Structure-directing effect on synthesis of layered aluminophosphates with same topology

Abstract

Three layered aluminophosphates(UiO-15, APDAP12-150 and APDAP-150) with same topology were crystallized from an initial mixture with a molar composition of Al2O3:1.5P2O5:5.5R:227H2O, where R is ethylene-diamine, 1,2-diaminopropane or 1,3-diaminopropane, respectively. The crystallization processes of UiO-15, APDAP12-150 and APDAP-150 were investigated using solid-state NMR in combination with XRD and other characterization techniques. The evolution of the coordination states of Al and P in the solid products was monitored, and the possible starting points of crystallization(core units) of UiO-15, APDAP12-150 and APDAP-150 were obtained and analyzed. The formation of a trimer as well as a hexamer of aluminophosphate, a monomer of PO4 and a nonamer containing two three-membered rings is critical for the start of crystallization of UiO-15. The formation of a hexamer and a pentamer is critical for the start of crystallization of APDAP12-150. The formation of an AlO6 monomer and a pentamer containing a three-membered ring is critical for the start of crystallization of APDAP-150. The crystal water played a co-structure-directing role in the formation of APDAP-150.