
|
Bouchevreau B, Martineau C, Mellot-Draznieks C, Dutour J, Tuel A, Suchomel MR, Trébosc J, Lafon O, Amoureux JP, Taulelle F. Corrigendum: An NMR-Driven Crystallography Strategy to Overcome the Computability Limit of Powder Structure Determination: A Layered Aluminophosphate Case. Chemistry 2016; 22:12588. [PMID: 27546180 DOI: 10.1002/chem.201602891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
59
|
Paluch P, Pawlak T, Jeziorna A, Trébosc J, Hou G, Vega AJ, Amoureux JP, Dracinsky M, Polenova T, Potrzebowski MJ. Analysis of local molecular motions of aromatic sidechains in proteins by 2D and 3D fast MAS NMR spectroscopy and quantum mechanical calculations. Phys Chem Chem Phys 2015; 17:28789-801. [PMID: 26451400 PMCID: PMC4890705 DOI: 10.1039/c5cp04475h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report a new multidimensional magic angle spinning NMR methodology, which provides an accurate and detailed probe of molecular motions occurring on timescales of nano- to microseconds, in sidechains of proteins. The approach is based on a 3D CPVC-RFDR correlation experiment recorded under fast MAS conditions (ν(R) = 62 kHz), where (13)C-(1)H CPVC dipolar lineshapes are recorded in a chemical shift resolved manner. The power of the technique is demonstrated in model tripeptide Tyr-(d)Ala-Phe and two nanocrystalline proteins, GB1 and LC8. We demonstrate that, through numerical simulations of dipolar lineshapes of aromatic sidechains, their detailed dynamic profile, i.e., the motional modes, is obtained. In GB1 and LC8 the results unequivocally indicate that a number of aromatic residues are dynamic, and using quantum mechanical calculations, we correlate the molecular motions of aromatic groups to their local environment in the crystal lattice. The approach presented here is general and can be readily extended to other biological systems.
Collapse
|
60
|
Lesot P, Kazimierczuk K, Trébosc J, Amoureux JP, Lafon O. Fast acquisition of multidimensional NMR spectra of solids and mesophases using alternative sampling methods. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:927-939. [PMID: 26332109 DOI: 10.1002/mrc.4290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 06/05/2023]
Abstract
Unique information about the atom-level structure and dynamics of solids and mesophases can be obtained by the use of multidimensional nuclear magnetic resonance (NMR) experiments. Nevertheless, the acquisition of these experiments often requires long acquisition times. We review here alternative sampling methods, which have been proposed to circumvent this issue in the case of solids and mesophases. Compared to the spectra of solutions, those of solids and mesophases present some specificities because they usually display lower signal-to-noise ratios, non-Lorentzian line shapes, lower spectral resolutions and wider spectral widths. We highlight herein the advantages and limitations of these alternative sampling methods. A first route to accelerate the acquisition time of multidimensional NMR spectra consists in the use of sparse sampling schemes, such as truncated, radial or random sampling ones. These sparsely sampled datasets are generally processed by reconstruction methods differing from the Discrete Fourier Transform (DFT). A host of non-DFT methods have been applied for solids and mesophases, including the G-matrix Fourier transform, the linear least-square procedures, the covariance transform, the maximum entropy and the compressed sensing. A second class of alternative sampling consists in departing from the Jeener paradigm for multidimensional NMR experiments. These non-Jeener methods include Hadamard spectroscopy as well as spatial or orientational encoding of the evolution frequencies. The increasing number of high field NMR magnets and the development of techniques to enhance NMR sensitivity will contribute to widen the use of these alternative sampling methods for the study of solids and mesophases in the coming years.
Collapse
|
61
|
Shen M, Trébosc J, Lafon O, Gan Z, Pourpoint F, Hu B, Chen Q, Amoureux JP. Solid-state NMR indirect detection of nuclei experiencing large anisotropic interactions using spinning sideband-selective pulses. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:104-117. [PMID: 26411981 DOI: 10.1016/j.ssnmr.2015.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/04/2015] [Accepted: 09/04/2015] [Indexed: 06/05/2023]
Abstract
Under Magic-Angle Spinning (MAS), a long radio-frequency (rf) pulse applied on resonance achieves the selective excitation of the center-band of a wide NMR spectrum. We show herein that these rf pulses can be applied on the indirect channel of Hetero-nuclear Multiple-Quantum Correlation (HMQC) sequences, which facilitate the indirect detection via spin-1/2 isotopes of nuclei exhibiting wide spectra. Numerical simulations show that this indirect excitation method is applicable to spin-1/2 nuclei experiencing a large chemical shift anisotropy, as well as to spin-1 isotopes subject to a large quadrupole interaction, such as (14)N. The performances of the long pulses are analyzed by the numerical simulations of scalar-mediated HMQC (J-HMQC) experiments indirectly detecting spin-1/2 or spin-1 nuclei, as well as by dipolar-mediated HMQC (D-HMQC) experiments achieving indirect detection of (14)N nuclei via (1)H in crystalline γ-glycine and N-acetyl-valine samples at a MAS frequency of 60kHz. We show on these solids that for the acquisition of D-HMQC spectra between (1)H and (14)N nuclei, the efficiency of selective moderate excitation with long-pulses at the (14)N Larmor frequency, ν0((14)N), is comparable to those with strong excitation pulses at ν0((14)N) or 2ν0((14)N) frequencies, given the rf field delivered by common solid-state NMR probes. Furthermore, the D-HMQC experiments also demonstrate that the use of long pulses does not produce significant spectral distortions along the (14)N dimension. In summary, the use of center-band selective weak pulses is advantageous for HMQC experiments achieving the indirect detection of wide spectra since it (i) requires a moderate rf field, (ii) can be easily optimized, (iii) displays a high robustness to CSAs, offsets, rf-field inhomogeneities, and fluctuations in MAS frequency, and (iv) is little dependent on the quadrupolar coupling constant.
Collapse
|
62
|
Shen M, Trébosc J, O'Dell LA, Lafon O, Pourpoint F, Hu B, Chen Q, Amoureux JP. Comparison of various NMR methods for the indirect detection of nitrogen-14 nuclei via protons in solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 258:86-95. [PMID: 26232366 DOI: 10.1016/j.jmr.2015.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 06/11/2015] [Accepted: 06/18/2015] [Indexed: 06/04/2023]
Abstract
We present an experimental comparison of several through-space Hetero-nuclear Multiple-Quantum Correlation experiments, which allow the indirect observation of homo-nuclear single- (SQ) or double-quantum (DQ) (14)N coherences via spy (1)H nuclei. These (1)H-{(14)N} D-HMQC sequences differ not only by the order of (14)N coherences evolving during the indirect evolution, t1, but also by the radio-frequency (rf) scheme used to excite and reconvert these coherences under Magic-Angle Spinning (MAS). Here, the SQ coherences are created by the application of center-band frequency-selective pulses, i.e. long and low-power rectangular pulses at the (14)N Larmor frequency, ν0((14)N), whereas the DQ coherences are excited and reconverted using rf irradiation either at ν0((14)N) or at the (14)N overtone frequency, 2ν0((14)N). The overtone excitation is achieved either by constant frequency rectangular pulses or by frequency-swept pulses, specifically Wide-band, Uniform-Rate, and Smooth-Truncation (WURST) pulse shapes. The present article compares the performances of four different (1)H-{(14)N} D-HMQC sequences, including those with (14)N rectangular pulses at ν0((14)N) for the indirect detection of homo-nuclear (i) (14)N SQ or (ii) DQ coherences, as well as their overtone variants using (iii) rectangular or (iv) WURST pulses. The compared properties include: (i) the sensitivity, (ii) the spectral resolution in the (14)N dimension, (iii) the rf requirements (power and pulse length), as well as the robustness to (iv) rf offset and (v) MAS frequency instabilities. Such experimental comparisons are carried out for γ-glycine and l-histidine.HCl monohydrate, which contain (14)N sites subject to moderate quadrupole interactions. We demonstrate that the optimum choice of the (1)H-{(14)N} D-HMQC method depends on the experimental goal. When the sensitivity and/or the robustness to offset are the major concerns, the D-HMQC sequence allowing the indirect detection of (14)N SQ coherences should be employed. Conversely, when the highest resolution and/or adjusted indirect spectral width are needed, overtone experiments are the method of choice. The overtone scheme using WURST pulses results in broader excitation bandwidths than that using rectangular pulses, at the expense of reduced sensitivity. Numerically exact simulations also show that the sensitivity of the overtone (1)H-{(14)N} D-HMQC experiment increases for larger quadrupole interactions.
Collapse
|
63
|
Nguyen TT, Jung J, Trivelli X, Trébosc J, Cordier S, Molard Y, Le Pollès L, Pickard CJ, Cuny J, Gautier R. Evaluation of 95Mo Nuclear Shielding and Chemical Shift of [Mo6X14]2– Clusters in the Liquid Phase. Inorg Chem 2015. [DOI: 10.1021/acs.inorgchem.5b00396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
64
|
Pourpoint F, Yehl J, Li M, Gupta R, Trébosc J, Lafon O, Amoureux JP, Polenova T. Back Cover: NMR Crystallography of an Oxovanadium(V) Complex by an Approach Combining Multinuclear Magic Angle Spinning NMR, DFT, and Spin Dynamics Simulations (ChemPhysChem 8/2015). Chemphyschem 2015. [DOI: 10.1002/cphc.201590045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
65
|
Benito Q, Le Goff XF, Nocton G, Fargues A, Garcia A, Berhault A, Kahlal S, Saillard JY, Martineau C, Trébosc J, Gacoin T, Boilot JP, Perruchas S. Geometry Flexibility of Copper Iodide Clusters: Variability in Luminescence Thermochromism. Inorg Chem 2015; 54:4483-94. [DOI: 10.1021/acs.inorgchem.5b00321] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
66
|
Pourpoint F, Yehl J, Li M, Gupta R, Trébosc J, Lafon O, Amoureux JP, Polenova T. NMR Crystallography of an Oxovanadium(V) Complex by an Approach Combining Multinuclear Magic Angle Spinning NMR, DFT, and Spin Dynamics Simulations. Chemphyschem 2015; 16:1619-26. [DOI: 10.1002/cphc.201500033] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Indexed: 11/08/2022]
|
67
|
Wang Q, Li Y, Trébosc J, Lafon O, Xu J, Hu B, Feng N, Chen Q, Amoureux JP, Deng F. Population transfer HMQC for half-integer quadrupolar nuclei. J Chem Phys 2015; 142:094201. [DOI: 10.1063/1.4913683] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
68
|
Paluch P, Trébosc J, Nishiyama Y, Potrzebowski MJ, Malon M, Amoureux JP. Theoretical study of CP-VC: a simple, robust and accurate MAS NMR method for analysis of dipolar C-H interactions under rotation speeds faster than ca. 60 kHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:67-77. [PMID: 25662360 DOI: 10.1016/j.jmr.2015.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 12/24/2014] [Accepted: 01/05/2015] [Indexed: 06/04/2023]
Abstract
We show that Cross-Polarization with Variable Contact-time (CP-VC) allows an accurate determination of C-H dipolar interactions, which permits an easy detailed analysis of bond lengths and local dynamics, e.g. in biomolecules. The method presents a large dipolar scaling factor of 1/√2, leading to a better determination of dipolar interactions, especially for long C-H distances, and it allows the observation of very small local details such as those related either to CH(2) three spin systems, or even to hydrogen bonds. CP-VC is very simple to set up and very robust with respect to most experimental parameters, such as: rf-offsets, chemical-shift anisotropies, imperfect Hartmann-Hahn setting, and rf-inhomogeneity. The only required condition is the use of a sufficiently fast MAS spinning speed of at least ca. 60 kHz.
Collapse
|
69
|
Li S, Trébosc J, Lafon O, Zhou L, Shen M, Pourpoint F, Amoureux JP, Deng F. Observation of 1H-13C and 1H-1H proximities in a paramagnetic solid by NMR at high magnetic field under ultra-fast MAS. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 251:36-42. [PMID: 25557861 DOI: 10.1016/j.jmr.2014.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/28/2014] [Accepted: 11/30/2014] [Indexed: 06/04/2023]
Abstract
The assignment of NMR signals in paramagnetic solids is often challenging since: (i) the large paramagnetic shifts often mask the diamagnetic shifts specific to the local chemical environment, and (ii) the hyperfine interactions with unpaired electrons broaden the NMR spectra and decrease the coherence lifetime, thus reducing the efficiency of usual homo- and hetero-nuclear NMR correlation experiments. Here we show that the assignment of (1)H and (13)C signals in isotopically unmodified paramagnetic compounds with moderate hyperfine interactions can be facilitated by the use of two two-dimensional (2D) experiments: (i) (1)H-(13)C correlations with (1)H detection and (ii) (1)H-(1)H double-quantum↔single-quantum correlations. These methods are experimentally demonstrated on isotopically unmodified copper (II) complex of l-alanine at high magnetic field (18.8 T) and ultra-fast Magic Angle Spinning (MAS) frequency of 62.5 kHz. Compared to (13)C detection, we show that (1)H detection leads to a 3-fold enhancement in sensitivity for (1)H-(13)C 2D correlation experiments. By combining (1)H-(13)C and (1)H-(1)H 2D correlation experiments with the analysis of (13)C longitudinal relaxation times, we have been able to assign the (1)H and (13)C signals of each l-alanine ligand.
Collapse
|
70
|
Li S, Pourpoint F, Trébosc J, Zhou L, Lafon O, Shen M, Zheng A, Wang Q, Amoureux JP, Deng F. Host-Guest Interactions in Dealuminated HY Zeolite Probed by (13)C-(27)Al Solid-State NMR Spectroscopy. J Phys Chem Lett 2014; 5:3068-72. [PMID: 26278262 DOI: 10.1021/jz501389z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Host-guest interactions in dealuminated HY zeolite have been investigated by advanced (13)C-(27)Al solid-state NMR experiments. This analysis allows us to report new insights into the adsorption geometry of acetone and its interaction with acid sites in the zeolite channels.
Collapse
|
71
|
O’Keefe CA, Johnston KE, Sutter K, Autschbach J, Gauvin R, Trébosc J, Delevoye L, Popoff N, Taoufik M, Oudatchin K, Schurko RW. An Investigation of Chlorine Ligands in Transition-Metal Complexes via 35Cl Solid-State NMR and Density Functional Theory Calculations. Inorg Chem 2014; 53:9581-97. [DOI: 10.1021/ic501004u] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
72
|
Shen M, Trébosc J, Lafon O, Pourpoint F, Hu B, Chen Q, Amoureux JP. Improving the resolution in proton-detected through-space heteronuclear multiple quantum correlation NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 245:38-49. [PMID: 24929867 DOI: 10.1016/j.jmr.2014.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 06/03/2023]
Abstract
Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong (1)H-(1)H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t1 evolution period of dipolar-mediated HMQC (D-HMQC) experiment. We demonstrate that (1)H-(1)H dipolar decoupling sequences during t1, such as symmetry-based schemes, phase-modulated Lee-Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave (1)H irradiation. We also report that high resolution requires the preservation of (1)H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D-HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t1 period. Moreover, we show that (1)H-(1)H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t1-noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D (1)H-{(13)C} D-HMQC experiments on [U-(13)C]-L-histidine⋅HCl⋅H2O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t1 period enable the detection of heteronuclear correlation between aliphatic protons and ammonium (14)N sites in L-histidine⋅HCl⋅H2O.
Collapse
|
73
|
Taoufik M, Szeto KC, Merle N, Rosal ID, Maron L, Trébosc J, Tricot G, Gauvin RM, Delevoye L. Cover Picture: Heteronuclear NMR Spectroscopy as a Surface-Selective Technique: A Unique Look at the Hydroxyl Groups of γ-Alumina. (Chem. Eur. J. 14/2014). Chemistry 2014. [DOI: 10.1002/chem.201490054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
74
|
Taoufik M, Szeto KC, Merle N, Rosal ID, Maron L, Trébosc J, Tricot G, Gauvin RM, Delevoye L. Heteronuclear NMR Spectroscopy as Surface-Selective Technique: A Unique Look at the Hydroxyl Groups of γ-Alumina. Chemistry 2014. [DOI: 10.1002/chem.201400425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
75
|
Taoufik M, Szeto KC, Merle N, Rosal ID, Maron L, Trébosc J, Tricot G, Gauvin RM, Delevoye L. Heteronuclear NMR Spectroscopy as a Surface-Selective Technique: A Unique Look at the Hydroxyl Groups of γ-Alumina. Chemistry 2014; 20:4038-46. [DOI: 10.1002/chem.201304883] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Indexed: 11/12/2022]
|