INEPT experiments involving quadrupolar nuclei in solids.

Coherence transfer from quadrupolar 27Al (I = 52) nuclei to 31P (I = 12) via INEPT experiments is investigated. 27Al --> 31P INEPT experiments on a (CH3)3P-AlCl3 complex in zeolite NaX are performed, and the results demonstrate that the 31P INEPT signals strongly depend on whether or not the 27Al pulses are applied synchronously with the rotor period, and on the length of the 27Al pulses. A density-matrix calculation involving the use of the spin operators for spin 32 and 12 nuclei has been performed to help understand the evolution behavior of the density matrix under the influence of the quadrupolar interaction, the dipolar and J-couplings, and the pulse lengths applied to the quadrupolar nuclei. The theoretical predictions obtained from these calculations are consistent with the INEPT experimental observations. Copyright 1998 Academic Press.