High-resolution heteronuclear correlation spectra between 31P and 27Al in microporous aluminophosphates

A solid-state nuclear magnetic resonance (NMR) experiment, which provides high-resolution two-dimensional heteronuclear correlation (HETCOR) spectra between Al-27 and P-31, is described. The first part of the experiment uses triple-quantum or quintuple-quantum magic-angle spinning (MQMAS) NMR of spin-5/2 nuclei (Al-27) to produce an isotropic echo that is unaffected by the second-order quadrupolar broadening. The magnetization is then transferred to the spin-1/2 (P-31) nuclei via cross-polarization (CP), resulting in isotropic resolution in both spectral dimensions. To illustrate its usefulness, this method (referred to as MQHETCOR) is applied to two important microporous framework aluminophosphates, hydrated VPI-5 and AIPO(4)-40. (C) 2002 Elsevier Science (USA).