Coherence transfer involving quadrupolar nuclei in solids: aluminum-27 .tautm. phosphorus-31 cross-polarization NMR in the molecular sieve VPI-5

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

“…The 31p NMR signal at -33 ppm is attributed via cross peak C to the phosphorus atoms at Pl(2· All, A12, A13) which show a preferred coupling with the octahedrally coordinated aluminum atoms at All. The same signal assignment was deduced by Fyfe et al [291,292] from 2D TEDOR (transferred-echo double resonance) experiments. Extensive studies of the thermal stability ofVPI -5 and its structural transformation to AIP0 4 -8 have been carried out [282,286,287,293,294].…”

High-Resolution Heteronuclear Correlation Spectra between 31P and 27Al in Microporous Aluminophosphates

“…4a) recorded using standard CPMAS (Fig. 1) is similar to the spectrum previously observed by van Eck and Veeman [23] and Fyfe et al [9] using 27 Al→ 31 P TEDOR. The 3QHETCOR spectrum (Fig.…”

“…Such CPMASbased HETCOR experiments between quadrupolar (I) and spin-1/2 (S) nuclei have been extensively used by Fyfe and coworkers [9,10]. However, these spectra are poorly resolved in the quadrupolar dimension because the second-order quadrupolar interaction is not fully averaged out by MAS.…”

Structural information from quadrupolar nuclei in solid state NMR

“…It has been demonstrated that these two-dimensional heteronuclear experiments, generally termed HETCOR experiments, are also feasible when either I or S is a half-integer quadrupolar nucleus, using either cross-polarization (126) or TEDOR (127) transfer. In both cases, the spectra are able to provide information unavailable by one-dimensional methods owing to the increase in resolution obtained from the presence of a second spectral dimension.…”