Structural analysis of ZON-type aluminophosphates by solid state NMR

Solid-state NMR spectroscopy has been used to study the new aluminophosphate material AlPO4-ZON. Highly resolved multiple quantum magic-angle spinning NMR spectra showed all four Al sites in the framework of AlPO4-ZON. Additional Al-27 resonances were detected in some samples. They were assigned to an impurity phase of AlPO4-AFR and to six-coordinated aluminum in the extra-lattice positions. High-speed MAS NMR of H-1 yielded the OH concentration in the samples synthesized from the fluoride-modified gels of different pH, The location of fluorine in the AlPO4-ZON framework has been verified by measuring the internuclear distances between F-19 and all Al-27 sites using the MQ-REDOR technique. MQ-REDOR has been also used to measure the distances between H-1 and Al-27 nuclei in this material.