High-resolution solid-state magic-angle spinning nuclear magnetic resonance studies on the layered antimony hydrogen phosphate, HSb(PO 4) 2·2H 2O and some organic amine intercalation compounds

Abstract

n-propylamine and tri- n-octylamine were intercalated into the layered host antimony hydrogen phosphate, HSb(PO 4) 2·2H 2O (henceforth written as H 1SbP 2). Powder X-ray diffraction (PXRD) indicated that the reaction products were all polyphasic microcrystalline materials and suggested that the arrangement of amine molecules in (i) the n-propylamine intercalation product were similar to that observed for amine intercalated α-Zr(HPO 4) 2 and α-tin (IV) hydrogen phosphates, and that (ii) the tri- n-octylamine molecules formed a bilayered structure within the H 1SbP 2 interlayer in which the terminal methyl groups repulse one another. Fourier transformed infrared (FTIR) studies also suggested the presence of intercalated amine molecules within the H 1SbP 2 layered structure. High-resolution 15 N solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) indicated that for both reaction products a single amine species was intercalated into the H 1SbP 2 interlamellar region as expected. 31 P solid-state MAS NMR studies confirmed that the intercalating amine species were all protonated and that in the case of the n-propylamine reaction products, there were a variety of orientated intercalating species. 31 P MAS NMR also suggested that there was perturbation of the adjacent phosphate groups by the large tri- n-octylamine alkyl chains. This type of perturbation has previously been observed for iron complexes intercalated into the H 1SbP 2 host.