Jean-Paul Amoureux

East China Normal University, Shanghai, Shanghai Shi, China

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Publications (77)262.7 Total impact

  • Yi Qian, Ming Shen, Jean-Paul Amoureux, Isao Noda, Bingwen Hu
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    ABSTRACT: The dependence of SNR on number-of-scans relationship in COV2D is analyzed for the first time, and we found SNRcov∝n/2 while SNRFT∝n.
    Solid State Nuclear Magnetic Resonance 01/2014; · 2.10 Impact Factor
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    ABSTRACT: We show how (27)Al-(13)C proximities in the microporous metal-organic framework MIL-100(Al) can be probed using advanced (27)Al-(13)C NMR methods boosted by Dynamic Nuclear Polarization.
    Chemical Communications 12/2013; · 6.38 Impact Factor
  • Source
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    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 (DN(K)). The excitation profile of DN(K) scheme is a comb of rf-spikelets with NνR=N/TR spacing from the carrier frequency, and a width of each spikelet inversely proportional to the length, KTR, of DN(K) scheme. Since the individual pulse lengths, τp, are typically of a few hundreds of ns, DN(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/(KTR), DN(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 θtot=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 DN(K) with N>1, only spinning sidebands separated by intervals of NνR with respect to the carrier frequency are observed as if the effective spinning speed was NνR. 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 DN(K) train do not have a simple cumulative effect and the optimal cumulated flip angle for optimal excitation, θtot(opt)=NK2πν1τp, exceeds 90°. Such DN(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 DN(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 DN(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.
    Journal of Magnetic Resonance 09/2013; 236C:105-116. · 2.30 Impact Factor
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    ABSTRACT: Advanced multinuclear solid state NMR experiments were developed to probe the structure of two organometallic aluminum derivatives, Li[Al(CH3)3CH2Si(CH3)3] (1) and Li[Al(CH3)4] (2), which are relevant to olefin polymerization processes. For the first time, NMR observation of 27Al–13C covalent bonds in solids is performed with the natural abundance material 1. Unprecedented triple-resonance (1H–13C–27Al) and quadruple-resonance (1H–7Li–13C–27Al) heteronuclear correlation two-dimensional NMR experiments are also introduced to probe 27Al–13C and 13C–7Li proximities for 2. High-resolution solid-state NMR spectra thus obtained provide information on the local structure of these representative organometallic derivatives that proved to be most complementary and in full agreement with the structures obtained by X-ray diffraction.
    The Journal of Physical Chemistry C. 08/2013; 117(35):18091–18099.
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    ABSTRACT: A series of transition-metal organometallic complexes with commonly occurring metalchlorine bonding motifs were characterized using (35) Cl solid-state NMR (SSNMR) spectroscopy, (35) Cl nuclear quadrupole resonance (NQR) spectroscopy, and first-principles density functional theory (DFT) calculations of NMR interaction tensors. Static (35) Cl ultra-wideline NMR spectra were acquired in a piecewise manner at standard (9.4 T) and high (21.1 T) magnetic field strengths using the WURST-QCPMG pulse sequence. The (35) Cl electric field gradient (EFG) and chemical shielding (CS) tensor parameters were readily extracted from analytical simulations of the spectra; in particular, the quadrupolar parameters are shown to be very sensitive to structural differences, and can easily differentiate between chlorine atoms in bridging and terminal bonding environments. (35) Cl NQR spectra were acquired for many of the complexes, which aided in resolving structurally similar, yet crystallographically distinct and magnetically inequivalent chlorine sites, and with the interpretation and assignment of (35) Cl SSNMR spectra. (35) Cl EFG tensors obtained from first-principles DFT calculations are consistently in good agreement with experiment, highlighting the importance of using a combined approach of theoretical and experimental methods for structural characterization. Finally, a preliminary example of a (35) Cl SSNMR spectrum of a transition-metal species (TiCl4 ) diluted and supported on non-porous silica is presented. The combination of (35) Cl SSNMR and (35) Cl NQR spectroscopy and DFT calculations is shown to be a promising and simple methodology for the characterization of all manner of chlorine-containing transition-metal complexes, in pure, impure bulk and supported forms.
    Chemistry 08/2013; · 5.93 Impact Factor
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    ABSTRACT: We explore modulation-sideband recoupling conditions of the (13)C-(13)C Second-order Hamiltonian among Analogous nuclei plus pulse sequence (SHA+), and found that this sequence can be used in two different recoupling regimes. The first regime, νR>Δνiso(max), is recommended for broad-band recoupling to avoid any rotational resonance broadening. In this regime, the spinning speed should be only slightly larger than Δνiso(max), to obtain the best transfer efficiency. The second regime, νR<Δνiso(max), can be used to observe long-range constraints with lower spinning speed, which increases the transfer efficiency, and may allow using bigger rotors to increase the S/N ratio.
    Solid State Nuclear Magnetic Resonance 08/2013; · 2.10 Impact Factor
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    ABSTRACT: We show that for half-integer quadrupolar nuclei, the manipulation of the satellite transitions can accelerate and enhance coherence transfer to other isotopes. This novel strategy is demonstrated to improve the sensitivity of (31)P-{(27)Al} J-HMQC experiments for a layered aluminophosphate Mu-4.
    Chemical Communications 06/2013; · 6.38 Impact Factor
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    ABSTRACT: We demonstrate that a very simple experiment, Cross-Polarization with Variable Contact-time (CP-VC), is very efficient at ultra-fast MAS (νR⩾60kHz) to measure accurately the C-H and N-H distances, and to analyze the dynamics of bio-molecules. This experiment can be performed with samples that are either (13)C or (15)N labeled or without any labeling. The method is very robust experimentally with respect to imperfect Hartman-Hahn setting, and presents a large scaling factor allowing a better dipolar determination, especially for long C-H or N-H distances, or for CH3 or NH3 moieties with three-site hopping. At ultra-fast MAS, it can be used quantitatively in a 2D way, because its scaling factor is then little dependent on the offsets. This robustness with respect to offset is related to the ultra-fast spinning speed, and hence to the related small rotor diameter. Indeed, these two specifications lead to efficient n=±1 zero-quantum Hartman-Hahn CP-transfers with large RF-fields on proton and carbon or nitrogen channels, and large dipolar scaling factor.
    Journal of Magnetic Resonance 05/2013; 233C:56-63. · 2.30 Impact Factor
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    ABSTRACT: We recently described a family of experiments for R2n(v) Driven Spin Diffusion (RDSD) spectroscopy suitable for homonuclear correlation experiments under fast MAS conditions [G. Hou, S. Yan, S.J. Sun, Y. Han, I.J. Byeon, J. Ahn, J. Concel, A. Samoson, A.M. Gronenborn, T. Polenova, Spin diffusion drive by R-symmetry sequencs: applications to homonuclear correlation spectroscopy in MAS NMR of biological and organic solids, J. Am. Chem. Soc. 133 (2011) 3943-3953]. In these RDSD experiments, since the broadened second-order rotational resonance conditions are dominated by the radio frequency field strength and the phase shifts, as well as the size of reintroduced dipolar couplings, the different R2n(v) sequences display unique polarization transfer behaviors and different recoupling frequency bandwidths. Herein, we present a series of modified R2n(v) sequences, dubbed COmbined R2n(v)-Driven (CORD), that yield broadband homonuclear dipolar recoupling and give rise to uniform distribution of cross peak intensities across the entire correlation spectrum. We report NMR experiments and numerical simulations demonstrating that these CORD spin diffusion sequences are suitable for broadband recoupling at a wide range of magnetic fields and MAS frequencies, including fast-MAS conditions (νr=40kHz and above). Since these CORD sequences are largely insensitive to dipolar truncation, they are well suited for the determination of long-range distance constraints, which are indispensable for the structural characterization of a broad range of systems. Using U-(13)C,(15)N-alanine and U-(13)C,(15)N-histidine, we show that under fast-MAS conditions, the CORD sequences display polarization transfer efficiencies within broadband frequency regions that are generally higher than those offered by other existing spin diffusion pulse schemes. A 89-residue U-(13)C,(15)N-dynein light chain (LC8) protein has also been used to demonstrate that the CORD sequences exhibit uniformly high cross peak intensities across the entire chemical shift range.
    Journal of Magnetic Resonance 04/2013; 232C:18-30. · 2.30 Impact Factor
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    ABSTRACT: Just in time: An NMR-driven structure resolution that allows structure determination from the powder diffraction data of a highly complex layered aluminophosphate, and was otherwise not possible despite the high quality of the synchrotron diffraction data, is proposed. This study shows that the strategy is general and allows reduction of the number of free parameters to search for a structure and converge under the limit of the combinatorial explosion of computing time.
    Chemistry 03/2013; · 5.93 Impact Factor
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    ABSTRACT: Two-dimensional covariance (COV2D) spectroscopy offers an alternative approach to 2D Fourier transformation (FT2D) to obtain homo-nuclear correlation NMR spectra. Considerable saving in experimental time, without loss of resolution, can be achieved by incorporating COV2D with: (i) uniform sampling with a t1 cut-off (CUO) or non-uniform sampling (NUS), and (ii) constant or Gaussian accumulation profiles. We find that covariance treatment, combined with the CUO sampling and Gaussian accumulation profile provides better gain in experimental time, with respect to that required with FT2D NMR. This is in contrast with the maximum entropy (MaxEnt) reconstruction for 2D spectra, which works better with the NUS scheme rather than with the CUO scheme. We further discuss the experimental conditions that define this optimum acquisition, and explain how these parameters can easily be optimized 'on the fly' according to the desired resolution, which is quite sample-dependent.
    The Analyst 03/2013; · 4.23 Impact Factor
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    ABSTRACT: We systematically studied the enhancement factor (per scan) and the sensitivity enhancement (per unit time) in 13C and 29Si cross-polarization magic angle spinning (CP-MAS) NMR boosted by dynamic nuclear polarization (DNP) of functionalized mesoporous silica nanoparticles (MSNs). Specifically, we separated contributions due to: (i) microwave irradiation, (ii) quenching by paramagnetic effects, (iii) the presence of frozen solvent, (iv) the temperature, as well as changes in (v) relaxation and (vi) cross-polarization behaviour. No line-broadening effects were observed for MSNs when lowering the temperature from 300 to 100 K. Notwithstanding a significant signal reduction due to quenching by TOTAPOL radicals, DNP-CP-MAS at 100 K provided global sensitivity enhancements of 23 and 45 for 13C and 29Si, respectively, relative to standard CP-MAS measurements at room temperature. The effects of DNP were also ascertained by comparing with state-of-the-art two-dimensional heteronuclear 1H{13C} and 29Si{1H} correlation spectra, using, respectively, indirect detection or Carr-Purcell-Meiboom-Gill (CPMG) refocusing to boost signal acquisition. This study highlights opportunities for further improvements through the development of high-field DNP, better polarizing agents, and improved capabilities for low-temperature MAS.
    Physical Chemistry Chemical Physics 03/2013; · 4.20 Impact Factor
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    ABSTRACT: The origin of the exceptionally high activity of (B, Ag)-codoped TiO2 catalysts under solar-light irradiation has been investigated by XPS and 11B solid-state NMR spectroscopy in conjunction with density functional theory (DFT) calculations. XPS experimental results demonstrated that a portion of the dopant Ag (Ag3+) ions were implanted into the crystalline lattice of (B, Ag)-codoped TiO2 and were in close proximity to the interstitial B (Bint.) sites, forming [Bint.-O-Ag] structural units. In-situ XPS experiments were employed to follow the evolution of the chemical states of the B and Ag dopants during Uv-Vis irradiation. It was found that the [Bint.-O-Ag] units could trap the photoinduced electron to form an unique intermediate structure in the (B, Ag)-codoped TiO2 during the irradiation, which is responsible for the photoinduced shifts of the B 1s and Ag 3d peaks observed in the in-situ XPS spectra. Solid-state NMR experiments including 11B triple-quantum and double-quantum magic angle spinning (MAS) NMR revealed that up to six different boron species were present in the catalysts and only the tri-coordinated interstitial boron (T*) species was in close proximity to the substitutional Ag species, leading to formation of [T*-O-Ag] structural units. Furthermore, as demonstrated by DFT calculations, the [T*-O-Ag] structural units were responsible for trapping the photoinduced electrons, which prolongs the life of the photoinduced charge carriers and eventually leads to a remarkable enhancement in the photocatalytic activity. All these unprecedented findings are expected to be crucial for understanding the roles of B and Ag dopants and their synergy effect in numerous titania-mediated photocatalytic reactions.
    Journal of the American Chemical Society 01/2013; · 10.68 Impact Factor
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    ABSTRACT: We show how the (29)Si NMR signals of dispersed inorganic nanoparticles of laponite® can be enhanced by Dynamic Nuclear Polarization (DNP). The direct DNP enhances the signals of (29)Si nuclei near unpaired electrons, whereas the indirect DNP via(1)H enhances the signals of more remote sites.
    Chemical Communications 01/2013; 49(28):2864-2866. · 6.38 Impact Factor
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    ABSTRACT: We present a novel cross-polarization MAS NMR pulse sequence to probe proximities between half-integer quadrupolar isotopes. This sequence employs a multi-pulse cross-polarization (MP-CP) transfer, instead of the previous continuous-wave CP (CW-CP) transfer. With respect to CW-CP transfers, our sequence is more robust with respect to offsets and Rotary Resonance Recoupling detrimental effects, especially when taking into account rf-inhomogeneity. Moreover, by using a frequency splitter and a single channel MAS probe, this MP-CP sequence may allow analyzing the through-space connectivities between two isotopes with half-integer spin values and close Larmor frequencies.
    Journal of Magnetic Resonance 12/2012; · 2.30 Impact Factor
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    ABSTRACT: This Letter shows that interleaved sequences of short pulses in the manner of ‘Delays Alternating with Nutation for Tailored Excitation’ (DANTE) with N = 1, 2, 3 … equidistant pulses per rotor period extending over K rotor periods can be used to excite, invert or refocus a large number of spinning sidebands of spin-1/2 nuclei in paramagnetic samples where hyperfine couplings lead to very broad spectra that extend over more than 1 MHz. The breadth of the response is maintained for rf-field amplitudes as low as 30 kHz since it results from cumulative effects of individual pulses with very short durations.
    Chemical Physics Letters 11/2012; 553:68–76. · 2.15 Impact Factor
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    ABSTRACT: It is demonstrated that reliable aluminum-carbon distances can be measured in samples with (13) C natural abundance by NMR spectroscopy. Overcoupled resonators, with only one radio-frequency synthesizer and one amplifier, are used to irradiate in the same pulse sequence (27) Al and (13) C nuclei, which differ by only 3.6 % in Larmor frequencies. The combination of (27) Al saturation pulse with heteronuclear dipolar recoupling yields dipolar dephasing of the (13) C signal, which only depends on the AlC distance and the efficiency of the saturation pulse. Therefore, reliable distances can be obtained by rapid fitting of experimental data to an analytical expression. It is demonstrated that with natural isotopic abundance this approach allows recovery of AlC distances of 216 pm for the covalent bond in lithium tetraalkyl aluminates, commonly used as a co-catalyst in olefin polymerization processes, and which range from 274 to 381 pm for the three carbon atoms in aluminum lactate. The accuracy of the measured internuclear distances is carefully estimated.
    ChemPhysChem 09/2012; · 3.35 Impact Factor
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    ABSTRACT: We analyze and compare the specifications of TIMES and TIMES(0) proton high-resolution NMR methods for solid-state samples. This comparison is performed in terms of resolution versus magic-angle spinning (MAS) spinning speed, ν(R), rf-field amplitude, ν(1), and tilt-angle for the effective rf-field, θ(p). The chemical-shift and homo-nuclear dipolar scaling factors are calculated for both methods. For all MAS speeds, the best resolution is always observed with rf-field of ν(1)≈120-130kHz. At slow MAS speed (ν(R)⩽10kHz), the best resolution is observed for a tilt-angle of θ(P)≈90°. At moderate spinning speed (15⩽ν(R)⩽35kHz), θ(P)≈55° gives the best resolution. At higher MAS speed (ν(R)⩾60kHz), with TIMES and TIMES(0) the best resolution is obtained for θ(P)⩽40°; but we then recommend TIMES(0), owing to its simpler set-up. We also show that in addition to the usual high rf-field regime (ν(1)≈120-130kHz), another low rf-regime (ν(1)≈40-50kHz) exists at MAS speed higher than ν(R)⩾60kHz, which also gives a good (1)H resolution. This low rf-regime should be useful for multi-dimensional analyses of bio-molecules with (1)H detection under high-resolution, in order to limit the heating of the sample.
    Journal of Magnetic Resonance 08/2012; 223:219-27. · 2.30 Impact Factor
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    ABSTRACT: I still see you: A new pulse sequence, SHA+, little sensitive to dipolar truncation, allows direct or relayed polarization transfer between (13) C atoms, distant by 3.5-9.6 Å, in amyloid fibrils. SHA+ can also be used in a broadband way with the weak rf-condition of ν(1) /ν(R) ≈0.2-0.3 which permits the investigation of temperature-sensitive biological systems.
    ChemPhysChem 08/2012; · 3.35 Impact Factor
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    ABSTRACT: We demonstrate that inter-residue (13)C-(13)C proximities (of about 380pm) in uniformly (13)C-labeled proteins can be probed by applying robust first-order recoupling during several milliseconds in single-quantum single-quantum dipolar homo-nuclear correlation (SQ-SQ D-HOMCOR) 2D experiments. We show that the intensity of medium-range homo-nuclear correlations in these experiments is enhanced using broadband first-order finite-pulse radio-frequency-driven recoupling (fp-RFDR) NMR sequence with a nested (XY8)4(1) super-cycling. The robustness and the efficiency of the fp-RFDR-(XY8)4(1) method is demonstrated at high magnetic field (21.1T) and high Magic-Angle Spinning (MAS) speeds (up to 60kHz). The introduced super-cycling, formed by combining phase inversion and a global four-quantum phase cycle, improves the robustness of fp-RFDR to (i) chemical shift anisotropy (CSA), (ii) spread in isotropic chemical shifts, (iii) rf-inhomogeneity and (iv) hetero-nuclear dipolar couplings for long recoupling times. We show that fp-RFDR-(XY8)4(1) is efficient sans(1)H decoupling, which is beneficial for temperature-sensitive biomolecules. The efficiency and the robustness of fp-RFDR-(XY8)4(1) is investigated by spin dynamics numerical simulations as well as solid-state NMR experiments on [U-(13)C]-l-histidine·HCl, a tetra-peptide (Fmoc-[U-(13)C,(15)N]-Val-[U-(13)C,(15)N]-Ala-[U-(13)C,(15)N]-Phe-Gly-t-Boc) and Al(PO(3))(3).
    Journal of Magnetic Resonance 07/2012; 223:107-19. · 2.30 Impact Factor

Publication Stats

426 Citations
262.70 Total Impact Points

Institutions

  • 2011–2014
    • East China Normal University
      • Department of Physics
      Shanghai, Shanghai Shi, China
    • Kyoto University
      • Division of Chemistry
      Kyoto, Kyoto-fu, Japan
    • JEOL
      Edo, Tōkyō, Japan
  • 2013
    • U.S. Department of Energy
      • Ames Lab
      Washington, Washington, D.C., United States
    • Université de Versailles Saint-Quentin
      • Institut Lavoisier de Versailles (ILV)
      Versailles, Ile-de-France, France
  • 2010–2013
    • Wuhan Institute of Physics and Mathematics
      Wu-han-shih, Hubei, China
    • Chinese Academy of Sciences
      Peping, Beijing, China
  • 2009–2013
    • University of Lille Nord de France
      Lille, Nord-Pas-de-Calais, France
    • National Graduate School of Engineering Chemistry of Lille (ENSCL)
      Lille, Nord-Pas-de-Calais, France
    • National High Magnetic Field Laboratory
      Tallahassee, Florida, United States
    • Lille Catholic University
      Lille, Nord-Pas-de-Calais, France
  • 2008
    • University of Aveiro
      • Department of Chemistry
      Aveiro, Aveiro, Portugal
  • 1996–2008
    • Université des Sciences et Technologies de Lille 1
      • • Laboratoire de Spectrochimie Infrarouge et Raman (LASIR)
      • • Unité de Catalyse et Chimie du Solide (UCCS)
      Lille, Nord-Pas-de-Calais, France
    • University of Illinois at Chicago
      Chicago, Illinois, United States
  • 2006
    • Iowa State University
      • Ames Laboratory
      Ames, IA, United States
  • 2003
    • CNRS Orleans Campus
      Orléans, Centre, France
    • CSIR - National Chemical Laboratory, Pune
      Poona, Mahārāshtra, India