27Al Multiple-Quantum Magic Angle Spinning NMR Study of the Thermal Transformation between the Microporous Aluminium Methylphosphonates AlMePO-beta and AlMePO-alpha

Steven P Brown, Sharon Elizabeth Ashbrook, Stephen Wimperis

Research output: Contribution to journalArticlepeer-review

Abstract

The Al-27 multiple-quantum ma,alc angle spinning (MQMAS) NMR technique is used to investigate the thermal transformation between AlMePO-beta and AlMePO-alpha. The required spectral resolution is achieved using a novel split-t(1) version of the basic five-quantum MAS experiment. The five-quantum split-t(1) Al-27 MAS NMR spectrum of a sample where the thermal transformation has been interrupted before complete conversion is compared with that of a simple physical mixture of the alpha- and beta-polymorphs. The two spectra are shown to be different, a result that does not appear to support the proposition by Carter et al. (J. Mater. Chem. 1997, 7, 2287) of a topotactic reconstructive transformation. On the basis of our Al-27 MQMAS results, we outline a possible alternative (and rather more commonplace) mechanism for the thermal transformation.

Original languageEnglish
Pages (from-to)812-817
Number of pages6
JournalJournal of Physical Chemistry B
Volume103
DOIs
Publication statusPublished - 4 Feb 1999

Keywords

  • MAS-NMR
  • QUADRUPOLAR NUCLEI
  • UNIDIMENSIONAL CHANNELS
  • CROSS-POLARIZATION
  • SPECTROSCOPY
  • RESOLUTION
  • MQMAS
  • REMOVAL
  • SPECTRA

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