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

A new layered aluminophosphate named Mu-4 was recently obtained from a quas i non-aqueous mixture involving mainly diethylformamide (DEF) as solvent in addition to limited amounts of water. During the synthesis, DEF is decompo sed and the resulting protonated diethylamine is occluded in the as-synthes ized material, neutralizing the negative charge of the inorganic layers. Th e structure consists of anionic double sheets essentially built from double four-ring (D4R) units. The framework topology of the as-synthesized alumin ophosphate was investigated by various solid-state nuclear magnetic resonan ce (NMR) techniques. In particular, Al-27-P-31 two-dimensional heteronuclea r correlation experiments were useful to evidence the P-Al connectivities p resent in this new layered aluminophosphate. (C) 2000 Elsevier Science B.V. All rights reserved.