Charlotte Martineau

Publications (3)13.34 Total impact

• Article: An NMR-Driven Crystallography Strategy to Overcome the Computability Limit of Powder Structure Determination: A Layered Aluminophosphate Case.

  Boris Bouchevreau, Charlotte Martineau, Caroline Mellot-Draznieks, Alain Tuel, Matthew R Suchomel, Julien Trébosc, Olivier Lafon, Jean-Paul Amoureux, Francis Taulelle
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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
• Article: High-resolution through-space correlations between spin-1/2 and half-integer quadrupolar nuclei using the MQ-D-R-INEPT NMR experiment.

  Charlotte Martineau, Boris Bouchevreau, Francis Taulelle, Julien Trébosc, Olivier Lafon, Jean Paul Amoureux
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  ABSTRACT: The multiple-quantum dipolar refocused-INEPT (MQ-D-R-INEPT) NMR experiment is presented. This new pulse sequence allows the generation of two-dimensional through-space NMR correlation spectra between spin-½ and quadrupolar nuclei under high-resolution. Compared to the existing sequences, the MQ-D-R-INEPT sequence benefits from increased robustness, due to the reduced sensitivity to offsets and radio-frequency field inhomogeneity of the R-INEPT recoupling scheme as compared to the classical cross-polarization transfer involving a quadrupolar nucleus, and applicability to quadrupolar nuclei with any half-integer spin value. Here, the heteronuclear dipolar couplings have been reintroduced using the rotary resonance recoupling (R(3)) sequence, chosen because it is γ-encoded, and thus robust to spinning speed instabilities and to radio-frequency inhomogeneities in the case of nuclei subjected to large chemical shift anisotropy (e.g., (31)P). In the course of the article, a new definition of γ-encoding is introduced, more general and practical than the previous ones, as it does not depend on the implementation of the recoupling sequence, and is independent of the considered frame. The efficiency of the MQ-D-R-INEPT experiment is demonstrated for the observation of (31)P-(27)Al proximities. It is first tested on AlPO(4)-VPI-5, and then applied to a complex aluminophosphate AlPO(4)-(Al(5)P(7))-DAE of incompletely established structure. For this latter sample, the high-resolution provided by the MQMAS filter allows the resolution of a large number of (31)P-(27)Al correlations, which represent an essential step towards the determination of its structural model.
  Physical Chemistry Chemical Physics 04/2012; · 3.57 Impact Factor
• Article: SMARTER crystallography of the fluorinated inorganic-organic compound Zn3Al2F12·[HAmTAZ]6.

  Charlotte Martineau, Amandine Cadiau, Boris Bouchevreau, Jürgen Senker, Francis Taulelle, Karim Adil
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  ABSTRACT: We present in this paper the structure resolution of a fluorinated inorganic-organic compound--Zn(3)Al(2)F(12)·[HAmTAZ](6)--by SMARTER crystallography, i.e. by combining powder X-ray diffraction crystallography, NMR crystallography and chemical modelling of crystal (structure optimization and NMR parameter calculations). Such an approach is of particular interest for this class of fluorinated inorganic-organic compound materials since all the atoms have NMR accessible isotopes ((1)H, (13)C, (15)N, (19)F, (27)Al, (67)Zn). In Zn(3)Al(2)F(12)·[HAmTAZ](6), (27)Al and high-field (19)F and (67)Zn NMR give access to the inorganic framework while (1)H, (13)C and (15)N NMR yield insights into the organic linkers. From these NMR experiments, parts of the integrant unit are determined and used as input data for the search of a structural model from the powder diffraction data. The optimization of the atomic positions and the calculations of NMR parameters ((27)Al and (67)Zn quadrupolar parameters and (19)F, (1)H, (13)C and (15)N isotropic chemical shifts) are then performed using a density functional theory (DFT) based code. The good agreement between experimental and DFT-calculated NMR parameters validates the proposed optimized structure. The example of Zn(3)Al(2)F(12)·[HAmTAZ](6) shows that structural models can be obtained in fluorinated hybrids by SMARTER crystallography on a polycrystalline powder with an accuracy similar to those obtained from single-crystal X-ray diffraction data.
  Dalton Transactions 04/2012; 41(20):6232-41. · 3.84 Impact Factor