(31)P NMR investigation of some microporous zincophosphates

Abstract

High field magic-angle spinning (MAS) (31)P-NMR investigations of novel porous zincophosphates and their cobalt-containing derivatives confirm the framework structure of alternating Zn(Co)O4 and PO4 tetrahedra. The MAS NMR spectrum of cobalt-containing products exhibits a large anisotropy manifested in numerous side bands. This effect is attributed to paramagnetic shifts induced by dipolar interactions between the unpaired electrons of Co(2+) and the (31)P nuclei. The relative intensity of the side bands is significantly lower in the cobalt-exchanged sample (where the Co(2+) does not occupa framework sites) than direct evidence of extra-framework cobalt(II) or of Co(II) incorporation in the zincophosphate lattice.