Structural investigation by 31P and 27Al solid-state NMR of the new layered aluminophosphate Mu-4

Abstract

A new layered aluminophosphate named Mu-4 was recently obtained from a quasi non-aqueous mixture involving mainly diethylformamide (DEF) as solvent in addition to limited amounts of water. During the synthesis, DEF is decomposed and the resulting protonated diethylamine is occluded in the as-synthesized material, neutralizing the negative charge of the inorganic layers. The structure consists of anionic double sheets essentially built from double four-ring (D4R) units. The framework topology of the as-synthesized aluminophosphate was investigated by various solid-state nuclear magnetic resonance (NMR) techniques. In particular, 27Al– 31P two-dimensional heteronuclear correlation experiments were useful to evidence the PAl connectivities present in this new layered aluminophosphate.