51
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Robertson AJ, Pandey MK, Marsh A, Nishiyama Y, Brown SP. The use of a selective saturation pulse to suppress t1 noise in two-dimensional (1)H fast magic angle spinning solid-state NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 260:89-97. [PMID: 26432398 DOI: 10.1016/j.jmr.2015.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 09/01/2015] [Accepted: 09/07/2015] [Indexed: 06/05/2023]
Abstract
A selective saturation pulse at fast magic angle spinning (MAS) frequencies (60+kHz) suppresses t1 noise in the indirect dimension of two-dimensional (1)H MAS NMR spectra. The method is applied to a synthetic nucleoside with an intense methyl (1)H signal due to triisopropylsilyl (TIPS) protecting groups. Enhanced performance in terms of suppressing the methyl signal while minimising the loss of signal intensity of nearby resonances of interest relies on reducing spin diffusion--this is quantified by comparing two-dimensional (1)H NOESY-like spin diffusion spectra recorded at 30-70 kHz MAS. For a saturation pulse centred at the methyl resonance, the effect of changing the nutation frequency at different MAS frequencies as well as the effect of changing the pulse duration is investigated. By applying a pulse of duration 30 ms and nutation frequency 725 Hz at 70 kHz MAS, a good compromise of significant suppression of the methyl resonance combined with the signal intensity of resonances greater than 5 ppm away from the methyl resonance being largely unaffected is achieved. The effectiveness of using a selective saturation pulse is demonstrated for both homonuclear (1)H-(1)H double quantum (DQ)/single quantum (SQ) MAS and (14)N-(1)H heteronuclear multiple quantum coherence (HMQC) two-dimensional solid-state NMR experiments.
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Affiliation(s)
- Aiden J Robertson
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom; Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Manoj Kumar Pandey
- RIKEN CLST-JEOL Collaboration Centre, Yokohama, Kanagawa 230-0045, Japan
| | - Andrew Marsh
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Yusuke Nishiyama
- RIKEN CLST-JEOL Collaboration Centre, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan
| | - Steven P Brown
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
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52
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Pandey MK, Nishiyama Y. Determination of relative orientation between (1)H CSA tensors from a 3D solid-state NMR experiment mediated through (1)H/(1)H RFDR mixing under ultrafast MAS. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 70:15-20. [PMID: 26065628 DOI: 10.1016/j.ssnmr.2015.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/14/2015] [Accepted: 05/07/2015] [Indexed: 06/04/2023]
Abstract
To obtain piercing insights into inter and intramolecular H-bonding, and π-electron interactions measurement of (1)H chemical shift anisotropy (CSA) tensors is gradually becoming an obvious choice. While the magnitude of CSA tensors provides unique information about the local electronic environment surrounding the nucleus, the relative orientation between these tensors can offer further insights into the spatial arrangement of interacting nuclei in their respective three-dimensional (3D) space. In this regard, we present a 3D anisotropic/anisotropic/isotropic proton chemical shift (CSA/CSA/CS) correlation experiment mediated through (1)H/(1)H radio frequency-driven recoupling (RFDR) which enhances spin diffusion through recoupled (1)H-(1)H dipolar couplings under ultrafast magic angle spinning (MAS) frequency (70kHz). Relative orientation between two interacting 1H CSA tensors is obtained by fitting two-interacting (1)H CSA tensors by fitting two-dimensional (2D) (1)H/(1)H CSA/CSA spectral slices through extensive numerical simulations. To recouple (1)H CSAs in the indirect frequency dimensions of a 3D experiment we have employed γ-encoded radio frequency (RF) pulse sequence based on R-symmetry (R188(7)) with a series of phase-alternated 2700(°)-90180(°) composite-180° pulses on citric acid sample. Due to robustness of applied (1)H CSA recoupling sequence towards the presence of RF field inhomogeneity, we have successfully achieved an excellent (1)H/(1)H CSA/CSA cross-correlation efficiency between H-bonded sites of citric acid.
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Affiliation(s)
- Manoj Kumar Pandey
- RIKEN CLST-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan
| | - Yusuke Nishiyama
- RIKEN CLST-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan.
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53
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Lüdeker D, Brunklaus G. NMR crystallography of ezetimibe co-crystals. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 65:29-40. [PMID: 25541425 DOI: 10.1016/j.ssnmr.2014.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/06/2014] [Accepted: 11/18/2014] [Indexed: 06/04/2023]
Abstract
An efficient, simplified protocol for solvent-drop assisted co-crystal preparation of ezetimibe (a drug for the treatment of primary hypercholesterolemia) with both imidazole and l-proline has been derived. The structures of the white powders were successfully solved via "NMR crystallography" combining solid-state NMR, powder X-ray diffraction and DFT chemical shift computations. Detailed insights into the likely crystallization mechanism were obtained from competition experiments, where efficient co-crystallization was feasible using ezetimibe monohydrate as precursor indicating that the crystal water acts as "molecular catalyst". It was also found that co-crystallization of imidazole is favored over l-proline, thus suggesting a clear preference of neutral hydrogen bonds compared to charge-assisted motifs.
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Affiliation(s)
- David Lüdeker
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 28, D-48149 Münster, Germany
| | - Gunther Brunklaus
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 28, D-48149 Münster, Germany.
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54
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Paudel A, Geppi M, Mooter GVD. Structural and Dynamic Properties of Amorphous Solid Dispersions: The Role of Solid-State Nuclear Magnetic Resonance Spectroscopy and Relaxometry. J Pharm Sci 2014; 103:2635-2662. [DOI: 10.1002/jps.23966] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/17/2014] [Accepted: 03/17/2014] [Indexed: 01/17/2023]
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55
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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.
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Affiliation(s)
- Ming Shen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - J Trébosc
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - O Lafon
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - F Pourpoint
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - Bingwen Hu
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Qun Chen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - J-P Amoureux
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France.
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56
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New Thermoresistant Polymorph from CO2 Recrystallization of Minocycline Hydrochloride. Pharm Res 2014; 31:3136-49. [DOI: 10.1007/s11095-014-1406-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 04/28/2014] [Indexed: 11/25/2022]
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57
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Rossini AJ, Widdifield CM, Zagdoun A, Lelli M, Schwarzwälder M, Copéret C, Lesage A, Emsley L. Dynamic nuclear polarization enhanced NMR spectroscopy for pharmaceutical formulations. J Am Chem Soc 2014; 136:2324-34. [PMID: 24410528 DOI: 10.1021/ja4092038] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Dynamic nuclear polarization (DNP) enhanced solid-state NMR spectroscopy at 9.4 T is demonstrated for the detailed atomic-level characterization of commercial pharmaceutical formulations. To enable DNP experiments without major modifications of the formulations, the gently ground tablets are impregnated with solutions of biradical polarizing agents. The organic liquid used for impregnation (here 1,1,2,2-tetrachloroethane) is chosen so that the active pharmaceutical ingredient (API) is minimally perturbed. DNP enhancements (ε) of between 40 and 90 at 105 K were obtained for the microparticulate API within four different commercial formulations of the over-the-counter antihistamine drug cetirizine dihydrochloride. The different formulations contain between 4.8 and 8.7 wt % API. DNP enables the rapid acquisition with natural isotopic abundances of one- and two-dimensional (13)C and (15)N solid-state NMR spectra of the formulations while preserving the microstructure of the API particles. Here this allowed immediate identification of the amorphous form of the API in the tablet. API-excipient interactions were observed in high-sensitivity (1)H-(15)N correlation spectra, revealing direct contacts between povidone and the API. The API domain sizes within the formulations were determined by measuring the variation of ε as a function of the polarization time and numerically modeling nuclear spin diffusion. Here we measure an API particle radius of 0.3 μm with a single particle model, while modeling with a Weibull distribution of particle sizes suggests most particles possess radii of around 0.07 μm.
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Affiliation(s)
- Aaron J Rossini
- Centre de RMN à Trés Hauts Champs, Institut de Sciences Analytiques, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) , 69100 Villeurbanne, France
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58
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Lu X, Trébosc J, Lafon O, Carnevale D, Ulzega S, Bodenhausen G, Amoureux JP. Broadband excitation in solid-state NMR using interleaved DANTE pulse trains with N pulses per rotor period. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 236:105-116. [PMID: 24095842 DOI: 10.1016/j.jmr.2013.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/06/2013] [Accepted: 09/08/2013] [Indexed: 06/02/2023]
Abstract
We analyze the direct excitation of wide one-dimensional spectra of nuclei with spin I=1/2 or 1 in rotating solids submitted to pulse trains in the manner of Delays Alternating with Nutations for Tailored Excitation (DANTE), either with one short rotor-synchronized pulse of duration τp in each of K rotor periods (D1(K)) or with N interleaved equally spaced pulses τp in each rotor period, globally also extending over K rotor periods (D(N)(K)). The excitation profile of D(N)(K) scheme is a comb of rf-spikelets with Nν(R)=N/T(R) spacing from the carrier frequency, and a width of each spikelet inversely proportional to the length, KT(R), of D(N)(K) scheme. Since the individual pulse lengths, τp, are typically of a few hundreds of ns, D(N)(K) scheme can readily excite spinning sidebands families covering several MHz, provided the rf carrier frequency is close enough to the resonance frequency of one the spinning sidebands. If the difference of isotropic chemical shifts between distinct chemical sites is less than about 1.35/(KT(R)), D(N)(K) scheme can excite the spinning sidebands families of several sites. For nuclei with I=1/2, if the homogeneous and inhomogeneous decays of coherences during the DANTE sequence are neglected, the K pulses of a D1(K) train have a linearly cumulative effect, so that the total nutation angle is θ(tot)=K2πν1τp, where ν1 is the rf-field amplitude. This allows obtaining nearly ideal 90° pulses for excitation or 180° rotations for inversion and refocusing across wide MAS spectra comprising many spinning sidebands. If one uses interleaved DANTE trains D(N)(K) with N>1, only spinning sidebands separated by intervals of Nν(R) with respect to the carrier frequency are observed as if the effective spinning speed was Nν(R). The other sidebands have vanishing intensities because of the cancellation of the N contributions with opposite signs. However, the intensities of the remaining sidebands obey the same rules as in spectra obtained with νR. With increasing N, the intensities of the non-vanishing sidebands increase, but the total intensity integrated over all sidebands decreases. Furthermore, the NK pulses in a D(N)(K) train do not have a simple cumulative effect and the optimal cumulated flip angle for optimal excitation, θ(tot)(opt)=NK2πν1τp, exceeds 90°. Such D(N)(K) pulse trains allow achieving efficient broadband excitation, but they are not recommended for broadband inversion or refocusing as they cannot provide proper 180° rotations. Since D(N)(K) pulse trains with N>1 are shorter than basic D1(K) sequences, they are useful for broadband excitation in samples with rapid homogeneous or inhomogeneous decay. For nuclei with I=1 (e.g., for (14)N), the response to basic D1(K) pulse train is moreover affected by inhomogeneous decay due to 2nd-order quadrupole interactions, since these are not of rank 2 and therefore cannot be eliminated by spinning about the magic angle. For large quadrupole interactions, the signal decay produced by second-order quadrupole interaction can be minimized by (i) reducing the length of D(N)(K) pulse trains using N>1, (ii) fast spinning, (iii) large rf-field, and (iv) using high magnetic fields to reduce the 2nd-order quadrupole interaction.
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Affiliation(s)
- Xingyu Lu
- Unit of Catalysis and Chemistry of Solids (UCCS), UMR 8181 CNRS, Lille North of France University, 59652 Villeneuve d'Ascq, France
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59
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Czernek J, Brus J. Theoretical predictions of the two-dimensional solid-state NMR spectra: A case study of the 13C–1H correlations in metergoline. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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60
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Kong X, Shan M, Terskikh V, Hung I, Gan Z, Wu G. Solid-State 17O NMR of Pharmaceutical Compounds: Salicylic Acid and Aspirin. J Phys Chem B 2013; 117:9643-54. [DOI: 10.1021/jp405233f] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xianqi Kong
- Department
of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, K7L 3N6, Canada
| | - Melissa Shan
- Department
of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, K7L 3N6, Canada
| | - Victor Terskikh
- Department
of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, K7L 3N6, Canada
- National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario, K1A
0R6, Canada
| | - Ivan Hung
- Center of Interdisciplinary
Magnetic
Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United
States
| | - Zhehong Gan
- Center of Interdisciplinary
Magnetic
Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United
States
| | - Gang Wu
- Department
of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, K7L 3N6, Canada
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61
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Vogt FG, Yin H, Forcino RG, Wu L. 17O Solid-State NMR as a Sensitive Probe of Hydrogen Bonding in Crystalline and Amorphous Solid Forms of Diflunisal. Mol Pharm 2013; 10:3433-46. [DOI: 10.1021/mp400275w] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Frederick G. Vogt
- Product Development, GlaxoSmithKline plc, 709 Swedeland Rd., King of Prussia,
Pennsylvania 19406, United
States
| | - Hao Yin
- Product Development, GlaxoSmithKline plc, 709 Swedeland Rd., King of Prussia,
Pennsylvania 19406, United
States
| | - Rachel G. Forcino
- Product Development, GlaxoSmithKline plc, 709 Swedeland Rd., King of Prussia,
Pennsylvania 19406, United
States
| | - Lianming Wu
- Product Development, GlaxoSmithKline plc, 709 Swedeland Rd., King of Prussia,
Pennsylvania 19406, United
States
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62
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Tatton AS, Pham TN, Vogt FG, Iuga D, Edwards AJ, Brown SP. Probing Hydrogen Bonding in Cocrystals and Amorphous Dispersions Using 14N–1H HMQC Solid-State NMR. Mol Pharm 2013; 10:999-1007. [DOI: 10.1021/mp300423r] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew S. Tatton
- Department
of Physics, University of Warwick, Coventry
CV4 7AL, United Kingdom
| | - Tran N. Pham
- GlaxoSmithKline plc, Product Development, Gunnels Wood Road, Stevenage
SG1 2NY, United Kingdom
| | - Frederick G. Vogt
- GlaxoSmithKline plc, Product Development, 709 Swedeland
Road, King of Prussia, Pennsylvania
19406, United States
| | - Dinu Iuga
- Department
of Physics, University of Warwick, Coventry
CV4 7AL, United Kingdom
| | - Andrew J. Edwards
- GlaxoSmithKline plc, Product Development, Gunnels Wood Road, Stevenage
SG1 2NY, United Kingdom
| | - Steven P. Brown
- Department
of Physics, University of Warwick, Coventry
CV4 7AL, United Kingdom
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63
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O'Dell LA, He R, Pandohee J. Identifying H–N proximities in solid-state NMR using 14N overtone irradiation under fast MAS. CrystEngComm 2013. [DOI: 10.1039/c3ce40967h] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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64
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Rossini AJ, Zagdoun A, Hegner F, Schwarzwälder M, Gajan D, Copéret C, Lesage A, Emsley L. Dynamic nuclear polarization NMR spectroscopy of microcrystalline solids. J Am Chem Soc 2012; 134:16899-908. [PMID: 22967206 DOI: 10.1021/ja308135r] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dynamic nuclear polarization (DNP) solid-state NMR has been applied to powdered microcrystalline solids to obtain sensitivity enhancements on the order of 100. Glucose, sulfathiazole, and paracetamol were impregnated with bis-nitroxide biradical (bis-cyclohexyl-TEMPO-bisketal, bCTbK) solutions of organic solvents. The organic solvents were carefully chosen to be nonsolvents for the compounds, so that DNP-enhanced solid-state NMR spectra of the unaltered solids could be acquired. A theoretical model is presented that illustrates that for externally doped organic solids characterized by long spin-lattice relaxation times (T(1)((1)H) > 200 s), (1)H-(1)H spin diffusion can relay enhanced polarization over micrometer length scales yielding substantial DNP enhancements (ε). ε on the order of 60 are obtained for microcrystalline glucose and sulfathiazole at 9.4 T and with temperatures of ca. 105 K. The large gain in sensitivity enables the rapid acquisition of (13)C-(13)C correlation spectra at natural isotopic abundance. It is anticipated that this will be a general method for enhancing the sensitivity of solid-state NMR experiments of organic solids.
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Affiliation(s)
- Aaron J Rossini
- Centre de RMN a Tres Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
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65
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Mao K, Kennedy GJ, Althaus SM, Pruski M. Spectral editing in 13C solid-state NMR at high magnetic field using fast MAS and spin-echo dephasing. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2012; 47-48:19-22. [PMID: 22951436 DOI: 10.1016/j.ssnmr.2012.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 06/01/2023]
Abstract
A simple method is proposed for separating NMR resonances from protonated and non-protonated aromatic carbons in solids under fast magic angle spinning (MAS). The approach uses a MAS-synchronized spin-echo to exploit the differences in rotational recoupling of the dipolar interactions while fully refocusing the isotropic chemical shifts. This strategy extends the relevant time scale of spin evolution to milliseconds and circumvents the limitation of the traditional dipolar dephasing method, which in fast rotating solids is disrupted by rotational refocusing. The proposed approach can be used for quantitative measurement of carbon aromaticities in complex solids with poorly resolved spectra, as demonstrated for model compounds.
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Affiliation(s)
- Kanmi Mao
- ExxonMobil Research and Engineering Co., 1545 Route 22E, Annandale, NJ 08801, USA.
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66
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Tatton AS, Bradley JP, Iuga D, Brown SP. 14N–1H Heteronuclear Multiple-Quantum Correlation Magic-Angle Spinning NMR Spectroscopy of Organic Solids. ACTA ACUST UNITED AC 2012. [DOI: 10.1524/zpch.2012.0308] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
14N–1H heteronuclear multiple-quantum correlation (HMQC) solid-state magic-angle spinning (MAS) NMR spectra recorded at a 1H Larmor frequency of 850 MHz are presented for the dipeptide β-AspAla. A modified version of the pulse sequence presented by Gan et al. (Chem. Phys. Lett. 435 (2007) 163) that utilises rotary resonance recoupling (R3) at the n = 2 condition (ν
1 = 2ν
R
) is employed. Spectra recorded with a short recoupling period (under 200 μs) show two correlation peaks corresponding to the NH and NH3 moieties in the dipeptide. The quadrupolar product, P
Q = C
Q √ [1 + (η
Q
2/3)], is determined experimentally as 3.1 MHz (NH) and 1.0 MHz (NH3) by a comparison of the 14N and 15N isotropic chemical shifts which differ due to the isotropic second-order quadrupolar shift for the spin I = 1 14N nucleus. It is shown that the peak sensitivities increase markedly upon increasing the MAS frequency from 30 to 45 to 60 kHz due to a combination of the reduced residual dipolar broadening of the 1H resonances and a lengthening of the coherence lifetimes under R
3
recoupling. Increasing the recoupling period leads to the observation of additional peaks corresponding to longer range intra- and intermolecular NH proximities. Reasonable agreement is evident upon comparing the experimental build-up of correlation peak intensity to that observed for eight-spin density-matrix simulations.
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Affiliation(s)
- Andrew S. Tatton
- University of Warwick, Department of Physics, Coventry, CV4 7AL, Großbritannien
| | - Jonathan P. Bradley
- University of Warwick, Department of Physics, Coventry, CV4 7AL, Großbritannien
| | - Dinu Iuga
- University of Warwick, Department of Physics, Coventry, CV4 7AL, Großbritannien
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67
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Sardo M, Siegel R, Santos SM, Rocha J, Gomes JRB, Mafra L. Combining Multinuclear High-Resolution Solid-State MAS NMR and Computational Methods for Resonance Assignment of Glutathione Tripeptide. J Phys Chem A 2012; 116:6711-9. [DOI: 10.1021/jp302128r] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Mariana Sardo
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
| | - Renée Siegel
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
| | - Sérgio M. Santos
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
| | - João Rocha
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
| | - José R. B. Gomes
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
| | - Luis Mafra
- Department of Chemistry, CICECO, University of Aveiro, P-3810-193 Aveiro, Portugal
- Departamentos de
Química Física y Analítica y Química Orgánica
e Inorgánica, Universidad de Oviedo, 33006 Oviedo, Spain
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Maruyoshi K, Iuga D, Antzutkin ON, Alhalaweh A, Velaga SP, Brown SP. Identifying the intermolecular hydrogen-bonding supramolecular synthons in an indomethacin–nicotinamide cocrystal by solid-state NMR. Chem Commun (Camb) 2012; 48:10844-6. [DOI: 10.1039/c2cc36094b] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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