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Ehresmann JO, Wang W, Herreros B, et al. Theoretical and experimental investigation of the effect of proton transfer on the (27)al MAS NMR line shapes of zeolite-adsorbate complexes: an independent measure of solid Acid strength. J Am Chem Soc. 2002;124(36):10868-74doi: 10.1021/ja012336u.
Ehresmann, J. O., Wang, W., Herreros, B., Luigi, D. P., Venkatraman, T. N., Song, W., Nicholas, J. B., & Haw, J. F. (2002). Theoretical and experimental investigation of the effect of proton transfer on the (27)al MAS NMR line shapes of zeolite-adsorbate complexes: an independent measure of solid Acid strength. Journal of the American Chemical Society, 124(36), 10868-74. https://doi.org/10.1021/ja012336u
Ehresmann, Justin O, et al. "Theoretical and experimental investigation of the effect of proton transfer on the (27)al MAS NMR line shapes of zeolite-adsorbate complexes: an independent measure of solid Acid strength." Journal of the American Chemical Society vol. 124,36 (2002): 10868-74. doi: https://doi.org/10.1021/ja012336u
Ehresmann JO, Wang W, Herreros B, Luigi DP, Venkatraman TN, Song W, Nicholas JB, Haw JF. Theoretical and experimental investigation of the effect of proton transfer on the (27)al MAS NMR line shapes of zeolite-adsorbate complexes: an independent measure of solid Acid strength. J Am Chem Soc. 2002 Sep 11;124(36):10868-74. doi: 10.1021/ja012336u. PMID: 12207542.
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J Am Chem Soc. 2002 Sep 11;124(36):10868-74. doi: 10.1021/ja012336u.

Theoretical and experimental investigation of the effect of proton transfer on the (27)al MAS NMR line shapes of zeolite-adsorbate complexes: an independent measure of solid Acid strength.

Journal of the American Chemical Society

Justin O Ehresmann, Wei Wang, Bruno Herreros, Donat-Pierre Luigi, T N Venkatraman, Weiguo Song, John B Nicholas, James F Haw

Affiliations

  1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA 90089-1661, USA.

PMID: 12207542 DOI: 10.1021/ja012336u

Abstract

Assessing the degree of proton transfer from a Brønsted acid site to one or more adsorbed bases is central to arguments regarding the strength of zeolites and other solid acids. In this regard certain solid-state NMR measurements have been fruitful; for example, some (13)C, (15)N, or (31)P resonances of adsorbed bases are sensitive to protonation, and the (1)H chemical shift of the Brønsted site itself reflects hydrogen bonding. We modeled theoretically the structures of adsorption complexes of several bases on zeolite HZSM-5, calculated the quadrupole coupling constants (Q(cc)) and asymmetry parameters (eta) for aluminum in these complexes and then in turn simulated the central transitions of their (27)Al MAS NMR spectra. The theoretical line width decreased monotonically with the degree of proton transfer, reflecting structural relaxation around aluminum as the proton was transferred to a base. We verified this experimentally for a series of adsorbed bases by way of single-pulse MAS and triple quantum MQMAS (27)Al NMR. The combined theoretical and experimental approach described here provides a strategy by which (27)Al data can be applied to resolve disputed interpretations of proton transfer based on other evidence.

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