AL-27 P-31 SOLID-STATE NMR STRUCTURAL INVESTIGATIONS OF ALPO4-5 MOLECULAR-SIEVE/

Al-27/P-31 solid-state n.m.r. connectivity experiments were used to in vestigate the structure of the molecular sieve AlPO4-5 hydrated with D 2O. Hydration with D2O resulted in an increased efficiency of coherenc e transfer from octahedral Al-27 to P-31 compared with hydration with H2O. The experiments prove directly that both the tetrahedral aluminum and the octahedral aluminum formed upon hydration are connected to ph osphorus in the framework. The two-dimensional Al-27 --> P-31 transfer red-echo double-resonance and cross-polarization experiments show a do wnfield offset of the octahedral Al-27 correlation from the tetrahedra l Al-27 correlation, consistent with the growth of a downfield shoulde r on the P-31 resonance as water is incorporated into the lattice.