Hydrothermal Synthesis and Structural Characterization of Open-Framework Metal Phosphates Templated With Organic Diamines

Abstract

In recent years, hydrothermal synthesis and structural characterization of open-framework metal phosphates templated with organic diamines have attracted the attention of scientists because they represent the interaction between organic and inorganic chemistry and can be applied in lots of branches of chemistry with their different characteristic properties. In this study, a novel open-framework polyoxometal phosphate compound (4,4’-bpyH2)2(4,4’-bpyH)[PCoW11O39].H2O was synthesized with hydrothermal method as red crystals. The compound crystallizes in the space group P2(1)/n of the monoclinic system with four formula units in a cell. The crystal is a Keggin polyoxometalate structure and contains free 4,4’-bipyridine groups and water molecule between the clusters. In addition to this novel compound, three known compounds were synthesized. Co(4,4’-bpy)2(VO2)2(HPO4)2 red crystals were synthesized hydrothermally and the compound crystallizes in the space group C2/c of the monoclinic system with four formula units in a cell. The crystal consists of [(VO2)(HPO4)]∠helical chains and [Co(4,4’-bpy)2]2+ frameworks. Also, NaCo3(PO4)(HPO4)2 pink crystals were obtained with using hydrothermal synthesis. The compound crystallizes in the space group C2/c of the monoclinic system with four formula units in a cell. In the structure, CoO6 chains connect to the PO4 and HPO4 groups. Lastly, (enH2)3[CoW4P4O28] blue crystals were synthesized with hydrothermal method and crystallizes in the space group I4(1)/a of the tetragonal system with four formula units in a cell. The crystal consists of a [Co3W4P4O28]6- anion and three free ethylenediaminium (N2H10C2)2+ cations.