Ionothermal Synthesis, Characterization And Property Of Anion Open-Framework Metal Phosphates

The synthesis of novel inorganic open-framework compounds with new structures and interesting properties is always among the attracting research topics in chemistry and material science. Metal phosphates are one kind of inorganic open-frame work materials showing diverse structures and rich components, which usually show interesting optical-, electrical-and magnetic properties. Until now, these materials have been intensively studied by academicians and find wide applications in the fields of catalysis, separation, adsorption, ion exchange and host-guest chemistry. In this thesis, we report here the synthesis of cobalt phosphates and vanadium phosphates by the ionothermal synthesis approach, followed by the structural analysis and property studies. The main achievements are concluded below:1. We have synthesized two cobalt phosphate compounds with anionic framework sstructures under ionothermal conditions, compound 1 and 2. Cobalt phosphate 1, ?NH₄?₂[?Co₃O₄??HPO₄?2] possesses two dimensional layered structure and compound 2, ?NH₄?[Co₃O₂?HPO₄?₂?H₂PO₄?], possesses three dimensional structure. Both compounds were charge balanced by the ammonium cation in the structure. It is worth to note that the 3D structure of compound 2 can be built from compound 1, linking the layers in compound 1 by H₂PO₄ tetrahedral groups. It is interesting to find characteristic CO₃ units in both compounds, which should have potentially magnetic property. The magnetic behaviors of these two compounds were studied in detail, and also their proton conductivity was investigated.2. Two new anionic open-framework compounds of vanadium phosphates 3 and 4 were synthesized by ionothermal method. Compound 3, ?NH₄?₂[?VO₂??PO₄?], crystallize in the tetragonal I4/m space group showing three dimensional framework structure. There are ammonium cations exist to balance the negative charge of the framework. Compounds 4, Na₆[VO₂?VO?₂?PO₄?₂F₆]. crystallizes in the orthogonal Pnma space group with 2D vanadium phosphate framework. Instead of ammonium cation, sodium cation was located between the layers in the structure to charge balance the negative layered framework. The detailed ionothermal synthesis was investigated and the as-prepared compounds were fully characterized.