Synthesis And Characterization Of New Gallium Phosphites

Application of inorganic microporous materials has not only been limited to catalysis, adsorption, ion exchange fields, but gradually turns to the energy storage and conversion, nonlinear optics, information storage and processing, chemical choose sensing, quantum electronics, environmental protection and life science areas. Therefore, the study of the synthesis of microporous materials has aroused great interest. The introduction of rigid organic linkers, such as oxalate, as part of the inorganic framework has opened up tremendous possibilities for research in this area giving rise to new inorganic-organic hybrid compounds. In recent years, people succeeded in replacing the tetrahedron phosphate [PO4]3-with pseudo-pyramidal phosphite [HPO3]2-. The pyramidal phosphite group [HPO3]2-merely connects with three adjacent cations via P-O-M (M=metal) bonds, which is different from phosphate [PO4]3-group, producing series of new interesting structures.This paper focus on the synthesis and characterization of gallium phosphite-oxalate and gallium phosphite under hydrothermal and solvothermal conditions so as to enrich the inorganic microporous materials which can be used as catalysts, adsorbents, ion exchangers and other fields.With an aim towards searching for novel organically templated metal phosphites, we conducted our study on the synthesis with respect to gallium phosphite-oxalates under different solvent systems. Finally, using N, N-dimethyl-piperazine as structure directing agent, two novel open-framework gallium phosphite-oxalate compounds [Ga2(HPO3)2(H2PO3)2(C2O4)](C6N2H16)(1) and [Ga2(HP03)2(H2P03)(C204)](C6N2H16)o.5(2) are obtained by adjusting the variety of the solvents. Then using imidazole as structure directing agent and water-ethanol as solvent, one3D compound Ga8(H2O)6(HPO3)14·(C3N2H6)3·H3O(3) is synthesized. Compound1is solvothermally synthesized from a mixed water-ethanol solvent system while compound2is hydrothermally synthesized from a single solvent system of water. It is noted that the same SBU occurs in both compounds. However, due to the different connecting fashions of SBUs,[C2O4]2-groups and [H2PO3]-pseudo-pyramids, the final frameworks of1and2are obviously different. Compound1shows2D layered framework with8-MR windows in the ab plane while compound2possesses3D open-framework structure. Compound3is built up by alternation of octahedral GaO6and pseudo-pyramidal [HPO3]2-units to form infinite2D layers, and these layers are interconnected by sharing vertex-oxygen with octahedral GaO6units to generate a3D open-framework structure with12-membered ring channels along c axis. Herein we describe the synthesis, crystal structure and characterization of compound1, compound2and3, along with the influence of solvents and other elements on the formation of microporous compounds.