Determination of Al-27-Si-29 connectivities in zeolites with 2D Al-27 -> Si-29 RAPT-CPMG-HETCOR NMR

TitleDetermination of Al-27-Si-29 connectivities in zeolites with 2D Al-27 -> Si-29 RAPT-CPMG-HETCOR NMR
Publication TypeJournal Article
Year of Publication2008
AuthorsKennedy GJ, Wiench JW, Pruski M
Journal TitleSolid State Nuclear Magnetic Resonance
Date PublishedMay
Type of ArticleArticle
ISBN Number0926-2040
Accession NumberISI:000258048000003
Keywords3-DIMENSIONAL LATTICE CONNECTIVITIES, angle-spinning nmr, cross-polarization, crystal-structure, hetcor, MAGNETIC-RESONANCE, MAZ, nmr, NUCLEI, QUADRUPOLAR, RESOLUTION HETERONUCLEAR CORRELATION, SI-29 MAS-NMR, solid-state nmr, SPIN-1/2 NUCL, zeolite, ZSM-4

The recently introduced concept of the combined use of rotor assisted population transfer (RAPT) and Carr-Purcell-Meiboom-Gill (CPMG) techniques to boost the sensitivity of cross polarization (CP) based NMR experiments is applied to a synthetic zeolite (ZSM-4). The sensitivity was increased by a factor of similar to 4, which enabled acquisition of a high quality two-dimensional Al-27-Si-29 HETCOR (heteronuclear correlation) spectrum. By separating the resonances in two dimensions, through-space connectivities between spins were revealed and the effective resolution was improved in both dimensions, which allowed determination of the existing ambiguities in spectral assignments in this material. The spectra provided clear indication of random distribution of aluminum and silicon within the ZSM-4 network. Additionally, unexpected correlations were observed between different components of in homogeneously broadened Si-29 and Al-27 lines, which are most likely due to differences in the second coordination sphere environments. (c) 2008 Elsevier Inc. All rights reserved.

Alternate JournalSolid State Nucl. Magn. Reson.