Crystallographic site probing in the triclinic CHA-like AlPO4 by 27Al 2D quintuple-quantum NMR

Abstract : The triclinic CHA-like precursor of AlPO4-34 was prepared in the presence of HF by using pyridine as a template. The three resonance lines corresponding to one 6-coordinated (Al(1)) and two 4-coordinated Al atoms (Al(2) and Al(3)) expected from a previous structure analysis are clearly visible on the well resolved 27Al 2D-quintuple-quantum NMR spectrum. The actual isotropic chemical shifts of the three lines were easily determined from the 2D spectrum; the corresponding values are −3.7 ppm (Al(1)), 46.7 ppm (Al(2)) and 52.5 ppm (Al(3)) with respect to Al(H2O)63+. On the contrary, the two tetrahedral sites could not be differentiated by the MAS technique; only two lines were observed, one in the octahedral region (Al(1)) and one in the tetrahedral region (Al(2)) + Al(3)) with a 1:2 intensity ratio.
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https://hal-normandie-univ.archives-ouvertes.fr/hal-02280885
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Soumis le : vendredi 6 septembre 2019 - 16:42:53
Dernière modification le : lundi 23 septembre 2019 - 09:49:52

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Christian Fernandez, J.P. Amoureux, L. Delmotte, H. Kessler. Crystallographic site probing in the triclinic CHA-like AlPO4 by 27Al 2D quintuple-quantum NMR. Microporous Materials, Elsevier, 1996, 6 (3), pp.125-130. ⟨10.1016/0927-6513(95)00087-9⟩. ⟨hal-02280885⟩

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