Synthesis And Characterization Of Metal Diphosphates In The Hydrothermal System

Inorganic microporous materials benefiting from their own unique pore architectures and then providing special characteristics, have popular application in catalysis, adsorption, ion-exchange, separation and host-guest assemblies. And the rational design and synthesis of new microporous compounds, as well as the development of new synthetic ways are becoming the topics of microporous chemistry. In the last decade, the synthesis of new materials that might combine the nanoporosity of zeolites with the magnetic and optical properties, electronic conductivity and ferrodlectricity of transition metal phosphates such as TiPOs, VPOs, FePOs, ZnPOs and CoPOs have been reported in the literature. Many of these materials exhibit unique structures and may have potential applications in catalysis and magnetic field. In addition to phosphates, open framework metal arsenates, phosphite, selenite, germinates, sulfates and carbonate have also been reported in the literature. The successful syntheses of these new compounds with open-framework open a new field for the microporous compounds.In the traditional synthesis of microporous phosphonate crystals, PO₄^3- is replaced by bifunctional anionic units ,for example: diphosphonates ([O₃P-R-PO₃]^4-), aminophosphonates ([O₃P-R-NH₂]^2-), and phosphonocarboxylates ([O₃P-R-COO]^3-). So this realm attracting so much attention, consequentially so many new three-dimensional compounds of di-, tri-, and tetra-valent metals appear. In this work, we used the diphosphonate [O₃P-CH₂-PO₃]^4- as the organic ligand, three organic-inorganic hybrid compounds have successfully been designed and synthesized.Compound 1 Sr₂[O₃PCH₂PO₃] is 3-dimenment structure constituted by edge-sharing chains pillared by the organic ligand P-CH₂-P. All metal comers Sr are in 8 coordination environment with eight oxygen atoms. For changing the coordinative numbers of atom Sr to add a certain quantity of transition metal compound, a novel compound 2 Sr_1.5[O₃PCH₂PO₃][H₃O⁺] has obtained and consists of two-dimensional Sr-O inorganic layers intersected by organic ligand P-CH₂-P. to form a three-dimensional framework. All mental corners Sr has two different coordination numbers: eight and six. Compound 3 Ba₂[O₃PCH₂PO₃H]₂[H₃O⁺]₂, consists of two- dimensional Ba-O layers intersected by the phosphonate ligand P-CH2-P to construct three-dimensional framework. And all metal corners Ba possess of night coordination oxygen atoms. The framework of the compound 4 Ca[O₃PCH₂PO₃][H₃O]₂⁺ is that the the phosphonate ligand P-CH₂-P directly connects the metal center Ca and then a three-demensional structure has been built.