Exploration of a Simple Universal Route to the Myriad of Open-Framework Metal Phosphates

The reaction of a single amine phosphate, piperazine phosphate, with ZnII ions is shown to yield a variety of open-framework metal phosphate structures. It is noteworthy that the reaction of this amine phosphate with ZnII ions yields a hierarchy of structures, including the linear chain, layer and 3-dimensional systems. Of particular interest is the isolation of the linear chain structure consisting of corner-shared four-membered rings, which has been considered to be the primary building block. By the reaction of piperazine phosphate with CoII ions, we obtained a new strip and a layer structure. Reaction of piperazine phosphate with SnII yields a layer structure. The significant role of the amine phosphates in the formation of open-framework metal phosphate structures is also supported by the isolation of a monomeric four-membered zinc phosphate, which on heating transforms to an open-framework structure.